Guest

Preview Tool

Cisco Bug: CSCvs91165 - Cat4500 STP not stable when receive multicast traffic more than 12G

Last Modified

Jun 18, 2020

Products (1)

  • Cisco Catalyst 4000 Series Switches

Known Affected Releases

15.2(7)E

Description (partial)

Symptom:
Cat4500 series chassis with SUP8-E and WS-X4712-SFP+E linecard installed
There are multiple 10G links terminated on this linecard
If there are multiple multicast sources on these 10G links connected on WS-X4712-SFP+E linecard sending at high rate [over 12Gbps] STP topology might reconverge frequently due to loss of STP BPDUs

Conditions:
Cat4k switch with WS-X4712-SFP+E linecard
This linecard is 2,5:1 oversubscribed.
Each 3 front panel SFP+ ports are belonging to the same port-group.
48Gbps backplane bandwidth is split evenly into each of the 4 port-groups [12Gbps per port-group]
This means that 3 SFP+ front panel interfaces [3x10Gbps] have 12Gbps connection to the backplane, hence 2,5:1 oversubscription.
If there is more than 12Gbps in total arriving on a SFP+ ports belonging to the same port-group then due to oversubscription traffic loss will occur and if STP BPDUs are lost it will result in STP instability and frequent reconvergence
Bug details contain sensitive information and therefore require a Cisco.com account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.