> On 2009-07-29 19:43, Benny Amorsen wrote: > > Brian E Carpenter <[email protected]> writes: > > > >> Er, do your routers do that when they throw away packets due to > >> congestion? > > > > If a router throws away a packet due to congestion, there's a good > > chance that a retransmission will go through. In this case you can > > retransmit as many no-UDP-checksum packets you want, none of them will > > get through. The host really ought to be told that it is wasting its > > time. > > There's no retransmission in UDP. > > Presumably there is no harm in sending back some kind of ICMP error, > most likely Parameter Problem, at a throttled rate. But we shouldn't > mandate > it IMHO, and you certainly can't rely on a host stopping a UDP stream > as a result.
What happened to being conservative with what we send and permissive with what we receive? It seems that the direct application should be: 1) Be conservative: hosts should not send UDP packets with null checksums. 2) Permissive: gateways who receive UDP packets with null checksum should compute a checksum based on the received bytes, and then forward the packet. I understand there may be resource limits on gateways, and that the UDP checksum compute requirement might throw the packet back to some kind of slow path, with potential packet loss due to congestion. But that's way better than a black hole. -- Christian Huitema -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
