Cisco 2821 <----T1----> Nortel AN (15.4.0.0) 1

[kbing]

I have a Nortel AN router at a remote site and am replacing the head-end site Nortel router with a Cisco 2821. So the desired configuration would be to continue to use the Nortel AN at the remote site and a new Cisco 2821 router at the head-end site.

Right now I have a Nortel ASN at the head-end site. The circuit is a T1 with an external CSU on both ends. Both Nortel Routers are configured for "standard" as the WAN protocol.

My understanding to get the Cisco to talk to the Nortel router is to configure each for PPP. So I switched the Nortel WAN protocol to PPP and configured the Cisco encapsulation to PPP.

The circuit did not come up. On the Cisco router I did see the serial interface was UP but the line protocol was down.

Has anyone gotten this to work or has done this before successfully?

I appreciate any help.


Here is the config of the Cisco router:
interface Serial0/0/0
ip address 172.17.0.1 255.255.255.252
no ip redirects
no ip unreachables
no ip proxy-arp
encapsulation ppp
ip route-cache flow


Here is the config of the Nortel AN:

Name: S11 Number: 201101 Slot/Connector: 1/1
Admin State: up Operational State: up

MAC Address: 00.80.2D.CB.9D.65
MTU: 1600 Wan Protocol: standard
Local Address: addressexplicit Remote Address: addressexplicit
BOFL: enabled BOFL TMO: 5

IP Address: 172.17.0.2 Mask: 255.255.255.252
Encapsulation: enet ARP Type: arp


Any ideas? I found an article on experts-exchange talking about setting the WAN protocol to PPP and adjusting the MTU to 1506 on the Nortel. I did this and it did not work. Only the physical interface would come up but the data link layer would not.

 

[jneiberger]

Turn on PPP debugging and you'll probably see the problem immediately.

 

[burtsbees]

MTU on Cisco routers is 1492. Looks like the Nortel Don't know if this has anything to do with it...but PPP is industry-wide, HDLC is default on Cisco, and it is Cisco proprietary. What was the encapsulation Nortel was using?
Also, jneilberger is right...
router#debug ppp negotiation
router#debug ppp authentication
router#debug ppp authorization

Burt

 

[kbing]

Cisco said the MTU on their router is 1500. Nortel is 1600. On Nortel's knowledge base they have an article about this where I need to modify the MTU on Nortel from 1600 to 1506.

I tried that before but didn't work. I just found another article that talks about setting the Nortel line parameters to:

PPP
16bit CRC
MTU = 1506

I also found a document that said the circuit configuration on the Nortel router needs to be deleted and then re-created due to the software leaving ghost entries.

I will test this tomorrow. My last test was with all of the above however never deleted the circuit and re-created from scratch on the Nortel Router.

I'll post my results to see what happens.

 

[kbing]

Ok. I have it working. For anyone in the future - here's how to do it.

a) cisco router using "encap ppp" on serial interface is correct.
b) on Nortel router
b.1: pull a copy of the config file via site manager to local disk
b.2: edit the local config file - delete the serial interface circuit and rebuild using
- Wan Protocol PPP
- MTU = 1506
- CRC = 16bit

save the local config file. using site manager upload back to the nortel router using a different file name
telnet to the router
type boot - <newconfigfilename>
this will reboot the router to the new configuration file. The original config file will still be there in case you need to restore it. To restore it just reboot again.

Once the router comes up - the T1 should be working.

This is with external CSU's on both ends and the clocking configuration is handled by the CSU's not the routers.

Walla!!!

 

[jneiberger]

Further advice to those using Nortel routers: don't use Nortel routers. ;-)

 

[avidube]

kbing and others.

I'm glad to see some others out there still have to trudge through dealing with Nortel routers too. Anyhow, I just wanted to add that a) your post is accurate, but b) your should consider replacing the Nortel router any way you can because the whole BayRS suite will become end of life/manufacture discontinuation during 2007. Just food for thought, if you have budget, get rid of them. Myself, I have to figure out how to find budget to plan the replacement of quite a few ARNs myself. Wish me luck