INTERNET-DRAFTRouting WG V. Gill draft-ietf-rtgwg-rfc3682bis-05.txtInternet-Draft J. Heasley D. Meyer Category Proposed StandardObsoletes: RFC3682 (if approved) D. Meyer Intended status: Standards Track P. Savola Expires: March 1, 2007 August 28, 2006 The Generalized TTL Security Mechanism (GTSM) <draft-ietf-rtgwg-rfc3682bis-05.txt> Status of this Memodraft-ietf-rtgwg-rfc3682bis-06.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 3 of RFC 3667.By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomebecomes aware will be disclosed, in accordance with RFC 3668.Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This document is a product of the RTGWG WG. Comments should be addressed to the authors, or the mailing list at firstname.lastname@example.org.Internet-Draft will expire on March 1, 2007. Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved.(2006). Abstract The use of a packet's Time to Live (TTL) (IPv4) or Hop Limit (IPv6) to protect a protocol stack from CPU-utilization based attacksverify whether the packet originated within the same link has been proposedused in many settings (see for example, RFC 2461).recent protocols. This document generalizes these techniques for use by other protocols such as BGP (RFC 1771), Multicast Source Discovery Protocol (MSDP), Bidirectional Forwarding Detection, and Label Distribution Protocol (LDP) (RFC 3036). While the Generalized TTL Security Mechanism (GTSM) is most effective in protecting directly connected protocol peers, it can also provide a lower level of protection to multi-hop sessions. GTSM is not directly applicable to protocols employing flooding mechanisms (e.g., multicast), and use of multi-hop GTSM should be considered on a case-by-case basis.this technique. This document obsoletes RFC 3682. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Assumptions Underlying GTSM.GTSM . . . . . . . . . . . . . . . . . 43 2.1. GTSM Negotiation.Negotiation . . . . . . . . . . . . . . . . . . . . . 4 2.2. Assumptions on Attack Sophistication.Sophistication . . . . . . . . . . . 54 3. GTSM Procedure . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Multi-hop Scenarios4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 3.1.1. Intra-domain Protocol Handling5. Security Considerations . . . . . . . . . . . . . 7 4. Acknowledgments.. . . . . . 6 5.1. TTL (Hop Limit) Spoofing . . . . . . . . . . . . . . . . . 7 5. Security Considerations.5.2. Tunneled Packets . . . . . . . . . . . . . . . . . . . 7 5.1. TTL (Hop Limit) Spoofing.. . 7 5.2.1. IP in IP . . . . . . . . . . . . . . . 8 5.2. Tunneled Packets.. . . . . . . . 8 5.2.2. IP in MPLS . . . . . . . . . . . . . 8 5.2.1. IP in IP. . . . . . . . . 8 5.3. Multi-Hop Protocol Sessions . . . . . . . . . . . . . . . 9 5.2.2. IP in MPLS6. Applicability Statement . . . . . . . . . . . . . . . . . . . 10 7. IANA Considerations . . . . 10 5.3. Multi-Hop Protocol Sessions. . . . . . . . . . . . . . . . 11 6. Applicability Statement.. 10 8. Changelog . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations.. . . . . . . 10 8.1. Changes between -05 and -06 . . . . . . . . . . . . . . . 12 8.10 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1.11 9.1. Normative References.References . . . . . . . . . . . . . . . . . . . 12 8.2.11 9.2. Informative References.References . . . . . . . . . . . . . . . . . . 14 9.11 Appendix A. Multihop GTSM . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 14 1.. . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 1. Introduction The Generalized TTL Security Mechanism (GTSM) is designed to protect a router's TCP/IPIP based control plane from CPU-utilization based attacks. In particular, while cryptographic techniques can protect the router-basedrouter- based infrastructure (e.g., BGP [RFC1771], [RFC1772])[RFC4271], [RFC4272]) from a wide variety of attacks, many attacks based on CPU overload can be prevented by the simple mechanism described in this document. Note that the same technique protects against other scarce-resource attacks involving a router's CPU, such as attacks against processor- line card bandwidth. GTSM is based on the fact that the vast majority of protocol peerings are established between routers that are adjacent [PEERING]. Thus most protocol peerings are either directly between connected interfaces