02-24-2009 01:56 AM - edited 03-06-2019 04:12 AM
Hi to all,
can you check the following discussion about the "tagging native VLAN" and tell me if the tagging of the native VLAN is the deafult or not (on cat. 3560/37xx/45xx) with the latest IOS releases ?
http://www.networkworld.com/community/node/38732
If someone have a lab can do the following and paste the output :
1) configure a trunk between 2 switches
2) on the trunk interface "sh int x/x switchport"
3) configure the following (It must be enabled globally before the per-port settings take effect):
vlan dot1q tag native
4) on the previous same trunk interface "sh int x/x switchport"
Thanks to all
Roberto Taccon
02-24-2009 02:23 AM
Hello Roberto,
I performed a test
Generally in the sh int type x/y switchport
only the lines with "operational" attribute describe the effective settings on the port.
For example in a new 4507 with 12.2(46)SG that we have recently installed it shows:
Administrative Native VLAN tagging: enabled
without any operational line (the port is member of a Port-channel)
if I give
vlan dot1q tag native
the show doesn't change and appears only line with administrative attribute
sh run | inc tag
vlan dot1q tag native
sh int g6/1 switchport
Name: Gi6/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk (member of bundle Po1)
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
This can be a problem in the sh output.
To check this a frame capture on a trunk port is needed
Hope to help
Giuseppe
02-24-2009 03:31 AM
Hi
As has already been said, it's the operational status that matters and by default cisco does not tag the native vlan but cisco switches seem to show the Admin status as enabled.
Some switches like the ME3400 dont show you the Operational status, just the admin status so you can use the following command for quick reference
sh vlan dot1q tag native
02-24-2009 04:43 AM
Hi to All,
can someone @ Cisco (maybe the TAC team)write the FINAL words about the:
- "Tagging NATIVE VLAN" is the dafault or not on Cisco switches ?
- How to check (surely) if on a trunk the NATIVE VLAN is tagged ?
Regards.
Roberto Taccon
02-24-2009 04:58 AM
Hello Roberto,
I've followed Adam's suggestions
on the same c4507
sh vlan dot1q tag native
dot1q native vlan tagging is disabled globally
Per Port Native Vlan Tagging State
----------------------------------
Port Operational Native VLAN
Mode Tagging State
-------------------------------------------
Gi6/1 trunk disabled
Gi6/2 trunk disabled
Gi7/47 trunk disabled
Gi7/48 trunk disabled
Po1 trunk disabled
Po2 trunk disabled
then I add the global command
vlan dot1q tag native
I check again and I see:
sh vlan dot1q tag native
dot1q native vlan tagging is enabled globally
Per Port Native Vlan Tagging State
----------------------------------
Port Operational Native VLAN
Mode Tagging State
-------------------------------------------
Gi6/1 trunk enabled
Gi6/2 trunk enabled
Gi7/47 trunk enabled
Gi7/48 trunk enabled
Po1 trunk enabled
Po2 trunk enabled
So it is a problem of output format in sh switchport: the default is still native vlan untagged
Hope to help
Giuseppe
02-19-2013 11:18 PM
Very useful post, I had some doubts about this command, too.
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