September 2022 - Bird-users

EBGP ECMP w/o add paths capability
by Milovancevic, Nemanja 04 Oct '22

04 Oct '22

Dear all, Since some of our customers have devices which are not supporting EBGP add-path capability, I was wondering would there be an option that BIRD announces also other “not only best” paths, since it looks like that now only the best one elected, based on (router-id) RID is announced to the other customers (customers have normally 2 devices connected and announce the same prefixes) RID would be tie breaker as all the other attributes are the same. BGP RS Best Path Selection: * Prefer route with the highest Local Preference attribute. * Prefer route with the shortest AS path. * Prefer IGP origin over EGP and EGP origin over incomplete. * Prefer the lowest value of the Multiple Exit Discriminator. * Prefer routes received via eBGP over ones received via iBGP. * Prefer routes with lower internal distance to a boundary router. * Prefer the route with the lowest value of router ID of the advertising router. I don’t know if there would be something like Cisco based command: bgp bestpath as-path multipath-relax Thanks. Best regards, Nemanja Milovancevic

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BIRD Crashes
by Ian Chilton 04 Oct '22

04 Oct '22

Hi, We are an IXP running 2x route servers with BIRD, each running separate daemons for IPv4 and IPv6. We are running BIRD 2.0.8-1 on Debian 10 and have around 250 peers, ~150k routes on v4 and ~50k routes on v6. Since upgrading to BIRD 2 nearly 3 years ago, it was really stable until May this year. Since then we've had 3 crashes of the daemon for v4 on one of the servers. The v6 daemon on that server has been fine, as has the second route server, running the same, with the same peers and therefore in theory, the same routes. The first two of these crashes happened a week apart, after which I rebooted the VM to ensure everything was clean and it was fine for 90 days, but then did the same yesterday. Our BIRD configuration is generated by IXP Manager and updated hourly. We then run a "bird re-validate" cron job every hour (at twenty past the hour): /usr/sbin/birdc -s /run/bird-ipv6.ctl reload in all > /dev/null ; /usr/sbin/birdc -s /run/bird-ipv4.ctl reload in all Interestingly all 3 crashes have happened at just after twenty past the hour, i.e soon after this cron job has run. It looks like the following in the logs: Aug 17 17:20:01 rs1 CRON[29229]: (root) CMD (/usr/sbin/birdc -s /run/bird-ipv6.ctl reload in all > /dev/null ; /usr/sbin/birdc -s /run/bird-ipv4.ctl reload in all > /dev/null) Aug 17 17:20:01 rs1 bird: Reloading protocol device1 Aug 17 17:20:01 rs1 bird: Reloading protocol pp_0121_asxx ..etc.. Aug 17 17:20:01 rs1 bird: Reloading protocol pp_1082_asxxxxxx Aug 17 17:20:01 rs1 bird: Reloading protocol pb_1082_asxxxxxx Aug 17 17:20:01 rs1 bird: Tagging invalid ROA 2001:xxxx:xxxx::/48 for ASN xxxxx ..etc.. Aug 17 17:21:17 rs1 bird: Tagging invalid ROA x.x.x.x/23 for ASN xxxx Aug 17 17:21:19 rs1 kernel: [7811815.959943] bird[586]: segfault at f30021 ip 000055a1bf450fc3 sp 00007ffe64f3da98 error 4 in bird[55a1bf42a000+d8000] Aug 17 17:21:19 rs1 kernel: [7811815.966760] Code: 95 78 01 00 00 5b 5d 41 5c c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 48 85 ff b8 01 00 00 00 74 15 48 85 f6 0f 84 a6 00 00 00 <0f> b6 46 21 0f b6 57 21 29 d0 74 11 f3 c3 0f 1f 44 00 00 66 2e 0f Aug 17 17:21:19 rs1 systemd[1]: bird-ipv4.service: Main process exited, code=killed, status=11/SEGV Aug 17 17:21:19 rs1 systemd[1]: bird-ipv4.service: Failed with result 'signal'. Aug 17 17:21:19 rs1 systemd[1]: bird-ipv4.service: Service RestartSec=100ms expired, scheduling restart. Aug 17 17:21:19 rs1 systemd[1]: bird-ipv4.service: Scheduled restart job, restart counter is at 1. Aug 17 17:21:19 rs1 systemd[1]: Stopped BIRD - ipv4. Aug 17 17:21:19 rs1 systemd[1]: Starting BIRD - ipv4... Aug 17 17:21:22 rs1 systemd[1]: Started BIRD - ipv4. Aug 17 17:21:22 rs1 bird: Started When the second crash happened, we happened to be at RIPE84 so we chatted to Maria in person. She said that it was possible to debug it, but would need a core dump. After looking in to this, I did: ulimit -S -c unlimited and installed the systemd-coredump package. ...which was supposed to dump a core file if a process crashed. I tested this by killing a sleep command from the shell with kill -s 6 and it worked. When the crash happened again yesterday, I hoped to have a core file to send, but there is no sign of it having generated one :( Testing on a test server, killing sleep generates a core file, but not killing bird. So two things - has anyone experienced similar crashes or have any ideas why we might be seeing this? Can anyone advise how to reliably get a core dump if bird crashes? Thanks! Ian

