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New Member

2620 connections over isdn problems

hello all,

I have 2 * 2620's and I am trying to connect them via their serial wics to run ospf. I have set them up in a lab and I am trying to connect over a constantly up isdn connection. This is done using 2 * adtran terminal adapters and the 'dialer in-band' command. The adtrans are happily talking to each other but I cant get the ciscos to see each other (either via ping,cdp, or ospf). I am using unnumbered serial ports.

The script I am using is basic and taken off the cisco website, and works when I replace the 2620's with 3640's.

Can anyone think of any reason why the 2620's will not talk? I have only 1 wic in each 2620 and nothing else,

many thanks

Richard

7 REPLIES

Re: 2620 connections over isdn problems

This is very little info to go on. A (partial) config would be helpful.

What is the interface status of the WICs in the 2620's?

New Member

Re: 2620 connections over isdn problems

please find attached a copy of config I used, identical for both except for ip's obviously:

hostname router1

!

interface loopback0

ip address 1.1.1.1 255.0.0.0

!

interface fastethernet0/0

ip address 4.0.0.1 255.0.0.0

!

interface serial0/0

ip unnumbered fastethernet0/0

bandwidth 64

dialer in-band

pulse-time 1

!

router ospf 1

network 4.0.0.0 0.255.255.255 area 0

!

end

That is basically the script for both. The wics all show up when I look in 'sh int ser 0/0'. When I issue the 'no shut' command the adtrans come immediately up and stay up but I cant see across the link. I am using ios 12.2

Is this any help?

Re: 2620 connections over isdn problems

It looks like the TA's are connecting when DTR becomes active. This means that the dialer in-band is not required.

You state that tha TA is coming up, but how about the line protocol?

Is the line protocol on your router serial interfaces up or down?

Are you using V35 or V24 connectors to connect the TA's?

In this config, the router would require clocking from the TA. Did you check that clock signals are received on both sides?

(sh contr serial)

New Member

Re: 2620 connections over isdn problems

Thanks for the replies chaps,

We are using v35 and one of the ta's is configured to dial the other on dtr with a stored number. We need the dial in-band command for this to happen. The line protocol between the ta's is 64k clear channel. The clocking is being given by the ta's at 64000. Both ta's are set the same except one dials and one receives.

When we look at ser0/0 both admin and line protocol are up, on both routers.

The conf does work with 3640's, we were wondering whether there is someting different/new about the 2620's. Maybe a missed conf line or something similar? We are sure that the script is proven and working but just not on 2620's for some reason.

Thanks

Richard

Re: 2620 connections over isdn problems

Maybe this is caused while you do not have your ethernet interface up. With unnumbered interfaces there is a requirement for the interface that you use the ip from must be active. This is one of the reasons that a loopback interface is the best choice as source for ip unnumbered.

New Member

Re: 2620 connections over isdn problems

The interfaces are active (apologies if my script did not reflect this), and I have tried using both the loopback and the ethernet addresses as the unnnumbered reference point. I can ping both. The script is very basic and taken from cisco themselves as a simple ospf network. Any more ideas?

Thanks

Richard

Silver

Re: 2620 connections over isdn problems

Richard

Without the config on the remorte side it is difficult to judge, but I think your problem is that you are using ip unnumbered, on each side, this is causing the bri interfaces to be on separate subnets ,hence ping or OSPF would not be possible. You should however see eachother in CDP , is cdp enabled ?

Also on the Adtran TA's I beleive the reason they come up immediately is because there is a setting to dial when DTR is raised , it is under the config menu DTR options , the setting is something like ignore DTR .

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