netdev - Re: VRF NS for lladdr sent on the wrong interface

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Message-ID: <20201201190055.GA16436@ICIPI.localdomain>
Date:   Tue, 1 Dec 2020 14:00:55 -0500
From:   Stephen Suryaputra <ssuryaextr@...il.com>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: VRF NS for lladdr sent on the wrong interface

On Mon, Nov 30, 2020 at 06:15:06PM -0700, David Ahern wrote:
> On 11/23/20 5:23 PM, Stephen Suryaputra wrote:
> > Hi,
> > 
> > I'm running into a problem with lladdr pinging all-host mcast all nodes
> > addr. The ping intially works but after cycling the interface that
> > receives the ping, the echo request packet causes a neigh solicitation
> > being sent on a different interface.
> > 
> > To repro, I included the attached namespace scripts. This is the
> > topology and an output of my test.
> > 
> > # +-------+     +----------+   +-------+
> > # | h0    |     |    r0    |   |    h1 |
> > # |    v00+-----+v00    v01+---+v10    |
> > # |       |     |          |   |       |
> > # +-------+     +----------+   +-------+
> > 
> 
> 
> 
> after setup,
> 
> ip netns exec h0 ping -c 1 ff02::1%h0_v00
> 
> works, but
> 
>  ip netns exec h1 ping -c 1 ff02::1%h1_v10
> 
> does not. No surprise then that cycling v00 in r0 causes the reverse.
> The problem is the route order changes:
> 
> root@...ntu-c-2-4gib-sfo3-01:~# diff -U3 /tmp/1 /tmp/2
> --- /tmp/1	2020-12-01 01:07:39.795361392 +0000
> +++ /tmp/2	2020-12-01 01:07:51.991808848 +0000
> @@ -1,6 +1,6 @@
>  local fe80::8466:b3ff:fecc:3a4f dev r0_v01 table 10 proto kernel metric
> 0 pref medium
>  local fe80::b4ec:a8ff:fec3:33d9 dev r0_v00 table 10 proto kernel metric
> 0 pref medium
> -fe80::/64 dev r0_v00 table 10 proto kernel metric 256 pref medium
>  fe80::/64 dev r0_v01 table 10 proto kernel metric 256 pref medium
> -ff00::/8 dev r0_v00 table 10 metric 256 pref medium
> +fe80::/64 dev r0_v00 table 10 proto kernel metric 256 pref medium
>  ff00::/8 dev r0_v01 table 10 metric 256 pref medium
> +ff00::/8 dev r0_v00 table 10 metric 256 pref medium
> 
> With your patch does ping from both hosts work?

Yes, it does.

> What about all of the tests in
> tools/testing/selftests/net/fcnal-test.sh? specifically curious about
> the 'LLA to GUA' tests (link local to global). Perhaps those tests need
> a second interface (e.g., a dummy) that is brought up first to cause the
> ordering to be different.

The script needs nettest to be in the path...

Thanks,

Stephen.