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Date: Wed, 10 Jun 2015 21:14:27 -0700
From: Scott Feldman <sfeldma@...il.com>
To: Andy Gospodarek <gospo@...ulusnetworks.com>
Cc: Netdev <netdev@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>, ddutt@...ulusnetworks.com,
Alexander Duyck <alexander.duyck@...il.com>,
Hannes Frederic Sowa <hannes@...essinduktion.org>,
"stephen@...workplumber.org" <stephen@...workplumber.org>
Subject: Re: [PATCH net-next 1/3 v3] net: track link-status of ipv4 nexthops
On Wed, Jun 10, 2015 at 8:28 PM, Andy Gospodarek
<gospo@...ulusnetworks.com> wrote:
> On Wed, Jun 10, 2015 at 07:53:59PM -0700, Scott Feldman wrote:
>> On Wed, Jun 10, 2015 at 7:37 PM, Andy Gospodarek
>> <gospo@...ulusnetworks.com> wrote:
>>
>> > @@ -1129,7 +1142,15 @@ int fib_sync_down_dev(struct net_device *dev, int force)
>> > dead++;
>> > else if (nexthop_nh->nh_dev == dev &&
>> > nexthop_nh->nh_scope != scope) {
>> > - nexthop_nh->nh_flags |= RTNH_F_DEAD;
>> > + switch (event) {
>> > + case NETDEV_DOWN:
>> > + case NETDEV_UNREGISTER:
>> > + nexthop_nh->nh_flags |= RTNH_F_DEAD;
>> > + /* fall through */
>> > + case NETDEV_CHANGE:
>> > + nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
>> > + break;
>> > + }
>> > #ifdef CONFIG_IP_ROUTE_MULTIPATH
>> > spin_lock_bh(&fib_multipath_lock);
>> > fi->fib_power -= nexthop_nh->nh_power;
>> > @@ -1139,14 +1160,22 @@ int fib_sync_down_dev(struct net_device *dev, int force)
>> > dead++;
>> > }
>> > #ifdef CONFIG_IP_ROUTE_MULTIPATH
>> > - if (force > 1 && nexthop_nh->nh_dev == dev) {
>> > + if (event == NETDEV_UNREGISTER && nexthop_nh->nh_dev == dev) {
>> > dead = fi->fib_nhs;
>> > break;
>> > }
>> > #endif
>> > } endfor_nexthops(fi)
>> > if (dead == fi->fib_nhs) {
>> > - fi->fib_flags |= RTNH_F_DEAD;
>> > + switch (event) {
>> > + case NETDEV_DOWN:
>> > + case NETDEV_UNREGISTER:
>> > + fi->fib_flags |= RTNH_F_DEAD;
>> > + /* fall through */
>> > + case NETDEV_CHANGE:
>> > + fi->fib_flags |= RTNH_F_LINKDOWN;
>>
>> RTNH_F_LINKDOWN is to mark linkdown nexthop devs....why is the route
>> fi being marked RTNH_F_LINKDOWN?
>>
>> The RTNH_F_LINKDOWN comment says:
>>
>> #define RTNH_F_LINKDOWN 16 /* carrier-down on nexthop */
>
> This is done with the dead flag already. I'm actually following the
> precedent already set there.
>
>> It's a per-nh flag, not per-route flag, correct?
>>
>> Can you show an ECMP example with only a subset of the nexthops dev
>> linkdowned? Show the ip route output after going thru some link
>> down/up events on some of the nexthops devs.
>
> Sure! This is exactly what I've been using for testing.
>
> # ip route show
> 70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
> 80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1
> 90.0.0.0/24 via 70.0.0.2 dev p7p1
> 90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 10
> 100.0.0.0/24
> nexthop via 70.0.0.2 dev p7p1 weight 1
> nexthop via 80.0.0.2 dev p8p1 weight 1
> 192.168.56.0/24 dev p2p1 proto kernel scope link src 192.168.56.2
> # # take p8p1 link down
> # ip route show
> 70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
> 80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1 dead linkdown
> 90.0.0.0/24 via 70.0.0.2 dev p7p1
> 90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 10 dead linkdown
> 100.0.0.0/24
> nexthop via 70.0.0.2 dev p7p1 weight 1
> nexthop via 80.0.0.2 dev p8p1 weight 1 dead linkdown
> 192.168.56.0/24 dev p2p1 proto kernel scope link src 192.168.56.2
> # ip route get 100.0.0.2
> 100.0.0.2 via 70.0.0.2 dev p7p1 src 70.0.0.1
> cache
> # ip route get 100.0.0.2
> 100.0.0.2 via 70.0.0.2 dev p7p1 src 70.0.0.1
> cache
> # # take p8p1 link up
> # ip route show
> 70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
> 80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1
> 90.0.0.0/24 via 70.0.0.2 dev p7p1
> 90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 10
> 100.0.0.0/24
> nexthop via 70.0.0.2 dev p7p1 weight 1
> nexthop via 80.0.0.2 dev p8p1 weight 1
> 192.168.56.0/24 dev p2p1 proto kernel scope link src 192.168.56.2
> # ip route show
> 100.0.0.2 via 70.0.0.2 dev p7p1 src 70.0.0.1
> cache
> # ip route get 100.0.0.2
> 100.0.0.2 via 80.0.0.2 dev p8p1 src 80.0.0.1
> cache
> # ip route get 100.0.0.2
> 100.0.0.2 via 70.0.0.2 dev p7p1 src 70.0.0.1
> cache
> # ip route get 100.0.0.2
> 100.0.0.2 via 80.0.0.2 dev p8p1 src 80.0.0.1
> cache
> # # you can see the round robin happening
> # # take all ports p8p1 and p7p1 down
> # ip route show
> 70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1 dead linkdown
> 80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1 dead linkdown
> 90.0.0.0/24 via 70.0.0.2 dev p7p1 dead linkdown
> 90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 10 dead linkdown
> 100.0.0.0/24
> nexthop via 70.0.0.2 dev p7p1 weight 1 dead linkdown
> nexthop via 80.0.0.2 dev p8p1 weight 1 dead linkdown
> 192.168.56.0/24 dev p2p1 proto kernel scope link src 192.168.56.2
> # ip route get 100.0.0.2
> RTNETLINK answers: Network is unreachable
> # ip route get 80.0.0.2
> RTNETLINK answers: Network is unreachable
> # ip route get 80.0.0.1
> local 80.0.0.1 dev lo src 80.0.0.1
> cache <local>
> # ip route get 70.0.0.1
> local 70.0.0.1 dev lo src 70.0.0.1
> cache <local>
> # # local addrs are still reachable
Perfect, looks good, thanks.
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