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Cisco Bug: CSCul20045 - VPN packet drops on VPNv4 RR failover (with associated IGP changes)

Last Modified

May 10, 2018

Products (10)

  • Cisco Carrier Routing System
  • Cisco IOS XR Software
  • Cisco ASR 9922 Router
  • Cisco ASR 9010 Router
  • Cisco XR 12410 Router
  • Cisco ASR 9006 Router
  • Cisco XR 12404 Router
  • Cisco XR 12416 Router
  • Cisco ASR 9001 Router
  • Cisco XR 12406 Router

Known Affected Releases

3.9.1.BASE 4.2.3.BASE

Description (partial)

In an MPLS VPN network with redundant Route-Reflectors (RR), if the preferred RR becomes unavailable (or comes back up), a small amount of customer VRF traffic may be dropped.

In a network with around 200 PE's and 250,000 VPNv4 routes, it was observed up to 60ms traffic loss in some VRFs.

This is a typical MPLS VPN scenario with redundant Route-Reflectors. Both RRs advertise prefixes with the same best path next-hop (remote PE). When the primary RR (lowest IP address) goes down and/or comes back up, occasionally VPN traffic is dropped.

This bug effects all platforms running IOS XR.
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