Date: Tue, 14 Jan 2014 19:15:34 +0000 From: Nikolay Denev <nike_d@cytexbg.com> To: Attila Nagy <bra@fsn.hu> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: ECMP hash keys? Message-ID: <CA%2BP_MZFQU4%2B05Pk5cZ4NMZujD9vXDrV=mehN7_vz1OZ6r2-f1Q@mail.gmail.com> In-Reply-To: <52D5138B.8050100@fsn.hu> References: <52D5138B.8050100@fsn.hu>
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Hi,
Currently it's implemented using Modulo-N Hash (RFC2991), see
radix_mpath.c:rtalloc_mpath_fib()
And as hash the xor of source and destination IP is supplied, look for
rtalloc_mpath_fib() in ip_output.c :
...
#ifdef RADIX_MPATH
rtalloc_mpath_fib(ro,
ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
#else
...
I've tried to hack this to use m_pkthdr.flowid if it exists, but in my
case my network cards were not setting this (vr(4) on soekris) so I
did not saw any change. Maybe my idea was completely wrong, but the
XOR of src and dst IP is 4 bytes, and this is the size of the flowid
as well. (haven't tried with FLOWTABLE enabled though).
--Nikolay
On Tue, Jan 14, 2014 at 10:38 AM, Attila Nagy <bra@fsn.hu> wrote:
> Hi,
>
> Does equal cost multipath take only the destination address into
> consideration when choosing the route? (I've spent only about two minutes
> reading radix_mpath.h, but I've got this impression)
>
> What would be needed to use src and dst addresses and ports -if appropriate?
>
> Thanks,
>
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