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diff --git a/doc/rfc/rfc7039.txt b/doc/rfc/rfc7039.txt new file mode 100644 index 0000000..b1cbd9b --- /dev/null +++ b/doc/rfc/rfc7039.txt @@ -0,0 +1,787 @@ + + + + + + +Internet Engineering Task Force (IETF) J. Wu +Request for Comments: 7039 J. Bi +Category: Informational Tsinghua Univ. +ISSN: 2070-1721 M. Bagnulo + UC3M + F. Baker + Cisco + C. Vogt, Ed. + October 2013 + + + Source Address Validation Improvement (SAVI) Framework + +Abstract + + Source Address Validation Improvement (SAVI) methods were developed + to prevent nodes attached to the same IP link from spoofing each + other's IP addresses, so as to complement ingress filtering with + finer-grained, standardized IP source address validation. This + document is a framework document that describes and motivates the + design of the SAVI methods. Particular SAVI methods are described in + other documents. + +Status of This Memo + + This document is not an Internet Standards Track specification; it is + published for informational purposes. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Not all documents + approved by the IESG are a candidate for any level of Internet + Standard; see Section 2 of RFC 5741. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + http://www.rfc-editor.org/info/rfc7039. + + + + + + + + + + + + + +Wu, et al. Informational [Page 1] + +RFC 7039 SAVI Framework October 2013 + + +Copyright Notice + + Copyright (c) 2013 IETF Trust and the persons identified as the + document authors. All rights reserved. + + This document is subject to BCP 78 and the IETF Trust's Legal + Provisions Relating to IETF Documents + (http://trustee.ietf.org/license-info) in effect on the date of + publication of this document. Please review these documents + carefully, as they describe your rights and restrictions with respect + to this document. Code Components extracted from this document must + include Simplified BSD License text as described in Section 4.e of + the Trust Legal Provisions and are provided without warranty as + described in the Simplified BSD License. + + This document may contain material from IETF Documents or IETF + Contributions published or made publicly available before November + 10, 2008. The person(s) controlling the copyright in some of this + material may not have granted the IETF Trust the right to allow + modifications of such material outside the IETF Standards Process. + Without obtaining an adequate license from the person(s) controlling + the copyright in such materials, this document may not be modified + outside the IETF Standards Process, and derivative works of it may + not be created outside the IETF Standards Process, except to format + it for publication as an RFC or to translate it into languages other + than English. + +Table of Contents + + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 + 2. Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3. Deployment Options . . . . . . . . . . . . . . . . . . . . . 5 + 3.1. IP Address Assignment Methods . . . . . . . . . . . . . . 6 + 3.2. Binding Anchors . . . . . . . . . . . . . . . . . . . . . 6 + 4. Scalability Optimizations . . . . . . . . . . . . . . . . . . 7 + 5. Reliability Optimizations . . . . . . . . . . . . . . . . . . 9 + 6. Scenario with Multiple Assignment Methods . . . . . . . . . . 10 + 7. Prefix Configuration . . . . . . . . . . . . . . . . . . . . 10 + 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 + 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11 + 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 + 10.1. Normative References . . . . . . . . . . . . . . . . . . 12 + 10.2. Informative References . . . . . . . . . . . . . . . . . 12 + + + + + + + + +Wu, et al. Informational [Page 2] + +RFC 7039 SAVI Framework October 2013 + + +1. Introduction + + Since IP source addresses are used by hosts and network entities to + determine the origin of a packet and as a destination for return + data, spoofing of IP source addresses can enable impersonation, + concealment, and malicious traffic redirection. Unfortunately, the + Internet architecture does not prevent IP source address spoofing + [RFC6959]. Since the IP source address of a packet generally takes + no role in forwarding the packet, it can be selected arbitrarily by + the sending host without jeopardizing packet delivery. Extra methods + are necessary for IP source address validation to augment packet + forwarding with an explicit check of whether a given packet's IP + source address is legitimate. + + IP source address validation can happen at different granularity. + Ingress filtering [BCP38] [BCP84], a widely deployed standard for IP + source address validation, functions at the coarse granularity of + networks. It verifies that the prefix of an