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Groups > linux.kernel > #1563015
| From | Eric Dumazet <eric.dumazet@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: Inconsistency in packet drop due to MTU (eth vs veth) |
| Date | 2017-01-19 20:10 +0100 |
| Message-ID | <t1qfU-5uo-5@gated-at.bofh.it> (permalink) |
| References | <t1o4q-3Xc-47@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, 2017-01-19 at 17:41 +0100, Fredrik Markstrom wrote:
> Hello,
>
> I've noticed an inconsistency between how physical ethernet and veth handles mtu.
>
> If I setup two physical interfaces (directly connected) with different mtu:s, only the size of the outgoing packets are limited by the mtu. But with veth a packet is dropped if the mtu of the receiving interface is smaller then the packet size.
>
> This seems inconsistent to me, but maybe there is a reason for it ?
>
> Can someone confirm if it's a deliberate inconsistency or just a side effect of using dev_forward_skb() ?
It looks this was added in commit
38d408152a86598a50680a82fe3353b506630409
("veth: Allow setting the L3 MTU")
But what was really needed here was a way to change MRU :(
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Inconsistency in packet drop due to MTU (eth vs veth) Fredrik Markstrom <fredrik.markstrom@gmail.com> - 2017-01-19 17:50 +0100 Re: Inconsistency in packet drop due to MTU (eth vs veth) Eric Dumazet <eric.dumazet@gmail.com> - 2017-01-19 20:10 +0100
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