03-02-2015 11:00 AM - edited 03-07-2019 10:54 PM
I configured a few vlans on a switch. 3 vlans, each assigned only one port. The ouput of show vlan brief shows me exactly what I would expect:
IOU1#show vlan bri
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Et0/0, Et0/3, Et1/3
101 VLAN0101 active Et1/0
102 VLAN0102 active Et1/1
103 VLAN0103 active Et1/2
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
But confusingly when I do a show vlan id for one of my vlans it lists the vlan's interface and then two other interfaces:
IOU1#show vlan id 102
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
102 VLAN0102 active Et0/1, Et0/2, Et1/1
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
102 enet 100102 1500 - - - - - 0 0
Primary Secondary Type Ports
------- --------- ----------------- ------------------------------------------
Et0/1 and Et0/2 are trunks to two other switches. I don't get why its listing those trunk ports though I was only expecting it to show Et1/1. Is listing those ports there because this vlan is connected via trunk ports to other switches? I don't know exactly what those two interfaces there is telling me.
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03-03-2015 06:05 AM
I think IOU and IOL behave this way. When you say real switch, on nexus platforms in my experience they are same as what you have shown above as IOU.
A switch like C3750, C3560, C3650, C3850 etc.... they will have regular output that you might be used to, i.e. not showing trunk interfaces in the vlan id output.
Hope this helps.
03-02-2015 11:55 PM
I think that the linux/unix versions of IOS, and we can usually include NXOS with this behaviour, shows every trunk and access port (in the case of NXOS port-channel and also members of port-channels too) carrying the vlan.
I'm not entirely sure why there's a change, but thats the way it is.
03-03-2015 05:50 AM
So this is just IOU/IOL behavior?
If this was a real switch, in this example, I would only see Et1/1 correct?
03-03-2015 06:05 AM
I think IOU and IOL behave this way. When you say real switch, on nexus platforms in my experience they are same as what you have shown above as IOU.
A switch like C3750, C3560, C3650, C3850 etc.... they will have regular output that you might be used to, i.e. not showing trunk interfaces in the vlan id output.
Hope this helps.
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