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diff --git a/doc/rfc/rfc4678.txt b/doc/rfc/rfc4678.txt new file mode 100644 index 0000000..186069a --- /dev/null +++ b/doc/rfc/rfc4678.txt @@ -0,0 +1,2691 @@ + + + + + + +Network Working Group A. Bivens +Request for Comments: 4678 IBM Research +Category: Informational September 2006 + + + Server/Application State Protocol v1 + +Status of This Memo + + This memo provides information for the Internet community. It does + not specify an Internet standard of any kind. Distribution of this + memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2006). + +IESG Note + + This RFC is not a candidate for any level of Internet Standard. The + IETF disclaims any knowledge of the fitness of this RFC for any + purpose and in particular notes that the decision to publish is not + based on IETF review for such things as security, congestion control, + or inappropriate interaction with deployed protocols. The RFC Editor + has chosen to publish this document at its discretion. Readers of + this document should exercise caution in evaluating its value for + implementation and deployment. See RFC 3932 for more information. + +Abstract + + Entities responsible for distributing work across a group of systems + traditionally do not know a great deal about the ability of the + applications on those systems to complete the work in a satisfactory + fashion. Workload management systems traditionally know a great deal + about the health of applications, but have little control over the + rate in which these applications receive work. The + Server/Application State Protocol (SASP) provides a mechanism for + load balancers and workload management systems to communicate better + ways of distributing the existing workload to the group members. + + + + + + + + + + + + +Bivens Informational [Page 1] + +RFC 4678 SASPv1 September 2006 + + +Table of Contents + + 1. Introduction ....................................................3 + 1.1. Overview ...................................................3 + 1.2. Identities .................................................4 + 2. Requirements Notation ...........................................4 + 3. Conventions Used in This Document ...............................4 + 4. General Message Structure .......................................4 + 4.1. TLV Structure ..............................................6 + 4.2. Component Types ............................................6 + 4.3. SASP Protocol Header .......................................7 + 4.4. Version Negotiation ........................................8 + 5. Singular Protocol Components ....................................9 + 5.1. Member Data Component ......................................9 + 5.2. Group Data Component ......................................11 + 5.3. Weight Entry Data Component ...............................12 + 5.4. Member State Instance Component ...........................14 + 6. Group Protocol Components ......................................15 + 6.1. Group of Member Data Component ............................15 + 6.2. Group of Weight Data Component ............................16 + 6.3. Group of Member State Data Components .....................17 + 7. Protocol Messages ..............................................17 + 7.1. Registration Request and Reply ............................18 + 7.1.1. Registration Request ...............................18 + 7.1.2. Registration Reply .................................19 + 7.2. DeRegistration Request and Reply ..........................20 + 7.2.1. DeRegistration Request .............................21 + 7.2.2. DeRegistration Reply ...............................22 + 7.3. Get Weights Request and Reply .............................23 + 7.3.1. Get Weights Request ................................24 + 7.3.2. Get Weights Reply ..................................25 + 7.4. Send Weights ..............................................26 + 7.5. Set Member State Request and Reply ........................27 + 7.5.1. Set Member State Request ...........................28 + 7.5.2. Set Member State Reply .............................29 + 7.6. Set Load Balancer State Request and Reply .................30 + 7.6.1. Set LB State Request ...............................30 + 7.6.2. Set LB State Reply .................................32 + 8. Example of SASP Message Encoding ...............................32 + 9. Protocol Flow ..................................................37 + 9.1. Normal Protocol Flow ......................................37 + 9.2. Behavior in Error Cases ...................................39 + 9.3. Example Flow 1: Load Balancer Registration, + Getting Weights, and Application-Side Quiescing ...........41 + 9.4. Example Flow 2: Set Load Balancer State, Application + Registration, and Load Balancer Group DeRegistration ......43 + 9.5. Avoiding Single Points of Failure .........................44 + + + + +Bivens Informational [Page 2] + +RFC 4678 SASPv1 September 2006 + + + 10. Security Considerations .......................................45 + 11. Normative References ..........................................46 + Appendix A. Acknowledgements ......................................47 + +1. Introduction + +1.1. Overview + + The Server/Application State Protocol is designed to enable load + balancers or schedulers (1) to receive traffic weight recommendations + from Workload Managers, (2) to register with Workload Managers + members of load balancing/scheduling groups, and (3) to enable + Workload Managers to suggest new load balancing group members to load + balancers and schedulers + + The figure below shows where the SASP entities are in typical load + balancing topology. + + ---------- + | Group | + -------->|Member 1|<--| + | ---------- | + | | + --------- ---------- | ---------- | + |Request|<------>| Load |---| | Group | | + |Origins|<------>|Balancer|----------->|Member 2|<--| + --------- | |---| ---------- | + ---------- | | + ^ | ---------- | + | -------->| Group | | + SASP | |Member 3|<--| + ------- ---------- | + | | + | -------------------- | + | | Group | SASP | + ------>| Workload Manager |<---------- + -------------------- + + Figure 1 + + SASP is a binary protocol that facilitates communication from load + balancers/schedulers to Workload Managers. The connection between + the Group Workload Manager (GWM) and the load balancer/scheduler is + expected to be a long-running TCP connection. In SASP interactions, + the GWM acts as a SASP server waiting to receive connections from the + other SASP components. Server port 3860 has been registered with the + IANA for SASP communications. It is expected that all SASP + components are configured with the DNS name of the GWM to develop + + + +Bivens Informational [Page 3] + +RFC 4678 SASPv1 September 2006 + + + this connection. Security in SASP is handled by transporting binary + messages over Secure Socket Layer/Transport Layer Security (SSL/TLS). + This document only describes the message format and protocol behavior + above the connection and security layers. Connection and security + aspects including SSL's authentication and encryption will be + implementation specific. + +1.2. Identities + + SASP identifies a load balancer by a UTF-8 string called a "LB UID". + A group of "equivalent" servers providing a service is identified by + a UTF-8 string called a "Group Name", which is interpreted in the + context of the LB UID. A server is identified by its IP address and + (optional) port and protocol numbers. A GWM is only identified + implicitly as the entity on the other end of the TCP connection from + a load balancer or group member. All of these identifiers are local; + there are no globally unique identifiers. The LB UID and GroupName + fields are unstructured so that components could assign values to + these fields that are meaningful to an administrator. For example, + in many cases, a load balancer would use the name an administrator + provided for the serverfarm group as the groupname in a SASP- + specified group. Since the naming options in industry load balancers + do not carry explicit naming restrictions, SASP naming options also + carry no naming restrictions. + +2. Requirements Notation + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this + document are to be interpreted as described in [RFC2119]. + +3. Conventions Used in This Document + + o Load Balancer - Entity responsible for distributing requests + amongst the available members. + + o Member - Machine, process, or application used to service + requests. + + o Group Workload Manager (GWM) - Entity responsible for reporting or + managing a group of members on multiple machines. + +4. General Message Structure + + Any string interpreted by the group workload manager is assumed to + use UTF8. Components implementing SASP MUST support the printable + ASCII subrepertoire of UTF8 (0x20-0x7E). Components MAY also choose + to provide support for additional UTF8 character encodings. It is + + + +Bivens Informational [Page 4] + +RFC 4678 SASPv1 September 2006 + + + recommended that customers using SASP-enabled products configure the + string-generating components (load balancers and group members) to + use the same character repertoire. + + Many of the SASP structures involve the transfer of multi-byte + integer values. In all cases where multi-byte integer values are + used, they are considered to be in network-byte order (big-endian). + + SASP is organized into several message