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Re: Bird 2.0.9 Crash when 16K routes sent from our App to Bird module
by mukund 27 Sep '22

27 Sep '22

Hi, We are using bird version 2.0.9. We have IXIA traffic which is sending 16K OSPF routes to our App which we send to Bird. Issue is seen when we restart our App. As part of our restart app handling, we restart Bird as well.We see a crash with following BT VT33-VT33_PRI:~/backup/cores/coredump_2022-09-20.20.31.33# gdb bird core.bird.30975GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-120.0.1.el7Copyright (C) 2013 Free Software Foundation, Inc.License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>This is free software: you are free to change and redistribute it.There is NO WARRANTY, to the extent permitted by law. Type "show copying"and "show warranty" for details.This GDB was configured as "x86_64-redhat-linux-gnu".For bug reporting instructions, please see:<http://www.gnu.org/software/gdb/bugs/>...Reading symbols from /home/talariuser/backup/cores/coredump_2022-09-20.20.31.33/bird...done.[New LWP 30975][Thread debugging using libthread_db enabled]Using host libthread_db library "/lib64/libthread_db.so.1".Core was generated by `/home/talariuser/bird/sbin/bird -f'.Program terminated with signal 8, Arithmetic exception.#0 0x000000000047262e in sl_free (s=0x783170, oo=0x7ffff6e1fc60) at /tn-build/src/third_party/bird/lib/slab.c:315315 /tn-build/src/third_party/bird/lib/slab.c: No such file or directory.Missing separate debuginfos, use: debuginfo-install glibc-2.17-325.0.1.el7_9.x86_64 openssl-libs-1.0.2k-22.el7_9.x86_64 zlib-1.2.7-19.el7_9.x86_64(gdb) bt#0 0x000000000047262e in sl_free (s=0x783170, oo=0x7ffff6e1fc60) at /tn-build/src/third_party/bird/lib/slab.c:315#1 0x0000000000462e33 in fib_delete (f=0x75f508, E=0x7ffff6e1fc60) at /tn-build/src/third_party/bird/nest/rt-fib.c:479#2 0x0000000000420915 in rt_sync (p=0x75f350) at /tn-build/src/third_party/bird/proto/ospf/rt.c:2104#3 0x00000000004218da in ospf_rt_spf.part.31 (p=0x75f350) at /tn-build/src/third_party/bird/proto/ospf/rt.c:1721#4 0x000000000041f403 in ospf_rt_spf (p=0x75f350) at /tn-build/src/third_party/bird/proto/ospf/rt.c:1692#5 0x000000000042fb8f in ospf_disp (timer=0x782f10) at /tn-build/src/third_party/bird/proto/ospf/ospf.c:482#6 0x00000000004736cf in timers_fire (loop=0x74e0e0 <main_timeloop>) at /tn-build/src/third_party/bird/lib/timer.c:235#7 0x0000000000408d0a in io_loop () at /tn-build/src/third_party/bird/sysdep/unix/io.c:2260#8 0x0000000000405af6 in main (argc=2, argv=0x7fffffffeb68) at /tn-build/src/third_party/bird/sysdep/unix/main.c:952 Since all routes are newly passed and OSPF SPF calculation is done from scratch, not sure why delete / free has an issue. Also issue is not seen when there are less routes say ~200. Seems to be specific to huge number.If any pointers to this will be helpful Thanks in advance . RegardsMukund

