Continuing problems in a bridged VNET setup

[Nick Wolff]

Marko,

Are you aware of any write ups for using ng_eiface and ng_bridge instead of
if_bridge?

Thanks,

Nick Wolff

On Fri, Dec 20, 2019 at 6:22 AM Marko Zec <zec at fer.hr> wrote:

> Perhaps you could ditch if_bridge(4) and epair(4), and try ng_eiface(4)
> with ng_bridge(4) instead?  Works rock-solid 24/7 here on 11.2 / 11.3.
>
> Marko
>
> On Fri, 20 Dec 2019 11:19:24 +0100
> "Patrick M. Hausen" <hausen at punkt.de> wrote:
>
> > Hi all,
> >
> > we still experience occasional network outages in production,
> > yet have not been able to find the root cause.
> >
> > We run around 50 servers with VNET jails. some of them with
> > a handful, the busiest ones with 50 or more jails each.
> >
> > Every now and then the jails are not reachable over the net,
> > anymore. The server itself is up and running, all jails are
> > up and running, one can ssh to the server but none of the
> > jails can communicate over the network.
> >
> > There seems to be no pattern to the time of occurrance except
> > that more jails on one system make it "more likely".
> > Also having more than one bridge, e.g. for private networks
> > between jails seems to increase the probability.
> > When a server shows the problem it tends to get into the state
> > rather frequently, a couple of hours inbetween. Then again
> > most servers run for weeks without exhibiting the problem.
> > That's what makes it so hard to reproduce. The last couple of
> > days one system was failing regularly until we reduced the number
> > of jails from around 80 to around 50. Now it seems stable again.
> >
> > I have a test system with lots of jails that I work with gatling
> > that did not show a single failure so far :-(
> >
> >
> > Setup:
> >
> > All jails are iocage jails with VNET interfaces. They are
> > connected to at least one bridge that starts with the
> > physical external interface as a member and gets jails'
> > epair interfaces added as they start up. All jails are managed
> > by iocage.
> >
> > ifconfig_igb0="-rxcsum -rxcsum6 -txcsum -txcsum6 -vlanhwtag
> > -vlanhwtso up" cloned_interfaces="bridge0"
> > ifconfig_bridge0_name="inet0"
> > ifconfig_inet0="addm igb0 up"
> > ifconfig_inet0_ipv6="inet6 <host-address>/64 auto_linklocal"
> >
> > $ iocage get interfaces vpro0087
> > vnet0:inet0
> >
> > $ ifconfig inet0
> > inet0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0
> > mtu 1500 ether 90:1b:0e:63:ef:51
> >       inet6 fe80::921b:eff:fe63:ef51%inet0 prefixlen 64 scopeid 0x4
> >       inet6 <host-address> prefixlen 64
> >       nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
> >       groups: bridge
> >       id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
> >       maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
> >       root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
> >       member: vnet0.4 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
> >               ifmaxaddr 0 port 7 priority 128 path cost 2000
> >       member: vnet0.1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
> >               ifmaxaddr 0 port 6 priority 128 path cost 2000
> >       member: igb0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
> >               ifmaxaddr 0 port 1 priority 128 path cost 2000000
> >
> >
> > What we tried:
> >
> > At first we suspected the bridge to become "wedged" somehow. This was
> > corroborated by talking to various people at devsummits and EuroBSDCon
> > with Kristof Provost specifically suggesting that if_bridge was
> > still under giant lock and there might be a problem here that the
> > lock is not released under some race condition and then the entire
> > bridge subsystem would be stalled. That sounds plausible given the
> > random occurrance.
> >
> > But I think we can rule out that one, because:
> >
> > - ifconfig up/down does not help
> > - the host is still communicating fine over the same bridge interface
> > - tearing down the bridge, kldunload (!) of if_bridge.ko followed by
> >   a new kldload and reconstructing the members with `ifconfig addm`
> >   does not help, either
> > - only a host reboot restores function
> >
> > Finally I created a not iocage managed jail on the problem host.
> > Please ignore the `iocage` in the path, I used it to populate the
> > root directory. But it is not started by iocage at boot time and
> > the manual config is this:
> >
> > testjail {
> >         host.hostname = "testjail";   # hostname
> >         path = "/iocage/jails/testjail/root";     # root directory
> >         exec.clean;
> >         exec.system_user = "root";
> >         exec.jail_user = "root";
> >         vnet;
> >       vnet.interface = "epair999b";
> >         exec.prestart += "ifconfig epair999 create; ifconfig
> > epair999a inet6 2A00:B580:8000:8000::1/64 auto_linklocal";
> > exec.poststop += "sleep 2; ifconfig epair999a destroy; sleep 2";
> >         # Standard stuff
> >         exec.start += "/bin/sh /etc/rc";
> >         exec.stop = "/bin/sh /etc/rc.shutdown";
> >         exec.consolelog = "/var/log/jail_testjail_console.log";
> >         mount.devfs;          #mount devfs
> >         allow.raw_sockets;    #allow ping-pong
> >         devfs_ruleset="4";    #devfs ruleset for this jail
> > }
> >
> > $ cat /iocage/jails/testjail/root/etc/rc.conf
> > hostname="testjail"
> >
> > ifconfig_epair999b_ipv6="inet6 2A00:B580:8000:8000::2/64
> > auto_linklocal"
> >
> > When I do `service jail onestart testjail` I can then ping6 the jail
> > from the host and the host from the jail. As you can see the
> > if_bridge is not involved in this traffic.
> >
> > When the host is in the wedged state and I start this testjail the
> > same way, no communication across the epair interface is possible.
> >
> > To me this seems to indicate that not the bridge but all epair
> > interfaces stop working at the very same time.
> >
> >
> > OS is RELENG_11_3, hardware and specifically network adapters vary,
> > we have igb, ix, ixl, bnxt ...
> >
> >
> > Does anyone have a suggestion what diagnostic measures could help to
> > pinpoint the culprit? The random occurrance and the fact that the
> > problem seems to prefer the production environment only makes this a
> > real pain ...
> >
> >
> > Thanks and kind regards,
> > Patrick
>
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