Re: Lost UDP packets
Re: Lost UDP packets
- Subject: Re: Lost UDP packets
- From: "Peter Lovell" <email@hidden>
- Date: Fri, 24 Sep 2004 18:04:43 -0400
>Hi
>
>I have a strange problem with lost broadcast UDP packets.
>
>There is a lot of traffic, around 110 x 1k packets every 1/30th of a
>second - over 3000k per second.
>
>There is no other traffic on the (Gigabit) network. The network
>consists of the sending station, and multiple receiving stations.
>
>Every so often, a few packets go missing, but different packets are
>missed by different machines on the network. For every lost packet,
>there's another receiving node that does get it.
>
>Reducing the traffic below 30 packets at 30Hz (900 per second) makes
>the system work properly.
>
>It seems that the data is on the wire (how else could it be received by
>any station), but is being lost in the IP stack somewhere.
>
>I've tried setting SO_RCVBUF to 224k (biggest I can get) with no
>effect. I would expect at least some improvement.
>
>Any ideas? Is there a lower level version of SO_RCVBUF I need to set?
>
>Mark
Lost packets are often victims of collision, and collision depends upon
physical layout on the network. So it's not at all surprising, on some
network setups, that one machine would have a packet corrupted by a
collision while another machine would get the two in sequence.
Remember that light travels a foot per nanosecond (in rough terms).
Signals on a network are somewhat slower. At Gigabit speeds, packet
length on the wire starts to become "interesting", and different machines
will see different results.
Cheers.....Peter
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