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Cisco Bug: CSCvs84137 - Breakout ports out-of-service in port-channel connected to FEX due to MTU mismatch

Last Modified

Oct 13, 2020

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases

15.0(0.68)

Description (partial)

Symptom:
ifav120-leaf1# show interface brief
Ethernet VLAN Type Mode Status Reason Speed Port
Interface Ch #
--------------------------------------------------------------------------------
Eth1/1/1 0 eth trunk up out-of-service 10G(D) 7 --->the uplink breakout port still shows as "trunk" not as a fabric port


+ The MTU programmed in the port-channel and it's members don't match

ifav120-leaf1# cat /mit/sys/aggr-\[po8\]/summary | grep mtu
mtu : 9222

ifav120-leaf1# cat /mit/sys/phys-\[eth1--1--1\]/summary | grep mtu
mtu : 9000 mtu of 1/1/1


ifav120-leaf1# cat /mit/sys/aggr-\[po8\]/summary
# Aggregated Interface
id : po8
accvePorts : 0
adminSt : up
autoNeg : on
lastSt : failed
lastStCause : port not compatible [MTU] <<<<<<<<<<<<<<<<<

Conditions:
+ Breakout ports bundled in port-channel
+ Port-channel connected to FEX
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