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PW Endpoint Fast F ailure Protection draft-shen-pwe3-endpoint-fast-protection-04

Yimin Shen (Juniper) Rahul Aggarwal ( Arktan Inc) Wim Henderickx (Alcatel-Lucent) IETF 87, Berlin. PW Endpoint Fast F ailure Protection draft-shen-pwe3-endpoint-fast-protection-04. Update. LDP “Egress Protection Capability” TLV

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PW Endpoint Fast F ailure Protection draft-shen-pwe3-endpoint-fast-protection-04

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  1. Yimin Shen (Juniper) Rahul Aggarwal (Arktan Inc) Wim Henderickx (Alcatel-Lucent) IETF 87, Berlin PW Endpoint Fast Failure Protectiondraft-shen-pwe3-endpoint-fast-protection-04

  2. Update • LDP “Egress Protection Capability” TLV • Advertised by a protector to a primary PE; also to a backup PE in centralized model. • Carried in Initialization and Capability message.

  3. Motivation PW traffic • To specify a local repair mechanism to protect egress AC, egress/terminating PE, and switching PE. • 50 ms restoration time. • The final piece for end-to-end fast restoration. • Can complement global repair. CE1 PE1 PE2 CE2 S-PE1 AC seg-1 seg-2 AC PW

  4. Scenario 1: Egress AC failure PE2/PLR PE1 PW1 (label=X) PLR is the primary PE (PE2). It has established a bypass to protector (PE4). Protector (PE4): • Learns PW1’s label X from PE2 via the LDP extension. • Installs a FIB entry for label X in a context label table. Nexthop is CE2. • Assigns a UHP label Y for the bypass, pointing to this context label table. Local repair: • PE2 redirects PW packets through the bypass. • PE4 receives packets with outer label Y and inner label X. • PE4 looks up label X in the context label table, and sends packets to CE2. bypass label=Y CE2 CE1 PW2 (backup) PE3 PE4 protector

  5. Scenario 2: Egress (T-)PE failure PE2 PE1 PLR PW1 (label=X) PLR is the penultimate hop router. It has established a bypass to protector (PE4). Protector (PE4) • Learns PW1’s label X from PE2 via the LDP extension. • Installs a FIB entry for label X in a context label space. Nexthop is CE2. • Assigns a UHP label Y for the bypass, pointing to this context label table. Local repair: • PLR redirects PW packets through the bypass. • PE4 receives packets with outer label Y and inner label X. • PE4 looks up label X in the context label table, and sends packets to CE2. bypass label=Y CE2 CE1 PW2 (backup) PE3 PE4 protector

  6. Scenario 3: S-PE failure S-PE1 PE1 PE2 PLR PLR is the penultimate hop router of seg-1. It has a bypass to protector (S-PE2). Protector (S-PE2) • Learns PW1’s label X from S-PE1 via the LDP extension. • Installs a FIB entry for label X in a context label table. Nexthop is seg-4. • Assigns a UHP label Y for the bypass, pointing to this context label table. Local repair: • PLR redirects PW packets through the bypass. • S-PE2 receives packets with outer label Y and inner label X. • S-PE2 looks up label X in context label table, swaps to label Z, pushes a transport label to PE4. seg-1, label=X seg-2 bypass label=Y CE2 CE1 seg-4, label=Z seg-3 PE3 S-PE2 protector PE4

  7. Context ID • A unique IP address that identifies and associates a pair of <primary PE, protector>. • Advertised by IGP or IGP-TE to be reachable via both routers. • Via primary PE, by default. • Via protector, when bypassing primary PE.

  8. Local protection on PLR • Transport tunnel’s destination = context ID. • The tunnel is routed or signaled to primary PE. • PLRs are automatically provided with the identity of protector. • PLRs set up bypass tunnels to protector, by avoiding primary PE. • PLRs install bypass routes in forwarding plane, in anticipation of failures.

  9. Forwarding state on protector • Protector learns PW labels from primary PE. • Targeted LDP session. • Primary PE tags each PW label with context ID. • Protector installs the PW labels in a context label table, identified by the context ID. • Protector points incoming bypass tunnels (destination = context ID) to this context label table. • During local repair, PW packets received on a bypass tunnel are looked up in this context label table, and forwarded to target CE.

  10. Summary • Single- and multi-segment PWs. • MPLS and IP transport tunnels and bypass tunnels. • LDP Extensions: • Egress Protection Capability TLV. • Protection FEC Element TLV, for FEC 128 and 129. • Protection models: • Co-located protector – simplicity. • Centralized protector – scalability.

  11. Next steps • The document has been stable. • Would like to ask for WG adoption.

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