or at the worst case, are between loopback and loopback, with static routes to loopbacks. Since TTL spoofing is considered nearly impossible, a mechanism based on an expected TTL value can provide a simple and reasonably robust defense from infrastructure attacks based on forged protocol packets from outside the network. Note, however, that GTSM is not a substitute for authentication mechanisms. In particular, it does not secure against insider on-the- wireon- the-wire attacks, such as packet spoofing or replay. Finally, the GTSM mechanism is equally applicable to both TTL (IPv4) and Hop Limit (IPv6), and from the perspective of GTSM, TTL and Hop Limit have identical semantics. As a result, in the remainder of this document the term "TTL" is used to refer to both TTL or Hop Limit (as appropriate). 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 BCP 14,RFC 2119 [RFC2119]. 2. Assumptions Underlying GTSM GTSM is predicated upon the following assumptions: (i)1. The vast majority of protocol peerings are between adjacent routers [PEERING]. (ii)2. It is common practice for many service providers to ingress filter (deny) packets that have the provider's loopback addresses as the source IP address. (iii)3. Use of GTSM is OPTIONAL, and can be configured on a per-peer (group) basis. (iv)4. The peer routers both implement GTSM. 5. The router supports a method of classifying traffic destined forto use separate resource pools (e.g., queues, processing quotas) for differently classified traffic. Note that this document does not prescribe further restrictions that a router may apply to the route processor into interesting/controlpackets not matching the GTSM filtering rules, such as dropping packets that do not match any configured protocol session and rate-limiting the rest. This document also does not suggest the actual means of resource separation, as those are hardware and not-control queues. (v)implementation-specific. The peer routers both implement GTSM.possibility of DoS attack prevention, however, is based on the assumption that packet classification and separation of their paths is done before they go through a scarce resource in the system. In practice, this means that, the closer GTSM processing is done to the line-rate hardware, the more resistant the system is to the DoS attacks. 2.1. GTSM Negotiation This document assumes that, when used with existing protocols, GTSM will be manually configured between protocol peers. That is, no automatic GTSM capability negotiation, such as is envisioned by RFC 2842 [RFC2842]3392 [RFC3392] is assumed or defined. If a new protocol is designed with built-in GTSM support, then it is recommended that procedures are always used for sending and validating received protocol packets (GTSM is always on, see for example [RFC2461]). If, however, dynamic negotiation of GTSM support is necessary, protocol messages used for such negotiation MUST be authenticated using other security mechanisms to prevent DoS attacks. Also note that this specification does not offer a generic GTSM capability negotiation mechanism, so messages of the protocol augmented with the GTSM behavior will need to be used if dynamic negotiation is deemed necessary. 2.2. Assumptions on Attack Sophistication Throughout this document, we assume that potential attackers have evolved in both sophistication and access to the point that they can send control traffic to a protocol session, and that this traffic appears to be valid control traffic (i.e., has the source/destination of configured peer routers). We also assume that each router in the path between the attacker and the victim protocol speaker decrements TTL properly (clearly, if either the path or the adjacent peer is compromised, then there are worse problems to worry about). Since the vast majority of ourpeerings are between adjacent routers, we can set the TTL on the protocol packets to 255 (the maximum possible for IP) and then reject any protocol packets that come in from configured peers which do NOT have an inbound TTL of 255. GTSM can be disabled for applications such as route-servers and other large diameter multi-hop peerings. In the event that an the attack comes in from a compromised multi-hop peering, that peering can be shut down (a method to reduce exposure to multi-hop attacks is outlined below). 