Continuing problems in a bridged VNET setup

Fri Dec 20 11:32:11 UTC 2019

On December 20, 2019 11:22:01 AM UTC, 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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Does it work with pf?
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