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Cisco Bug: CSCuj56227 - IGMP proxy reports may loop on the network

Last Modified

Nov 27, 2020

Products (2)

  • CiscoPro Workgroup EtherSwitch Software
  • CiscoPro Workgroup EtherSwitch Software

Known Affected Releases

5.2(1)N1(5) 6.0(2)N2(1)

Description (partial)

Symptom:
++ Proxy leaves and proxy reports looping between peer switches.

++ This condition can create IGMP loops which could affect the use of queuing by other transit traffic leading to said transit traffic to be dropped

++ This IGMP loop between the 5K vPC switches can also cause high CPU on upstream devices that punt the IGMP Reports to their SUPs.

++ Quick way of diagnosing this (note the all 0.0.0.0 Source IP):

Cisco-Switch# ethanalyzer local interface inbound-low display-filter "ip.src==0.0.0.0" limit-c 0
 
Capturing on inband
2018-06-19 15:37:13.711850      0.0.0.0 -> 224.1.1.20   IGMP V2 Membership Report / Join group 224.1.1.20
2018-06-19 15:37:13.711859      0.0.0.0 -> 224.1.1.20   IGMP V2 Membership Report / Join group 224.1.1.20
2018-06-19 15:37:13.711866      0.0.0.0 -> 224.1.1.20   IGMP V2 Membership Report / Join group 224.1.1.20
2018-06-19 15:37:13.712143      0.0.0.0 -> 224.1.1.20   IGMP V2 Membership Report / Join group 224.1.1.20
<snip>

Conditions:
++ Nexus 5000 setup in vPC.

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