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Cisco Bug: CSCvu07615 - Switches downstream of a Cat4k using 1g ports may see giants in the form of 1526B frames

Last Modified

Sep 03, 2020

Products (1)

  • Cisco Catalyst 4000 Series Switches

Known Affected Releases


Description (partial)

Switches that are downstream of a Cat4500 series switch which is using interfaces at 1G or less speeds may see intermittent connectivity or traffic performance issues when 1500B packets are used. 

Interfaces facing the 4500 series switches may increment giants in the presence of 1500B traffic.

First seen on Cat4500 series deployments running 3.8.8 or 3.11.2 where 1G transceivers are in use for ingress traffic. 

Ports can be operating in 10, 100, or 1000M speeds and can impose a 4 Byte trailer on ingress traffic. This trailer is carried over in the traffic leaving the switch regardless of its port. TenGig ports using 1g transceivers can also impose this trailer on ingress. 

If traffic ingresses a 10g interface operating at 10g speeds only, this trailer is not added.
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