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kernel protocol ignores default preference during scan
by Alexander Zubkov 27 Sep '22

27 Sep '22

Hi, Bird from master branch ignores the default preference set in channel for a kernel protocol, like that: protocol kernel { learn yes; ipv4 { preference 200; import all; export none; }; } Version 2.0.10 seems ok. I suppose the change was introduced with this commit: https://gitlab.nic.cz/labs/bird/-/commit/eb937358c087eaeb6f209660cc7ecfe6d6… It adds setting of the preference to the krt_learn_async() function. But as I understand when route is learned with netlink hook it is processed like this: nl_parse_route -> krt_got_route_async -> krt_learn_async But when it is learned from scan, it is processed like this: nl_parse_route -> krt_got_route -> krt_learn_scan And setting preference was not added to krt_learn_scan() function. I also saw that in my test - when I added a new route to the kernel while bird was running, it appeared in bird with correct preference. But some time after, the scan updated the route and it was replaced with the default preference.

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Garbage collection of unused dynamic BGP neighbours
by Tore Anderson 21 Sep '22

21 Sep '22

Hi Is it possible to garbage collect unused dynamic BGP neighbours? In my environment, these come and go because the dynamic BGP neighbours are themselves quite dynamic (orchestrated containers that get a new IP address every time they are updated or restarted). This causes BIRD to accumulate non-Established «dynbgpN» protocol instances. I would like to get rid of them. Ideally the protocol instance would have vanished by itself the moment it exited the Established state, but since that does not happen, I am hoping there might be a way of deleting them manually (e.g., with birdc)? Tore

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Re: MPLS L3VPN using bird
by Jose Miguel Bentue 16 Sep '22

16 Sep '22

Hello, The goal is to gain communication from a linux based host to another PE-CE by using MPLS L3VPN. To your question: * "configure the PE functionality, connecting to other PE via BGP with MPLS (AFI 1 / SAFI 128) + mpls-labeled packets" Yes, I understand that's first step and it is done by using "vpn4 mpls" channel, am I right? Once the BGP session is established, I see the routes in bird's vpn4 table. * " CE via BGP AFI 1 / SAFI 1 (unicast) + normal IP packets" Actually, I don't know. I understand I have to send traffic to PE so it is routed into MPLS L3VPN but I don't know how to do it. I would appreciate if you could clarify. Thanks and Best Regards, -------------------------------------------------- José Miguel Bentué Support Engineer GSM: +34649930789 FIX: +34912032938 FAX: +34916501100 Mail: josemiguel.bentue(a)emea.nec.com NEC IBERICA S.L. c/Anabel Segura, 7 28108-Alcobendas Madrid ________________________________ From: Bird-users on behalf of Maria Matejka Sent: Thursday, September 15, 2022 8:07 PM To: bird-users(a)network.cz Subject: Re: MPLS L3VPN using bird Hello! This part of MPLS is not implemented for now. Yet to clarify this, you want to configure the PE functionality, connecting to other PE via BGP with MPLS (AFI 1 / SAFI 128) + mpls-labeled packets and also to CE via BGP AFI 1 / SAFI 1 (unicast) + normal IP packets? Thanks Maria On 9/15/22 19:33, Jose Miguel Bentue wrote: > Hello, > > I'm trying to establish MPLS L3VPN between bird and another router. > > CE1 -- PE1 --- MPLS VPN --- PE2 -- CE2 > > Can anybody help me with a configuration example? > > I have set the configuration at the end of the mail and can see bird > establish the BGP session and get routes in alt_ipv4_table. But I don't > see the traffic is being routed according to that table. > > Thanks in advance and Best Regards > > =========================================== > vpn4 table alt_ipv4_table; > > log syslog all; > > router id 10.7.3.106; > > protocol device { > scan time 10; > } > > protocol kernel { > learn; > persist; > scan time 2; > ipv4 { > import all; > export all; > }; > graceful restart; > merge paths on; > } > > protocol bgp uplink1 { > description "My BGP uplink"; > local 10.7.3.106 as 64516; > neighbor 10.7.3.180 as 64513; > ipv4 { > import filter {reject;}; > export filter {accept;}; > }; > vpn4 mpls { > table alt_ipv4_table; > import all; > export none; > }; > multihop; > graceful restart; > connect delay time 2; > connect retry time 5; > error wait time 5,30; > } > ============================================ > > > -------------------------------------------------- > > *José Miguel Bentué* > > Support Engineer > > > > ------------------------------------------------------------------------ > *Jose Miguel Bentue *| VAS Support Engineer | NEC Iberica S.A.U. | C/ > Anabel Segura 7, Madrid, 28108, ES | t: +34912032938 | m: +34649930789 | > w: www.nec.com<http://www.nec.com> > > This email (including any attached files) is private and confidential > and the exclusive property of NEC Ibérica S.L.U. This message is > addressed exclusively to its recipient. If you have received this > message by mistake, please notify the sender immediately and proceed to > delete the message. Unless you have express permission to do so, please > do not distribute or copy this email. Except as otherwise stated, the > sender does not intend to create a legal relationship and this email > shall not constitute an offer or acceptance which could give rise to a > contract. View our privacy policy here: > https://es.nec.com/es_ES/emea/privacy/index.html > > Este correo electrónico (incluyendo cualquier archivo adjunto) contiene > información privada y confidencial y es propiedad exclusiva de NEC > Iberica S.L. Este mensaje se dirige exclusivamente a su destinatario. Si > ha recibido este mensaje por error, por favor notifíquelo al remitente > de inmediato y proceda a eliminarlo de su sistema. A menos que tenga > permiso expreso para hacerlo, por favor no distribuya ni copie este > correo electrónico. Salvo que se indique lo contrario, el remitente no > tiene la intención de establecer una relación legal y este correo > electrónico no constituirá una oferta o aceptación que pueda dar lugar a > un contrato. Vea nuestra política de privacidad aquí: > https://es.nec.com/es_ES/emea/privacy/index.html | Registered Office: > NEC Ibérica S.L., Calle Anabel Segura 7, 2ª Plta- 28108 Alcobendas, > Madrid, Spain

