Help with sho int x/xx switchport command

Answered Question
Jan 28th, 2009
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I'm trying to find out if all vlans are allowed or are they pruned??


not easy to tell..


ss-us-sjc-640-102#sho int gi 0/22 switchport

Name: Gi0/22

Switchport: Enabled

Administrative Mode: static access

Operational Mode: down

Administrative Trunking Encapsulation: negotiate

Negotiation of Trunking: Off

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Administrative Native VLAN tagging: enabled

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk Native VLAN tagging: enabled

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL

Correct Answer by Roberto Salazar about 8 years 5 months ago

they are allowed but not necessarily being forwarded, the last part of this output will tell you if they are being forwarded.


"Vlans in spanning tree forwarding state and not pruned"


If you want to clear some of the vlans on that trunk port, you will need to clear it from that trunk:

Defining the Allowed VLANs on a Trunk

http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.2_25_sec/configuration/guide/swvlan.html#wp1150302

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Roberto Salazar Wed, 01/28/2009 - 09:08
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From the output above the port is shutdown mode >> Operational Mode: down. do a show run int g 0/22, do you see "shutdown" under that interface's running config? To see what vlans are being forwarded and not pruned do a "show int trunk" but if the port is in shutdown state you will not see that interface in the output. To see what vlans are cleared from the trunk - show run int g x/x.



Yudong Wu Wed, 01/28/2009 - 09:15
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Port 0/22 is in access mode.

Administrative Mode: static access <<<<<


It is in default vlan 1.

Packet in vlan 1 will be forwarded.

Access Mode VLAN: 1 (default) <<<<<

Roberto Salazar Wed, 01/28/2009 - 09:24
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Kevin is right, this port is in access mode which means even if it is up it will not be trunking, thefore the onle vlan allowed will be, in your case, vlan 1.

jonesm111 Wed, 01/28/2009 - 10:40
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Sorry Guys, that was the wrong int..

Here is the right one.. looks to me like it's part of po2 and all vlans are trunked?


ss-us-sjc-640-101#sho int gi 0/23 switchport

Name: Gi0/23

Switchport: Enabled

Administrative Mode: dynamic desirable

Operational Mode: trunk (member of bundle Po2)

Administrative Trunking Encapsulation: dot1q

Operational Trunking Encapsulation: dot1q

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Administrative Native VLAN tagging: enabled

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk Native VLAN tagging: enabled

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL


Protected: false

Unknown unicast blocked: disabled

Unknown multicast blocked: disabled

Appliance trust: none

ss-us-sjc-640-101#sho int trunk


Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

Po2 desirable 802.1q trunking 1


Port Vlans allowed on trunk

Po1 1-4094

Po2 1-4094

Correct Answer
Roberto Salazar Wed, 01/28/2009 - 10:51
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they are allowed but not necessarily being forwarded, the last part of this output will tell you if they are being forwarded.


"Vlans in spanning tree forwarding state and not pruned"


If you want to clear some of the vlans on that trunk port, you will need to clear it from that trunk:

Defining the Allowed VLANs on a Trunk

http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.2_25_sec/configuration/guide/swvlan.html#wp1150302

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