3. GTSM Procedure If GTSM is not built into the protocol and used as an additional feature (e.g., for BGPv4,BGP, LDP, or LDP),MSDP), it SHOULD NOT be enabled by default. Each session protected withIf GTSM is associated withenabled for a variable TrustRadius that denotes the distance from the node performing the GTSM check to the trusted sources ofprotocol packets. (i) If GTSM is enabled, an implementation performssession, the following procedure: (a) For directly connected routers, o Setsteps are added to the outboundIP packet sending and reception procedures: Sending protocol packets: The TTL field in all IP packets used for thetransmission of messages associated with GTSM-enabled protocol connectionsessions MUST be set to 255. o For each configured protocol peer: Update the receive path Access Control List (ACL)This also related error handling messages such as TCP RSTs or firewall to only allow protocol packets to pass onto the Route Processor (RP) that haveICMP errors. On some architectures, the correct <source, srcPort, destination, destPort, TTL> tuple. TheTTL must either be 255 (for a directly connected peer), or 255 - TrustRadius for a multi-hop peer. We specify a range here to achieveof control plane originated traffic is under some robustness to changes in topology. Any directly connected (i.e., such as may be usedconfigurations decremented in a BGP implementation to determine whether a peer is directly connected) checkthe forwarding plane. The TTL of GTSM-enabled sessions MUST NOT be disabled for such peerings. It is assumed that a receive path ACL is an ACL that is designeddecremented. Receiving protocol packets: The GTSM packet identification step associates each received packet addressed to the router's control which packetsplane with one of the following three trustworthiness categories: + Unknown: these are allowed to go topackets that cannot be associated with any registered GTSM-enabled session, and hence GTSM cannot make any judgement on the RP. This procedure will only allow protocollevel of risk associated with them. + Trusted: these are packets from adjacent routerthat have been identified as belonging to pass ontoone of the RP. (b) Otherwise, aGTSM-enabled sessions, and their TTL value in a received packet is considered valid if it is not less than (255 - TrustRadius). In summary, if TrustRadius is set to zero for a particular session, only packets from directly connected neighbors (TTL=255) will be considered valid. As a result, TrustRadiusvalues greater than 0 will allow packets from more remote nodes to be accepted. (ii) If GTSM is not enabled, normal protocol behavior is followed. 3.1. Multi-hop Scenarios When a multi-hop protocol session is required, we setare within the expected TTL valuerange. + Dangerous: these are packets that have been identified as belonging to be 255 - TrustRadius. This approach provides a qualitatively lower degreeone of security forthe protocol implementing GTSM (i.e., a DoS attack could theoretically be launched by compromising some box inGTSM-enabled sessions, but their TTL values are NOT within the path). However,expected range, and hence GTSM will still catch the vast majority of observed DDoS attacks (launched from outside the network) againstbelieves there is a given protocol. Noterisk that sincethe numberpackets have been spoofed. The exact policies applied to packets of hops can change rapidly in real network situations, it is considered that GTSM maydifferent classifications are not be able to handlepostulated in this scenario adequatelydocument and an implementation MAY provide OPTIONAL support. 3.1.1. Intra-domain Protocol Handling In general, GTSM SHOULD NOT used for intra-domain protocol peers or adjacencies. The special case of iBGP peers canare expected to be protected by filtering atconfigurable. Configurability is likely necessary particular with the network edge for any packet that has a source address of onetreatment of related messages such as ICMP errors and TCP RSTs. It should be noted that fragmentation may restrict the loopback addresses used foramount of information available to the intra-domain peering. In addition,classification. However, by default, the current best practice is to further protect such peers or adjacenciesimplementations: + SHOULD ensure that packets classified as Dangerous do not compete for resources with an MD5 signature [RFC2385].packets classified as Trusted or Unknown. + MUST NOT drop (as part of GTSM processing) packets classified as Trusted or Unknown. + MAY drop packets classified as Dangerous. 