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New Member

wan problem

hi guys

i have two routets 3660 nad 1721

when i use ppp the line protocl will go down and when i use hdlc the line protocol will be back

any idea?

Hall of Fame Super Gold

Re: wan problem

PPP authentication probably. Do "term mon" and "debug ppp auth" to know.

Anyway, for most purposes, there is no advantage in using PPP Vs HDLC. And with the latter, you save few bytes of overhead for each packet.

Hope this helps, please rate post if it does!

Re: wan problem


in my experience, both the end routers should have the same protocol for encapsulation, one side if you use HDLC & other side if you use PPP, certainly you will face this kind of problem, the reason in ur case is on the other router HDLC protocol is enabled, that is why u face this kind of problem.

New Member

Re: wan problem

thx guys

acctually i have 3660 with E1 controller on central

recently i have increased from 64 to 256K

(I HAVE JUST ADDED TIMESLOT TO CHANNEL-GROUP)and telcom are absolutly fine!

but still ppp is with line protocol down problem.

i have changed ppp to hdlc but the problem in this issue was cant ping even my own serial ip.

on brach i have a modem with WIC-1T

pleaser help me.its urgent


Re: wan problem

Hi ,

Can you paste the config of the routers ?



Re: wan problem


I completely agree with Satish, please paste configs from both the Router's interfaces and we shall be in a better position to help you out.

Kind Regards

Wilson Samuel

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