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different Native vlans on the ends of trunk link...
Hello Guys...
I am have a doubt in trunking.
If I configure different native vlan on each ends of a trunk, will trunking will still work or not ?
I am have a doubt in trunking.
If I configure different native vlan on each ends of a trunk, will trunking will still work or not ?
" You Should Be The Change - That You Want to See " - Mahatma Gandhi :thumbup:
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luke_bibby
Member Posts: 162
A trunk with mismatched native VLANs will still stay operational. Here's one I prepared earlier:
On switch B:
SwitchB#sh int tru
Port Mode Encapsulation Status Native vlan
Fa0/15 auto 802.1q trunking 2
Port Vlans allowed on trunk
Fa0/15 1-4094
Port Vlans allowed and active in management domain
Fa0/15 1,10,15,20
Port Vlans in spanning tree forwarding state and not pruned
Fa0/15 1,10,20
On switch A:
SwitchA#show int tru
Port Mode Encapsulation Status Native vlan
Fa0/2 desirable 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/2 1-4094
Port Vlans allowed and active in management domain
Fa0/2 1,10,15,20
Port Vlans in spanning tree forwarding state and not pruned
Fa0/2 1,10,20
However the following syslog message gets printed to the console every minute (provided CDP is enabled):
00:14:19: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/15 (2), with SwitchA FastEthernet0/2 (1). -
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Cyclades
Member Posts: 26 ■□□□□□□□□□
Hey Luke,
Thank you so much. I got the same kinda syslog messages. That's were I go confused.
Thanks Once Again" You Should Be The Change - That You Want to See " - Mahatma Gandhi :thumbup: -
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notgoing2fail
Member Posts: 1,138
I would also check to see if dot1q and ISL handles this differently. -
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trackit
Member Posts: 224
notgoing2fail wrote: »I would also check to see if dot1q and ISL handles this differently.
there is no such thing as native vlan in ISL -
Optionsnotgoing2fail
Member Posts: 1,138
there is no such thing as native vlan in ISL
Well there you go then!! LOL good to know.... -
OptionsCyclades
Member Posts: 26 ■□□□□□□□□□
Ya .. ISL encapsulates all the packets irrespective of the vlan" You Should Be The Change - That You Want to See " - Mahatma Gandhi :thumbup:
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Optionscreamy_stew
Member Posts: 406 ■■■□□□□□□□
Ya .. ISL encapsulates all the packets irrespective of the vlan
So what happens if you "tag native" at both ends? Will the CDP warnings still show up? Will the switches have any idea which id thee other side is using for "native" I've never tried this.
That seems like "The Loop of Doom" waiting to happen, lol
