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IETF 74 th meeting, San Francisco – L3VPN WG

Multicast VPN fast fail-over draft-morin-l3vpn-mvpn-fast-failover-00 Wim Henderickx , Praveen Muley – Alcatel Lucent Thomas Morin – FT Orange Yakov Rekhter, Rahul Aggarwal – Juniper. IETF 74 th meeting, San Francisco – L3VPN WG. Introduction. Goal

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IETF 74 th meeting, San Francisco – L3VPN WG

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  1. Multicast VPN fast fail-overdraft-morin-l3vpn-mvpn-fast-failover-00 Wim Henderickx, Praveen Muley – Alcatel Lucent Thomas Morin – FT Orange Yakov Rekhter, Rahul Aggarwal – Juniper IETF 74th meeting, San Francisco – L3VPN WG

  2. Introduction • Goal • Minimize connectivity restoration time for multicast VPN services in the presence of failures • Relying on rerouting for multicast connectivity restorationtypically involves: • Waiting for unicast routing to converge • Additional signaling to restore multicast forwarding state (“join”) • That may not be fast enough for certain multicast applications... • Certain multicast applications often have high availability expectations • This work proposes tools to provide fast connectivity restoration for multicast VPN traffic: • Two complementary mechanisms providing different levels of failure coverage and restoration performance • Focus on upstream failures in the provider scope: • Upstream PE failures • Core node/link failures • (other failures too, depending on the strategy implemented)

  3. UMH selection based on tunnel status • UMH selection taking into account tunnel status • Reminder: • “UMH Selection” specifies procedures by which a downstream PE determines the PE from which it will receive a said multicast flow (C-S, C-G) • In the current spec, “UMH Selection” is done solely based on the VPN unicast routing information • Does not take into account the state of the P-tunnel that the selected UMH uses to send (C-S, C-G) to the local PE • Idea: let UMH procedures take into account the state of the P-tunnel from the selected/primary UMH to the PE • Make “UMH Selection” on a (downstream) PE switch to a backup (upstream) PE as soon as the (downstream) PE determines that the P-tunnel from the selected/primary (upstream) PE is down, without waiting for unicast VPN convergence • Different possible ways for a PE to detect that a P-tunnel from the selected/primary UMH to the PE is down: • P2MP OAM (Multipoint BFD) • Traffic counters • P-Tunnel signaling (RSVP-TE PathTear) • IGP tunnel root tracking • … • Key: avoid waiting for unicast convergence

  4. Standby BGP C-Multicast route • Standby BGP C-Multicast route • Idea : prepare the backup PE so that it is ready to become UMH when the primary PE fails • How ? • Besides advertising a normal (C-S,C-G) C-multicast Tree Join route to the nominal upstream PE, downstream PEs advertise a Standby C-multicast Tree Join route to the backup upstream PE • The backup upstream PE prepares for a possible failure (e.g. by joining the source) • The backup upstream PE monitors the reachability of C-S through the nominal/primary PE • On failure, traffic is forwarded by backup PE • Failure detection can be done, for instance: • based on P2MP OAM • based on unicast VPN reachability to C-S • Key: avoid additional signaling at failure time

  5. Standby C-multicast route - Example Standby BGP C-multicast route Secondaryupstream PE receivers ? source downstreamCE upstreamCE PrimaryupstreamPE downstreamPE receivers "normal" BGP C-multicast route Warm standbyExample

  6. Different protection levels • Cold standby • Backup PE joins towards the CE only after it detects failure of the primary PE • Warm standby • Backup PE is ready to send traffic when it detects the failure of the primary PE (backup PE is “pre-joined” toward the CE) • Hot standby • Backup PE sends the traffic before the failure occurs • Downstream PE switch to backup tunnel based on VPN unicast routes • Hot leaf standby • Backup PE sends the traffic before the failure occurs • Downstream PE switch to backup tunnel based on tunnel status

  7. Conclusion • Wrap up: two simple mechanisms to reduce connectivity restoration time for multicast traffic in a VPN context, for upstream failures in the provider scope (upstream PE & core failures) • UMH Selection based on P-tunnel status : avoid waiting for unicast convergence • Standby C-multicast route : avoid signaling at failure-time by preparing the backup upstream PE • These mechanisms can be used, each one alone or together, depending on the failure coverage and level of protection wanted • Different levels of protection: cold, warm, hot, leaf hot • Working group feedback ?

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