point-to-point ds3 config

[smikes19]

I've got a point-to-point clear channel DS3 circuit running between two 7120 routers, and its giving me grief:

- with "framing bypass", the serial int is up/up, but it won't pass any traffic
- with "framing c-bit", the serial int constantly flaps. If I ping, a few packets will get through every few seconds.

Some things I know about the circuit:
- clear channel
- unchannelized
- Adtran CSU on one end, not sure about the other
- supposedly the LEC is providing the clock source, but not 100% sure

Here is my Serial config for one side:

interface Serial1/0
ip address 192.168.168.1 255.255.255.0
no keepalive
framing bypass
cablelength 75
dsu bandwidth 44210
clock source internal
serial restart-delay 0

and the other:

interface Serial1/0
ip address 192.168.168.2 255.255.255.0
no keepalive
framing bypass
cablelength 200
dsu bandwidth 44210
serial restart-delay 0

I'd appreciate any help!!!

 

[smikes19]

I'm wondering if this is a cable problem. loopback local and loopback dte both work ok on both ends, but a "loopback network line" fails from both ends. What does this mean exactly? Is the wiring to the NIU at least good?

 

[nemotek]

whats the name of the circuit provider ? do you have backup ISDN ? since you are using Adtran..

 

[smikes19]

Its through XO communications. No backup ISDN. Actually the 7120 goes to an Adtran NIU3 which then connects to a Nortel Metro fiber mux.

 

[Googer]

Are you useing scrambling on this DS3 link? I had a simular issue on a DS3 link between two Adtran CSUs and the problem was long strings of 1's and 0's causing a loss of clocking. As soon as we turned on scrambling the link flapping problem cleared up.

Good Luck,

Googer

 

[smikes19]

If I enable scrambling on both ends, neither comes up/up...

 

[jtho]

Looking at the config for our DS3, the only difference I see is the lack of "encapsulation ppp". Not too sure if that helps but I thought I'd throw it out there... Good Luck!

interface Serial6/0
description DS3
bandwidth 3000
ip address 12x.xxx.xxx.xxx 255.255.255.252
encapsulation ppp
no ip route-cache cef
framing c-bit
cablelength 50
dsu bandwidth 44210
serial restart-delay 0

 

[smikes19]

Thanks, but it turns out that our Serial interface was bad, even though a hard-loopback test works fine. We swapped it out, and with no changes to the config, everything started working beautifully.