[p2p-hackers] How reliable is UDP?
Stephen Samuel (leave the email alone)
samnospam at bcgreen.com
Fri Dec 24 20:32:02 UTC 2004
ping (or mtr) can generally give you a good estimation of
packet loss in a connection.
1% packet loss is generally considered bad. More than that will cause
severe performance penalties for things like NFS and also slow down
TCP transmissions noticably.
Local connections should generally have 0% packet loss (It's not
unusuall for me to leave ping sessions running for days to a local
box and get things like 80000 packets transmitted with 0 or 1 packet
From a quick test with 10 packets/second:(about a 2500 mile round trip).
1626 packets transmitted, 1626 received, 0% packet loss, time 164186ms
rtt min/avg/max/mdev = 28.195/29.424/52.322/1.056 ms, pipe 2, ipg/ewma 101.037/29.204 ms
I get similar results for a ping session transcontinental * transatlantic.
472 packets transmitted, 470 received, 0% packet loss, time 54703ms
rtt min/avg/max/mdev = 200.554/202.114/230.265/2.298 ms, pipe 4, ipg/ewma 116.143/201.708 ms
and pinging a chinese SPAM site:
[samuel at me samuel]% ping -f -i.1 184.108.40.206
PING 220.127.116.11 (18.104.22.168) 56(84) bytes of data.
--- 22.214.171.124 ping statistics ---
1762 packets transmitted, 1694 received, 3% packet loss, time 178508ms
rtt min/avg/max/mdev = 466.896/479.661/621.438/6.357 ms, pipe 8, ipg/ewma 101.367/479.347 ms
[root at me samuel]#
David E. Meier wrote:
> Hi p2p-hackers,
> I know that UDP traffic is not reliable by design. However, I wonder how
> reliable UDP packets reach their destination. Does someone on the list
> have experience with UDP packet loss? Is this usually in the range of a
> percent or more or less? Or is it even a common case that all packets
> arrive? Dave.
Stephen Samuel +1(604)876-0426 samnospam at bcgreen.com
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