components. For extendibility + and ease of processing, each message component is described in a TLV + (Type, Length, Value) format. An illustration of the SASP structure + can be found in the example below. The first section is the header + followed by the message component type. As mentioned, the header, + message component, and all other components have a TLV format. Each + component value contains a variable number of fields, some of which + refer to upcoming components (explained component descriptions are in + upcoming sections). After the first message component, any number of + additional components may be included (as stipulated in the fields of + the message type). + + ------------------------------------------------- + | |T| Type (SASP Header Type) | + | SASP |----------------------------------| + | Header |L| Length of SASP header TLV | + | |----------------------------------| + | |V| Header fields | + |-----------------------------------------------| + | |T| Type (Message Type) | + | Message |----------------------------------| + | Type |L| Length of this Message Type TLV| + | Component |----------------------------------| + | |V| Component fields | + |-----------------------------------------------| + | |T| Type (Component Type) | + | |----------------------------------| + |Component-1 |L| Length of this TLV | + | |----------------------------------| + | |V| Component fields | + |-----------------------------------------------| + | ... | + |-----------------------------------------------| + | |T| Type (Component Type) | + | |----------------------------------| + |Component-n |L| Length of this TLV | + | |----------------------------------| + | |V| Component fields | + ------------------------------------------------- + + + + +Bivens Informational [Page 5] + +RFC 4678 SASPv1 September 2006 + + + Figure 2 + +4.1. TLV Structure + + An illustration of the TLV format is shown below. The Type is a + two-byte field containing a binary value for the component type. The + Length is a two-byte field containing the size of the TLV in bytes + (including the Type and Length fields). The Value field is a + variable-length field that actually contains the data of the + component. + + < xxxx xxxx xxxx xxxx, xxxx xxxx xxxx xxxx, xxxx...........xxxx > + |-----------------| |-----------------| |-----------------| + Type(2 bytes) Length(2 bytes) Value(variable) + + Figure 3 + +4.2. Component Types + + The TLV structure requires a type value for each protocol component. + All SASP types are listed in this section. + + Reserved 0x0000-0x1000 + + Message Types + + Registration Request 0x1010 + + Registration Reply 0x1015 + + DeRegistration Request 0x1020 + + DeRegistration Reply 0x1025 + + Get Weights Request 0x1030 + + Get Weights Reply 0x1035 + + Send Weights 0x1040 + + Set Load Balancer State Request 0x1050 + + Set Load Balancer State Reply 0x1055 + + Set Member State Request 0x1060 + + Set Member State Reply 0x1065 + + + + +Bivens Informational [Page 6] + +RFC 4678 SASPv1 September 2006 + + + Utility Component Types + + SASP Header 0x2010 + + Singular Component Types + + Member Data 0x3010 + + Group Data 0x3011 + + Weight Entry Data 0x3012 + + Member State Instance 0x3013 + + Group Component Types + + Group of Member Data 0x4010 + + Group of Weight Entry Data 0x4011 + + Group of Member State Data 0x4012 + + Reserved 0xF000-0xFFFF + +4.3. SASP Protocol Header + + An illustration of the SASP Header is found in the table below. It + is expected that every message will start with the SASP Protocol + Header component. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | SASP header type (0x2010) | Size of this TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Version | Message Length + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Message ID + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | + +-+-+-+-+-+-+-+-+ + + Figure 4 + + o Version: The version of the protocol used in this message. + + + + + + +Bivens Informational [Page 7] + +RFC 4678 SASPv1 September 2006 + + + o Message Length: A 4-byte signed integer value representing the + total length of the SASP message. It is said to be a signed + 4-byte value to make any Java implementations easier (or any other + implementations without unsigned values); however, no negative + lengths are valid. + + o Message ID: Each request message is given a 4-byte Message ID by + the message originator, which is simply returned in the Message ID + field of the reply. This field is meant to assist the requester + in correlating replies to the appropriate request when many + requests have been sent. In the Send Weights message (the only + message transaction that has no reply), this field serves no + purpose. + +4.4. Version Negotiation + + To negotiate the version of the protocol used by the entities + involved in the connection, the GWM views the version included in the + load balancer request as the load balancer's proposed version. + + If the GWM supports the version proposed by the load balancer, it + will respond to the connection with the appropriate response code and + the load balancer's proposed version in the response header. This + proposed version should be the version used for all messages in this + connection. + + If the GWM does not support the version proposed by the load + balancer, the GWM will respond with a "message not understood" + response code and the GWM's highest supported SASP version in the + version field of the response header. This is an indication for the + load balancer to come down to GWM's SASP version level. + + + + + + + + + + + + + + + + + + + + +Bivens Informational [Page 8] + +RFC 4678 SASPv1 September 2006 + + +5. Singular Protocol Components + + The most basic of SASP components are singular components because + they describe a single instance of a member, member resource, member + weight, or group. Some of the SASP components reuse other SASP + components. When this is the case, any component being reused by a + base component will simply be given immediately following the base + component. Some examples of this technique are seen and explained in + the Weight Entry and Member State Instance components. + +5.1. Member Data Component + + The member data component describes a particular member and is + referred to by other components. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Member Data Type (0x3010) | Size of this TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Protocol | Port | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | | + + + + | | + + IP Address of Member + + | | + + +-+-+-+-+-+-+-+-+ + | | Label Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | + . . + . Label . + . . + | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 5 + + o Protocol: The assigned number of the IP transport layer used in + the Protocol Field of the IP header. These are defined in + [RFC1700]; however, a current list is maintained at + http://www.iana.org. + for example: TCP = 0x06, UDP = 0x11, etc. + + + + + + + +Bivens Informational [Page 9] + +RFC 4678 SASPv1 September 2006 + + + o Port: The port number used for communication to the member. + *** A value of 0 can be given for the Protocol and Port to signify + a system level member. However, 0 shouldn't be perceived as a + wildcard for either Port or Protocol fields (i.e., a + deregistration request that includes a MemberData component with a + 0 for the port doesn't mean deregister all applications listening + on any port of that IP and protocol). + + o IP Address: The current format is described by the following 16 + bytes, where IPv4 addresses are represented as "IPv4-compatible + IPv6 addresses" [RFC4291]. In the following example, the x's and + zeros represent 4-bit hex values. The x's describe arbitrary hex + values. + + IPv4 Address: 00 00 00 00 00 00 00 00 00 00 00 00 xx xx xx xx + + IPv6 Address: xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx + + o Label length: The length, in bytes, of the label string to follow. + + o Label: A UTF8 string that may be set while registering a member. + This string is opaque to the GWM and is simply included with any + correspondence containing the member data component. Note that + the size of this label is <= 255 bytes. Because UTF8 character + encodings may be up to 6 bytes, care must be exercised by the load + balancer or member to make sure the UTF8 string it sends the GWM + is in fact <= 255 bytes. + + + + + + + + + + + + + + + + + + + + + + + + +Bivens Informational [Page 10] + +RFC 4678 SASPv1 September 2006 + + +5.2. Group Data Component + + The group data component simply describes a group with which to + associate other singular components. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Group Data Type (0x3011) | Size of this TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | LB UID Length | | + +-+-+-+-+-+-+-+-+ + + . . + . LB UID . + . . + + +-+-+-+-+-+-+-+-+ + | |Group Name Len | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . Group Name . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 6 + + o LB UID Length: Length of the LB UID to follow (in bytes). + + o LB UID: A UTF8 string used as a unique identifier and a context + for the Group Name (e.g., a UTF8 representation of the MAC address + of the load balancer or some type of Universally Unique Identifier + (UUID)). This string is used by the Group Workload Manager to + associate application registration and deregistration, and to set + state messages with the correct load balancer. This unique + identifier should not be any longer than 64 bytes. + + o Group Name Len: Length of the Group Name field to follow (in + bytes). + + o Group Name: A UTF8 string the load balancer has chosen to tell the + Group Workload Manager that members being registered with this + Group Name are equivalent in function. In Get Weight and + DeRegistration messages, the Group Name may be omitted (Group Name + Length = 0) to indicate all groups from the associated load + balancer. + + + + + + + +Bivens Informational [Page 11] + +RFC 4678 SASPv1 September 2006 + + +5.3. Weight Entry Data Component + + The Weight Entry Component is used by the get and send weight + messages to associate a weight with a particular member (or Member + Data). It also uses an opaque member state field and a general + member flags field to denote extra information about a member + (described below). When the Weight Entry component is used, the + Member Data TLV it refers to is listed first, immediately followed by + the Weight Entry TLV. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Member Data Type (0x3010) | Size of this Member Data TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . Member Data Fields . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Weight Entry Type (0x3012) | Size of this Weight Entry TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | State Field | Flags Field | Weight | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 7 + + o State Field: This field is used by the member to communicate state + information to the scheduler. The information placed in this + field is opaque to the GWM and will simply be forwarded to the + scheduler with the member weights. There are no defined values + for this field. + + o Flags Field: This field has several flag values that describe + several attributes of the member. + + A. Contact Success Flag (set by the GWM): describes whether the + member is currently running. If the contact success flag is + off, this member should be avoided by the load balancer. + + + xxxx xxx1 The GWM has located this running system or + application. + + + xxxx xxx0 The GWM has not located this running system or + application. + + B. Quiesce Flag (set by the load balancer or Member): used when + an administrator would like to temporarily remove a member + from the weight calculation, but not deregister it from the + + + +Bivens Informational [Page 12] + +RFC 4678 SASPv1 September 2006 + + + group. When quiesced, the member will still show up in the + weights, but the quiesce flag will be set, and its weight will + be zero. When the administrator returns this member to + active, the quiesce flag will be 0, and a weight will be + provided. If the quiesce flag is on, this member should be + avoided by the load balancer. + + + xxxx xx1x The member is quiesced. + + + xxxx xx0x The member is active (not quiesced). + + C. Registration Flag (set by the GWM): stores how the member was + registered. + + + xxxx x1xx This member has been registered by the load + balancer/scheduler. + + + xxxx x0xx This member has registered itself. + + D. Confident Flag (set by the GWM): describes whether the GWM has + knowledge of this member's state. If this flag is off for + only some of the members in the group while the remaining + members have valid weights, the load balancer should avoid + sending work to those members with the confident flag off. If + the confident flag is off for all valid group members, the + load balancer should disregard any recommendation from the GWM + until the confident flag comes back on for at least one + member. In this case where all confident flags are off, the + load balancer should determine the correct distribution of + work by other means (perhaps a different advisor, previously + configured static weights, etc.). + + The goal of the confident flag is to convey to the load + balancer that it should look to other methods of distribution + recommendations if the GWM cannot give recommendations for any + of the valid group members. If some members of the group have + the confident flag on but the contact flag off or the quiesced + flag on (meaning these members should always be avoided) while + the remaining members of the group have their confident flag + off, the load balancer should determine the appropriate + distribution of work for those members with the confident flag + off by other means. + + + xxxx 1xxx GWM has determined it has knowledge of the state + of this member. + + + xxxx 0xxx GWM has no knowledge of the state of this member. + + + + +Bivens Informational [Page 13] + +RFC 4678 SASPv1 September 2006 + + + E. Leftmost four bits are reserved (0000 xxxx - 1111 xxxx). + + o Weight: This field represents the GWM's recommendation for the + relative amount of work that should be sent to this member. This + is a 16-bit field with a possible range of 0 to 65536. Load + balancers should be prepared to receive a wide range of weight + values. Load balancers with limited maximum weight values may + restrict the granularity of management by the GWM and in turn + cause less than optimal performance. Many existing + implementations have supported a minimum raw weight range from 0 + to 100. + +5.4. Member State Instance Component + + The Member State Instance Component is used by the set member state + message to indicate the sender's perceived state of the member + mentioned. This component is used to set values that will ultimately + end up in the WeightEntry component. When the Member State Instance + component is used, the Member Data TLV it refers to is listed first, + immediately followed by the Member State Instance TLV. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Member Data Type (0x3010) | Size of this Member Data TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . Member Data Fields . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Member State Instance(0x3013) | Size of Member State Inst TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | State Field | Flags Field | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 8 + + o State Field: This field is used by the member to communicate state + information to the load balancer or scheduler. There are no + defined values for this field. + + o Flags Field: This field describes attributes of the member. + Currently the only flag value defined is that of the quiesce flag. + The quiesce flag is used when an administrator would like to + temporarily remove a member from the weight calculation, but not + deregister it from the group. When quiesced, the member will + still show up in the weights, but the quiesce flag will be set, + + + + +Bivens Informational [Page 14] + +RFC 4678 SASPv1 September 2006 + + + and its weight will be zero. When the administrator returns this + member to active, the quiesce flag will be 0, and a weight will be + provided. + + A. Quiesce Flag + + + xxxx xxx1 The member or load balancer setting this state is + quiescing this member. + + + xxxx xxx0 The member or load balancer setting this state is + placing the member in a non-quiesced state. + + B. Leftmost seven bits are reserved (0000 000x - 1111 111x). + +6. Group Protocol Components + + Group protocol components each contain a collection of related + singular components. In particular, they associate Member Data, + Weight Entry, or Member State Instance components to a particular + Group Data component. In these cases, the particular "Group of x" + component will be immediately followed by the Group Data component. + The Group Data component will be immediately followed by any number + of singular components the group contains. In figures listed in this + document, a component type with an asterisk denotes a component that + is repeated a number of times. + +6.1. Group of Member Data Component + + The "group of member data" component describes a particular group of + members and is used in the registration message components. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Group of Member Data (0x4010) | Size of GroupOfMemberData TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Member Count | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . Group Data TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . *Array of Member Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 9 + + + +Bivens Informational [Page 15] + +RFC 4678 SASPv1 September 2006 + + + o Member Count: The number of Member Data Components immediately + following the Group Data structure. + + o Array of Member Data Components: There will be as many Member Data + TLVs as Member Count has specified. A load balancer/scheduler + would use these components to pass information that would enable + the Group Workload Manager to identify the members to associate + with this Group Name. The Member Data Component was described in + Section 5.1. In DeRegistration messages, the Member Count may be + set to 0 to indicate all members of a particular group. + +6.2. Group of Weight Data Component + + The "Group of Weight Data" Component is used by the get and send + weight messages to create a list of Weight Entry Components for a + particular group. