The MPLS WG Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] [mpls] Proposed G.8110.1 Amendment 1 Laision response
In response to the following liaison https://datatracker.ietf.org/public/liaison_detail.cgi?detail_id=287 concerning G.8110.1 Amendment 1 I propose that we respond with the following statement: "The PWE3 WG agrees with the concerns expressed by the MFA and wishes to be copied on the result of the SG15 analysis of these concerns. "The PWE3 WG will perform a further review of G.8110.1 Amendment 1 and will respond in time for the ITU SG15 meeting in June." I need to send this out in the next couple of days in time for their interim meeting next week. I append the MFA text of the MFA liaison response. - Stewart =============== The MFA Forum thanks ITU-T SG 15 for the liaisons from Q12/15, (from Geneva meeting) on an amendment to G.8110.1 covering the architectural aspects of T-MPLS unidirectional p2mp connections, T-MPLS OAM and T-MPLS survivability. The MFA Forum also appreciates and thanks Q12/15 for asking for comments on the proposed draft G.8110.1 Amendment 1. The text below provides comments on the draft Amendment 1. 1 Point-to-multipoint connections The text for point-to-multipoint connections does not provide any details. The current text only indicates that a unidirectional point-to-multipoint sub-network connection broadcasts the traffic from the root to a number of leaves. The Recommendation G.8110.1 describes the functional architecture of Transport MPLS using the components in G.8110. However, Recommendation G.8110 does not specify any details of point-to-multipoint LSPs and therefore it is insufficient to base G.8110.1 on G.8110 alone. With out providing additional details, it is not possible specify the point-to-multipoint LSPs. Some of the missing details are: Next hop label forwarding entries or packet replication; FEC; data plane (e.g., tree or point to point); Label assignment and Hierarchy. Just as Recommendation G.8110 referred to the base IETF Recommendations in its scope (e.g., RFC 3031, etc.), the MFA Forum suggests that G.8110.1 similarly refer in its scope to the base IETF RFCs on point to multipoint to provide these details. As was done previously, it is necessary to describe the functional architecture of MPLS point-to-multipoint using the modeling methodology described in ITU-T Recs G.805 and G.809. Following the same method used to develop G.8110 therefore, the basis for this work is the MPLS point-to-multipoint specification in the following IETF RFCs (Drafts). IETF defines data plane for p2mp connections, two label distribution protocols for setting up p2mp connections (RSVP-TE and LDP). IETF defines two possible applications of p2mp connections: 2547 VPNs and VPLS. IETF also extends MPLS architecture by defining upstream-assigned labels and the notion of context-specific label space. IETF defines extensions to RSVP-TE and LDP to support distribution of upstream-assigned labels. Upstream-assigned labels are used for (a) optimizing p2mp operations over multi-access media (LANs), and (b) p2mp LSP hierarchy. The list of relevant Internet Drafts: p2mp Data plane: draft-ietf-mpls-multicast-encaps p2mp Label distribution protocols (for information): draft-ietf-mpls-ldp-p2mp draft-ietf-mpls-rsvp-te-p2mp Upstream assigned labels: draft-ieft-mpls-upstream-label Extensions to RSVP-TE and LDP in support of upstream- assigned labels (for information): draft-ietf-mpls-rsvp-upstream draft-ietf-mpls-ldp-upstream p2mp OAM (for information): draft-ietf-mpls-p2mp-oam-reqs draft-ietf-mpls-p2mp-lsp-ping It is not clear what is supported in T-MPLS for point-to- multipoint connections. 1.1 EtherType for Point-to-multipoint frames T-MPLS uses the same data-link protocol ID (e.g. EtherType), frame format and forwarding semantics as defined for MPLS frames. For point-to-point frames EtherType 0x8847 is used over Ethernet interfaces. It is not clear from the current draft how Ethertype is used after point-to-multipoint connections are added. IETF is working updating RFC 3032 MPLS Multicast Encapsulations. RFC 3032 established two data link layer codepoints for MPLS: one to indicate that the data link layer frame is carrying an MPLS unicast packet, and the other to indicate that the data link layer frame is carrying an MPLS multicast packet. The new specification updates RFC3032 by redefining the meaning of these two codepoints. The former "multicast codepoint" is now to be used only on multi-access media, and it is to mean "the top label of the following label stack is an upstream-assigned label". The former "unicast codepoint" is to be used in all other cases. Whether the data link layer payload is a unicast MPLS packet or a multicast MPLS packet is now to be determined by looking up the top label, rather than by the codepoint. The new draft also specifies “MAC DA” field of an Ethernet frame which carries MPLS multicast packet. Please see IETF draft “MPLS Multicast Encapsulations” draft-ietf-mpls-multicast-encaps-02.txt, September 2006. 1.2 OAM support for Point-to-multipoint Point-to multipoint LSPs are unidirectional. However, there is T-MPLS OAM information, such as BDI, “Linktrace-Reply” and “Loopback-Reply”, that should be transmitted from the leaves to the root. The architecture does not specify how the data is transmitted from the leaves to the root. With out this capability it is not possible to support some of the OAM capabilities. 2 Generic requirements One of the major capabilities missing in the T-MPLS architecture is security capabilities. The following security capabilities are suggested for inclusion. These requirements are derived from the MFA Forum Service provider council MPLS-ICI requirements. Since T-MPLS supports NNI, these requirements are applicable. The capabilities are: • Authentication of OAM messages with MD5 or other. • Control of labels used over NNI • IPSec all tunnels over which control messages are exchanged. The MFA Forum thanks ITU-T SG 15 for the opportunity to provide comments and suggestions in relation to T-MPLS as a packet transport network technology. Further, the MFA Forum is interested in receiving updates on this and the work you are initiating to address control plane aspects. The MFA Forum meets from March 6-8, 2007 in Chicago, IL USA. _______________________________________________ mpls mailing list mpls@lists.ietf.org https://www1.ietf.org/mailman/listinfo/mpls
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