We have 2 Nexus 9K switches running as a VPC pair. This got put into production with a single link in the port-channel used as the VPC peer-link, we would like to add another interface. Unfortunately when we try and configure it we get the following:
Nexus9k-02(config)# interface eth1/25
Nexus9k-02(config-if)# channel-group 1 mode active
command failed: port not compatible [MTU]
** You can use force option to override the port's parameters
** (e.g. "channel-group X force")
** Use "show port-channel compatibility-parameters" to get more information on failure
The following is the running-config (all) on the port-channel and the interface currently in the port-channel:
interface port-channel1
description Link to Nexus9K-01 Po1
switchport
switchport mode trunk
no switchport monitor
no switchport dot1q ethertype
priority-flow-control watch-dog-interval off
switchport access vlan 1
switchport trunk native vlan 1
no switchport vlan mapping enable
switchport trunk allowed vlan 150,454,457
priority-flow-control mode auto
spanning-tree port-priority 128
spanning-tree cost auto
spanning-tree link-type auto
spanning-tree port type network
no spanning-tree bpduguard
no spanning-tree bpdufilter
logging event port link-status default
logging event port trunk-status default
buffer-boost
speed auto
duplex auto
flowcontrol receive off
flowcontrol send off
mtu 9216
delay 1
snmp trap link-status
negotiate auto
storm-control broadcast level 100.00
storm-control multicast level 100.00
storm-control unicast level 100.00
no storm-control action
bandwidth 40000000
no bandwidth inherit
load-interval counter 1 30
load-interval counter 2 300
no load-interval counter 3
no switchport block multicast
no switchport block unicast
no switchport mac-learn disable
no shutdown lan
lacp graceful-convergence
lacp suspend-individual
lacp min-links 1
lacp max-bundle 32
no port-channel port load-defer
lacp fast-select-hot-standby
no port-channel port hash-distribution
no lacp mode delay
vpc peer-link
no shutdown
no switchport autostate exclude
Interface Config
interface Ethernet1/1
description Link to Nexus9k-01 Eth1/1
lacp port-priority 32768
lacp rate normal
cdp enable
switchport
switchport mode trunk
no switchport monitor
no switchport dot1q ethertype
switchport access vlan 1
switchport trunk native vlan 1
no switchport vlan mapping enable
switchport trunk allowed vlan 150,454,457
priority-flow-control mode auto
spanning-tree port-priority 128
spanning-tree cost auto
spanning-tree link-type auto
spanning-tree port type normal
no spanning-tree bpduguard
no spanning-tree bpdufilter
buffer-boost
speed auto
duplex auto
fec auto
flowcontrol receive off
flowcontrol send off
link debounce time 100
no beacon
mtu 9216
delay 1
snmp trap link-status
negotiate auto
logging event port link-status default
logging event port trunk-status default
storm-control broadcast level 100.00
storm-control multicast level 100.00
storm-control unicast level 100.00
no storm-control action
bandwidth 40000000
no bandwidth inherit
load-interval counter 1 30
load-interval counter 2 300
no load-interval counter 3
no switchport block multicast
no switchport block unicast
no switchport mac-learn disable
no shutdown lan
no switchport autostate exclude
channel-group 1 mode active
no shutdown
The MTU for both the physical interface and the port-channel are set to 9216, which is odd to me. If we try and set the MTU on the new interface we want to add to the port-channel, we get the following:
Nexus9k-02(config-if)# interface eth1/25
Nexus9K-02(config-if)# mtu 9216
^
% Invalid number, range is (1500:9090) at '^' marker.
Currently the system jumbomtu is set to 9090:
system jumbomtu 9090
It would appear I either need to modify system jumbomtu to 9216, or knock down the MTU on the port-channel and physical interfaces to 9090. So 2 questions for anyone willing to help, which I sincerely appreciate.
- Anyone have a theory on how these interfaces ever got set to 9216? Doesn't matter anymore but I'm curious.
- Would it be more sane to jump the system jumbomtu up to 9216, or change the MTU on the port-channel / physical interfaces?
- Will either of the above result in a traffic stop, eg outage?
As mentioned above I appreciate any input on this. Thanks!