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MPLS L3VPN using bird
by Jose Miguel Bentue 15 Sep '22

15 Sep '22

Hello, I'm trying to establish MPLS L3VPN between bird and another router. CE1 -- PE1 --- MPLS VPN --- PE2 -- CE2 Can anybody help me with a configuration example? I have set the configuration at the end of the mail and can see bird establish the BGP session and get routes in alt_ipv4_table. But I don't see the traffic is being routed according to that table. Thanks in advance and Best Regards =========================================== vpn4 table alt_ipv4_table; log syslog all; router id 10.7.3.106; protocol device { scan time 10; } protocol kernel { learn; persist; scan time 2; ipv4 { import all; export all; }; graceful restart; merge paths on; } protocol bgp uplink1 { description "My BGP uplink"; local 10.7.3.106 as 64516; neighbor 10.7.3.180 as 64513; ipv4 { import filter {reject;}; export filter {accept;}; }; vpn4 mpls { table alt_ipv4_table; import all; export none; }; multihop; graceful restart; connect delay time 2; connect retry time 5; error wait time 5,30; } ============================================ -------------------------------------------------- José Miguel Bentué Support Engineer ________________________________ Jose Miguel Bentue | VAS Support Engineer | NEC Iberica S.A.U. | C/ Anabel Segura 7, Madrid, 28108, ES | t: +34912032938 | m: +34649930789 | w: www.nec.com This email (including any attached files) is private and confidential and the exclusive property of NEC Ibérica S.L.U. This message is addressed exclusively to its recipient. If you have received this message by mistake, please notify the sender immediately and proceed to delete the message. Unless you have express permission to do so, please do not distribute or copy this email. Except as otherwise stated, the sender does not intend to create a legal relationship and this email shall not constitute an offer or acceptance which could give rise to a contract. View our privacy policy here: https://es.nec.com/es_ES/emea/privacy/index.html Este correo electrónico (incluyendo cualquier archivo adjunto) contiene información privada y confidencial y es propiedad exclusiva de NEC Iberica S.L. Este mensaje se dirige exclusivamente a su destinatario. Si ha recibido este mensaje por error, por favor notifíquelo al remitente de inmediato y proceda a eliminarlo de su sistema. A menos que tenga permiso expreso para hacerlo, por favor no distribuya ni copie este correo electrónico. Salvo que se indique lo contrario, el remitente no tiene la intención de establecer una relación legal y este correo electrónico no constituirá una oferta o aceptación que pueda dar lugar a un contrato. Vea nuestra política de privacidad aquí: https://es.nec.com/es_ES/emea/privacy/index.html | Registered Office: NEC Ibérica S.L., Calle Anabel Segura 7, 2ª Plta- 28108 Alcobendas, Madrid, Spain

