Vlans on VSS core switch and Nexus switch

[Shivu b]

Hi All,

 I am working in MNC company as Network Engineer.

I have question about Vlan.

we have VSS core switch and Number of vlans are configured.

 I have noticed few vlans are up and not assigned the physical port.

Could you please answer for below following questions.

* How vlan's are up without assign the physical port ?

* Why Vlans are not seen when exexcute the show ip int brief command ?

Regards,

sachin

[Reza Sharifi · Accepted solution]

Hi,

* How vlan's are up without assign the physical port ?

When you add a vlan to a trunk port (uplink port) it will come up.

Why Vlans are not seen when exexcute the show ip int brief command ?

If the vlan is just a layer-2 vlan (no SVI) sh ip int bri will not show it.

HTH

[glen.grant]

  If you do a "show vlan id <vlan number>  .  This will show you all ports including any trunk ports that the vlan is assigned to. 

[InayathUlla Sharieff · Accepted solution]

* How vlan's are up without assign the physical port ?

Answer:- Just to add what Reza said, IF you have manually not assigned any physical port to the vlan your understanding is perfectly correct that those vlans will not come up. But you have forgotton one thing if you have trunk link connecting to some other device from this switch then by default the port will be allowing all vlans to flow across the link due to which the vlans come active.( Example:- Trunk port were in you have all vlans allowed by default only then you would see the vlans to be in up state. In case you have a trunk port were in you have manually configured some vlans to be allowed in that case this new vlans will not come up.

Do " Show int trunk" command and see which is the interface which has allowed all the vlans and you must see that interface will not have specified vlans explicity to be allowed.

)

2-

* Why Vlans are not seen when exexcute the show ip int brief command ?

Answer:- Do you have vlans configured with ip address on the same?

Regards

Inayath

[Shivu b]

Inayath,

Thanks