Den fre 11 jan. 2019 kl 05:23 skrev Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>: > > On 2019/01/10 22:26, Fredrik Gustavsson wrote: > > commit affede4a779420bd8510ab937251a3796d3228df > > Author: Fredrik Gustavsson <gustf...@gmail.com> > > Date: Tue Jan 8 11:21:39 2019 +0100 > > > > veth: Do not drop packets larger then the mtu set on the receiving side > > > > Currently veth drops all packets larger then the mtu set on the receiving > > end of the pair. This is inconsistent with most hardware ethernet drivers > > that happily receives packets up the the ethernet MTU independent of the > > configured MTU. > > > > There should not be a need for dropping IP packets at receiver with > > size > configured IP MTU, IP MTU is for fragmentation at sender side. > > And IP packets with size > receiver L2 MTU will be dropped at sub-IP layer. > > But with current veth behavior setting MTU effectively sets MRU as well. > This may be being used to drop unexpectedly long packets e.g. from > containers on container host. If we unconditionally change this behavior > it can cause regression on some environment. This should be an option at > least. > > BTW there was a similar precedent attempt. You might want to take a look. > > https://www.mail-archive.com/netdev@vger.kernel.org/msg167636.html > https://www.mail-archive.com/netdev@vger.kernel.org/msg167899.html > > -- > Toshiaki Makita > Good argument, but do you agree that it shouldn't be working like it does? But not sure if such a case would exist but breaking compatitbility have been discussed in other threads. So your saying that people have actually used it as a receiving limit for IP packets?
Nice that you found that older thread it is also availble here: https://lkml.org/lkml/2017/5/12/254 Were I thought the ending argument was that if it shouldn't be dropped don't drop it. And that introducing a MRU parameter was just making things more complicated. But for my use case either way would work.