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State of development of the 3.0-alpha1 version
by Maria Matejka 14 Sep '22

14 Sep '22

Hello everybody! After the holiday period is over, I'm returning to occasional reporting of v3.0 development. This is NOT AN ANNOUNCEMENT, just a progress report. If you haven't read my previous reports, my last report is here in the archives: http://trubka.network.cz/pipermail/bird-users/2022-July/016222.html And now let's look at the progress. If you wanna see the commits, look at the thread-next branch. No liability and no guarantee indeed, please don't run that code on a production machine. * There are some backported changes to v2 branches and they'll be included in the next BIRD version, notably some changes in route attribute storage. Their performance impact should be negligible and there should be no changes in visible behavior, yet they'll make future v2 features more likely to be smoothly merged into v3 * The nexthop resolving, flowspec revalidation and also roa-induced autoreload procedures are now better fitting into the asynchronous nature of table change announcements. This will allow easy implementation of future improvements to reload only the affected routes. Now we simply reload everything but the path to partial reloads is open. * There are still pending performance improvements on attribute storage, yet they're to be done after BIRD based on thread-next branch is stable running tables, BGP, RPKI and Pipes in their own threads. * MRT is still insecure but finally quite high on the list. * I spent most of the past 3 months on merging v2 branches and pre-multithreading commits, trying to resolve all the problems. The goal is now to keep pace with the v2 branch tip and actively resolve merging conflicts by suggesting and choosing the right strategy of new feature implementation in v2 branches to be compatible with asynchronicity and locking. * With some help of Santiago, I constructed a lockless event queue, removing one of main problems in 3.0-alpha0 -- locking on event manipulation. Now it's possible for multiple threads to safely enqueue into the same queue without locking, and also to enqueue the same event to the same queue (which is idempotent as it should be). I'll thoroughly describe this data structure in a future blogpost. * We also decided to add another locking layer between Table and Protocol (see my blogpost[1]), called Service. In 3.0-alpha0, the table auxiliary routines (next hop update, route pruning etc.) were executed in an IO loop running on Table level; now it's moved to the Service level, slightly reducing the time when table is locked for maintenance and also fixing some previous problems. * The Service layer will also host some MRT and BMP routines. If we thought more about this formerly, we may have had also BFD on this layer, yet I think it isn't necessary to move BFD there now. * For now, I have BIRD in the state when the Pipes and Tables have their own threads and I'm going to spend like a week or so resetting our performance testing machinery, producing some data and hoping for good BIRD stablility. * After that, I'll continue merging 3.0-alpha0 to thread-next, hoping that I get to RPKI and BGP threads in a meaningful time. In theory, this merge should be smooth, supposing that I'll probably revert most of the commits in 3.0-alpha0, having the issues already solved in thread-next in a different way. * I'm also trying to find some time to reset our issue tracker at gitlab.nic.cz and fill it at least with issues regarding multithreading, better also filling it with our almost infinite backlog. That should be a tool not only for the development organization but also for everybody else who is curious about how BIRD works inside. Let's test it and we'll see the outcomes. So here you are with the report. I hope it's complete. Feel free to ask for clarification. I'd like also to produce some more blogposts, hopefully during the next week. Maria [1] https://en.blog.nic.cz/2022/02/09/bird-journey-to-threads-chapter-3-paralle…

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TEXT in case constraint
by Mikhail Mayorov 03 Sep '22

03 Sep '22

Hi all! I'll try string variables in CASE. But I have error - "syntax error, unexpected TEXT" function casetest(string aaa) { if aaa ~ "a1" then print "ok"; case aaa { "a1" : print "a1"; "b1" : print "b1"; else: print "not a1, nor b1"; } } Sometimes it will be comfortable. Why it is error? -- Regards, Mikhail V. Majorov

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