IP source address routes + to the network from which the packet was received. An advantage of + ingress filtering is simplicity: the decision of whether to accept or + to reject an IP source address can be made solely based on the + information available from routing protocols. However, the + simplicity comes at the cost of not being able to validate IP source + addresses at a finer granularity, due to the aggregated nature of the + information available from routing protocols. Finer-grained IP + source address validation would ensure that source address + information is accurate, reduce the ability to launch denial-of- + service attacks, and help with localizing hosts and identifying + misbehaving hosts. Partial solutions [BA2007] exist for finer- + grained IP source address validation but are proprietary and hence + often unsuitable for corporate procurement. + + The Source Address Validation Improvement (SAVI) method was developed + to complement ingress filtering with standardized IP source address + validation at the maximally fine granularity of individual IP + addresses. It prevents hosts attached to the same link from spoofing + each other's IP addresses. To facilitate deployment in networks of + various kinds, the SAVI method was designed to be modular and + extensible. This document describes and motivates the design of the + SAVI method. + + Note that SAVI raises a number of important privacy considerations + that are discussed more fully in [RFC6959]. SAVI implementers must + take those privacy considerations into account when designing + solutions that match this framework and follow the recommendations + given in [RFC6959]. + + + + + +Wu, et al. Informational [Page 3] + +RFC 7039 SAVI Framework October 2013 + + +2. Model + + To enable network operators to deploy fine-grained IP source address + validation without a dependency on supportive functionality on hosts, + the SAVI method was designed to be purely network based. A SAVI + instance enforces the hosts' use of legitimate IP source addresses + according to the following three-step model: + + 1. Identify which IP source addresses are legitimate for a host, + based on monitoring packets exchanged by the host. + + 2. Bind a legitimate IP address to a link-layer property of the + host's network attachment. This property, called a "binding + anchor", must be verifiable in every packet that the host sends + and harder to spoof than the host's IP source address itself. + + 3. Enforce that the IP source addresses in packets match the binding + anchors to which they were bound. + + This model allows SAVI functionality (a SAVI instance) to be located + anywhere on the link to which the hosts attach, hence enabling + different locations for a SAVI instance. One way to locate a SAVI + instance is in the hosts' default router. IP source addresses are + then validated in packets traversing the default router, yet the IP + source addresses in packets exchanged locally on the link may bypass + validation. Another way to locate a SAVI instance is in a switch + between the hosts and their default router. Thus, packets may + undergo IP source address validation even if exchanged locally on the + link. + + The closer a SAVI instance is located to the host, the more effective + the SAVI method is. This is because each of the three steps of the + SAVI model can best be accomplished in a position close to the host: + + o Identifying a host's legitimate IP source addresses is most + efficient close to the host because the likelihood that the host's + packets bypass a SAVI instance, and hence cannot be monitored, + increases with the topological distance between the SAVI instance + and the host. + + o Selecting a binding anchor for a host's IP source address is + easiest close to the host because many link-layer properties are + unique for a given host only on a link segment directly attached + to the host. + + + + + + + +Wu, et al. Informational [Page 4] + +RFC 7039 SAVI Framework October 2013 + + + o Enforcing a host's use of a legitimate IP source address is most + reliable when pursued close to the host because the likelihood + that the host's packets bypass a SAVI instance, and hence do not + undergo IP source address validation, increases with the + topological distance between the SAVI instance and the host. + + The preferred location of SAVI instances is therefore close to hosts, + such as in switches that directly attach to the hosts whose IP source + addresses are being validated. + + Nevertheless, it is useful for SAVI mechanisms to be able to handle + situations where hosts are not directly attached to the SAVI-capable + device. For instance, deployments with both SAVI-capable and legacy + switches could be supported. In general, a SAVI solution needs to + specify how it deals with