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Cisco Bug: CSCun90694 - Traffic loss when VRRP Master changes on a l2vpn environment.

Last Modified

Oct 18, 2019

Products (7)

  • Cisco Carrier Routing System
  • Cisco ASR 9922 Router
  • Cisco IOS XR Software
  • Cisco ASR 9010 Router
  • Cisco ASR 9006 Router
  • Cisco ASR 9001 Router
  • Cisco ASR 9912 Router

Known Affected Releases

4.2.3.BASE 4.3.2.BASE 5.1.1.BASE

Description (partial)

After VRRP/HSRP master switches from one router to another, the newly elected master router fails to program VRRP/HSRP MAC address on BVI interfaces. Traffic sent to VRRP/HSRP master router is dropped on BVI interfaces when receiving traffic from L2 bridge.

VRRP/HSRP is configured on BVI interface. 
1. VRRP/HSRP failover happens back and forth rapidly within half MAC age (2 to 3 minutes by default).  Meanwhile, high speed traffic is sending from VRRP mater to BVI bridge.
2. In some rare case, local router becomes VRRP/HSRP master while the master's MAC address is learned on some NPs, not on the last NP on each NP. When the control plane pushes the master's MAC to NP, the NPs which flag the MAC as dynamically learned will refuse the MAC push from control plane. Those NP will not have VRRP/HSRP MAC correctly programmed.
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