Hi, But it's obviously inefficient. Is it due to some inability of PPP ? Or can you tell what reason makes the packets a round trip ? Since the router should have the information of its local interface, why should it always send packets out, the get it back ? regards, Yu Ning -----Original Message----- From: Dumb Kid <dumbkid0@yahoo.com> To: Yu Ning <yuning@cndata.com>; nanog-post <nanog@merit.edu> Date: Thursday, May 11, 2000 9:45 AM Subject: Re: Strange result while ping serial interface

Yeah , it's normal. The packet actually travels to the other end of the router over the serial and back. That's why the response time is doubled.

--- Yu Ning <yuning@cndata.com> wrote:

...

Hi nanog,

Strange thing happens everyday. When I were troubleshooting yestoday, I found a ping to my local serial interface (no matter it's 155M POS, or 2M Serial interface) takes nearly twice delay compared with a ping to the remote side of the serial interrface ! When I trace to my local serial interface, I got the first hop to the remote end, then second hop back to my local interface !

For example, 202.97.2.1 is local serial interface, while 2.2 is remote side. A trace on 2.1 to 2.1 first go to 2.2, then back to 2.1. And this situation can be verified on both side.

Have you ever seen this situation ? Is it due to our misconfiguration? or it's sheerly a mis-display of result in Cisco box (can't believe it)

The background is: we're using ISIS as IGP, and utilized level-1/2 link.

thanks for any input.

regards,

Yu Ning ------------------------------------------- (Mr.) Yu(2) Ning(2) ChinaNet Backbone Operation Networking Dep.,Datacom Bureau China Telecom.,Beijing(100088),P.R.C +86-10-66418121/66418122/66418123(fax) -------------------------------------------

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-- D.U.M.B.K.I.D.

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