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |Group Weight Entry Type(0x4011)| Size of GroupOfWeightEntry TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Weight Entry Count | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . Group Data TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . *Array of Weight Entry Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 10 + + o Weight Entry Count: The number of Member Data / Weight Entry + combinations to follow the Group Data TLV. + + o Array of Weight Entry Data TLVs: There will be as many [Member + Data / Weight Entry] TLVs as Weight Entry Count has specified. + Each Weight Entry component is preceded by its corresponding + Member Data component as explained in Section 5.3. This Member + Data / Weight Entry data combination will repeat to form as many + Weight Entry items as the Weight Entry Count specifies. + + + + + + + +Bivens Informational [Page 16] + +RFC 4678 SASPv1 September 2006 + + +6.3. Group of Member State Data Components + + The "group of member state data" component describes a particular set + of members and their corresponding state fields used in the Set + Member State messages. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |Group Weight Entry Type(0x4011)| Size of GroupOfWeightEntry TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Member State Instance Count | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . Group Data TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . *Array of Member State Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 11 + + o Member State Instance Count: The number of Member Data / Member + State Instance combinations following the Group Data component. + + o Array of Member State Data Components: Each Member State Instance + component is immediately preceded by its corresponding Member Data + component as explained in Section 5.4. This Member Data / Member + State Instance combination will repeat to form as many Member + State items as the Member State Instance Count specifies. + +7. Protocol Messages + + SASP messages are a collection of TLVs (Type, Length, and Value + components). The header has no information as to what type of + message it is part of; the purpose-specific information is in the + message component. This format could facilitate placing more than + one message component in a single message; however, this use of + multiple message components is not supported in every GWM and could + produce indeterminate behavior. Similar to the other protocol + components, when a message component needs to involve other + components, the additional components immediately follow the message + component. + + + + + + +Bivens Informational [Page 17] + +RFC 4678 SASPv1 September 2006 + + + All SASP requests sent to the GWM will be acknowledged with a reply. + The reply contains information requested as well as a single-byte + response code describing the success of the request. SASP defines + some general response codes in the range of 0x00 - 0x3F that may be + used regardless of the response message type. However, some request + types may cause specific error conditions not covered by the general + response codes. The response code range of 0x40 - 0xFF is used for + these message-specific response codes. Any given SASP response will + only contain one response code (depending on the error type). This + section explains the format and purpose of specific SASP messages. + +7.1. Registration Request and Reply + + This exchange happens between the load balancer/scheduler and the + Group Workload Manager as well as between the Group Workload Manager + and the member to register the members in a group specified by Group + Name. Applications are identified with an IP address, Protocol, and + Port. Systems are identified only with an IP Address (Port = 0x0000 + and Protocol = 0x00). All members in a group have equivalent + functionality, so the Group Workload Manager can direct routers, load + balancers, and schedulers to any member in the group. Even though + registrations can come from either the load balancer/scheduler or the + actual member, member-initiated registrations will only be considered + if the Trust flag is set while the state of the load + balancer/scheduler is set. + +7.1.1. Registration Request + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Registration Req. Type(0x1010)| Size of Registration Req. TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Flag Field | Group of Member Data Count | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . *Array of Group of Member Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + *There will be as many Group of Member Data Components as "Group of + Member Data Count" has specified. + + Figure 12 + + + +Bivens Informational [Page 18] + +RFC 4678 SASPv1 September 2006 + + + o Flag Field + + A. Load Balancer Flag + + + xxxx xxx1 The entity sending this message is the load + balancer. + + + xxxx xxx0 The entity sending this message is an + Application. + + B. Leftmost seven bits are reserved (0000 000x - 1111 111x). + + o Group of Member Data Count: The number of "Group of Member Data" + components immediately following the Registration Request + component. + + o Array of Group of Member Data Components: Each "Group of Member + Data" component is immediately followed by Group Data Components + and its Member Data components (as described in Section 6.1). In + the case where several of these "Group of Member Data" components + may be present, the second "Group of Member Data" component only + appears after all of the internal components that are referred to + by the first "Group of Member Data" component are listed. The + format is the same for all subsequent "Group of Member Data" + components in the message. + +7.1.2. Registration Reply + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |Registration Reply Type(0x1015)| Size of Registration Reply TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Return Code | + +-+-+-+-+-+-+-+-+ + + Figure 13 + + o General SASP return codes (0x00 - 0x3F) + + * 0x00 Successful + + * 0x10 Message not understood + + + + +Bivens Informational [Page 19] + +RFC 4678 SASPv1 September 2006 + + + * 0x11 GWM will not accept this message from the sender. Reasons + for this include the following: + a. The message was not sent by a LB and trust flag is off + b. LB attempted to address members of a different LB in the + message + c. Vendor specific criteria for this message type were not met. + + o Message-Specific return codes (0x40 - 0xFF) + + * 0x40 Member already registered + + * 0x44 Duplicate Member in Request + + * 0x45 Invalid Group (determined by the GWM) + + * 0x50 Invalid Group Name Size (size == 0) + + * 0x51 Invalid LB UID Size (size == 0 or > max) + + * 0x61 Member is registering itself, but LB hasn't yet contacted + the GWM. This registration will not be processed. + + **The Invalid Group error return code refers to the LB or member + attempting to form a group that the GWM considers invalid. For + example, some GWM vendors may not support the registration of both + System and Application members in the same group. To determine what + can cause a GWM to return this error code, the vendor's documentation + must be consulted. + +7.2. DeRegistration Request and Reply + + This exchange happens between the load balancer/scheduler and the + Group Workload Manager as well as between the Group Workload Manager + and the Member to deregister members from a group specified by Group + Name with the Group Workload Manager. Even though deregistrations + can come from either the load balancer/scheduler or the actual + member, member-initiated deregistrations will only be considered if + the Trust flag is set with a Set LB State message. + + + + + + + + + + + + + +Bivens Informational [Page 20] + +RFC 4678 SASPv1 September 2006 + + +7.2.1. DeRegistration Request + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |DeRegistration Req.Type(0x1020)|Size of DeRegistration Req. TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Flag Field | Reason | Group of Member Data Count | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . *Array of Group of Member Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + *There will be as many Group of Member Data Components as "Group of + Member Data Count" has specified. + + Figure 14 + + o Flag Field + + A. Load Balancer Flag + + + xxxx xxx1 The entity sending this message is the load + balancer. + + + xxxx xxx0 The entity sending this message is an + Application. + + B. Leftmost seven bits are reserved (0000 000x - 1111 111x). + + o Reason: Byte describing the reason for deregistering the group or + instance. + + A. SASP-defined Reason Codes (0x00-0x7F) + + + 0x00 No reason given. + + + 0x01 Learned and Purposeful, i.e., a human has deconfigured + this member from the load balancer configuration. + + + 0x80-0xFF Open for vendor specific deregistration reason + codes. + + + + +Bivens Informational [Page 21] + +RFC 4678 SASPv1 September 2006 + + + o Group of Member Data Count: The number of "Group of Member Data" + components immediately following the DeRegistration Request + component. + + o Array of Group of Member Data Components: Each "Group of Member + Data" component is immediately followed by Group Data Components + and its Member Data components (as described in Section 6.1). In + this case, where several of these "Group of Member Data" + components may be present, the second "Group of Member Data" + component only appears after all of the internal components that + are referred to by the first "Group of Member Data" component are + listed. The format is the same for all subsequent "Group of + Member Data" components in the message. + + ** If Member Count equals zero in the Group of Member Data component, + the Group Workload Manager will deregister the entire