Symptom

In a g8032 ring the switchover performance between the protected interfaces during switchover can be delayed by a factor proportional to the bridge-port scale under the impacted msti.

Conditions

IOS XR versions: This bug will impact all IOS XR Versions from 6.1.x to 7.9.x. Issue is not seen in 6.0.x or earlier. Issue is fixed from 7.10.x onwards. IOS XR platforms: This bug will impact all IOS XR Platforms. Example configuration: l2vpn ethernet ring g8032 test port0 interface TenGigE0/2/0/4 ! port1 interface TenGigE0/2/0/0 ! instance 1 profile test inclusion-list vlan-ids 1-4000 aps-channel port0 interface TenGigE0/2/0/4.1 port1 interface TenGigE0/2/0/0.1 ! bridge group bg bridge-domain bd1 interface TenGigE0/2/0/0.1 ! interface TenGigE0/2/0/3.1 ! interface TenGigE0/2/0/4.1 ! ... bridge group bg bridge-domain bd4000 interface TenGigE0/2/0/0.4000 ! interface TenGigE0/2/0/3.4000 ! interface TenGigE0/2/0/4.4000 ! Prior to event: #sh ethernet ring g8032 status Ethernet ring test instance 1 is RPL Owner node in Pending state Port0: TenGigE0/2/0/4 (Monitor: TenGigE0/2/0/4) APS-Channel: TenGigE0/2/0/4.1 Status: RPL, blocked Remote R-APS NodeId: 0000.0000.0000, BPR: 0 Port1: TenGigE0/2/0/0 (Monitor: TenGigE0/2/0/0) APS-Channel: TenGigE0/2/0/0.1 Status: NonRPL Remote R-APS NodeId: 0000.0000.0000, BPR: 0 APS Level: 7 Profile: test WTR interval: 1 minutes Guard interval: 500 milliseconds Hold-off interval: 0 seconds Revertive mode If TenGigE0/2/0/0 goes down, it will switchover to Te0/2/0/4. TE0/2/0/0 will move from forwarding to blocking state. Te0/2/0/4 will move from blocking state to forwarding state. The time for Te0/2/0/4 to move to forwarding state can be impacted by bridge-port events on Te0/2/0/0, and as the bridge-port scale increases, the delay can be more impactful.

Workaround

Reduce bridge-port scale on a particular MSTI to improve convergence during switchover.

Further Problem Description