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routing between subinterfaces on router

I have a router with two physical gi port.

I create two subinterface on each gi port.

internet = gi0/0.1

remote site = gi0/0.2

firewall = gi0/1.1

local lan = gi0/1.2

How can I create routing between the firewall and internet subinterface, and routing between remote and local lan subinterface?

It need to done correctly so that I don't get cross routing between all the subintefaces.

My default gateway on this router points to the ISP router through the internet subinterface.


Re: routing between subinterfaces on router


As long as you configure the default gateway on your hosts to point at the appropriate addresses on this router, routing will happen automatically between the VLANs. The router recognises that these networks are direcly connected and will route between them.

You will need to add a default route, however, that points out the gi0/0.1 interface in order to route to the Internet.

Pls do remember to rate posts.


Community Member

Re: routing between subinterfaces on router


I did static routes routing to revelent interface. That works, I can telnet to remote sites switches.

Default route to internet, that works.

Remote office can access server based here, but when they accesss internet via our firewall, which is in our local LAN, they are not able to go out.

So I am wondering is it is routing issues.

Remote office's pc points to their router as gateway (, BUT if they poing to, they are able to go to anywhere (local server here and internet access).

If they are to do a traceroute to some internet ip address. It shows, going thru , 10.1.1.? ...

It looks like it get lost among the ISP routers.

Re: routing between subinterfaces on router


The moment you create sub-interfaces on the router they all will be able to route packets among them as they are directly connected to router.

Please let us know more info on this, what you exactly want to achieve. Let us know the traffic flow as well between the interfaces.

Will the traffic flow between Lan and firewall and internet traffic. Will the traffic also flow between remote and internet interfaces.


-amit singh

Community Member

Re: routing between subinterfaces on router

Internet <-> Gi0/0.2 <-> Gi0/1.2 <-> ASA <-> LAN <-> Gi0/1.1 <-> Gi0/0.1 <-> ROUTER(remote office)

Hope this shows what I want to do.

Local LAN go to internet via the ASA,Gi0/1.2,Gi0/0.2,Internet.

Local LAN go to remote office via Gi0/1.1,Gi0/0.1,Router (remote office)

Remote Office come to local server via Router,Gi0/0.1,Gi0/1.1

Remote Office go to internet via Router,Gi0/0.1,Gi0/1.1,ASA,Gi0/1.2,Gi0/0.2

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