group. + + ** Recall that the Group Data Component contains both a Unique LB + Identifier field and a Group Name field. If the Group Data component + has no Group Name (GroupData's Group Name Length==0), the Group + Workload Manager will deregister all groups associated with this load + balancer. + +7.2.2. DeRegistration Reply + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | DeReg. Reply Type(0x1025) | Size of DeReg. Reply TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Return Code | + +-+-+-+-+-+-+-+-+ + + Figure 15 + + o Return Code: A byte return code indicating the status of action + taken. + + A. General SASP return codes (0x00 - 0x3F) + + + 0x00 Successful + + + 0x10 Message not understood + + + + +Bivens Informational [Page 22] + +RFC 4678 SASPv1 September 2006 + + + + 0x11 GWM will not accept this message from the sender. + Reasons for this include the following: + a. The message was not sent by a LB and trust flag is off + b. LB attempted to address members of a different LB in the + message + c. Vendor specific criteria for this message type were not + met. + + B. Message-Specific return codes (0x40 - 0xFF) + + + 0x41 Application or System not registered + + + 0x42 Unknown Group Name + + + 0x43 Unknown LB UID + + + 0x44 Duplicate Member in Request + + + 0x46 Duplicate Group in Request (for remove all + members/groups requests) + + + 0x51 Invalid LB UID Size (size == 0 or > max) + + + 0x61 Member is deregistering itself, but LB hasn't yet + contacted the GWM. This deregistration will not be + processed. + +7.3. Get Weights Request and Reply + + This exchange happens between the load balancer/scheduler and the + Group Workload Manager to get weights for the groups specified in the + list of GroupData objects. In the case of application load balancing + (balancing workloads between applications with the same + functionality), the load balancer would call the Group Workload + Manager every Interval (parameter returned by the Group Workload + Manager below) to get an array of weights and associated members + (e.g., Application1 20, SecondCopyOfApplication 30, + ThirdCopyOfApplication 5). The load balancer then uses these weights + to determine the fashion in which work will be sent to each of the + members. For example, in the case of weighted round robin, the load + balancer/scheduler would then send a request to Application1, the + next to SecondCopyOfApplication, and the next to + ThirdCopyOfApplication. After 15 requests, the load + balancer/scheduler would only send work to Application1 and + SecondCopyOfApplication. After an additional 30 requests, the load + balancer/scheduler would only send requests to + SecondCopyofApplication. After another 10 requests, the load + balancer/scheduler product would start over using the weights of 20, + + + +Bivens Informational [Page 23] + +RFC 4678 SASPv1 September 2006 + + + 30, and 5 again; or if the Interval number of seconds have passed, + the load balancer/scheduler would get a new set of weights. + +7.3.1. Get Weights Request + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Get Weights Req. Type(0x1030) | Size of Get Weights Req. TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Group Data Count | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . *Array of Group Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + *There will be as many Group Data Components as "Group Data Count" + has specified. + + Figure 16 + + o Group Data Count: The number of "Group Data" components + immediately following the Get Weights Request TLV. + + o Array of Group Data Components: This array of Group Data + Components lists the groups for which the load balancer wants to + get weights. + + ** If there is no group name in the Group Data structure of the Get + Weights Request, the load balancer is requesting weights for all + groups registered for the load balancer. + + + + + + + + + + + + + + + +Bivens Informational [Page 24] + +RFC 4678 SASPv1 September 2006 + + +7.3.2. Get Weights Reply + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Get Weights Reply Type(0x1035)| Size of Get Weights Reply TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Return Code | Interval | Group of Weight + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Entry Data Count| | + +-+-+-+-+-+-+-+-+ + + . . + . *Group of Weight Entry Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + * There will be as many Group of Weight Entry Data Components as + "Group of Weight Entry Data Count" has specified. + + Figure 17 + + o Return Code: A byte return code indicating the status of action + taken. + + A. General SASP return codes (0x00 - 0x3F) + + + 0x00 Successful + + + 0x10 Message not understood + + + 0x11 GWM will not accept this message from the sender. + Reasons for this include the following: + a. LB attempted to address members of a different LB in the + message + b. Vendor specific criteria for this message type were not + met. + + B. Message-Specific return codes (0x40 - 0xFF) + + + 0x42 Unknown Group Name + + + 0x43 Unknown LB UID + + + 0x46 Duplicate Group in Request + + + +Bivens Informational [Page 25] + +RFC 4678 SASPv1 September 2006 + + + + 0x51 Invalid LB uid Size (size == 0 or > max) + + o Interval: These two bytes indicate a recommended polling interval + for the load balancer to use. The Group Workload Manager is + stating that any polling interval smaller than the suggested + interval would probably retrieve values before they have had a + chance to change. + + o Group of Weight Entry Data Components: Each "Group of Weight Data" + component is immediately followed by Group Data Components and its + Weight Entry Data components (as described in Section 6.2). In + this case, where several "Group of Weight Data" components may be + present, the second "Group of Weight Data" component only appears + after all of the internal components that are referred to by the + first "Group of Weight Data" component are listed. The format is + the same for all subsequent "Group of Weight Data" components in + the message. + +7.4. Send Weights + + This exchange happens between the Group Workload Manager and the load + balancer/scheduler to send the new weights for the group specified in + Group Name. This message is unique in that it is the only message + exchange initiated by the Group Workload Manager and the only message + that has no reply. In the case of application load balancing + (balancing workloads between applications with the same + functionality), the Group Workload Manager would message the load + balancer at a possibly dynamic interval (chosen by the Group Workload + Manager) to send an array of weights and associated members (e.g., + Application1 20, SecondCopyOfApplication 30, ThirdCopyOfApplication + 5). The load balancer then uses these weights to determine the + fashion in which work will be sent to each of the members. For + example, in the case of weighted round robin, the load + balancer/scheduler would then send a request to Application1, the + next to SecondCopyOfApplication, and the next to + ThirdCopyOfApplication. After 15 requests, the load + balancer/scheduler would only send work to Application1 and + SecondCopyOfApplication. After another 30 requests, the load + balancer/scheduler would only send requests to + SecondCopyofApplication. After an additional 10 requests, the load + balancer/scheduler product would start over using the weights of 20, + 30, and 5 again, if it has not yet received a new set of weights. + The Group Workload Manager only sends this message if the Push flag + has been enabled using a Set Load Balancer State message. + + + + + + + +Bivens Informational [Page 26] + +RFC 4678 SASPv1 September 2006 + + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Send Weights Type(0x1040) | Size of Send Weights TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Group of Weight Data Count | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . *Group of Weight Entry Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + * There will be as many Group of Weight Entry Data Components as + "Group of Weight Data Count" has specified. + + Figure 18 + + o Group of Weight Entry Data Components: Each "Group of Weight Data" + component is immediately followed by Group Data Components and its + Weight Entry Data components (as described in Section 6.2). In + this case, where several "Group of Weight Data" components may be + present, the second "Group of Weight Data" component only appears + after all of the internal components that are referred to by the + first "Group of Weight Data" component are listed. The format is + the same for all subsequent "Group of Weight Data" components in + the message. + +7.5. Set Member State Request and Reply + + This is a special exchange that can take place between the load + balancer and the Group Workload Manager or between the Member and the + Group Workload Manager to pass information about the state of the + member including placing the member in quiesced or non-quiesced + states. In particular, the load balancer/scheduler can use this + message to quiesce a set of members. Members can also use this + message to quiesce themselves as well as to pass certain state + information to the load balancer/scheduler that is opaque to the + Group Workload Manager. This opaque state information is passed to + the load balancer/scheduler with the weights during get and send + weight messages. + + + + + + + +Bivens Informational [Page 27] + +RFC 4678 SASPv1 September 2006 + + +7.5.1. Set Member State Request + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |SetMemberState Req.Type(0x1060)|Size of SetMemberState Req. TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Flag Field | Group of MemberStateData Count| | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + . . + . *Array of Group of Member State Data Components . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + *There will be as many Group of Member State Data Components as + "Group of Member State Data Count" has specified. + + Figure 19 + + o Flag Field + + A. Load Balancer Flag + + + xxxx xxx1 The entity sending this message is the load + balancer. + + + xxxx xxx0 The entity sending this message is an + Application. + + B. Leftmost seven bits are reserved (0000 000x - 1111 111x). + + o Group of Member State Data Count: The number of "Group of Member + State Data" components immediately following the Set Member State + Request TLV. + + o Array of Group of Member Data Components: Each "Group of Member + State Data" component is immediately followed by Group Data + Components and its Member State Instance components (as described + in Section 6.3). In the case where several "Group of Member State + Data" components may be present, the second "Group of Member State + Data" component only appears after all of the internal components + that are referred to by the first "Group of Member State Data" + component are listed. The format is the same for all subsequent + "Group of Member State Data" components in the message. + + + +Bivens Informational [Page 28] + +RFC 4678 SASPv1 September 2006 + + +7.5.2. Set Member State Reply + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Set Member State Reply(0x1025)|Size of SetMemberStateReply TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Return Code | + +-+-+-+-+-+-+-+-+ + + Figure 20 + + o Return Code: A byte return code indicating the status of action + taken. + + A. General SASP return codes (0x00 - 0x3F) + + + 0x00 Successful + + + 0x10 Message not understood + + + 0x11 GWM will not accept this message from the sender. + Reasons for this include the following: + a. The message was not sent by a LB and trust flag is off + b. LB attempted to address members of a different LB in the + message + c. Vendor specific criteria for this message type were not + met. + + B. Message-Specific return codes (0x40 - 0xFF) + + + 0x41 Application or System not registered + + + 0x42 Unknown Group Name + + + 0x43 Unknown LB UID + + + 0x44 Duplicate Member in Request + + + 0x46 Duplicate Group in Request + + + 0x50 Invalid Group Name Size (size == 0) + + + 0x51 Invalid LB UID Size (size == 0 or > than max) + + + +Bivens Informational [Page 29] + +RFC 4678 SASPv1 September 2006 + + + + 0x61 Member is setting state for itself, but LB hasn't yet + contacted the GWM. This request will not be processed. + +7.6. Set Load Balancer State Request and Reply + + This is an exchange that can take place between the load balancer and + the Group Workload Manager to pass information about the state (and + partial configuration) of the load balancer. + +7.6.1. Set LB State Request + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |Set LB State Req. Type (0x1050)| Size of Set LB State Req. TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | LB UID Length | | + +-+-+-+-+-+-+-+-+ + + . . + . LB UID . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | LB Health | LB Flags | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 21 + + o LB UID Length: one-byte length field describing the size of the + following LB UID. + + o LB UID: This should be the same unique identifier given when + registering group members for this particular load balancer. + + o LB Health: This field gives the load balancer a chance to pass in + a metric describing its own health or state. + + 0x00 - 0x7F Least Healthy - Most Healthy + + 0x80 - 0xFF Reserved + + o LB Flags: + + A. Push Flag + + + + +Bivens Informational [Page 30] + +RFC 4678 SASPv1 September 2006 + + + + xxxx xxx1 The load balancer should receive weights through + the Send Weights message (GWM pushes weights to load + balancer). Even if this flag is set, the GWM must still + respond accordingly to any Get Weights messages from the + load balancer. + + + xxxx xxx0 The load balancer will send a Get Weights message + to get the new weights. This is the default behavior. + (load balancer pulls weights from GWM). + + B. Trust Flag + + + xxxx xx1x Trust any member-initiated registration, + deregistration, or set state message. Immediately reflect + the registration, deregistration, or new state in the + weights sent. + + + xxxx xx0x Do not trust any member-initiated registration, + deregistration, or set state message. Registration, + Deregistration, and State Setting of members can only occur + from the load balancer. Discard any member-initiated + registration, deregistration, or set state message. This + is the default behavior. + + C. No Change / No Send Flag + + + xxxx x1xx The GWM must not include members whose weights + and state (i.e., contact and quiesce flags) have not + changed since they were last sent. + + + xxxx x0xx The GWM must include the weights of all group + members when sending the weights to this load balancer + (including members whose weights and state have not + changed). This is the default behavior. + + D. Leftmost five bits are reserved (0000 0xxx - 1111 1xxx). + + + + + + + + + + + + + + + +Bivens Informational [Page 31] + +RFC 4678 SASPv1 September 2006 + + +7.6.2. Set LB State Reply + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . SASP Header TLV . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Set LB State Reply (0x1025) | Size of Set LB State Reply TLV| + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Return Code | + +-+-+-+-+-+-+-+-+ + + Figure 22 + + o Return Code: A byte return code indicating the status of action + taken. + + A. General SASP return codes (0x00 - 0x3F) + + + 0x00 Successful + + + 0x10 Message not understood + + + 0x11 GWM will not accept this message from the sender. + Reasons for this include the following: + a. LB attempted to address the state of a different LB + b. Vendor specific criteria for this message type were not + met. + + B. Message-Specific return codes (0x40 - 0xFF) + + + 0x51 Invalid LB UID Size (size == 0 or > max) + +8. Example of SASP Message Encoding + + This section provides an example of the actual SASP message encoding. + For this example, we will look at a sample GetWeights Reply in which + two webservers are registered to a serverfarm called FARM1. The IP + addresses of the two webservers are 10.10.10.1 and 10.10.10.2. + Currently the GWM has a weight of 40 for 10.10.10.1 and 20 for + 10.10.10.2. The load balancer has a unique Identifier of "LB1" and + the message example was sent by the GWM in response to a request + (MessageID: 0x32000000) for FARM1's weights. + + + + + + +Bivens Informational [Page 32] + +RFC 4678 SASPv1 September 2006 + + + The TLVs necessary for this message are shown in the following list. + + 1. SASP Header TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x2010 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x000D | + |-----------|---------|------------| + | | Version | 1 byte | 0x01 | + | |---------|---------|------------| + |V| Mesg Len| 4 bytes | 0x0000 006A| + | |---------|---------|------------| + | | Mesg ID | 4 bytes | 0x3200 0000| + ------------------------------------ + + Figure 23 + + 2. Get Weights Reply TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x1035 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x0009 | + |-----------|---------|------------| + | | RetCode | 1 byte | 0x00 | + | |---------|---------|------------| + |V| Interval| 2 bytes | 0x0040 | + | |---------|---------|------------| + | |GWD Count| 2 bytes | 0x0001 | + ------------------------------------ + *GWD Count = Group of Weight Data Count + + Figure 24 + + + + + + + + + + + + + +Bivens Informational [Page 33] + +RFC 4678 SASPv1 September 2006 + + + 3. Group of Weight Data TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x4011 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x0006 | + |-----------|---------|------------| + |V| WE Count| 2 bytes | 0x0002 | + ------------------------------------ + *WE Count = Weight Entry Count + + Figure 25 + + 4. Group Data TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x3011 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x000E | + |-----------|---------|------------| + | |LBUID len| 1 byte | 0x03 | + | |---------|---------|------------| + | | LBUID | 3 bytes | "LB1" or | + | | | | 0x4C 42 31 | + |V|---------|---------|------------| + | |GroupName| 1 byte | 0x05 | + | | Length | | | + | |---------|---------|------------| + | | Group | | "FARM1" or | + | | Name | 5 bytes | 0x46 41 52 | + | | | | 4D 31 | + ------------------------------------ + + Figure 26 + + + + + + + + + + + + + +Bivens Informational [Page 34] + +RFC 4678 SASPv1 September 2006 + + + 5. Member Data TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x3010 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x0018 | + |-----------|---------|------------| + | | Protocol| 1 byte | 0x06 | + | |---------|---------|------------| + | | Port | 2 bytes | 0x0050 | + | |---------|---------|------------| + |V| IP |16 bytes | 0x0000 0000| + | | Address | | 0000 0000| + | | | | 0000 0000| + | | | | 0A0A 0A01| + | |---------|---------|------------| + | |Label Len| 1 byte | 0x00 | + | |---------|---------|------------| + | | Label | 0 bytes | | + ------------------------------------ + + Figure 27 + + 6. Weight Entry Data TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x3012 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x0008 | + |-----------|---------|------------| + | | State | 1 byte | 0x00 | + | |---------|---------|------------| + |V| Flags | 1 byte | 0x0D | + | |---------|---------|------------| + | | Weight | 2 bytes | 0x0028 | + ------------------------------------ + + Figure 28 + + + + + + + + + +Bivens Informational [Page 35] + +RFC 4678 SASPv1 September 2006 + + + 7. Member Data TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x3010 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x0018 | + |-----------|---------|------------| + | | Protocol| 1 byte | 0x06 | + | |---------|---------|------------| + | | Port | 2 bytes | 0x0050 | + | |---------|---------|------------| + |V| IP |16 bytes | 0x0000 0000| + | | Address | | 0000 0000| + | | | | 0000 0000| + | | | | 0A0A 0A02| + | |---------|---------|------------| + | |Label Len| 1 byte | 0x00 | + | |---------|---------|------------| + | | Label | 0 bytes | | + ------------------------------------ + + Figure 29 + + 8. Weight Entry Data TLV + + ------------------------------------ + | | Field | Size | Value | + |-----------|---------|------------| + |T| Type | 2 bytes | 0x3012 | + |-----------|---------|------------| + |L| Length | 2 bytes | 0x0008 | + |-----------|---------|------------| + | | State | 1 byte | 0x00 | + | |---------|---------|------------| + |V| Flags | 1 byte | 0x0D | + | |---------|---------|------------| + | | Weight | 2 bytes | 0x0014 | + ------------------------------------ + + Figure 30 + + A hex stream representing this same message is below: + + 20 10 00 0D 01 00 00 00 6A 32 00 00 00 10 35 00 09 00 00 40 + + 00 01 40 11 00 06 00 02 30 11 00 0E 03 4C 42 31 05 46 41 52 + + + +Bivens Informational [Page 36] + +RFC 4678 SASPv1 September 2006 + + + 4D 31 30 10 00 18 06 00 50 00 00 00 00 00 00 00 00 00 00 00 + + 00 0A 0A 0A 01 00 30 12 00 08 00 0D 00 28 30 10 00 18 06 00 + + 50 00 00 00 00 00 00 00 00 00 00 00 00 0A 0A 0A 02 00 30 12 + + 00 08 00 0D 00 14 + + (106 bytes) + +9. Protocol Flow + + This section describes the expected general flow of the SASP + messages. + +9.1. Normal Protocol Flow + + SASP first starts with a connection from an LB to the GWM. This is + expected to be a long-running connection and will be used for many + messages. After establishing the connection, the LB either registers + a group of members or sets a Trust flag to allow the members to + register themselves. The Trust flag is set using a Set LB State + Request (both message flows are shown below). + + Registration from load balancer + + ------------ Registration Request ------------------ + | |----------------------->| | + | Load | | Group Workload | + | Balancer | Registration Reply | Manager | + | |<-----------------------| | + ------------ ------------------ + + Set LB State from load balancer + + ------------ Set LB State Request ------------------ + | |----------------------->| | + | Load | | Group Workload | + | Balancer | Set LB State Reply | Manager | + | |<-----------------------| | + ------------ ------------------ + + Figure 31 + + + + + + + + +Bivens Informational [Page 37] + +RFC 4678 SASPv1 September 2006 + + + The connection can start with other requests, but any other request + would likely result in an error (unless this connection is a + reconnection that has happened a short period of time after the + original connection). For example, if the load balancer issues a + deregistration request as its first message, it will receive an error + because it has not registered any groups. + + The load balancer always drops all state information after a loss of + connection and can recover it using a GetWeights message. The + establishment of a new connection causes the GWM to assume that the + old one is broken. In this case, the GWM will keep all state for the + load balancer for a limited time after a detected break. After the + limited time has expired, all state for the broken connection will be + discarded by the GWM. + + Registration of group members may be done at any time. A load + balancer can register anywhere from one group with one member to many + groups of many members. The member may also register itself if the + Trust flag has been set and it knows the appropriate load balancer + information. Registrations will add to groups that already exist, + but return errors if any of the registered members already exist. + + In the case of system load balancing, the representation of a member + is only the member's IP address with a 0 used as the value for the + port and protocol. In the case of application load balancing, the + representation of a member is the member's IP address and the + Application's port and protocol. + + Deregistration of group members may be done at any time. A load + balancer can deregister anywhere from one group with one member to + many groups of many members. The LB may also deregister entire + groups or deregister all of its groups at once. The member may also + deregister itself if the Trust flag has been set and it knows the + appropriate load balancer information. + + Once members are registered, the GWM will start the monitoring and + weight computation processes to determine weights to be sent back to + the load balancer. At any time the load balancer may issue a + GetWeights message and ask for the weights for members in a + particular group. The LB may also set a flag telling the GWM to send + the weights without waiting for the GetWeights message. If this flag + is set, the GWM will send the weights at an interval it feels is + appropriate (the interval could change depending on the algorithm + used and variance of the weights generated). + + At any time the LB or a particular member may quiesce the member + through the use of a SetMemberState message. In this case, the + member's weight will always be zero, and the quiesce flag will be + + + +Bivens Informational [Page 38] + +RFC 4678 SASPv1 September 2006 + + + turned on when sending its weight. Members may also use this message + to send an opaque state value that will also be presented when + sending weights. + + At any time, the load balancer may choose to send the GWM a + SetLBState request to configure its interaction. The message allows + the load balancer to set the Push, Trust, and NoChange_NoSend flags. + It also allows the load balancer to pass a health value to the GWM to + be displayed. + +9.2. Behavior in Error Cases + + While behaviors in many error conditions will be product specific, + the following error cases should have the following expected + behavior. + + + Case: The protocol is violated in an unrecoverable manner by either + end of the connection. + + Behavior: Either end of the connection may choose to disconnect to + avoid future message synchronization problems. The state kept + when disconnected is vendor specific. + + + Case: LB or application attempts to connect to the GWM before the + GWM is fully up and running. + + Behavior: The LB or application should wait at least 20 seconds to + retry the connection. + + + Case: Members attempt to register or deregister themselves before + the LB develops the connection with the GWM. + + Behavior: In this case, the members would receive a reply with an + error code signifying that there is no LB registered with that LB + UID. + + + Case: Member registers or deregisters for an LB who has not set the + Trust flag. + + Behavior: GWM will send Member a reply containing an error code. + + + + + + + +Bivens Informational [Page 39] + +RFC 4678 SASPv1 September 2006 + + + Case: LB asks for weights for a group that doesn't exist. + + Behavior: GWM will send LB a reply containing an error code. + + + Case: LB or Member attempts to register a member that is already + registered in that group. + + Behavior: GWM will send sender a reply containing an error code. + + + Case: LB or Member attempts to deregister a member or group that + doesn't exist. + + Behavior: GWM will send sender a reply containing an error code. + + + Case: LB or Member tries to set state for a non-registered server. + + Behavior: GWM will send sender a reply containing an error code. + + + Case: LB tries to Get Weights for an unregistered group. + + Behavior: GWM will send LB a reply containing an error code. + + + + + + + + + + + + + + + + + + + + + + + + + + +Bivens Informational [Page 40] + +RFC 4678 SASPv1 September 2006 + + +9.3. Example Flow 1: Load Balancer Registration, Getting Weights, and + Application-Side Quiescing + + Load Group Workload + Balancer Manager + | | + | 1) Registration Request | + |------------------------>| + |<------------------------| + | Registration Reply | + | | + | 2) Set LB State Request | + |------------------------>| + |<------------------------| + | Set LB State Reply | + | | + | 3) Get Weights Request | + |------------------------>| + |<------------------------| + | Get Weights Reply | + | | 4) Set Member State Req. -------- + | |<-------------------------|Member| + | |------------------------->| A | + | | Set Member State Reply -------- + | | + | | 5) Set Member State Req. -------- + | |<-------------------------|Member| + | |------------------------->| C | + | | Set Member State Reply -------- + | | + | 6) Get Weights Request | + |------------------------>| + |<------------------------| + | Get Weights