a number of deployment scenarios and + exceptional situations, including interaction with legacy devices, + hosts moving between wireless attachment points, network partitions, + and so on. + + Besides, in the case of legacy switches, the security level is lower, + as there is no full protection for the hosts connected to the legacy + server. + +3. Deployment Options + + The model of the SAVI method, as explained in Section 2, is + deployment specific in two ways: + + o The identification of legitimate IP source addresses is dependent + on the IP address assignment method in use on a link, since it is + through assignment that a host becomes the legitimate user of an + IP source address. + + o Binding anchors are dependent on the technology used to build the + link on which they are used, as binding anchors are link-layer + properties of a host's network attachment. + + To facilitate the deployment of the SAVI method in networks of + various kinds, the SAVI method is designed to support different IP + address assignment methods and to function with different binding + anchors. Naturally, both the IP address assignment methods in use on + a link and the available binding anchors have an impact on the + functioning and the strength of IP source address validation. The + following two subsections explain this impact and describe how the + SAVI method accommodates this. + + + + + + +Wu, et al. Informational [Page 5] + +RFC 7039 SAVI Framework October 2013 + + +3.1. IP Address Assignment Methods + + Since the SAVI method traces IP address assignment packets, it + necessarily needs to incorporate logic that is specific to particular + IP address assignment methods. However, developing SAVI method + variants for each IP address assignment method is alone not + sufficient since multiple IP address assignment methods may coexist + on a given link. The SAVI method hence comes in multiple variants, + e.g., for links with DHCP [RFC2131] [RFC3315], Stateless Address + Autoconfiguration (SLAAC) [RFC4862] with or without Secure Neighbor + Discovery (SEND) [RFC3971], Internet Key Exchange Protocol Version 2 + (IKEv2) [RFC5996] [RFC5739] [RFC5026], and combinations thereof. + + The reason to develop SAVI method variants for each single IP address + configuration method, in addition to the variant that handles all IP + address assignment methods, is to minimize the complexity of the + common case. Many link deployments today either are constrained to a + single IP address assignment method or, equivalently from the + perspective of the SAVI method, use different IP address assignment + methods within different IP address prefixes. The SAVI method for + such links can be simpler than the SAVI method for links with + multiple IP address assignment methods per IP address prefix. + +3.2. Binding Anchors + + The SAVI method supports a range of binding anchors: + + o The IEEE extended unique identifier, EUI-48 or EUI-64, of a host's + interface. + + o The port on an Ethernet switch to which a host attaches. + + o The security association between a host and the base station on + wireless links. + + o The combination of a host interface's link-layer address and a + customer relationship in cable modem networks. + + o An ATM virtual channel, a PPP session identifier, or a Layer 2 + Tunneling Protocol (L2TP) session identifier in a DSL network. + + o A tunnel that connects to a single host, such as an IP-in-IP + tunnel, a Generic Routing Encapsulation (GRE) tunnel, or an MPLS + label-switched path. + + + + + + + +Wu, et al. Informational [Page 6] + +RFC 7039 SAVI Framework October 2013 + + + The various binding anchors differ significantly in the security they + provide. IEEE extended unique identifiers, for example, fail to + render a secure binding anchor because they can be spoofed with + little effort. Switch ports alone may be insufficient because they + may connect to more than a single host, such as in the case of + concatenated switches. + + Given this diversity in the security provided, one could define a set + of possible binding anchors and leave it up to the administrator to + choose one or more of them. Such a selection of binding anchors + would, of course, have to be accompanied by an explanation of the + pros and cons of the different binding anchors. In addition, SAVI + devices may have a default binding anchor depending on the lower + layers. Such a default could be to use switch ports when available + and MAC addresses otherwise or to use MAC addresses and switch ports + in addition if available. + +4. Scalability Optimizations + + The preference to locate a SAVI instance close to hosts implies that + multiple SAVI instances must be able to coexist in order to support + large links. Although the model of the SAVI method is independent of + the