Re: [LARTC] Re: Multi-path routing only using last nexthop in default

[Alexander Samad <alex@samad.com.au>]

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On Tue, Jan 17, 2006 at 12:37:48AM -0500, Jody Shumaker wrote:
> Yes, it just shows you what is in the cache, but I was specifying ip
> addresses that weren't in the cache yet. I also tried doing traceroutes from
> an internal pc, and those always ended up going over the 1 interface. I've
> also tried adjusting the weights to 1:1 and opening up numerous connections
> to multiple ftp's.
> 
> Also for comparison, if I change the order of the nexthop's I'll instead get
> effectively the reverse.
> 
> # ip route get 66.1.1.11
> 66.1.1.11 via 66.189.76.1 dev eth1  src 71.248.183.63
>     cache  mtu 1500 advmss 1460 metric10 64
> # ip route get 66.1.1.12
> 66.1.1.12 via 66.189.76.1 dev eth1  src 66.189.76.198
>     cache  mtu 1500 advmss 1460 metric10 64

your right I tried it on my machine 
for x in $(seq 1 10); do ip r g 1.1.1.$x; done
1.1.1.1 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.2 via 220.233.1.45 dev ppp0  src 141.168.16.16 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.3 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.4 via 220.233.1.45 dev ppp0  src 141.168.16.16 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.5 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.6 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.7 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.8 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.9 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64
1.1.1.10 via 220.233.1.45 dev ppp0  src 220.233.15.63 
    cache  mtu 1492 advmss 1452 metric 10 64

just the src address is changing, I am pretty sure this used work at
some point in time, i am using 2.6.14-1-smp, iptables v1.3.3

> 
> It always is pointing to dev eth1 while with the reverse order it was ppp0.
> All this by only changing the order of the nexthops. I went through and
> double checked that I did apply julian's patches to the kernel source I last
> built with.
> 
> - Jody
> 
> On 1/16/06, Alexander Samad <alex@samad.com.au> wrote:
> >
> > On Mon, Jan 16, 2006 at 08:59:32PM -0500, Jody Shumaker wrote:
> > > I found that for ppp devices, i should ony define the next  hop with the
> > > dev, not a via.  However this still didn't fix my problem, but I've
> > narrowed
> > > down my problem a little further.
> > >
> > > # ip route get 66.189.123.136
> > > 66.189.123.136 dev ppp0  src 71.248.183.244
> > >     cache  mtu 1492 advmss 1452 metric10 64
> > > # ip route get 66.189.123.137
> > > 66.189.123.137 dev ppp0  src 66.189.76.198
> > >     cache  mtu 1492 advmss 1452 metric10 64
> >
> > doesnt the second ip r g just show you what you have in the route cache,
> > when I try it on my multi home machine
> >
> > default  metric 5
> >         nexthop via 141.168.16.1  dev eth0 weight 3
> >         nexthop via 220.233.1.45  dev ppp0 weight 4
> >
> > but this might be because I don't have the round-robin patch applied to
> > the kernel.
> >
> >
> > >
> > > It does properly do a 5:1 round robin choice , but only the src changes,
> > not
> > > the dev.  The above I believe should really have outputted for the
> > second
> > > route:
> > > 66.189.123.137 dev eth1  src 66.189.76.198
> > >     cache  mtu 1492 advmss 1452 metric10 64
> > >
> > > I'm not sure what is wrong with my config, as I've gone over and over
> > it. My
> > > best guess is that something is wrong in the kernel I compiled with the
> > > patches.
> > >
> > > # ip rule show
> > > 0:      from all lookup local
> > > 50:     from all lookup main
> > > 201:    from 71.248.183.244 lookup 201
> > > 202:    from 66.189.76.198/22 lookup 202
> > > 221:    from all lookup 221
> > > 32766:  from all lookup main
> > > 32767:  from all lookup default
> > >
> > > # ip route show table main
> > > 10.9.44.15 dev ppp0  proto kernel  scope link  src 71.248.183.244
> > > 192.168.100.0/24 dev eth1  proto kernel  scope link  src 192.168.100.2
> > > 192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.1
> > > 66.189.76.0/22 dev eth1  proto kernel  scope link  src 66.189.76.198
> > > 127.0.0.0/8 dev lo  scope link
> > >
> > > # ip route show table 201
> > > default via 10.9.44.15 dev ppp0  proto static  src 71.248.183.244
> > > prohibit default  proto static  metric 1
> > >
> > > # ip route show table 202
> > > default via 66.189.76.1 dev eth1  proto static  src 66.189.76.198
> > > prohibit default  proto static  metric 1
> > >
> > > # ip route show table 221
> > > default  proto static
> > >         nexthop via 66.189.76.1  dev eth1 weight 1
> > >         nexthop dev ppp0 weight 5
> >
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> >
> >
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