Showing results for 
Search instead for 
Did you mean: 

2 T1's and one Cisco router


I want to know if there is a way to implement a solution that utilizes Cisco's 2500 series routers, namely the 2524, which has 3 wic slots capible of fitting Cisco's csu/dsu.

I am wondering if ther is any way to make this router work(one router now), for 2 T1's. I guess the obvious confusion for me is what to do for the case of only one ethernet port. Is there a way to manage two networks given this scenario? If that is a resounding NO, would anybody be brave enough to reccommend the lowest price Cisco solution? Keep in mind, I shop at eBay, not a Cisco reseller.

I would be interested in hearing anyones opinion and advice. Thanks in advance for your time.


VIP Mentor

Hello Bob,

I guess the easiest way would be to use secondary addressing on the Ethernet interface, that way you can have two networks connected to your Ethernet port, which can then be forwarded separately to your two T1 connections.




Can you elaborate on that.....First though, just to confirm..we are talking about two Tq's coming into a 2524 with two sm25 WICs that are the csu/dsu for our respective T1's and this router has a 10 MB/s ethernet port.

Ok, now for the secondary addressing. I am not framiliar with that. but how does it work when I am plugging in to one switch? I am going to go from a single ethernet port on the route, which will have to be the default gateway for both of the T1 networks when going out to the internet, and that will be hooked to the switch. How is it that I am going to have two networks landing on the same port of the switch on one cable? Maybe I have misinterpreted your idea or maybe I am totally lost! Either way I am very interested in this idea...lets go with this.



Hi Bob,

To use secondary ip address..

Go to particular interface in your case ethernet0.

type the ip address for the second subnet and specify the default gateway at the end just type secondary.

This will allow you to use more than one Network..

Hope this will help...


I understand the configuration of the router for secondary addressing. That is no problem. The switching part is my question. As far as I know a switch will only support one logical network or subnet, out of the what has to be configured on the switch to be able to switch two different subnets or logical networks coming off of one interface? OR has this been overlooked?

MAybe I am not asking the right question here and am overlooking something obvious. If this is the case, can someone please let me I losing it?



I am interested in figuring out how the secondary addressing will work on a 2524 which will have 2 T1's coming into it and then one ethernet port leaving. The question is, is this possible and how will the switching be configured to have two different logical networks one one physical interface(the cable connecting the router and switch). I will have a 2924XL switch, so does this involve trunking?

What types of technologies should I be learning about to implement this? Since I only have a CCNA, I am not framiliar with all availible Cisco technologies, but am vary capable to learn them. I just need to be turned in the right direction. thanks




On the switch side, go the the respective interface vlan and assign the same range of secondry IP address on that also. There is not need to configure the trunk link.

If your router has IP plus feature set then you can configure the link as trunk link also and thus you have to create 2 seperate vlans on the switch and also setup the trunk.