number of SAVI instances per link, coexistence of multiple SAVI + instances without further measures can lead to higher-than-necessary + memory requirements. Since a SAVI instance creates bindings for the + IP source addresses of all hosts on a link, bindings are replicated + if multiple SAVI instances coexist on the link. High memory + requirements, in turn, increase the cost of a SAVI instance. This is + problematic in particular for SAVI instances that are located on a + switch since it may significantly increase the cost of such a switch. + + To reduce memory requirements for SAVI instances that are located on + a switch, the SAVI method enables the suppression of binding + replication on links with multiple SAVI instances. This requires + manual disabling of IP source address validation on switch ports that + connect to other switches running a SAVI instance. Each SAVI + instance is then responsible for validating IP source addresses only + on those ports to which hosts attach either directly or via switches + without a SAVI instance. On ports towards other switches running a + SAVI instance, IP source addresses are not validated. The switches + running SAVI instances thus form a "protection perimeter". The IP + source addresses in packets passing the protection perimeter are + validated by the ingress SAVI instance, but no further validation + takes place as long as the packets remain within or leave the + protection perimeter. + + + + + + +Wu, et al. Informational [Page 7] + +RFC 7039 SAVI Framework October 2013 + + + .............. + protection perimeter --> : +--------+ : + +---+ +---+ : | SAVI | : + | A | | B | <-- hosts : | switch | : + +---+ +---+ : +--------+ : + ...|......|.............................: | : + : +--------+ +--------+ +--------+ : + : | SAVI |----------| legacy | | SAVI | : + : | switch | | switch |----------| switch | : + : +--------+ +--------+ +--------+ : + : | ...............................|........: + : +--------+ : +--------+ + : | SAVI | : | legacy | + : | switch | : | switch | + : +--------+ : +--------+ + :............: | | + +---+ +---+ + hosts --> | C | | D | + +---+ +---+ + + Figure 1: Protection Perimeter Concept + + Figure 1 illustrates the concept of the protection perimeter. The + figure shows a link with six switches, of which four, denoted "SAVI + switch", run a SAVI instance. The protection perimeter created by + the four SAVI instances is shown as a dotted line in the figure. IP + source address validation is enabled on all switch ports on the + protection perimeter, and it is disabled on all other switch ports. + Four hosts, denoted A through D in the figure, attach to the + protection perimeter. + + In the example in Figure 1, the protection perimeter encompasses one + of the legacy switches, located in the middle of the depicted link + topology. This enables a single, unpartitioned protection perimeter. + A single protection perimeter minimizes memory requirements for the + SAVI instances because every binding is kept only once, namely, by + the SAVI instance that attaches to the host being validated. + Excluding the legacy switch from the protection perimeter would + result in two smaller protection perimeters to the left and to the + right of the depicted link topology. The memory requirements for the + SAVI instances would then be higher: since IP source address + validation would be activated on the two ports connecting to the + legacy switch, the SAVI instances adjacent to the legacy switch would + replicate all bindings from the other protection perimeter, + respectively. The reason why it is possible to include the legacy + switch in the protection perimeter is because the depicted link + topology guarantees that packets cannot enter the protection + perimeter via this legacy switch. Without this guarantee, the legacy + + + +Wu, et al. Informational [Page 8] + +RFC 7039 SAVI Framework October 2013 + + + switch would have to be excluded from the protection perimeter in + order to ensure that packets entering the protection perimeter + undergo IP source address validation. + + Note that if such configuration is used, care must be taken as any + hosts on subnets attached to non-enforcing ports will be able to use + spoofed source addresses. + +5. Reliability Optimizations + + The explicit storage of legitimate IP addresses in the form of + bindings implies that failure to create a binding, or the premature + removal of bindings, can lead to loss of legitimate packets. There + are three situations in which this can happen: + + o Legitimate IP address configuration packets, which should trigger + the creation of a binding in a SAVI instance, are lost before + reaching the SAVI instance. + + o A SAVI instance loses a binding, for example, due to a restart. + + o The link topology