Messages in this thread |  | | From | cs95rro@brunel ... | Subject | Re: 1.3.89+Solaris+PPP - still lots of extra packets | Date | Tue, 16 Apr 1996 10:43:44 +0100 (BST) |
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> David Monro <davidm@gh.cs.usyd.edu.au> writes: > >well, I have upgraded to 1.3.89, and I am still having ppp problems. > >Interactive response to our Solaris server has improved - I no longer > >get massive delays when attmepting to type-ahead into a shell. However, > >I still have the duplicate packets problem with paging text files on > >large xterms, and ftp transfers on a 68K (gzipped so no modem > >compressions) file run at 240cps on a 14.4k modem. Below are the dumps > >from both ends of the link for typing df on our server, which produces > >85 lines of output. This time I have managed to include time stamps and > >packet IDs at both ends. > > > It seems to me that SUNOS is choosing to retransmit packets much > to early. Say a 1460 byte packet gets injected into the network by > staff at time T, which then makes its way to your machine. > Just counding transmission time over the modem I'd expect there to > be a 1 second delay between the time staff sends the packet and the > linux box can see it and ACK it. If the linux box waits another 1/2 > second to send the ACK (which is about what we are doing now), > then sends it over the modem, you'd expected pretty much what > you are seeing for the round trip delay on the ACK. > Looking at staff's output log, it starts the first resend 1/2 second > after the first packet is sent. There is no way that fuzzbox can > even have the packet yet, never mind have responded.
I've had this problem, going via a Zylogics PPP box, on all versions of the kernel I've used. (1.2.1, 1.2.13, 1.3.[lots]) I've not gone as far as packet dumps (Mainly because tcpdump doesn't work on PPP and I haven't got time to do it any other way) but it seems to me as if SunOS (Both 4 and 5) is overdoing the source quench a bit. I generally get around 400cps on a good day (At 14.4k) but for much of the time the transfer goes at full speed but then the CS drops briefly and it waits for up to 30s. I hacked together a bit of C to spoon-feed ftp data to the Linux box at 1.2k and it seems to work.
Hope this helps.
* cs95rro@brunel.ac.uk ryan@bcs.org.uk * Ryan Richard O'Connell * * http://www.brunel.ac.uk:8080/~cs95rro * Finger: cs95rro@molnir.brunel.ac.uk * The modern idiot is here and plain to see.
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