• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1433
  • Last Modified:

Cisco router trunk concept

Hello all,

i had found in the past a web site that explains the difference between trunk concept on cisco switches and cisco router. In my case, between a catalyst 3550 and a cisco router 3600 with fast ethernet interfaces

In fact, as far as i remember, you cannot configure a cisco router interface as a trunk port like you do it on a cisco switch.

Any comment or information about that will help a lot.

  • 2
1 Solution
You're half right. You can't use the same 'set port trunk' type of commands, but you can still connect a router to a switch's trunk port and create sub-interface for each VLAN. The whole idea of a trunk is to pass vlan data, and of course data across the vlans.


  interface fast 0/12
   switchport access vlan 2

  interface fast 0/14
   switchport access vlan 4

  interface Fast0/28
   description uplink to router
   switchport mode trunk
 interface Fast0/0  <== one physical interface, multiple VLAN's
  Description this is VLAN1 <== physical interface is always switches' native vlan (vlan1 by default)
  ip address
 interface Fast 0/0.2  <== logical interface for VLAN2
  Description VLAN2
  encap dot1q 2  <== look for vlan2 tags
  ip address
 interface Fast 0/0.4
  Description VLAN4
  encap dot1q 4  <== look for vlan4 tags
  ip address

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now