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Cisco Bug: CSCvs10677 - [IMR2] L2 loop resulting in PIM nbr flap and eventually invalid PIM RPF

Last Modified

Nov 22, 2019

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases


Description (partial)

Traffic loss, since the BL is not sending PIM joins on the L3out. 
The reason PIM not sending joins is due to invalid RPF interface/ neighbor in PIM.

- IF FEX interfaces are used to replace the existing receiver, on the FEX interfaces STP was disabled.
- Sources are outside the Fabric, Receivers are deployed inside the fabric BLs. 
- When we are trying to replace existing receiver with FEX based receivers it is resulting in L2 loop.
- L2 loop keeps PIM busy causing PIM to drop hello packets resulting in neighbor-ship flap between BL and external Router.
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