Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Cisco > Connecting 2 Cisco Routers (back to back)

Reply
Thread Tools

Connecting 2 Cisco Routers (back to back)

 
 
cisconovice cisconovice is offline
Junior Member
Join Date: Oct 2006
Posts: 2
 
      10-13-2006
Hi! i was wondering if anyone can help me configure 2 2600 routers back to back using 2 wic t1 csu/dsu's.. i already have a t1 crossover cable. but i dont know how to configure them to talk using frame relay... thanks in advance!
 
Reply With Quote
 
 
 
 
katberts katberts is offline
Junior Member
Join Date: Apr 2011
Posts: 1
 
      04-02-2011
Hi there,
I wish I found this site when I was having my hair pulling issues when I tried to connect my two 2600 routers with integrated CSU/DSU (WIC1DSU). I had found plenty of sites with bits of information, but none that had all the information for what I wanted. I wanted to connect my 2 routers using frame relay sub interfaces.

Things I knew:
I needed a T1 crossover cable
Because each router has a T1 WIC1-DSU, I needed to verify/configure the service-module
I knew I needed to set the clocking on one of the routers to be the master
.

Things I thought I knew:
I assumed each router would need its own DLCI (since in the real world that's how you would do it to get them to talk)
One of the routers to be DCE since, by default, routers are DTE (but HOW to do it - ah, that was a bit of challenge for my addled pated mind!)

I got the crossover cable made and validated it. Then I configured the service module (most of these are defaults and do not show up under the serial interface). Note: The clocking need only be modified on the router you want to be the master.

service-module T1 line b8zs (default)
service-module T1 framing ESF (default)
service-module T1 timeslots 1-24 speed 64
service-module T1 clock source internal (one router only)

Then I went to the serial interface s0/0 and configured the following:

encapsulation frame-relay

I created a sub interface s0/0.100 and configured the following:

ip address 10.1.12.1 255.255.255.252
frame-relay interface-dlci 100

On the 2nd router, I mimicked the configs from serial interface s0/0 above as noted then on the sub interface, I assigned the ip address 10.1.12.2 and then assigned a DLCI of 200.

The interfaces came up in an up/down state and I could not get them to work. I eventually found out that when you put the 2 routers back to back, you must have each router's sub interfaces assigned with the SAME DLCI.

So I modified the configs of each sub interface so each router had the same DLCI.

Still didn't work.

Somewhere in the recess of my mind, I knew I needed to change one of the routers to be DCE but I could not find how (I did find a fancy youtube video where this guy has a GUI lab and when he clicks on the serial interface of his router picture, this little thing pops up and asks him if he wants this interface to be a DTE or a DCE. Nifty, but not helpful for my situation). I finally found a website which indicated the config I needed:

frame-relay intf-type dce

I added that to the serial s0/0 of one router only ( I put it on the router I was using as the master)

Still did not come up (well, it would come up for about 1 minute then go back into the up/down state).

I was getting somewhat frustrated by this point. I finally, out of desperation, added a config to my master router that I had seen in a few posts (but didn't think it applied to my situation). Viola, both sides came up and I was able to ping and send traffic across my links.

In global mode:

frame-relay switching

That little command I didn't think applied to me because I only was using 2 routers. In all the scenarios I found on the internet, there were at least 3 or 4 routers and one of the routers was acting like a cloud router. It never occurred to me that, even with 2 routers, using frame relay DLCI, one of them needs to still needs to be a cloud router.

Here are the complete configs I ended up using:

R1
config t
frame-relay switching

interface s0/0
encapsulation frame-relay
service-module T1 linecode b8zs
service-module T1 framing esf
service-module T1 clock source internal
service-module T1 timeslots 1-24 speed 64
frame-relay intf-type dce

interface s0/0.100 point-to-point
ip address 10.1.12.1 255.255.255.252
frame-relay interface-dlci 100

router eigrp 1
network 10.0.0.0
no auto-summary


R2

interface s0/0
encapsulation frame-relay
service-module T1 linecode b8zs
service-module T1 framing esf
service-module T1 timeslots 1-24 speed 64

interface s0/0.100 point-to-point
ip address 10.1.12.2 255.255.255.252
frame-relay interface-dlci 100

router eigrp 1
network 10.0.0.0
no auto-summary

Thanks to sites like these, I was finally able to get all the pieces together to get my lab up and running.
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
connecting cisco routers through the serial port sqrfolkdnc Cisco 3 03-10-2005 06:00 AM
connecting Cisco routers through their *AUX* ports sqrfolkdnc Cisco 2 03-10-2005 04:37 AM
cisco routers and netgear routers Jon L. Miller Cisco 2 02-05-2005 02:49 AM
Connecting 2 cisco 8xx ISDN routers Nic Cisco 3 06-24-2004 05:51 AM
Connecting 2 CISCO routers directly amn Cisco 4 05-10-2004 11:19 AM



Advertisments