Question about vlan trunk troubleshooting

szar

Ι have two switch sw1 ,sw2 with dif vlans assgned .they are connected with a trunk and working.when i for example disable vlan 10 (#interface vlan 10 ,shutdown .i can still use the trunk link and send frames.why is this hapening?



SW1#show interfaces trunk

Port Mode Encapsulation Status Native vlan
Gig0/1 desirable n-802.1q trunking 1


Port Vlans allowed on trunk
Gig0/1 1-1005


Port Vlans allowed and active in management domain
Gig0/1 1,10,20

Port Vlans in spanning tree forwarding state and not pruned

Gig0/1 1,10,20

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SW1#show interfaces vlan 10

Vlan10 is administratively down, line protocol is down
Hardware is CPU Interface, address is 00e0.f91c.b448 (bia 00e0.f91c.b44
Internet address is 192.168.10.1/24

Hondabuff

Spanning tree is still operational and sending BPDU's/CDP down the trunk. An SVI is just an virtual interface on the router and not a physical. When you get further down the road in CCNP switch it explains a lot of this. Good rule of thumb, If the port has a light on then its still talking and listening.

Port Vlans in spanning tree forwarding state and not pruned

Gig0/1 1,10,20 <

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VLans that are active on the trunk link.