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diff --git a/doc/rfc/rfc2335.txt b/doc/rfc/rfc2335.txt new file mode 100644 index 0000000..93f51d6 --- /dev/null +++ b/doc/rfc/rfc2335.txt @@ -0,0 +1,395 @@ + + + + + + +Network Working Group J. Luciani +Request for Comments: 2335 Bay Networks +Category: Standards Track April 1998 + + + A Distributed NHRP Service Using SCSP + +Status of this Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (1998). All Rights Reserved. + +Abstract + + This document describes a method for distributing an NHRP service + within a LIS [1]. This method uses the Server Cache Synchronization + Protocol (SCSP) [2] to synchronize the client information databases + held by NHRP Servers (NHSs) within a LIS. + +1. Introduction + + The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, + SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this + document, are to be interpreted as described in [4]. + + NHRP Clients (NHCs) register their existence and reachability + information with NHRP Servers (NHSs). There may be multiple NHSs in + a given Logical IP Subnet (LIS). NHCs do not necessarily register + with all NHSs in a LIS; however, all NHCs need to be able to query at + least one NHS about any NHC within the LIS. Thus, the contents of + the NHS databases in a LIS need to be synchronized across the LIS. + The Server Cache Synchronization Protocol (SCSP) solves the + generalized server synchronization/cache-replication problem for + distributed databases and thus SCSP may be applied to the NHS + database synchronization problem within the LIS. + + + + + + + + + +Luciani Standards Track [Page 1] + +RFC 2335 NHRP Using SCSP April 1998 + + + SCSP is defined in two parts: the protocol independent part and the + client/server protocol specific part. The protocol independent part + is defined in [2] whereas this document will specify the + client/server protocol specific part where NHRP is the client/server + protocol. + + This document is separate from [2] because it was felt that it was + desirable to allow the client/server protocol specific part + specification for NHRP to progress independently from the protocol + independent specification. + +2. Overview + + All NHSs belonging to a Logical IP Subnet (LIS) [1] are said to + belong to a Server Group (SG). An SG is identified by, not + surprisingly, its SGID which is contained in a field in all SCSP + packets. All SCSP packets contain a Protocol ID (PID) field as well. + This PID field is set to 0x0002 to signify that SCSP synchronizing + NHS databases as opposed to synchronizing some other protocol's + databases (see Section B.2.0.1 of [2] for more details). In general, + PIDs for SCSP will be assigned by IANA as described in Section C of + [2]. In the case of NHRP, the client/server protocol specific + specification was initially written at the same time as SCSP, and + thus a PID=0x0002 was assigned by the author. + + SCSP places no topological requirements upon an NHRP SG. Obviously, + however, the resultant graph of NHSs must span the set of NHSs to be + synchronized. For more information about the client/server protocol + independent part of SCSP, the reader is encouraged to see [2]. + + When a SG is using SCSP for synchronization, an NHC will register + with only one NHS, but the NHC MAY use any NHS in the SG. When an + NHC wishes to leave a SG, the NHC MUST do one of the following: 1) + the NHC MUST send an NHRP Purge Request for itself requesting a + reply, and it MUST wait for an NHRP Purge Reply, 2) the NHC MUST keep + the Request ID it used when registering itself in non-volatile RAM + and use a Request ID larger than the one saved when re-registering, + or 3) the NHC MUST not re-register for a time equal to the Holding + Time specified in the previous registration. It is necessary to do + one of the previous in order to prevent the unlikely case of race + conditions from occurring during updated. In the case where method 2 + is used, the NHS with which the NHC registered uses its ID as the OID + and the Request ID from the NHC as the CSA Sequence Number in the + CSA(S) Record. + + + + + + + +Luciani Standards Track [Page 2] + +RFC 2335 NHRP Using SCSP April 1998 + + +3. Format of the CSA Record NHRP Specific Part + + CSA Records in SCSP contain a "Client/Server Protocol Specific Part" + which contains the non-protocol independent information for a given + server's cache entry. + + 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 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Address Family Number | NHRP Protocol Type | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Snap | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Snap | NHRP Vers Num | Flags | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Request ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | State | Prefix Length | unused | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Maximum Transmission Unit | Holding Time | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Cli Addr T/L | Cli SAddr T/L | Cli Proto Len | Preference | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Client Subnetwork Address (variable length) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Client Subnetwork Subaddress (variable length) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Client Protocol Address (variable length) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + The following six fields contain values specified in the common + header of the mandatory part of an NHRP Registration Request or NHRP + Purge Request packet which caused the + creation/deletion/modification/update/etc. of an NHS's cache entry. + + Address Family Number + Defines the type of "link layer" addresses being carried. This + number is taken from the 'address family number' list specified in + [3]. This field is the same field which would be supplied in an + NHRP packet in the ar$afn field. + + NHRP Protocol Type + This field is the same field which would be supplied in an NHRP + packet