dheeraj@cs.umd.edu (Dheeraj Sanghi) (06/01/90)
I wonder if people have noticed duplicate IP packets in any study. Is there any possibility of duplication apart from because of some bug in the gateway software? Any pointers in this regard would be much appreciated. Thanks, -dheeraj -- Dheeraj Sanghi (h):301-794-6247 (o):301-454-1516 Internet: dheeraj@cs.umd.edu UUCP: uunet!mimsy!dheeraj If you want to judge the culture and civilization of a people you can find that out by the status and conditions of the women of the country. - Nehru
art@OPAL.ACC.COM (Art Berggreen) (06/01/90)
Newsgroups: comp.protocols.tcp-ip Subject: Re: Duplicate packets in Internet. Summary: Expires: References: <24688@mimsy.umd.edu> Sender: Reply-To: art@opalacc.com (Art Berggreen) Followup-To: Distribution: na Organization: Advanced Computer Communications, Santa Barbara, California Keywords: In article <24688@mimsy.umd.edu> dheeraj@cs.umd.edu (Dheeraj Sanghi) writes: > >I wonder if people have noticed duplicate IP packets in >any study. Is there any possibility of duplication apart >from because of some bug in the gateway software? The most common source would be from unneccessary transport level retransmissions. This is usually due to rapid build up of congestion. This is aggravated by non adapting retransmission strategies. The most famous situation is the "congestion collapse" first described (I believe) by Nagle. >Any pointers in this regard would be much appreciated. > >Thanks, > >-dheeraj > >-- >Dheeraj Sanghi (h):301-794-6247 (o):301-454-1516 >Internet: dheeraj@cs.umd.edu UUCP: uunet!mimsy!dheeraj >If you want to judge the culture and civilization of a people you can find >that out by the status and conditions of the women of the country. - Nehru Art Berggreen ACC
postel@VENERA.ISI.EDU (06/02/90)
Dheeraj: Just run "ping" thru any NSS. You get back more echo-replies than echo-requests you sent. Somebody is duplicating something somewhere. --jon. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ % ping lcs.mit.edu PING lcs.mit.edu: 56 data bytes 64 bytes from 18.26.0.36: icmp_seq=0. time=499. ms 64 bytes from 18.26.0.36: icmp_seq=1. time=360. ms 64 bytes from 18.26.0.36: icmp_seq=1. time=360. ms 64 bytes from 18.26.0.36: icmp_seq=2. time=340. ms 64 bytes from 18.26.0.36: icmp_seq=3. time=320. ms 64 bytes from 18.26.0.36: icmp_seq=4. time=360. ms 64 bytes from 18.26.0.36: icmp_seq=5. time=400. ms 64 bytes from 18.26.0.36: icmp_seq=5. time=440. ms 64 bytes from 18.26.0.36: icmp_seq=6. time=339. ms 64 bytes from 18.26.0.36: icmp_seq=6. time=339. ms 64 bytes from 18.26.0.36: icmp_seq=7. time=380. ms 64 bytes from 18.26.0.36: icmp_seq=8. time=340. ms 64 bytes from 18.26.0.36: icmp_seq=9. time=340. ms 64 bytes from 18.26.0.36: icmp_seq=10. time=380. ms 64 bytes from 18.26.0.36: icmp_seq=10. time=440. ms 64 bytes from 18.26.0.36: icmp_seq=11. time=340. ms ^C ----lcs.mit.edu PING Statistics---- 12 packets transmitted, 16 packets received, -33% packet loss round-trip (ms) min/avg/max = 320/373/499 % ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dheeraj@cs.umd.edu (Dheeraj Sanghi) (06/08/90)
>I wonder if people have noticed duplicate IP packets in >any study. Is there any possibility of duplication apart >from because of some bug in the gateway software? > >Any pointers in this regard would be much appreciated. > >Thanks, > >-dheeraj I have received lots of replies to my query. I wish to thank all of you. Because of large amount of mail I have received, I am sorry I would not be able to reply to all of you personally. Here is the summary of responses: Many people suggested that there is some problem with NSS gateways and they duplicate packets. It could be checked by pinging any of the NSS gateways. Many people suggested that duplicates are due to congestion, bad timers etc at the transport level. Sorry, I was interested in duplicates that the network generates, and not those which are generated by the source transport level protocol. Couple of people suggested that duplicates at the IP level could be the result of link level retransmission. Thanks once again to all of you, -dheeraj -- Dheeraj Sanghi (h):301-794-6247 (o):301-454-1516 Internet: dheeraj@cs.umd.edu UUCP: uunet!mimsy!dheeraj When you find you are on the side of the majority, it is time to reform. - Mark Twain