Quick Routing Question.

Unanswered Question
Apr 30th, 2008

Trying to set up a route to a remote site on a dedicated T1 from a 3660 router and I just have a very basic question.


As I mentioned, this 3660 is connected to a remote site via a dedicated T1. Am I safe to assume that if I set up another subnet at my local facility that is attahced to this 3660, I should be able to route out to the remote site. Note, that connectivity is fine to the remote site now, can ping it fine from the router.


Example. I create another subnet 192.168.1.0/24 and it is attached to FA3/1 on the 3660 - 192.168.1.2. Any packets hitting the 3660 destined for the remote site subnet 172.16.1.0/24 should route out fine correct?




thanks

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rais Wed, 04/30/2008 - 07:24

Yes, provided:


1. remote site knows how to get back to this new subnet 192.168.1.0/24


2. Hosts on 192.168.1.0/24 know how to get to the remote site.


Thanks.

Richard Burts Wed, 04/30/2008 - 07:26

DJ


Assuming that there is a correct route to the remote router and its subnets then yes any packet that hits the 3660 and has a destination in the remote subnet should be routed out just fine. Bear in mind that for the response to get back that the remote router must have a route to your other subnet. So your router needs a route to 172.16.1.0 and the remote router needs a route to 192.168.1.0.


Is there some other aspect of this situation that you are trying to get at but have not yet identified to the forum?


HTH


Rick

dj214 Fri, 05/02/2008 - 01:46

Rick - for some reason, everything seems to be in place as described by everyone here but for some reason, I can't route packets down to the remote site. I'm fairly new to routing but understand that routes are needed to and from destinations and I have that already established. Perhaps I can post the configs so everyone can take a look. I will do that shortly.


The crux of the problem is that I added a Sonicwall NSA3500 to an existing network. I needed a link from the NSA to our router that handle the T1 to our remote site. My thinking was as posted, as long as the 3660 can find its way and back from the remote site and the NSA can find its way to and from the 3660, then we're good. I wish.


If I trace to the remote site from the NSA, it dies at the interface on the 3660. However, if I trace to the remote site from the 3660, it's fine


So I'm stumped. I must be missing something somehwere.



Richard Burts Fri, 05/02/2008 - 04:52

DJ


Posting configs from the routers may be helpful. I believe that it would also be helpful if you would post the output of show ip route from both routers.


Your post describes a traceroute from the NSA that dies at the interface on the 3660. Can we be a bit specific here: does the trace get a response from the interface on the 3660 and die after the 3660, or does it fail to get a response from the interface on the 3660? It is a fairly frequent issue that people look at a trace that does not complete, look at the last response and decide that it is where the problem is. In fact the last response is usually a device that is ok and the problem is really the next hop after the last response. I am wondering if the remote router has a route to the address of the NSA that generated the trace?


HTH


Rick

dj214 Fri, 05/02/2008 - 17:42

Hi Rick - sorry for not getting back sooner. One of those days. I'll get the ip routes posted tomorrow sometime. Appreciate your taking the time with this.


DJ

bdube Wed, 04/30/2008 - 07:27

Your right for outgoing packets to the remote site. But the other router, at the remote site, must also knows the presence of 192.168.1.0/24 in his routing table to send back packets or have a default route to assure the return.


If the default route in the remote router doesn't forward packets to local site, or don't have any default route, then, you need a routing protocol between both routers or simply add a static route for the network 192.168.1.0/24 in this remote router.

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