My Cisco T1 intefaces need Viagra

[cjvon]

I have two 2610 Cisco routers with T1 interfaces with intregal CSU/DSUs. Both routers are running IOS v12.3. I have a T1 crossover cable I made to connect the routers.

I have tried a number of configs but regardless of what I do my interfaces show down/down.

I currently have a config like this:

Interface serial 0/0
service-module t1 clock source internal
service-module t1 timeslots 1-24 speed 64
service-module t1 framing esf
service-module t1 linecode b8zs
ip address 192.168.30.1 255.255.255.0
encapsulation ppp
fair-que
no shut

The other router has service-module T1 clock source line and
ip address 192.168.30.2 255.255.255.0

I'm a Cisco rookie and very green to T1 settings. This is just a home CCNA lab. I wonder if the linecode/framing/timeslot settings are not right.

One T1 interface blinks, the other lights up but doesn't blink. Is that because of the clock source difference?

I wouldn't be shocked if I didn't pin out the T1 crosscable correctly, I can test my ethernet cables but how do you test the crossover cable? Also, one router came from ebay and the other my boss gave me so there is a chance that one or more of the interfaces are dead.

TIA

 

[spidey07]

you have a cabling problem. Also, make sure your framing/linecode/timeslots are the same on both ends as well as your encapsupsulation.

The only difference on the configs between the two interfaces should be the clocking (and addressing of course).

What I mean is you are still at layer1 - clocking, framing, linecode, cabling, etc. If you then show up/down then you can move to layer2.

 

[cjvon]

Thanks Spyder. I'll give another go with my cat5 crimp tool.

Seems I should be able to use my simple cat 5 tester to show if I have the pin outs correct.

 

[ScottMac]

The crossover cable should have pins 1&2 crossing to 4&5 on both ends.

One router needs to be designated DCE and provide clock. The other router should be DTE and recover clock from the line.

Good Luck

Scott

 

[cjvon]

Originally posted by: ScottMac
The crossover cable should have pins 1&2 crossing to 4&5 on both ends.

One router needs to be designated DCE and provide clock. The other router should be DTE and recover clock from the line.

Good Luck

Scott

After making 3 more crossover cables I went back to the Cisco site after reading your post and realized I was making 56K CSU/DSU cables! OOPS.

My serial interfaces are now up/up and I can ping. Now to tie in my ethernet interfaces and get DHCP to route from one ethernet interface to the other.

Thanks again gents.

 

[networkman]

Congratulations on the accomplishment!

I too am still in the learning curve to get Cisco certified; my latest thrill has been getting Wake-on-Lan work across the WAN at work. Been scratching my head for some time, 'til I realized I needed to look at more than just one interface for the "ip directed-broadcast" statement. Of course now I need to lock it down a bit so not everything can make use of that.

 

[spidey07]

Just a comment - understanding how the traffic works at layer1, 2, 3, 4 and 7 will help immensely. It's not cisco specific as any capable router/switch will let you do whatever you want with the traffic.

The CLI is just there for you to tell it what to do and tell you what it's doing.

Also the "no forward protocol" is very helpful when dealing with ip helpers/ip directed broadcasts.