Re: [LTP] [PATCH] network/mpls: sleep 1 after setup in mpls02

From: Petr Vorel <pvorel@suse.cz>
To: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
Cc: pvorel <pvorel@suse.de>, suy.fnst@fujitsu.com, ltp@lists.linux.it
Subject: Re: [LTP] [PATCH] network/mpls: sleep 1 after setup in mpls02
Date: Fri, 10 Sep 2021 11:36:15 +0200	[thread overview]
Message-ID: <YTsnD0Uw4argiGOJ@pevik> (raw)
Message-ID: <20210910093615.JkDhxDDr57JkchVKTcR59_HofV6ZGpyg0RLf_SuITXA@z> (raw)
In-Reply-To: <8d93deac-eec1-5f87-57a5-c72b2f6e5973@bell-sw.com>

> On 09.09.2021 18:53, pvorel wrote:
> > Hi Su, Alexey,

> > On 2021-08-30 11:26, suy.fnst@fujitsu.com wrote:
> >> Hi,
> >>   I found that it's indeed related to ipv6 DAD as you said.
> >> Calling
> >> `ip netns exec ltp_ns sysctl -n net.ipv6.conf.ltp_ns_veth1.accept_dad=0`
> >> or tst_wait_ipv6_dad() at end of the setup both solves the problem.
> >> However there is one super strange part that the tentative address is
> >> the local link adress of the ltp_ns_veth1:

> >> 5: ltp_ns_veth1@if4: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
> >> state UP group default qlen 1000
> >>     link/ether f2:8f:24:d4:ba:26 brd ff:ff:ff:ff:ff:ff link-netnsid 0
> >>     inet 10.0.0.1/24 scope global ltp_ns_veth1
> >>        valid_lft forever preferred_lft forever
> >>     inet6 fd00:1:1:1::1/64 scope global nodad
> >>        valid_lft forever preferred_lft forever
> >>     inet6 fe80::f08f:24ff:fed4:ba26/64 scope link tentative
> >> <-------------------
> >>        valid_lft forever preferred_lft forever

> >> However, there is no place using the address in mpls02 test.>> It makes me wonder how could it be possible to trigger the issue..

> Looks like the problem here in the neighbor discovery of fd00:1:1:1::2
> using link-local address, and vice verse for the other side. mpls is
> using the following route with the address:

> fd00:23::2  encap mpls  60 via fd00:1:1:1::2 dev ltp_ns_veth1 metric 1024 pref medium
> so the address there should be in a reachable state...

Thanks for info! I wonder if it's a bug in mpls or elsewhere. WDYT?

> Adding it manually in setup might fix the test as well:

> ROD ip neigh replace $(tst_ipaddr rhost) lladdr $(tst_hwaddr rhost) dev $(tst_iface) nud reachable
> tst_rhost_run -s -c "ip neigh replace $(tst_ipaddr) lladdr $(tst_hwaddr) dev $(tst_iface rhost) nud reachable"

> > I wonder if test still needs be fixed to work on all setups.

> I think we could set accept_dad to 0 in generic setup of the
> test interfaces, in tst_net.sh/tst_init_iface().
Unless it's a bug we'd hide by setting it, I'd be for this general solution.

It'd be nice to get it fixed before release.

Kind regards,
Petr

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