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VPLS Best Site ID

Learn about streamlined VPLS site ID configuration, site ID problem solutions, and the best approach using 'best-site' for improved network resilience and efficiency. Understand control flags and additional add-ons for seamless network operation.

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VPLS Best Site ID

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  1. VPLS Best Site ID Anshu Verma (anshuverma@juniper.net) Wen Lin (wlin@juniper.net) Rodny Molina (rodny.molina.maldonado@ericsson.com) John Drake (jdrake@juniper.net)

  2. VPLS Site ID Requirements • Site IDs configured on each VPLS PE must be unique per VPLS domain. • Exception is multi-homing. • Site-IDs can be either provisioned or dynamically generated. • Exception is multi-homing as site-IDs need to be explicitly configured

  3. VPLS Site ID Problem • VPLS path selection mechanism picks the minimum site-id to determine the 'preferable' local site. • Whenever the elected site-id is declared down, the traffic to/from all other sites within the same VE is impacted as well. • Convergence period is impacted during transient intervals. • CPU cycles are spent in destroying/re-building affected PWs.

  4. VPLS Best Site ID Approach • When ‘best-site’ is enabled on PE, • It is elected as most preferable site by remote PEs • It remains permanently up regardless of access failure events. • Provides more provisioning flexibility. • Minimal traffic disruption for non-preferable sites in multi-site VPLS PEs during access-side failures. • No CPU cycles spent destroying and creating new PWs during failover events. • Backward compatible - Relies on their legacy/default site-election.

  5. Control Flag in Layer 2 Extended Community With reference to the Control Flags Bit Vector, the following bits in the Control Flags are defined; 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |D|A|F|B|T|R|C|S| (Z = MUST Be Zero) +-+-+-+-+-+-+-+-+ D Defined in l2vpn-vpls-multihoming draft A Defined in l2vpn-auto-site-id draft F Defined in l2vpn-vpls-multihoming draft B When the bit value is 1, the PE receiving the label-block will deem the corresponding site as the most preferable site from the remote neighbor. When the bit value is 0, the PE receiving the label-block will rely on its legacy/default site-election algorithm. T/R Defined in l2vpn-fat-pw-bgp draft C Defined in [RFC4761] S Defined in [RFC4761]

  6. Best Site ID Approach (1) Send Label Adv: B-bit=1 • Receive NLRIs • Send a label-block adv with B-bit set. • Received label-block adv has: • [B-bit=1] Establish PW rooted at best-site • [B-bit=0] use legacy site-election (1) Send Label Adv: B-bit=1 (2) Honor B-bit from PE3 estbPW (2) Honor B-bit from PE3 estb PW (1) Send Label Adv: B-bit=1 PE1 (2) Honor B-bit estbPW, except PE4 PE2 PE3 PE5 PE4 BGP VPLS NLRI (1) Send Label Adv: B-bit=0 (2) Honor B-bit from PE3 estb PW

  7. VPLS Best Site ID Add-Ons • With ‘best-site’, no core-facing PW are ever torn down; previously learned MAC entries continue pointing to an invalid PW • Requires ‘Explicit-mac-flush’ mechanism to ensure that MAC-to-PW bindings are cleared during DF transition. • PE can request a remote PE to flush mac-entries by setting/unsetting F-bit in Layer2 control flags.

  8. VPLS Best Site ID • More details: draft-anshuverma-bess-vpls-best-site-id Questions?

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