odd configuration, need help to understand

[jimfixit]

Every day I see something new in this place. Today I was trying to understand the way my predecessor hooked up a bunch of VMware boxes. These boxes have about 7 or 8 cables each (8 if they are HP/Compaq due to ILO port being hooked up; 7 if they are Dell for lack of same).

Anyway there is one port that is designated as application development's network port. We have a group of web programmers who have some virtual servers hosted on the VMware boxes and this is the nic they communicate through. But then, when I look at the nic, here is what it is set up as:

interface GigabitEthernet1/0/21
description application development
switchport access vlan 40
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,11-13
switchport mode trunk
switchport nonegotiate
no snmp trap link-status
spanning-tree portfast disable
spanning-tree bpduguard disable
spanning-tree link-type point-to-point

I'm not sure...how do you have a port that is both access and trunk? It does what they want it to do so I guess it isn't a problem but, it sure looks odd...

 

[brianinms]

Its not an access port, its a trunk port ... the command switchport mode trunk sets it as a trunk.

 

[burtsbees]

Probably used to be an access switchport for vlan 40, but was never removed.

Burt

 

[jimfixit]

ah, I see. I'm so used to when one command superceeds another, the previous command just goes away from the config. This is a new one on me. Thanks. I'll clean it up next maintenance cycle.

 

[burtsbees]

Not really---switchport mode trunk takes precedence over switchport mode access. I think---if you wanted to make that an access port again, I believe you'd have to do a "no switchport mode trunk" then "switchport mode access"...

Burt

 

[jeter]

I found this on another site....
>
> interface GigabitEthernet2/1
> switchport access vlan 800
> switchport trunk encapsulation dot1q
> switchport trunk native vlan 50
> switchport trunk allowed vlan 50,60,800
> switchport mode trunk

It sets the port VLAN for when the port is in access mode.

If you set the mode to access (switchport mode access) then the port VLAN would switch to 800 from 50; if you switch to one of the sensing modes(switchport mode dynamic ...)

then the state the port negotiates into will determine the port VLAN.






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