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MVPN Profiles

MVPN Profiles. Why do we need “profiles”? By design, architecture provides many choices: PE-PE C-multicast routing info distribution: PIM or BGP Multicast data distribution infrastructure: GRE encaps with PIM trees, MPLS encaps with RSVP-TE P2MP LSPs mLDP P2MP LSPs mLDP MP2MP LSPs

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MVPN Profiles

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  1. IETF 70 L3VPN WG MVPN Profiles • Why do we need “profiles”? • By design, architecture provides many choices: • PE-PE C-multicast routing info distribution: PIM or BGP • Multicast data distribution infrastructure: • GRE encaps with PIM trees, • MPLS encaps with • RSVP-TE P2MP LSPs • mLDP P2MP LSPs • mLDP MP2MP LSPs • Ingress replication with IP-based encaps … • No consensus (and not desirable) to eliminate all but one choice • No vendor wants to implement all possible combinations of options

  2. IETF 70 L3VPN WG What’s Good About Specifying Profiles? • Profile: A set of options which are: • useful together, and • wanted by a customer • Customer can ask for the profile it wants: • conformance to a profile is well-defined • i.e., multi-vendor interoperability is possible.‏ • Decisions can be based on customer demand, rather than IETF debate.

  3. IETF 70 L3VPN WG FUD About Profiles • “Wouldn’t it be better to have fewer options, or even no options?” • Only if you believe that one size fits all • Only if there’s enough real world experience to show that only one set of options is needed • Only if there’s real consensus behind a single profile • “Unless one profile is mandatory, there’s no guaranteed interoperability” • In fact, it doesn’t matter if one profile is mandatory, unless that’s the one that everyone wants!

  4. IETF 70 L3VPN WG Profiles Using PIM Control Plane • “PIM? Oh, that’s so passe!”  • Some facts: • All existing deployments use PIM • Not going away tomorrow • One big advantage: known to work, many years experience behind it • Scalability issues do exist, but not even close to approaching them in practice

  5. IETF 70 L3VPN WG Isn’t BGP the “new generation?” • WG docs do not favor either PIM or BGP over the other • BGP for multicast: new, experimental, with certain risks: • Increased J/P latency • Impact on other uses of BGP • Sparse Mode: we think BGP handles sparse mode okay, but there are some differences from PIM, impact remains to be seen • Some customer deployments use PIM in odd ways (e.g., use more control than data) that may not fit well with BGP • BGP great at disseminating state, less great at handling transactions • many PIM operations are transactional • this caused the BGP solution to become more complicated than originally envisaged, at least by me

  6. IETF 70 L3VPN WG Profiles with PIM • Primary Focus is one two profiles: • PIM+GRE • Existing deployments • Really two “sub-profiles”: • Legacy sub-profile that corresponds exactly to existing deployments • Fully standard sub-profile that provides PIM+GRE in a way which is fully compatible with WG docs • PIM+MPLS • We think MPLS data transport can provide a number of advantages that make it useful with a PIM control plane.

  7. IETF 70 L3VPN WG PIM+GRE Profile • Legacy sub-profile contains non-standard items, specified in draft: • MDT/SAFI, connector • Replaced by Intra-AS AD Route and VRF Route Import Extended Community in standards • PIM RD+vector Join Attribute, for unsegmented inter-AS trees in “vanilla” option B nets • IMHO should be added to WG standard, but has gotten tangled up in the “loose threads” • Draft also specified fully standard PIM+GRE sub-profile

  8. IETF 70 L3VPN WG PIM+MP2MP-LSP Profile • PIM control plane is used • MP2MP LSPs used for data and control packet distribution • MI-PMSI required for PIM, but: • the P-tunnels instantiating the MI-PMSI are created only as needed, • a PE joins a particular P-tunnel only as needed. • No full mesh of P-tunnels • unless needed anyway for data

  9. IETF 70 L3VPN WG MP2MP LSPs as P-Tunnels • Each P-tunnel is MP2MP LSP rooted at a given PE • To send a JP to a PE, join its MP2MP LSP and send the JP on that LSP • Bidir: joining based on RPA discovery, choose DF based on upstream multicast hop selection for RPA • To send data to the other PEs: • Non-bidir: send on the MP2MP LSP that you are the root of • Bidir: send on the MP2MP LSP rooted at the selected DF‏ • N.B.: If no one wants data from a particular PE, the P-tunnel rooted at that PE is never created

  10. IETF 70 L3VPN WG Interesting Properties • Number of P-tunnels determined by number of PEs that have data to send • generally much smaller than total number of PEs • therefore addresses PIM/MI-PMSI scalability issues • When receiving data on MI-PMSI, can always tell which PE transmitted it • inferred from LSP label, since only root transmits data on LSP • data arriving from “wrong” upstream PE easily discarded • makes efficient support of C-bidir possible • eliminates need for single forwarder selection • asserts never occur • Does not require a second (upstream-assigned) MPLS label • Still allows use of S-PMSIs as necessary

  11. IETF 70 L3VPN WG Future of This Draft • Offered now as individual/informational • Hopefully would progress to RFC after WG docs • One might infer the interest of certain vendors and customers in these profiles  • WG might or might not decide to bless the notion of profiles and standardize a few • In that case, we might want to reconsider the role of this doc

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