changes, resulting in hosts to communicate + through SAVI instances that do not have a binding for those hosts' + IP addresses. + + To limit the disruption that missing bindings for legitimate IP + addresses can have, the SAVI method includes a mechanism for reactive + binding creation based on regular packets. This mechanism + supplements the proactive binding creation based on IP address + configuration packets. Reactive binding creation occurs when a SAVI + instance recognizes excessive drops of regular packets originating + from the same IP address. The SAVI instance then verifies whether + said IP address is unique on the link. How the verification is + carried out depends on the IP address configuration method that the + SAVI instance supports. The SAVI method variant for Stateless + Address Autoconfiguration and for Secure Neighbor Discovery verifies + an IP address through the Duplicate Address Detection procedure. The + SAVI method variant for DHCP verifies an IP address through a DHCP + Lease Query message exchange with the DHCP server. If verification + indicates that the IP address is unique on the link, the SAVI + instance creates a binding for the IP address. Otherwise, no binding + is created, and packets sent from the IP address continue to be + dropped. These reliability issues should be addressed in all the + SAVI protocols describing particular SAVI methods. + + + + + + + +Wu, et al. Informational [Page 9] + +RFC 7039 SAVI Framework October 2013 + + +6. Scenario with Multiple Assignment Methods + + While multiple assignment methods can be used on the same link, the + SAVI device may have to deal with a mix of binding discovery methods. + If the address prefix used for each assignment method is different, + the "mix scenario" behaves the same as with the scenario with only + one assignment method. If different address assignment methods are + used to assign addresses from the same prefix, additional + considerations are needed because one binding mechanism may create a + binding violating an existing binding from another binding mechanism, + e.g., binding from First-Come, First-Served (FCFS) SAVI [RFC6620] may + violate a binding from SAVI-DHCP [SAVI-DHCP]. Thus, the collision + between different SAVI mechanisms in the mix scenario must be handled + in case more than one address assignment method is used to assign + addresses from the same prefix. + + The prioritization of relationships between different address + assignment methods is used as the basis to solve possible collisions. + Current standard documents of address assignment methods (DHCP + [RFC2131], DHCPv6 [RFC3315], SLAAC [RFC4862], and SEND [RFC3971]) + have implied the prioritization relationship in general cases. + However, in some scenarios, the default prioritization level may not + be quite suitable. A configurable prioritization level should be + supported in the SAVI solution for the mix scenario [SAVI-MIX]. + +7. Prefix Configuration + + Before setting up a host-level granularity binding, it is important + to configure correct prefixes on the SAVI device. This document + suggests a set of 3 prefix configuration mechanisms at a SAVI device: + + o Manual Prefix Configuration: The allowed prefix scope of IPv4 + addresses, IPv6 static addresses, IPv6 addresses assigned by + Stateless Address Autoconfiguration (SLAAC), and IPv6 addresses + assigned by DHCPv6 can be set manually at the SAVI device. + FE80::/64 is always a feasible prefix in IPv6. + + o Prefix Configuration by Router Advertisement (RA) Snooping: The + allowed prefix scope of IPv6 static addresses and IPv6 addresses + assigned by SLAAC can be set at the SAVI device through snooping + an RA message at the SAVI device. + + o Prefix Configuration by DHCP Prefix Delegation (DHCP-PD) Snooping: + The allowed prefix scope of IPv6 static addresses, IPv6 addresses + assigned by SLAAC, and IPv6 addresses assigned by DHCPv6 can be + set through snooping a DHCP-PD message at the SAVI device. + + + + + +Wu, et al. Informational [Page 10] + +RFC 7039 SAVI Framework October 2013 + + + If some of the prefix scopes are set to have no prefix, the + implication is that the corresponding address assignment method is + not allowed in the network. + + There is no need to explicitly present these prefix scopes, but these + restrictions should be used as the premier check in binding setup. + + When SAVI is partially deployed, binding may fail as RA messages and + DHCP-PD can be spoofed. So, it is recommended that Manual Prefix + Configuration be used unless SAVI gets fully deployed. + +8. Acknowledgments + + The authors would like to thank the SAVI working group for a thorough + technical discussion on the design and the framework of the SAVI + method as captured in this document, in particular Erik Nordmark, + Guang