Assigning a vlan on a trunk port

[samiaiyad]

Hi

I configured one port as a trunk port in cisco 2950 switch and i found that I can assign the same port to any vlan !!! and i did . It works fine I have no problem ... but i do not know what is the reason behined that since trunk ports deals with all vlans .!! is there any benefit of assigning a trunk port to a specific Vlan ?

Thanks

[matt.austin]

For management purposes, yes. Also, in my experience, when you consistentely use a specific VLAN for trunks, i.e. VLAN 1, or some other designated VLAN group, like we have VLAN 80; which is then used for all our switches, and other management devices. This has made it easier in creating ACL's and such for allowing only particular machines to access our management devices from both the outside or inside of our network, enabling a more secure network.

Let me know whether this helps?

[Prashanth Krishnappa]

The VLAN you specify on the trunk port will be your Native VLAN. If you are trunking to another switch, make sure the native VLAN on the other switch is same as well. By default VLAN 1 is the native VLAN

[wkumari]

As a small aside here, the native vlan travels untagged over a trunk. This means that frames in the native VLAN do not have the extra (admittedly tiny) ISL / .1Q tag. If I know that one VLAN is going to have MUCH more taffic than others (esp if it is many, small packets like voice or DNS) I try and place it in the native VLAN. With some testing that i did I got an extra 1.5 Mbs on FE (vs. having the heavy vlan being non-native.)