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The main issue we have found in the lab is having a long packet loss duration when configuring BoB and having the Stand-By RP ready. Using Dual N560-4-RSP4E. IOS XR 6.6.3
Bundle Ethernet configured using member on two different IM cards, having 50msec x 3 timers Condition occurs when a member link of the Bundle is shutdown at the peer router and then unshutdown: The BFD session on the member link starts and gets into dampening state. At this point the traffic using this member link drops for about 7 seconds. When all conditions get steady, the BFD session on the affected member link on the Stand-By RP does not sync to the established timers. Same test when using a single RP board, then the traffic is not lost at the time of unshutting the interface. RP/0/RP0/CPU0:NCS_560#show bfd session Thu Jul 23 12:31:10.688 UTC Interface Dest Addr Local det time(int*mult) State Echo Async H/W NPU ------------------- --------------- ---------------- ---------------- ---------- Te0/3/0/0 192.168.0.1 0s(0s*0) 150ms(50ms*3) UP Yes 0/RP0/CPU0 Te0/2/0/3 192.168.0.1 0s(0s*0) 150ms(50ms*3) UP Yes 0/RP0/CPU0 Te0/3/0/0 192.168.0.1 0s(0s*0) 150ms(50ms*3) UP Yes 0/RP1/CPU0 Te0/2/0/3 192.168.0.1 0s(0s*0) 6s UP Yes 0/RP1/CPU0 BE100 192.168.0.1 n/a n/a UP No n/a
N/A
NCS560-4 Bundle Ethernet operating correctly to Third-party device 7750SR TiMOS-C-16.0.R5 Bundle configured using two (02) different IM cards, ports Ten0/3/0/0 and Ten0/2/0/3 BFD session when configured: 50msec x 3 When 7750SR device shutdown one member link -> Packet loss duration measure with Ixia traffic generator = 20 msec. Result OK When 7750SR device unshut same member link -> Packet loss duration depends if the Bundle has configured BFD or not: - If no BFD configured -> Packet loss duration measured with Ixia traffic generator ~= 1 msec. Result OK - If BFD configured -> Packet loss duration measured with Ixia traffic generator ~= 7 seconds (7000 msec). Result NOT EXPECTED A second test: shutting down stand-by RP and unshutting the member on the far end to add it to the bundle. This result Bundle Ethernet not causing more than a few milliseconds of packet loss. Third test: shutting down BFD agent only on stand-by RP and unshutting the member on the far end to add it to the bundle. This result Bundle Ethernet not causing more than a few milliseconds of packet loss. Techzone with part of the analysis: https://techzone.cisco.com/t5/IOS-XR-L3FIB-Eng-Discussion/NCS560-ATT-MX-6-6-3-Bundle-with-BoB-has-long-packet-loss/m-p/1568563#M8585 When analysing the logs, the BFD dampening is ending on different times on the two RPs; first on Stand-by RP1 and later on active RP0. RP0: ===== RP/0/RP0/CPU0:Aug 13 10:42:54.201 UTC: bfd_agent[280]: %L2-BFD-6-SESSION_DAMPENING_ON : Session to neighbor 192.168.0.1 on interface TenGigE0/2/0/3 entered Dampened state (initial: 16000 ms,secondary: 20000 ms,maximum: 600000 ms). RP/0/RP0/CPU0:Aug 13 10:43:10.041 UTC: bfd_agent[280]: %L2-BFD-6-SESSION_DAMPENING_OFF : Session to neighbor 192.168.0.1 on interface TenGigE0/2/0/3 moved out of Dampened state. RP1: ==== RP/0/RP1/CPU0:Aug 13 10:42:54.212 UTC: bfd_agent[456]: %L2-BFD-6-SESSION_DAMPENING_ON : Session to neighbor 192.168.0.1 on interface TenGigE0/2/0/3 entered Dampened state (initial: 16000 ms,secondary: 20000 ms,maximum: 600000 ms). RP/0/RP1/CPU0:Aug 13 10:42:56.212 UTC: bfd_agent[456]: %L2-BFD-6-SESSION_DAMPENING_OFF : Session to neighbor 192.168.0.1 on interface TenGigE0/2/0/3 moved out of Dampened state. The main issue we have found in the lab is having a long packet loss duration when configuring BoB and having the Stand-By RP ready. Using Dual N560-4-RSP4E. IOS XR 6.6.3 Bundle Ethernet configured using a member on two different IM cards, having 50msec x 3 timers The condition occurs when a member link of the Bundle is shutdown at the peer router and then unshutdown: The BFD session on the member link starts and gets into dampening state. At this point, the traffic using this member link drops for about 7 seconds. When all conditions get steady, the BFD session on the affected member link on the Stand-By RP does not sync to the established timers. The same test when using a single RP board, then the traffic is not lost at the time of unshutting the interface.