Netowrking Cisco to a Baynetworks using PPP

[cmstanphill]

I have a 3640 with a T1 Wic card and a Baynetworks ARN router and I cant get the PPP to work. I set the MTU to 1500 on the Cisco. and on the Baynetworks I set the MTU to 1506 and the MRU to 1450 and still nothing. The Line is up but the Line Protocol is DOWN. any ideas
Thanks

 

[svermill]

Lots of things can go wrong with ppp negotiation. You need to run some debug to find out where it is failing. Start with these:

'debug ppp neg'
'debug ppp auth'

resort to adding:

'debug ppp error'

if the first two don't point you in the right direction.

 

[Saeed42]

If the line Protocol is DOWN, it has nothing to do with authentication, but it sounds like your problem could be caused by any of these settings,

Local or remote router misconfigured
Keep-alives not being sent by remote router
Leased-line or other carrier service problems, such as noisy lines or faulty switch
Timing problem on cable, possibly caused by the CSU/DSU not being set correctly.
Failed local or remote CSU/DSU. Router failure.

http://www.cisco.com/warp/public/125/25.html

 

[svermill]

Saeed42,

You need to hit the ppp books. Authentication is one of the first and foremost LCP options that must be negotiated before ppp protocol advances to NCP, and thus the protocol up status. Try setting up ppp authentication and intentionally mismatch the passwords. You will definately see ppp protocol down as a result. If you want to learn even more, turn on debug so you can watch it fail.

 

[Saeed42]

I might be wrong, but how I understood this problem is that he gets "The Line is up but the Protocol is down" when he looks at the interface, and if that is the case, it doesn't have anything to do with authentication, as it's not even trying to establish a connection, because the router sees that the Protocol is down

 

[svermill]

You make it sound as if the ppp protocol exists on the line. A router does not try to detect or "see" if the ppp protocol is active on a line. It negotiates it between itself and a neighboring router. In the case of ppp, the router starts with LCP. Authentication is one of the many LCP options that, if configured, must be successfully negotiated along the journey to "protocol up." If anything in the LCP process fails, the protocol stays down. Also, in the case of CHAP for ppp, authentication is renegotiated every two minutes. If at any time after "protocol up" the authentication doesn't pass, the router takes the interface back to "protocol down."

All of this and much more is widely available in books and on the internet. With all due respect, it is OK to make suggestions that you aren't sure of. We are all trying to help one another out and sometimes the best we can do is to make a suggestion that we aren't ourselves quite sure of. But you really shouldn't be stating things as fact that you obviously haven't read up on.