07-10-2009 04:25 PM - edited 03-06-2019 06:42 AM
Hi every body!
The command " show interfaces trunk" shows a lot of information. My focus is information appears under:
" vlans allowed and active in management domain" and " vlans in spanning tree forwarding state and not pruned".
Shouldn't the information be same?
Is there any possibility that information appears below these two above mentioned lines will be different?
thanks a lot and have a nice weekend!
Solved! Go to Solution.
07-10-2009 05:53 PM
You can have a Vlan 'Active and in Management Domain' without being forwarded on the switchport due to manual or vtp pruning.
__
Edison.
07-10-2009 09:49 PM
Hello Sarah,
>> Shouldn't the information be same?
Is there any possibility that information appears below these two above mentioned lines will be different?
the first line provides an administrative information, the second line provides an operational information
where the two information can differ?
on uplinks of access layer switches for examples connected to two distribution switches:
on link1 are in STP forwarding state the vlans that have STP root bridge on device dis1 connected to link1
the opposite happens on link2 to dis2
Example:
sh int gi1/1 trunk
Port Mode Encapsulation Status Native vlan
Gi1/1 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi1/1 1,64,68,75,85-87,90-93,209,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,750-751,800-803,805,810,850-853,860,870,880,904,1002-1005
Port Vlans allowed and active in management domain
Gi1/1 1,64,68,75,85-87,90-93,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,751,800-803,805,810,850-853,860,870,880,904
Port Vlans in spanning tree forwarding state and not pruned
Gi1/1 64,68,75,85-87,90-93,401-405,411,450,500,502-505,508,510,600-610,612,620,630,640,650-651,660,670,690,692,700-702,751,800-803,805,810,850-853,860,870,880
this is taken from production network the switch has two uplinks one on g1/1 the other on g1/2
the list of permitted vlans is the same on both links but in normal scenario the list of STP fwd vlans is complementary
Here it is the second link
sh int gi1/2 trunk
Port Mode Encapsulation Status Native vlan
Gi1/2 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi1/2 1,64,68,75,85-87,90-93,209,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,750-751,800-803,805,810,850-853,860,870,880,904,1002-1005
Port Vlans allowed and active in management domain
Gi1/2 1,64,68,75,85-87,90-93,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,751,800-803,805,810,850-853,860,870,880,904
Port Vlans in spanning tree forwarding state and not pruned
Gi1/2 1,64,90,301,420,550,552,904
I remember old CCNP switching book advising to look always at the last line to understand if a trunk is really carrying user data for a vlan.
Hope to help
Giuseppe
07-11-2009 04:52 AM
Giuseppe, thanks for the assist - rated.
07-10-2009 05:53 PM
You can have a Vlan 'Active and in Management Domain' without being forwarded on the switchport due to manual or vtp pruning.
__
Edison.
07-10-2009 06:24 PM
Thanks Edison.
"You can have a Vlan 'Active and in Management Domain' without being forwarded on the switchport due to manual or vtp pruning."
In my book, vlan 3 is removed by" switchport trunk allowed vlan remove 3 " command. Then " show interface trunk" shows the following:( output omitted)
port vlans allowed and active in domain
gio/1 1,4
port vlans is stp forwd state ,not pruned
gi0/1 1,4
Here the vlan is not listed under " vlans allowed and active in management domain" though it is manually removed.
Thanks a lot and have a nice weekend!
07-10-2009 06:38 PM
Stand corrected
I'll have to double-check the situation that you are after when I get a hold of a switch on Monday but I believe it could happen if the downstream switch does not have the Vlan being forwarded on its DB.
It can be active and allowed on the local switch but not being forwarded.
__
Edison.
07-10-2009 09:49 PM
Hello Sarah,
>> Shouldn't the information be same?
Is there any possibility that information appears below these two above mentioned lines will be different?
the first line provides an administrative information, the second line provides an operational information
where the two information can differ?
on uplinks of access layer switches for examples connected to two distribution switches:
on link1 are in STP forwarding state the vlans that have STP root bridge on device dis1 connected to link1
the opposite happens on link2 to dis2
Example:
sh int gi1/1 trunk
Port Mode Encapsulation Status Native vlan
Gi1/1 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi1/1 1,64,68,75,85-87,90-93,209,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,750-751,800-803,805,810,850-853,860,870,880,904,1002-1005
Port Vlans allowed and active in management domain
Gi1/1 1,64,68,75,85-87,90-93,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,751,800-803,805,810,850-853,860,870,880,904
Port Vlans in spanning tree forwarding state and not pruned
Gi1/1 64,68,75,85-87,90-93,401-405,411,450,500,502-505,508,510,600-610,612,620,630,640,650-651,660,670,690,692,700-702,751,800-803,805,810,850-853,860,870,880
this is taken from production network the switch has two uplinks one on g1/1 the other on g1/2
the list of permitted vlans is the same on both links but in normal scenario the list of STP fwd vlans is complementary
Here it is the second link
sh int gi1/2 trunk
Port Mode Encapsulation Status Native vlan
Gi1/2 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi1/2 1,64,68,75,85-87,90-93,209,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,750-751,800-803,805,810,850-853,860,870,880,904,1002-1005
Port Vlans allowed and active in management domain
Gi1/2 1,64,68,75,85-87,90-93,301,401-405,411,420,450,500,502-505,508,510,550,552,600-610,612,620,630,640,650-651,660,670,690,692,700-702,751,800-803,805,810,850-853,860,870,880,904
Port Vlans in spanning tree forwarding state and not pruned
Gi1/2 1,64,90,301,420,550,552,904
I remember old CCNP switching book advising to look always at the last line to understand if a trunk is really carrying user data for a vlan.
Hope to help
Giuseppe
07-11-2009 04:52 AM
Giuseppe, thanks for the assist - rated.
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