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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical =?gb2312?B?u9i4tDogPz86IFN0cmFuZ2UgcmVzdWx0IHdoaWxlIHBpbmcgc2VyaWFsIGk=?==?gb2312?B?bnRlcmZhY2U=?=
Thank you very much for your information. I get that page, and know it's for debugging reason. regards, Yu Ning -----Original Message----- From: Blake Fithen <[email protected]> To: 'Yu Ning' <[email protected]>; Dumb Kid <[email protected]>; nanog-post <[email protected]> Date: Thursday, May 11, 2000 10:07 AM Subject: RE: ??: Strange result while ping serial interface >>From the Cisco "System Management" document: > >http://www.cisco.com/univercd/cc/td/doc/product/software/ssr90/tsc_r90/5401 9 >.htm > > >"Note If the IP version of the ping command is used on a directly connected >interface, the packet is sent out the interface and should be forwarded >back to the router from the far end. The time travelled reflects this round >trip >route. This feature can be useful for diagnosing serial line problems. By >placing the local or remote CSU/DSU into loopback mode and "pinging" >your own interface, you can isolate the problem to the router or leased >line." > >blake > > >> -----Original Message----- >> From: Yu Ning [SMTP:[email protected]] >> Sent: Wednesday, May 10, 2000 9:00 PM >> To: Dumb Kid; nanog-post >> Subject: ??: Strange result while ping serial interface >> >> >> >> 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 <[email protected]> >> To: Yu Ning <[email protected]>; nanog-post <[email protected]> >> 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 <[email protected]> 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) >> >> ------------------------------------------- >> >> >> >> >> >> >> > >> > >> >===== >> > >> >-- >> >D.U.M.B.K.I.D. >> > >> >__________________________________________________ >> >Do You Yahoo!? >> >Send instant messages & get email alerts with Yahoo! Messenger. >> >http://im.yahoo.com/ >> > >> > |