4. Acknowledgments The use of the TTL field to protect BGP originated with many different people, including Paul Traina and Jon Stewart. Ryan McDowell also suggested a similar idea. Steve Bellovin, Jay Borkenhagen, Randy Bush, Alfred Hoenes, Vern Paxon, Pekka Savola,Robert Raszuk and Alex Zinin also provided useful feedback on earlier versions of this document. David Ward provided insight on the generalizationgeneralization of the original BGP-specific idea. Alex Zinin and Alia Atlas provided significant amount of feedback for the newer versions of the original BGP-specific idea.document. 5. Security Considerations GTSM is a simple procedure that protects single hop protocol sessions, except in those cases in which the peer has been compromised. In particular, it does not protect against the wide range of on-the-wire attacks; protection from these attacks requires more rigorous security mechanisms. 5.1. TTL (Hop Limit) Spoofing The approach described here is based on the observation that a TTL (or Hop Limit) value of 255 is non-trivial to spoof, since as the packet passes through routers towards the destination, the TTL is decremented by one. As a result, when a router receives a packet, it may not be able to determine if the packet's IP address is valid, but it can determine how many router hops away it is (again, assuming none of the routers in the path are compromised in such a way that they would reset the packet's TTL). Note, however, that while engineering a packet's TTL such that it has a particular value when sourced from an arbitrary location is difficult (but not impossible), engineering a TTL value of 255 from non-directly connected locations is not possible (again, assuming none of the directly connected neighbors are compromised, the packet hasn't been tunneled to the decapsulator, and the intervening routers are operating in accordance with RFC 791 [RFC791]).[RFC0791]). 5.2. Tunneled Packets The security of any tunneling technique depends heavily on authentication at the tunnel endpoints, as well as how the tunneled packets are protected in flight. Such mechanisms are, however, beyond the scope of this memo. An exception to the observation that a packet with TTL of 255 is difficult to spoof occursmay occur when a protocol packet is tunneled to a decapsulator who then forwards the packet to a directly connected protocol peer. In this case the decapsulator (tunnel endpoint) can either beand the penultimate hop, ortunnel is not integrity-protected (i.e., the last hop itself. A related case arises whenlower layer is compromised). When the protocol packet is tunneled directly to the protocol peer (the protocol peer is the decapsulator).decapsulator), the GTSM provides no added protection as the security depends entirely on the integrity of the tunnel. When the protocol packet is encapsulated in IP, it is possibletunneled to spoofthe TTL. It may also be impossible to legitimately getpenultimate hop which then forwards the packet to the protocol peer witha directly connected protocol peer, TTL of 255,is decremented as described below except in the IP in MPLSsome myriad Bump-in-the- Wire (BITW) cases [BITW]. In IP-in-MPLS cases described below. Finally, note thatbelow, the security of any tunneling technique depends heavily on authenticationTTL is always decremented by at the tunnel endpoints, as well as how the tunneled packets are protected in flight. Such mechanisms are, however, beyond the scope of this memo.least one. 5.2.1. IP in IP Protocol packets may be tunneled over IP directly to a protocol peer, or to a decapsulator (tunnel endpoint) that then forwards the packet to a directly connected protocol peer (e.g., in IP-in-IP [RFC2003], GRE [RFC2784], or various forms of IPv6-in-IPv4 [RFC2893]).