Messages in this thread | | | Date | Tue, 30 Jul 2019 14:35:42 +0200 | From | Florian Westphal <> | Subject | Re: [PATCH] bridge:fragmented packets dropped by bridge |
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Rundong Ge <rdong.ge@gmail.com> wrote: > Given following setup: > -modprobe br_netfilter > -echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables > -brctl addbr br0 > -brctl addif br0 enp2s0 > -brctl addif br0 enp3s0 > -brctl addif br0 enp6s0 > -ifconfig enp2s0 mtu 1300 > -ifconfig enp3s0 mtu 1500 > -ifconfig enp6s0 mtu 1500 > -ifconfig br0 up > > multi-port > mtu1500 - mtu1500|bridge|1500 - mtu1500 > A | B > mtu1300
How can a bridge forward a frame from A/B to mtu1300?
> With netfilter defragmentation/conntrack enabled, fragmented > packets from A will be defragmented in prerouting, and refragmented > at postrouting.
Yes, but I don't see how that relates to the problem at hand.
> But in this scenario the bridge found the frag_max_size(1500) is > larger than the dst mtu stored in the fake_rtable whitch is > always equal to the bridge's mtu 1300, then packets will be dopped.
What happens without netfilter or non-fragmented packets?
> This modifies ip_skb_dst_mtu to use the out dev's mtu instead > of bridge's mtu in bridge refragment.
It seems quite a hack? The above setup should use a router, not a bridge.
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