Le 30/11/2021 à 12:00, Ales Musil a écrit :

On Tue, Nov 30, 2021 at 11:16 AM Nathanaël Blanchet <blanchet@abes.fr> wrote:

Le 30 nov. 2021 10:31, Ales Musil <amusil@redhat.com> a écrit :

On Tue, Nov 30, 2021 at 10:08 AM Nathanaël Blanchet <blanchet@abes.fr> wrote:

Le 30/11/2021 à 07:25, Ales Musil a écrit :

On Mon, Nov 29, 2021 at 11:47 PM Nathanaël Blanchet <blanchet@abes.fr> wrote:

Hi all,

Hi,

 

I 've finished migration from 4.4.4 to 4.4.9 and I'm facing a strange
issue with routing table on my hosts: all IP addressed interfaces (and
in particular gluster and migration ones that requiere an IP) are not
part of the "254" or "0" usual ip rule.

Only network with default route role will be in the default table (254). This has been the case for quite a while.

What has changed in 4.4.8 is that now NetworkManager is aware of that, before the routes were managed outside of

NM and it might have caused some issues.

 

for instance:

[root@fuego ~]# nmcli con sh gluster |grep ipv4.route-table
ipv4.route-table:                       202179335

[root@fuego ~]# nmcli con sh migration |grep ipv4.route-table
ipv4.route-table:                       316605387

but ovirtmgmt:

[root@fuego ~]# nmcli con sh ovirtmgmt |grep ipv4.route-table
ipv4.route-table:                       254 (main)

and obviously the main route table is empty:

[root@ ~]# ip ro
default via 10.34.100.65 dev ovirtmgmt proto dhcp metric 425
10.34.100.0/24 dev ovirtmgmt proto kernel scope link src 10.34.100.116
metric 425

Well the main table should contain only the default route gateway.

You can take a look at other routes by:

ip route show table all

Indeed, other routes exists

 

[root@fuego ~]# ip ro sh table all
10.34.101.0/24 dev gluster table 202179335 proto kernel scope link src 10.34.101.140 metric 426
10.34.106.0/23 dev admin table 100729354 proto kernel scope link src 10.34.106.72 metric 425
10.34.108.0/23 dev migration table 316605387 proto kernel scope link src 10.34.108.56 metric 427

but don't seem to be used by kernel like they should be by the main table.

None of the concerned hosts can ping each other on such interface, and
live migrations systematically fail.

That might be a different issue related to BZ#2022354. To check if that's really the case

please take a look into oVirt engine and there you should see all affected networks out-of-sync.

On the BZ there are two possible workarounds.

Not seems to be that BZ because there is no out of sync network in my case, but the issue could be from the same root cause, because of NM routing table integration.

 

This behaviour is new with 4.4.9 and I don't know if it is a new (and
not achevied) network feature introduced with centos stream to deal
network filtering packets.

A simple workaround would be "nmcli connection mod migration
ipv4.route-table 0 && nmcli con up migration", but I'd like to
understand why such  strange (and unuseful ?) rule table are now
randomly attributed?

I would highly suggest against that because the default route in the default table should be only one, with exception to some backup scenarios.

Notice that this command doesn't add additionnal default route in addition to the main one, but only source route of the defined networks that allow hosts to be reachabled on that networks.

[root@fuego ~]# ip ro
default via 10.34.100.65 dev ovirtmgmt proto dhcp metric 425
10.34.100.0/24 dev ovirtmgmt proto kernel scope link src 10.34.100.116 metric 425
10.34.106.0/23 dev admin proto kernel scope link src 10.34.107.76 metric 450
10.34.108.0/23 dev migration proto kernel scope link src 10.34.108.121 metric 465

This behaviour is the same as before 4.4.8 and let the live migration to be effective because kernel is now aware to route the network to the correct bridge/interface.

To my mind, you can easily reproduce the bug because it is the same on my 10 hosts.

Thanks for your help.

If I understand it right your networks do not have any gateway (except the default route role) associated with them right?

So you are essentially missing the network routes to be in the main table.

In that case you can workaround it by setting the table to main as you did or copy the routes. But even better option would be to add gateway to those

networks so it can properly create route rules which will then tell the kernel where to route packets that are going from those networks.

Okay when defining static IPs but in my case with DHCP, there is no pushed gw for those networks(I could add then for each network into dchp conf but this is not what I want)

This was working before because the NM was not aware that we have some routes in different tables and created network routes in the default table.

Now the question is if it is a bug as this was more unintentional before. If you feel like this should be working the same way please open a bug and we can discuss it there.

Overall it is a bug because live migration fails and it is a regression!!! Nevermind how the network is dealt by NM if everything works as expected. 

Actually this is related to a different issue with dynamic source routing, that was fixed in 4.5, you are also missing the route rules.

E.g. for the migration network.

3200: from 10.34.108.0/23 lookup 316605387
3200: from all to 10.34.108.0/23 lookup  316605387

By adding them the network should work again:

ip rule add from 10.34.108.0/23 lookup 316605387 priority 3200

ip rule add from all to 10.34.108.0/23 lookup  316605387 priority 3200

Indeed it works now. So you mean it is a known and corrected bug in future 4.5 or 4.4.5 relased? Can you give me the BZ, I didn't find it.

Will the fix be incorporated in a 4.4.x release?

 

Thanks,

Ales

 

 

--
Nathanaël Blanchet

Supervision réseau
SIRE
227 avenue Professeur-Jean-Louis-Viala
34193 MONTPELLIER CEDEX 5       
Tél. 33 (0)4 67 54 84 55
Fax  33 (0)4 67 54 84 14
blanchet@abes.fr
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Let us know if it's the mentioned bug, if not we can investigate deeper what might be wrong.

Thank you.

Best Regards,

Ales

--

Ales Musil

Software Engineer - RHV Network

Red Hat EMEA

amusil@redhat.com    IM: amusil

-- 
Nathanaël Blanchet

Supervision réseau
SIRE
227 avenue Professeur-Jean-Louis-Viala
34193 MONTPELLIER CEDEX 5 	
Tél. 33 (0)4 67 54 84 55
Fax  33 (0)4 67 54 84 14
blanchet@abes.fr

--

Ales Musil

Software Engineer - RHV Network

Red Hat EMEA

amusil@redhat.com    IM: amusil

--

Ales Musil

Software Engineer - RHV Network

Red Hat EMEA

amusil@redhat.com    IM: amusil

-- 
Nathanaël Blanchet

Supervision réseau
SIRE
227 avenue Professeur-Jean-Louis-Viala
34193 MONTPELLIER CEDEX 5 	
Tél. 33 (0)4 67 54 84 55
Fax  33 (0)4 67 54 84 14
blanchet@abes.fr