[RFC4213]). These cases are depicted below. Peer router ---------- Tunnel endpoint router and peer TTL=255 [tunnel] [TTL=255 at ingress] [TTL=255 at egress] Peer router ------------------ Tunnel endpoint router ----- On-link peer TTL=255 [tunnel] [TTL=255 at ingress] [TTL=254 at ingress] [TTL=254 at egress] In the first case, in which the encapsulated packet is tunneled directly to the protocol peer, the encapsulated packet's TTL can be set arbitrary value. In the second case, in which the encapsulated packet is tunneled to a decapsulator (tunnel endpoint) which then forwards it to a directly connected protocol peer, RFC 2003 specifies the following behavior: When encapsulating a datagram, the TTL in the inner IP header is decremented by one if the tunneling is being done as part of forwarding the datagram; otherwise, the inner header TTL is not changed during encapsulation. If the resulting TTL in the inner IP header is 0, the datagram is discarded and an ICMP Time Exceeded message SHOULD be returned to the sender. An encapsulator MUST NOT encapsulate a datagram with TTL = 0. Hence the inner IP packet header's TTL, as seen by the decapsulator, can be set to an arbitrary value (in particular, 255). As a result, it may not be possible to deliver the protocol packet to the peer with a TTL of 255. 5.2.2. IP in MPLS Protocol packets may also be tunneled over MPLS to a protocol peer which either the penultimate hop (when the penultimate hop popping (PHP) is employed [RFC3032]), or one hop beyond the penultimate hop. These cases are depicted below. Peer router ------------------ Penultimate Hop (PH) and peer TTL=255 [tunnel] [TTL=255 at ingress] [TTL<=254 at egress] Peer router ------------------ Penultimate Hop -------- On-link peer TTL=255 [tunnel] [TTL=255 at ingress] [TTL <=254 at ingress] [TTL<=254 at egress] TTL handling for these cases is described in RFC 3032. RFC 3032 states that when the IP packet is first labeled: ... the TTL field of the label stack entry MUST BE set to the value of the IP TTL field. (If the IP TTL field needs to be decremented, as part of the IP processing, it is assumed that this has already been done.) When the label is popped: When a label is popped, and the resulting label stack is empty, then the value of the IP TTL field SHOULD BE replaced with the outgoing TTL value, as defined above. In IPv4 this also requires modification of the IP header checksum. where the definition of "outgoing TTL" is: The "incoming TTL" of a labeled packet is defined to be the value of the TTL field of the top label stack entry when the packet is received. The "outgoing TTL" of a labeled packet is defined to be the larger of: a) one less than the incoming TTL, b) zero. In either of these cases, the minimum value by which the TTL could be decremented would be one (the network operator prefers to hide its infrastructure by decrementing the TTL by the minimum number of LSP hops, one, rather than decrementing the TTL as it traverses its MPLS domain). As a result, the maximum TTL value at egress from the MPLS cloud is 254 (255-1), and as a result the check described in section 3 will fail. 5.3. Multi-Hop Protocol Sessions While theGTSM method is less effective for multi-hop protocol sessions, it does close the window on several forms of attack. However, in thecould possibly offer a slightly more limited security properties also when used with multi-hop scenario GTSM is an OPTIONAL extension. Protection of theprotocol infrastructure beyond what is provided by the GTSM method will likely require cryptographic machinery such as is envisioned by Secure BGP (S-BGP) [SBGP1,SBGP2], and/or other extensions. Finally, note that in the multi-hop case described above, we specify a range of acceptable TTLs in order to achieve some robustness to topology changes. This robustness to topological change comes at the cost of the loss of some robustnesssessions (see Appendix A), we do not specify GTSM for multi-hop scenarios due to different formssimplicity, lack of attack.deployment and implementation. 6. Applicability Statement As described above,GTSM is only applicable to environments with inherently limited topologies (and is most effective in those cases where protocol peers are directly connected). In particular, its application should be limited to those cases in which protocol peers are eitherdirectly connected, orconnected. Experimentation on GTSM's applicability and security properties is needed in whichmulti-hop scenarios. The multi-hop scenarios where GTSM might be applicable is expected to have the following characteristics: the topology between peers is fairly static and well known, and in which the intervening network (between the peers) is trusted. 