Yao, Eric Levy-Abegnoli, and Alberto Garcia. Thanks also to + Torben Melsen for reviewing this document. + +9. Security Considerations + + This document only discusses the possible methods to mitigate the + usage of forged IP addresses. Some such methods may rely on + cryptographic methods, but not all do. As a result, it is generally + not possible to prove address ownership in any strong sense. If a + binding anchor is not exclusive for each IP address, or is without + strong security, addresses can still be forged. Besides, the binding + may not accord with the address management requirement, which can be + more specified for each client. However, given no new protocol is + introduced, the improvements are still acceptable. If strong + security is required when using IP addresses, then cryptographic- + based authentication must be used as it is the only way to provide + strong security. + + Section 2 explains how the preferred location of SAVI instances is + close to hosts. However, in some cases, this makes the SAVI + instances themselves vulnerable and may defeat the purpose of + deploying a SAVI solution. For instance, deployments should not + place SAVI functionality in devices that are physically exposed. + Even if the device correctly monitors the source address usage of + hosts, an attacker could replace the device with one that does not + check or hook up to a trusted interface from the device to the rest + of the network. Similarly, deployments where SAVI instances are + distributed across administrative boundaries are not recommended. + For instance, in most cases, it would be undesirable to deploy a + distributed SAVI solution on both sides of a customer-provider + interface if the solution required trusting the correct operation of + the SAVI devices on the other side of the interface. + + + +Wu, et al. Informational [Page 11] + +RFC 7039 SAVI Framework October 2013 + + +10. References + +10.1. Normative References + + [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC + 2131, March 1997. + + [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., + and M. Carney, "Dynamic Host Configuration Protocol for + IPv6 (DHCPv6)", RFC 3315, July 2003. + + [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure + Neighbor Discovery (SEND)", RFC 3971, March 2005. + + [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless + Address Autoconfiguration", RFC 4862, September 2007. + + [RFC5026] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6 + Bootstrapping in Split Scenario", RFC 5026, October 2007. + + [RFC5739] Eronen, P., Laganier, J., and C. Madson, "IPv6 + Configuration in Internet Key Exchange Protocol Version 2 + (IKEv2)", RFC 5739, February 2010. + + [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, + "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC + 5996, September 2010. + + [RFC6620] Nordmark, E., Bagnulo, M., and E. Levy-Abegnoli, "FCFS + SAVI: First-Come, First-Served Source Address Validation + Improvement for Locally Assigned IPv6 Addresses", RFC + 6620, May 2012. + + [RFC6959] McPherson, D., Baker, F., and J. Halpern, "Source Address + Validation Improvement (SAVI) Threat Scope", RFC 6959, + May 2013. + +10.2. Informative References + + [BA2007] Baker, F., "Cisco IP Version 4 Source Guard", Work in + Progress, November 2007. + + [BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering: + Defeating Denial of Service Attacks which employ IP + Source Address Spoofing", BCP 38, RFC 2827, May 2000. + + [BCP84] Baker, F. and P. Savola, "Ingress Filtering for + Multihomed Networks", BCP 84, RFC 3704, March 2004. + + + +Wu, et al. Informational [Page 12] + +RFC 7039 SAVI Framework October 2013 + + + [SAVI-DHCP] Bi, J., Wu, J., Yao, G., and F. Baker, "SAVI Solution for + DHCP", Work in Progress, June 2013. + + [SAVI-MIX] Bi, J., Yao, G., Halpern, J., and E. Levy-Abegnoli, "SAVI + for Mixed Address Assignment Methods Scenario", Work in Progress, May + 2013. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Wu, et al. Informational [Page 13] + +RFC 7039 SAVI Framework October 2013 + + +Authors' Addresses + + Jianping Wu + Tsinghua University + Computer Science, Tsinghua University + Beijing 100084 + China + + EMail: jianping@cernet.edu.cn + + + Jun Bi + Tsinghua University + Network Research Center, Tsinghua University + Beijing 100084 + China + + EMail: junbi@tsinghua.edu.cn + + + Marcelo Bagnulo + Universidad Carlos III de Madrid + Avenida de la Universidad 30 + Leganes, Madrid 28911 + Spain + + EMail: marcelo@it.uc3m.es + + + Fred Baker + Cisco Systems + Santa Barbara, CA 93117 + United States + + EMail: fred@cisco.com + + + Christian Vogt (editor) + 3507 Palmilla Drive + San Jose, CA 95134 + United States + + EMail: mail@christianvogt.net + + + + + + + + +Wu, et al. Informational [Page 14] + |