Reply | + | | + | | 7) Set Member State Req. -------- + | |<-------------------------|Member| + | |------------------------->| C | + | | Set Member State Reply -------- + | | + | 8) Get Weights Request | + |------------------------>| + |<------------------------| + | Get Weights Reply | + | | + + Figure 32 + + + + +Bivens Informational [Page 41] + +RFC 4678 SASPv1 September 2006 + + + 1. The LB registers Members A, B, and C in a group named GRP1. The + GWM replies with no error. + + 2. The LB turns its trust flag on by issuing a Set LB State message: + + LB Health: 0x00 Flags: 0000 0010 + + 3. The LB sends a Get Weights message for GRP1 and gets the reply: + + Members Opaque State Flags Weight + -------- ------------ --------- ------ + Member A 0x00 0000 1101 20 + Member B 0x00 0000 1101 40 + Member C 0x00 0000 1101 5 + + 4. Member A sends a Set Member State message with flags: + + Members Opaque State Flags + -------- ------------ --------- + Member A 0x32 0000 0000 + + 5. Member C sends a Set Member State message to quiesce itself with + the following flags: + + Members Opaque State Flags + -------- ------------ --------- + Member C 0x0A 0000 0001 + + 6. The LB sends the Get Weights message for GRP1 and receives the + following: + + Members Opaque State Flags Weight + -------- ------------ --------- ------ + Member A 0x32 0000 1101 20 + Member B 0x00 0000 1101 40 + Member C 0x0A 0000 1111 5 + + 7. Member C sends a Set Member State message to resume (un-quiesce + itself) with the following flags: + + Members Opaque State Flags + -------- ------------ --------- + Member C 0x0A 0000 0000 + + + + + + + + +Bivens Informational [Page 42] + +RFC 4678 SASPv1 September 2006 + + + 8. The LB sends a Get Weights message for GRP1 and gets the reply: + + Members Opaque State Flags Weight + -------- ------------ --------- ------ + Member A 0x32 0000 1101 20 + Member B 0x00 0000 1101 40 + Member C 0x0A 0000 1101 5 + +9.4. Example Flow 2: Set Load Balancer State, Application + Registration, and Load Balancer Group DeRegistration + + Load Group Workload + Balancer Manager + | | + | 1) Set LB State Request | + |------------------------>| + |<------------------------| + | Set LB State Reply | + | | + | | 2) Registration Request -------- + | |<-------------------------|Member| + | |------------------------->| A | + | | Registration Reply -------- + | | + | | 3) Registration Request -------- + | |<-------------------------|Member| + | |------------------------->| B | + | | Registration Reply -------- + | | + | 4) Send Weights Mesg | + |<------------------------| + | | + | | 5) Registration Request -------- + | |<-------------------------|Member| + | |------------------------->| C | + | | Registration Reply -------- + | | + | 6) Send Weights Mesg | + |<------------------------| + | | + |7) Deregistration Request| + |------------------------>| + |<------------------------| + | Deregistration Reply | + | | + + Figure 39 + + + + +Bivens Informational [Page 43] + +RFC 4678 SASPv1 September 2006 + + + 1. The LB sets its state with the Set LB State message and the + following parameters. + + Health: 0x7F Flags: 0000 0011 + + + 2. Member A registers itself for work in GRP1 using the Register + message. + + + 3. Member B registers itself for work in GRP1 using the Register + message. + + + 4. The GWM issues a Send Weights message to the LB. + + Members Opaque State Flags Weight + -------- ------------ --------- ------ + Member A 0x00 0000 1001 20 + Member B 0x00 0000 1001 40 + + 5. Member C registers itself for work in GRP1 using the Register + message. + + + 6. The GWM issues a Send Weights message to the LB. + + Members Opaque State Flags Weight + -------- ------------ --------- ------ + Member A 0x00 0000 1001 20 + Member B 0x00 0000 1001 40 + Member C 0x00 0000 1001 5 + + 7. LB deregisters GRP1 by using the DeRegister message with the + Member Data Count = 0 + +9.5. Avoiding Single Points of Failure + + o To avoid having a single point of failure at the load balancer, an + administrator may choose to have multiple load balancers in his or + her environment. SASP provides for the GWM to keep track of + multiple load balancers through the use of load balancer unique + identifiers (LB UIDs). + + o To avoid having a single point of failure at the GWM or enhance + the load balancing strategy by utilizing the strengths of several + different GWMs, an administrator may choose to have multiple GWMs + in his or her environment. In this case, the load balancer would + + + +Bivens Informational [Page 44] + +RFC 4678 SASPv1 September 2006 + + + connect to multiple GWMs and register the same groups with + corresponding members. The load balancer may choose to coordinate + the recommendations of each GWM by any method it chooses (e.g., + statistical combination such as averaging). The coordination of + weights from multiple GWMs is product specific and not addressed + in this protocol. + +10. Security Considerations + + SASP is a binary stream expected to be transported over a TCP + connection. To secure this protocol, it is expected that + implementers of the protocol use a secure mode of transport such as + SSL/TLS. Discussions around security concerns have been listed + below: + + + Security Issue: In insecure environments, if the LB UID becomes + known by another system, the other system could initiate a + connection and send messages to the GWM causing the GWM to replace + the previous (possibly valid) connection for the new (potentially + bad) connection. + + Solution: This may not be a concern if the load balancer and GWM are + in protected parts of the network. If the administrator is + concerned about this vulnerability, she should use SSL or TLS to + provide authentication for the connection. When using SSL or TLS + to secure the connection, the administrator SHOULD use both server + and client authentication through client and server certificates. + The GWM will trust any certificate that is signed by an authority + it's been configured to trust. + + + Security Issue: In insecure environments, if the load balancer turns + the Trust Flag on, any member or other system can send a + Registration Message and be included in the serverfarm to receive + work. A person with bad intentions and the correct information + could exploit this feature and register his own application to + receive work. His counterfeit application could capture valuable + data from unsuspecting clients as their transactions are sent to + his system. + + Solution: This may not be a concern if the GWM and its members are + in protected parts of the network. If the administrator is + concerned about this vulnerability, she should use SSL or TLS to + provide authentication for the member connections. When using SSL + or TLS to authenticate the connection, the administrator would + need to explicitly install valid certificates on each component + + + + +Bivens Informational [Page 45] + +RFC 4678 SASPv1 September 2006 + + + while at the same time establishing the trusted certificates of + each component. This would make certain that only those trusted + components would be permitted to connect to the GWM. + +11. Normative References + + [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, + RFC 1700, October 1994. + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + + [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing + Architecture", RFC 4291, February 2006. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Bivens Informational [Page 46] + +RFC 4678 SASPv1 September 2006 + + +Appendix A. Acknowledgements + + The author gratefully acknowledges contributions by Mark Albert, + David McCowan, John Fenton, Derek Huckaby, Dyan Collins, and Stefano + Testa. Mark Albert, David McCowan, John Fenton, Derek Huckaby, Dyan + Collins, and Stefano Testa were supported for this work by Cisco + Systems Inc. + + The author would also like to thank John Arwe, Dave Bostjancic, Brian + Carpenter, Donna Dillenberger, Gus Kassimis, and Thomas Narten for + their efforts in the creation and refining of this work. + +Author's Address + + Alan Bivens + IBM T.J. Watson Research Center + 19 Skyline Drive + Hawthorne, NY 10532 + US + + EMail: jbivens@us.ibm.com + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Bivens Informational [Page 47] + +RFC 4678 SASPv1 September 2006 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2006). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78 and at www.rfc-editor.org/copyright.html, and + except as set forth therein, the authors retain all their rights. + + This document and the information contained herein are provided on an + "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS + OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET + ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, + INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE + INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED + WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + this document or the extent to which any license under such rights + might or might not be available; nor does it represent that it has + made any independent effort to identify any such rights. Information + on the procedures with respect to rights in RFC documents can be + found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at + ietf-ipr@ietf.org. + +Acknowledgement + + Funding for the RFC Editor function is provided by the IETF + Administrative Support Activity (IASA). + + + + + + + +Bivens Informational [Page 48] + |