Solved: assistance for configuring Internet router

saidfrh · ‎03-07-2008

Hi,

We are not able to browse the Internet using the Cisco 1721 router. The router is connected using straight-through cable to the T1/smartjack. A firewall sits behind the router. A host behind the ASA5505 firewall can telnet to the router, however cannot browse the internet. The T1 circuit/smartjack has two green light, the lower two lights are amber. Sh ip int br is 'up' and 'down'. AT&T tests the circuit to the smartjack to be good. AT&T's router shows 'down' and 'down'.

I would appreciate any suggestions. the attachment has the config.

Rick Morris · ‎03-10-2008

With your Smartjack showing amber lights it typically means that their is a carrier issue. I would open a ticket with the provider that the T-1 is down and have it tested. I would work with them to provide a hard loop at the cable end right before your router to make sure the smartjack card is good.

With having an up/down you are seeing the smartjack but not the line.

When you say AT&T Router down down, what is that in the topology?

View solution in original post

lamav · ‎03-07-2008

Said:

The "up, down" indication on your router means that your router is receiving a T1 signal from the network, but is not synchronizing on the layer 2 level. I imagine you're running either HDLC or PPP layer 2 encapsulation on this T1 link.

1.) Check the framing and coding on the CSU to see if it is set correctly - I imagine its an ESF/B8ZS circuit.

2.) Check your clocking. You should probably be set for "line" or "network" timing and AT&T should be set for "internal." One side has to be internal and the other line.

3.) If its a FRAC-T1, make sure you have the correct number of DS0s enabled. A full T1 is 24 DS0s, where each DS0 is 64kbps.

4.) Ask AT&T to loop up your CSU/DSU. If they cannot, then you should try replacing the cable between the router and the Smart Jack with a KNOWN good cable.

5.) If it still doesnt work, you have 2 choices: either you demand that AT*T go out and run a head-to-head test with the distant end or you just take the hit and try replacing the serial interface.

HTH

Feel free to come back with more questions.

If you found this post helpful, please rate it.

Victor

Rick Morris · ‎03-10-2008

With your Smartjack showing amber lights it typically means that their is a carrier issue. I would open a ticket with the provider that the T-1 is down and have it tested. I would work with them to provide a hard loop at the cable end right before your router to make sure the smartjack card is good.

With having an up/down you are seeing the smartjack but not the line.

When you say AT&T Router down down, what is that in the topology?

saidfrh · ‎03-10-2008

The AT&T router's serial int was down. Shut and then no shut command brought it up.