subinterface

Answered Question
Dec 8th, 2008

how to create subinterface on 2800 router? what is the purpose of creating subinterface? thanks!

I have this problem too.
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Correct Answer by viyuan700 about 8 years 2 days ago

attaching 2 documents hope it helps you

google it for Router on stick or inter vlan routing you will get some utube video also those videos will be better than these document

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viyuan700 Mon, 12/08/2008 - 20:14

Suppose u want to create subinterface on your fast ethernet 0/0 port then

Config t

int f0/0.1 (instead of 0 it is 0.1 if want more 0.2,0.3etc)

you will see prompt as subinterface

then you can define ip etc

Subinterface are used for intervlan routing. So that host on vlan1 can talk to host on vlan 2.

If you are not using suninterface you need 2 fastethernet port on your router for intervlan routing.

Richard Burts Mon, 12/08/2008 - 20:23

Oliver

Perhaps there is an aspect of the response from Vishwamurti which could be clarified. Using subinterfaces on a router FastEthernet interface configures it to do trunking and to communicate with a switch whose interface connecting to the router is configured as a trunk. Each subinterface of the router interface corresponds to a VLAN in the trunked interface from the switch.

HTH

Rick

Correct Answer
viyuan700 Mon, 12/08/2008 - 23:08

attaching 2 documents hope it helps you

google it for Router on stick or inter vlan routing you will get some utube video also those videos will be better than these document

lejoe.thomas Mon, 12/08/2008 - 20:30

Oliver,

Again adding to the usage of subinterfaces. Apart from it's use in intervlan routing, sub interfaces are also used in Frame-relay networks, to divide partially meshed network into smaller fully meshed sub networks.

Point-to-Point sub interfaces are generally the preferred method in frame-relay networks.

HTH

Lejoe

Joseph W. Doherty Tue, 12/09/2008 - 04:58

Subinterfaces are also often used for ATM network too.

The key concept of subinterfaces, they allow for multiple logical interfaces off one physical interface. As other posters have described, these logical interfaces would behave much a physical interfaces connected to various networks whether they are Ethernet VLANs, frame-relay or ATM virtual circuits, etc.

A couple of issues using subinterfaces, because they share a physical interface, there are sometimes configuration restrictions compared to what might be done on the physical interface, and since they share a physical interface they also share its bandwidth.

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