in the ar$pro.type field. + + Snap + This field is the same field which would be supplied in an NHRP + packet in the ar$pro.snap field. + + + +Luciani Standards Track [Page 3] + +RFC 2335 NHRP Using SCSP April 1998 + + + NHRP Vers Num + This field indicates what version of generic address mapping and + management protocol that is represented by this message. This + field contains 0x01 for the NHRP protocol version 1. This field is + the same field which would be supplied in an NHRP packet in the + ar$op.version field. + + Flags + Defined flags are as follows: + + 0 1 + 0 1 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|A| unused | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U + This is the Uniqueness bit. + + A + When set, this bit specifies that the cache entry was created + as a result of ATMARP client interaction with the NHS. + + Request ID + This field contains the Request ID value placed in the cache entry + of the NHS as a result of an NHRP Registration Request. This NHS + is the NHS causing a synchronization event. + + State + This field contains a value which represents the new state of the + client. + + 0 - Client is registered and available. + 1 - Client reregistered. + 2 - Client has been purged. + 3 - No such client data in server cache + + Note that a time-out of a cache entry does not cause a CSA Record + to be sent because, if everything is working properly then all NHSs + have the cache entry timing out at the same time. Thus, the + individual NHSs would take the appropriate actions necessary. + + The following ten fields contain values specified in or derived from + the CIE of an NHRP Registration Request or NHRP Purge Request packet + which caused the creation/deletion/modification/update/etc. of an + NHS's cache entry. + + + + +Luciani Standards Track [Page 4] + +RFC 2335 NHRP Using SCSP April 1998 + + + Prefix Length + This field contains the internetwork layer address prefix length + value covered by the cache entry being synchronized. + + Maximum Transmission Unit + This field contains a value supplied by or derived from information + in the CIE of the NHRP Registration Request packet. + + Holding Time + The Holding Time field specifies the number of seconds remaining + for which the Next Hop NBMA information specified in the CIE of the + NHRP Registration Request is considered to be valid by the NHS + initiating the synchronization event. + + Cli Addr T/L + Type & length of next hop NBMA address (see [1]). + + Cli SAddr T/L + Type & length of next hop NBMA subaddress (see [1]). + + Cli Proto Len + This field holds the length in octets of the Client Protocol + Address. + + Preference + This field specifies the preference value for use of the next hop + NBMA information specified. + + Client NBMA Address + This is the client's NBMA address. + + Client NBMA SubAddress + This is the client's NBMA subaddress. + + Client Protocol Address + This is the client's internetworking layer address. + +4. Values for SCSP Protocol Independent Part + + The following sections give values for fields of the SCSP Protocol + Independent Part of the various SCSP messages. + +4.1 Values for the SCSP "Mandatory Common Part" + + Protocol ID = 0x0002 + Sender ID Len = 0x04 + Recvr ID Len = 0x04 + + + + +Luciani Standards Track [Page 5] + +RFC 2335 NHRP Using SCSP April 1998 + + + See Section B.2.0.1 of [2] for a detailed description of these + fields. + +4.2 Values for the SCSP "CSAS Record" + + Cache Key Len = 0x04 + Orig ID Len = 0x04 + + See Section B.2.0.2 of [2] for a detailed description of these + fields. + +5. Security Considerations + + Relevant security considerations are documented in [1] and [2]. + +References + + [1] Luciani, J., Katz, D., Piscitello, D., Cole, B., and N. + Doraswamy, "NMBA Next Hop Resolution Protocol (NHRP)", RFC 2332, + April 1998. + + [2] Luciani, J., Armitage, G., Halpern, J., and N. Doraswamy, "Server + Cache Synchronization Protocol (SCSP)", RFC 2334, April 1998. + + [3] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1700, + October 1994. + + [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement + Levels", BCP 14, RFC 2119, March 1997. + +Acknowledgments + + I would like to thank (in no particular order) Maxine Burns of ISR + and Joel Halpern of Newbridge. I would also like to thank the + members of the ION working group of the IETF, whose review and + discussion of this document has been invaluable. + +Author's Address + + James V. Luciani + Bay Networks, Inc. + 3 Federal Street, BL3-03 + Billerica, MA 01821 + + Phone: +1-978-916-4734 + EMail: luciani@baynetworks.com + + + + + +Luciani Standards Track [Page 6] + +RFC 2335 NHRP Using SCSP April 1998 + + +Full Copyright Statement + + Copyright (C) The Internet Society (1998). All Rights Reserved. + + This document and translations of it may be copied and furnished to + others, and derivative works that comment on or otherwise explain it + or assist in its implementation may be prepared, copied, published + and distributed, in whole or in part, without restriction of any + kind, provided that the above copyright notice and this paragraph are + included on all such copies and derivative works. However, this + document itself may not be modified in any way, such as by removing + the copyright notice or references to the Internet Society or other + Internet organizations, except as needed for the purpose of + developing Internet standards in which case the procedures for + copyrights defined in the Internet Standards process must be + followed, or as required to translate it into languages other than + English. + + The limited permissions granted above are perpetual and will not be + revoked by the Internet Society or its successors or assigns. + + This document and the information contained herein is provided on an + "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + TASK FORCE DISCLAIMS 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. + + + + + + + + + + + + + + + + + + + + + + + + +Luciani Standards Track [Page 7] + |