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[Bug 1463911] Re: IPV6 fragmentation and mtu issue
This bug causes issues when ip6tables modules are loaded with IPv6
fragmented packets traversing a bridge. The extant conntrack processing
will reassemble the IPv6 fragments for netfilter processing, but is
incapable of re-fragmenting these datagrams for subsequent forwarding.
This causes the fragmented IPv6 datagrams to be dropped.
This is resolved by backporting functionality from mainline that
re-fragments the IPv6 datagrams upon bridge egress.
The patch commit log includes a test case; to summarize:
A bridge is configured with two ports and interfaces are attached
to these ports. A traffic source beyond one port generates fragmented
IPv6 datagrams, e.g., ping6 -s 2000, destined for a host beyond the
With ip6tables modules unloaded, the IPv6 fragments will traverse
the bridge. Loading ip6tables, e.g., "ip6tables -t nat -L", will cause
IPv6 fragmented datagrams to be dropped on the unpatched kernel.
These datagrams are correctly forwarded with the patch applied.
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IPV6 fragmentation and mtu issue
Status in neutron:
Status in OpenStack Compute (nova):
Status in linux package in Ubuntu:
Fragmented IPv6 packets are REJECTED by ip6tables on compute nodes.
The traffic is goign through an intra-VM network and the packet loss
is hurting the system.
There is a patch for this issue:
I would like to know is there any bug report or official release date
for this issue ?
This is pretty critical for my deployment.
Thanks in advance,
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