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Cisco Bug: CSCvv54636 - 9K EOR NLB multicast on a stick blackholed if ingress PC split across ASICs

Last Modified

Oct 10, 2020

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases

9.3(1) 9.3(5)

Description (partial)

Symptom:
traffic may be blackholed
some load-balancing combinations may work

513E.C.14-N9K-C9508-1# sh ip igmp snooping groups vlan 1818
Type: S - Static, D - Dynamic, R - Router port, F - Fabricpath core port

Vlan  Group Address      Ver  Type  Port list
1818  */*                -    R     Vlan1818
1818  239.255.185.89     v2   D     Po5   << MNLB multicast group


513E.C.14-N9K-C9508-1# show forwarding distribution l2 multicast vlan 1818
Vlan: 1818, Group: 3031.3030.2e35, Source: 3030.3030.2e30
  Outgoing Interface List Index: 131069
  Reference Count: 4
  Num L3 usages: 0
  Platform Index: 0x0
  Number of Outgoing Interfaces: 0

Vlan: 1818, Group: 3031.3030.2e35, Source: 3030.3030.2e30   << Group should match L2 MAC 0100.5e7f.b959
  Outgoing Interface List Index: 16
  Reference Count: 1
  Num L3 usages: 0
  Platform Index: 0xa00010
  Number of Outgoing Interfaces: 1
    port-channel5

module-2# show system internal forwarding tahoe l2 multicast vlan 1818 | beg "DMAC: 0100.5e7f.b959"
Vlan: 1818  DMAC: 0100.5e7f.b959  RID: 16 Met_ptr: 0x9  << correct DMAC
Group Index: 2296000  G hash Index: 3107  G dst_ptr: 8193
Group_FP: 10  Group_TILE: 0
TCAM: 0  Tcam_idx: 0
  MET PTR: 9
  MET Entries:
    Flags: None  BD: 1818,  MCIDX: 4714,  FTAG_BASE: 0,  NUM_FTAGS: 0,  ASIC: 0,  SLICE_LIST: 0
  ASIC: 1,  SLICE_LIST: 0
  ASIC: 2,  SLICE_LIST: 0
  ASIC: 3,  SLICE_LIST: 0

Conditions:
MNLB with multicast on a stick on EOR
configure new port-channel with member ports across different ASICs
(show interface hardware-mapping)
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Bug Details Include

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