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  • From: Yu Ning
  • Date: Wed May 10 23:13:38 2000

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 <fithen@NetworksPlus.com>
To: 'Yu Ning' <yuning@cndata.com>; Dumb Kid <dumbkid0@yahoo.com>; nanog-post
<nanog@merit.edu>
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:yuning@cndata.com]
>> 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 <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)
>> >> -------------------------------------------
>> >>
>> >>
>> >>
>> >
>> >
>> >=====
>> >
>> >--
>> >D.U.M.B.K.I.D.
>> >
>> >__________________________________________________
>> >Do You Yahoo!?
>> >Send instant messages & get email alerts with Yahoo! Messenger.
>> >http://im.yahoo.com/
>> >
>>
>






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