Re: [PATCH net-next 5/5] ipv6: Compute multipath hash for forwarded ICMP errors from offending packet

From: Hannes Frederic Sowa
Date: Tue Nov 01 2016 - 12:25:19 EST

On 31.10.2016 20:25, Tom Herbert wrote:
> The normal hash for TCP or UDP using ECMP is over <protocol, srcIP,
> dstIP, srcPort, dstPort>. For an ICMP packet ECMP would most likely be
> done over <protocol, srcIP, dstIP>. There really is no way to ensure
> that an ICMP packet will follow the same path as TCP or any other
> protocol. Fortunately, this is really isn't so terrible. The Internet
> has worked this way ever since routers started using ports as input to
> ECMP and that hasn't caused any major meltdown.

The normal hash for forwarding is without srcPort or dstPort, so the
same as ICMP and especially also because of fragmentation problematic I
don't think a lot of routers use L4 port information for ECMP either.