7. IANA Considerations This document createsrequires no new requirements on IANA namespaces [RFC2434].action from IANA. 8. ReferencesChangelog NOTE to the RFC-editor: please remove this section before publication. 8.1. Changes between -05 and -06 o Clarify the assumptions wrt. resource separation and protection based on comments from Alex Zinin. o Rewrite the GTSM procedure based on text from Alex Zinin. o Reduce TrustRadius and multi-hop scenarios to a mention in an Appendix. o Describe TCP-RST, ICMP error and "related messages" handling. o Update the tunneling security considerations text. o Editorial updates (e.g., shortening the abstract). 9. References 9.1. Normative References [RFC791][RFC0791] Postel, J., "Internet Protocol Specification",Protocol", STD 5, RFC 791, September 1981. [RFC1771] Rekhter, Y. and T. Li (Editors), "A Border Gateway Protocol (BGP-4)", RFC 1771, March 1995. [RFC1772] Rekhter, Y. and P. Gross, "Application of the Border Gateway Protocol in the Internet", RFC 1772, March 1995.[RFC2003] Perkins, C., "IP Encapsulation withwithin IP", RFC 2003, October 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 Signature Option", RFC 2385, August 1998.[RFC2461] Narten, T., Nordmark, E.E., and W. Simpson, "Neighbor DiscoverDiscovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000. [RFC2842] Chandra, R. and J. Scudder, "Capabilities Advertisement with BGP-4", RFC 2842, May 2000. [RFC2893] Gilligan, R. and E. Nordmark, "Transition Mechanisms for IPv6 Hosts and Routers", RFC 2893, August 2000. [RFC3036] Andersson, L., Doolan, P., Feldman, N., Fredette, A. and B. Thomas, "LDP Specification", RFC 3036, January 2001.[RFC3032] Rosen, E.E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T.T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, January 2001. [RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78,[RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement with BGP-4", RFC 3667, February, 2004. [RFC3668] Bradner, S., "Intellectual Property Rights in IETF Technology", BCP 79,3392, November 2002. [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", RFC 3668, February, 2004. [SBGP1] Kent, S., C. Lynn,4213, October 2005. [RFC4271] Rekhter, Y., Li, T., and K. Seo, "SecureS. Hares, "A Border Gateway Protocol (Secure-BGP)", IEEE Journal on Selected Areas in Communications, volume 18, number 4, April 2000. [SBGP2] Kent,4 (BGP-4)", RFC 4271, January 2006. [RFC4272] Murphy, S., C. Lynn, J. Mikkelson, and K. Seo, "Secure Border Gateway Protocol (S-BGP) -- Real World Performance and Deployment Issues", Proceedings of the IEEE Network and Distributed System"BGP Security Symposium, February, 2000. 8.2.Vulnerabilities Analysis", RFC 4272, January 2006. 9.2. Informative References [BFD] Katz, D.[BITW] "Thread: 'IP-in-IP, TTL decrementing when forwarding and D. Ward, "Bidirectional Forwarding Detection", draft-ietf-bfd-base-02.txt, Work in Progress.BITW' on int-area list, Message-ID: <Pine.LNX.email@example.com>", June 2006, <http://www1.ietf.org/mail-archive/web/ int-area/current/msg00267.html>. [PEERING] Empirical"Empirical data gathered from the Sprint and AOL backbones, October,backbones", October 2002. [RFC2434] Narten, T.,Appendix A. Multihop GTSM NOTE: This is a non-normative part of the specification. The main applicability of GTSM is for directly connected peers. GTSM could be used for non-directly connected sessions as well, where the recipient would check that the TTL is within "TrustRadius" (e.g., 1) of 255 instead of 255. As such deployment is expected to have a more limited applicability and H. Alvestrand, "Guidelines for Writing an IANA Considerations Sectiondifferent security implications, it is not specified in RFCs", BCP 26, RFC 2434, October 1998. [RFC3618] Meyer, D. and W. Fenner, Eds., "The Multicast Source Discovery Protocol (MSDP)", RFC 3618, October 2003. 9.this document. Authors' Addresses Vijay Gill EMail:Email: firstname.lastname@example.org John Heasley EMail:Email: email@example.com David Meyer EMail:Email: firstname.lastname@example.org Pekka Savola Espoo Finland Email: email@example.com Full Copyright Statement Copyright (C) The Internet Society (2006). 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