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Cisco Bug: CSCvv14816 - [920] MVPN_GRE mcast traffic loss on local receivers and across VRF after Access BDI flap

Last Modified

Oct 09, 2020

Products (1)

  • Cisco ASR 920 Series Aggregation Services Router

Known Affected Releases

17.3.1

Description (partial)

Symptom:
If we look at the details for the multicast prefix, we are seeing a mdt_type of NL3MM NATIVE MCAST, where it should be NL3MM VRF ENCAP

R-MPLS-Larino-1#show platform hardware multicast ipv4 224.0.224.1/32 134.1.96.164/32 vrf SCCT
Multicast Prefix Details:

Prefix: (134.1.96.164,224.0.224.1/64), RPF I/F: GigabitEthernet0/0/4 (4101)
TCAM Idx: 0x4362, RouteD: 0x39b1
RPF Pass Queue: 0, RPF Fail Queue: 6, vrf_id : 4
mdt_type : NL3MM NATIVE MCAST mdt_src : 0x0 mdt_grp : 0x0 mdt_vrf_id : 0
OuterAcl Tcam Index : 0 InnerAcl Tcam Index : 0 MLDP Encap Magic : 0

L3 OCE entries:
L3 I/F: GigabitEthernet0/0/0 (4097), Flags: F NS (0x9), State: 0x0
Pltf Flags: F (0x1)
mdt_type : NL3MM NATIVE MCAST mdt_src : 00000000 mdt_grp : 00000000 mdt_vrf_id : 0 <<<<<<<<<< should be NL3MM VRF ENCAP
TEFP :
EFP :
L3 I/F: GigabitEthernet0/0/4 (4101), Flags: A (0x2), State: 0x0
Pltf Flags: A (0x2)
mdt_type : NL3MM NATIVE MCAST mdt_src : 00000000 mdt_grp : 00000000 mdt_vrf_id : 0 <<<<<<<<<< should be NL3MM VRF ENCAP
TEFP :
EFP :
L3 I/F: BDI53 (53), Flags: F NS (0x9), State: 0x8
Pltf Flags: F (0x1)
mdt_type : NL3MM NATIVE MCAST mdt_src : 00000000 mdt_grp : 00000000 mdt_vrf_id : 0 <<<<<<<<<< should be NL3MM VRF ENCAP
TEFP :
EFP :Gi0/0/2.Efp53
L3 I/F: (0), Flags: F (0x1), State: 0x80
Pltf Flags: F MDT (0x21)
mdt_type : NL3MM NATIVE MCAST mdt_src : 0XA003FA5 mdt_grp : 0XEFE80101 mdt_vrf_id : 4 <<<<<<<<<< should be NL3MM VRF ENCAP
TEFP :
EFP :

Conditions:
- MVPN_GRE mcast scenario
- Encap PE node, we have incoming interface as BDI and Egress will be tunnel.

In this case, when we send Bi-directional traffic (S,G) entries will be created and traffic will flow end to end. Performing shut/no shut on incoming interface on this PE node results in partial traffic loss on local receivers directly connected to this node and also on nodes which are remotely connected across VRF.
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