Problems connecting 2500 to 4000 for CCNA labs

[soma56]

Greetings!

Yet, another Cisco problem however I'm sure most of you are more advanced then me..



I have a 2500 and 4000 series routers that I'm trying to directly connect. The cable between them is a db60 male (2500) to a db50 male (4000) and plug directly into the serial ports provided by both routers. When I try to bring the interface up it doesn't stay up for very long. The status is up however the protocol is down on both sides. I have tried two different clock rates of 56000 and 64000 to no avail. The cable between them is brand new and as far as I know the routers are fine. Due to my inexperience with Cisco configurations I am guessing that there is something that I am not doing correctly on my end.

ip address 4.0.0.1 255.0.0.0
clock rate 64000
no shutdown
exit

ctrl-z
router rip
network 4.0.0.0
exit

ctrl-z
copy run start

Is there anything else I should consider with trying to connect these two routers? I have tried the other serial interfaces with no luck. Like I said the status will come up fine. The line protocol will come up only briefly and shutdown. My experience is NIL as I am trying to set up this home network to work towards my CCNA.
I would really appreciate any advice or help that any of you can offer.

 

[ADB100]

The clock rate command should only be configured on the DCE end. The back-to-back cable should have either DTE or DCE written on it, the router that has the connector 'DCE' should be configured with a clock.

Andy

 

[soma56]

Thanks. I tried that at 64000 and 56000 for the 2500 series as the end of the cable is labelled DCE. Do I have to give any other commands besides setting the clock rate with respect to this router? Again, the status is up however the line protocol is down.

 

[ADB100]

No, that should be it. The default encapsulation should be HDLC, so clock the DCE end and do a no shut on both routers and it should come up. Have you tried a different cable, and or differnt serial ports?

I am not sure whether a 2500 will show you the information but the command 'show controllers serial x' should show you whether the cable is DCE etc and whether clocks are detected.

Andy

 

[soma56]

Andy, the cable is brand new. This is the scenario for the last day or so: The line protocol goes up briefly and then shuts down (permantley). DCE is labelled on the DB60 end of the cable and will only fit into the 2500 (it will only accept a 60pin male connection). The other end other the cable is labelled DTE and has 50 pins (and will only fit into the 4000). There is only one cable with this connection and I am aware that I have to set the clock rate on the 2500 to which the cable labelled DCE is at. This is what I am doing:

For the 2500:

enable
config t
hostname 2500
no ip domain-lookup
no service config
int e0
ip address 10.0.0.1 255.0.0.0
no shutdown
int s0
ip address 4.0.0.1 255.0.0.0
clock rate 64000
no shutdown
exit
router rip
network 4.0.0.0
network 10.0.0.0
exit
line con 0
password XXXX
login
line vty 0 4
password XXXX
login
Z
sho run
copy run start

Everything is the same with respect to configuring the 4000 with the exception of; the hostname, the ip addresses and I do not set a clock rate.

Again, the status will say it's up and the line protocol goes up briefly (only on the serial interface, the ethernet interface seems to be working fine). After a few seconds after bringing up the interface the line protocol goes down for no reason. I looked at the different ways of connecting these two routers as per aryoba's post with the exact same results.

 

[jneiberger]

As I recall, on some of the older 4000-series routers there is a jumper inside the chassis that has to be moved to switch it from DCE to DTE and vice versa. If that's the case with the one you have then it's possible that the jumper is set to DCE, which you can't have because you don't have a DB50 DCE cable.

I'll see if I can find some documentation about this. I may not be remembering this correctly but it's worth checking into.

John

 

[GSTEFANICK]

you may have a problem with the media or there is an encapsulation mismatch.

 

[jneiberger]

After a bit of looking I see that I was only partially right. Some of the modules on the 4000 have jumpers but they don't determine whether or not the interface is DCE or DTE. Rather, they determine whether NRZ or NRZI line coding is being used. The default is NRZ, which I think is the default on the 2500, as well.

http://tinyurl.com/8qvkd

If that jumper has been changed on the 4000 you can either move the jumper back to the NRZ position or configure NRZI on the 2500.

That's just a thought. Another thought might be that you have a bug that is causing a lack of interoperability between the two versions of HDLC. I've seen this type of bug with frame relay in older IOS images. Perhaps this one has an HDLC bug.

 

[soma56]

Thanks for the link. I haven't read it completley yet however I"m sure I'll get to the bottom of this problem. I just want to connect two routers to do some CCNA labs. It doesn't seem fair that I get problem after problem after problem...

 

[jneiberger]

That's one of the best ways to learn! ;-)