June 2017 - Bird-users - Mailing Lists

Adding more then one bgp community at once
by Борис Коваленко 05 May '23

05 May '23

Hello! Is this possible to add many communites at once? bgp_community.add([(1,1), (1,2)]) is wrong "Setting clist attribute to non-clist value" Regards, Boris -- С уважением, Борис Коваленко

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manipulating the best path, eBGP, MED?
by Thomas＠PhaseHosting 14 Apr '18

14 Apr '18

Supp, I implemented bird in our Private cloud running proxmox to distribute our public address with eBGP to our serverhost. Through iBGP and a ucarp interface i have a HA gateway, the problem is that our host receives the routes but there are multiple entry points to our subnet ( the proxmox hosts). This makes that a diffrent in & out route doenst work. through following link: https://supportforums.cisco.com/document/126691/understanding-bgp-best-path… I learned that my hosts selects its route based on age ( the bird with the first connection is chosen). Can i send a multi-exit discriminator with my eBGP connection to my host? I googled but could find 2 answers that did't change anything: # your default gateway IP below here protocol bgp eBGP { import none; export where proto = "static_packet"; local as 65000; neighbor 10.80.x.x as 65530; password "SECRET"; #med metric 10; #default bgp_med 10; } (offcourse i tried both without # and waited till export) Or is there an other way to make sure that our host routes always to the first server and so on. -- Thomas Valgaeren thomas(a)phasehosting.io +32477915307

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Version 1.6.2
by Ondrej Filip 31 Aug '17

31 Aug '17

Dear users, a new version of the 1.6.x branch is out: Version 1.6.2 (2016-09-29) o Fixes serious bug introduced in the previous version Upgrade from 1.6.1 is highly recommended. Enjoy it! Ondrej

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Re: Unexpected behavior of static routes
by Alexander Demenshin 10 Aug '17

10 Aug '17

On 2017-05-10 13:16, Ondrej Zajicek wrote: > But such design would bring plenty of issues w.r.t. multiple routing > tables - may next hops resolve just in the same routing table or also > in > another routing table? Well, at least in Linux device/direct routes may exist in any table, so where is the difference between device/direct routes and arbitrary next-hop route? How I would implement this: - Try to find if next-hop is routable via any of existing devices (including explicitly routed networks - as in my case); - If it is routable (which also means that device has to be up), install it (so it can be exported to the kernel tables). > What if the device route is available, but not exported to kernel? You mean if it is configured but not exported? Then it should be ignored, obviously, though this could happen only in few cases: - device does not exists (yet) - device is not up (kernel will not accept any routes in this case) - protocol is disabled If no kernel export is configured at all then the route does not make any sense anyway. > Static onlink routes is something that probably could be implemented > and > it is a good idea. This could solve one of the most typical scenarios - keep static (local) routes up for specified set of devices/gateways - once they become available. What is interesting, quagga behaves exactly in the same way as bird, and only cisco (well, may be other routers too) does what is (logically) expected - and it allows Linux-like onlink routes, which specify both device and gateway address, and those routes are linked to device state (i.e. exported and used when device is active). --- Best regards, Alexander.

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BGP Monitoring Protocol (BMP) support in Bird?
by Baptiste Jonglez 11 Jul '17

11 Jul '17

Hi, I am wondering if somebody is working on BGP Monitoring Protocol (BMP) support in Bird? Note that I'm just asking, I'm not requesting our beloved Bird developers to add this feature with a deadline set to yesterday :) I might try to implement it if nobody else already did. Basically, this is just a way to export BGP data over a TCP connection: http://tools.ietf.org/html/rfc7854 This looks like a useful alternative to dumping to mrtdump files, there are already several free software clients: https://code.google.com/archive/p/bmpreceiver/ http://www.openbmp.org/#!index.md Baptiste

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Re: Next-hop check not needed?
by Vincent Bernat 04 Jul '17

04 Jul '17

❦ 28 juin 2017 14:01 +0200, Ondrej Zajicek <santiago(a)crfreenet.org> : > Note that when learning route from the kernel you could workaround it by > using 'onlink' route flag. Great! It seems to work: $ ip route show table public dev eth2 203.0.113.1 scope link metric 10 203.0.113.10 via 203.0.113.1 metric 10 onlink bird> show route table public 203.0.113.10/32 via 203.0.113.1 on eth2 [kernel_public 15:58:09] * (200) 203.0.113.1/32 dev eth2 [kernel_public 15:58:09] * (200) But BIRD (1.6.3) still seems to be a bit confused, since I got this message in a loop: 2017-06-28 16:01:20 <ERR> KRT: Received route 203.0.113.10/32 with strange next-hop 203.0.113.1 2017-06-28 16:01:20 <WARN> Netlink: File exists Other than that, everything works as expected. I don't know how to interpret the first message (is it receiving two routes?) but the second message seems to say that it tries to reinstall the same route it received. -- 10.0 times 0.1 is hardly ever 1.0. - The Elements of Programming Style (Kernighan & Plauger)

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Re: Identifying BGP convergence bottleneck
by Patrick.deNiet＠os3.nl 28 Jun '17

28 Jun '17

Thanks for your info Ondrej, it's much appreciated! I've done both unique, overlapping and identical prefixes on these peers. The unique one costs the routeserver more memory than I had unfortunately. I'll let you know if I have anything to share. Regards, Patrick > On Thu, Jun 22, 2017 at 10:26:03AM +0200, Patrick.deNiet(a)os3.nl wrote: >> Hi everyone! >> >> I am currently looking into the performance of BIRD (bgp) as a >> route-server with ~700 peers with 10k prefixes each. I'm noticing an >> increase in convergence time as I increase these numbers (which is not a >> surprise). >> >> Unfortunately, I do not have a deep enough understanding of the code and >> have not managed to identify these points. Is anyone here able to give >> some pointers as to where in the code we could place these markings to >> measure this? > > Hi > > It is hard to tell, esp. it depends on your setting and configuration and > would need some benchmarking. It is single-table or multi-table route > server [1][2]? Personally i would guess that it is in TX, because you > receive a route and then send it about ~700 times (but that depends on > whether prefixes from different peers are shared or unique). You could > benchmark it with 'export none' to see the difference. > > Also note that hash table used for routing table has max size of 64k > buckets. You could try attached patches to fix that. That may help > significantly. > > I would be interested in your performance results. > > [1] > https://gitlab.labs.nic.cz/labs/bird/wikis/Route_server_with_community_base… > [2] > https://gitlab.labs.nic.cz/labs/bird/wikis/Route_server_with_community_base… > > -- > Elen sila lumenn' omentielvo > > Ondrej 'Santiago' Zajicek (email: santiago(a)crfreenet.org) > OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) > "To err is human -- to blame it on a computer is even more so." >

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Identifying BGP convergence bottleneck
by Patrick.deNiet＠os3.nl 28 Jun '17

28 Jun '17

Hi everyone! I am currently looking into the performance of BIRD (bgp) as a route-server with ~700 peers with 10k prefixes each. I'm noticing an increase in convergence time as I increase these numbers (which is not a surprise). Currently, I am forcing these convergence times by flapping the link which causes all peers to start sending updates at the same time. My particular interest here is to find out what action specifically is causing this convergence time. With convergence time I mean the time it takes for the bird to process all updates and drop down from 100% cpu to a more "idle" level. In order to identify what is causing this, I'm looking to mark the start and end of each phase as described in RFC4271 9.1. Decision Process. This way I may be able to get an idea of where the cpu time in spent during all this (best path calc, sending out updates, etc..). Unfortunately, I do not have a deep enough understanding of the code and have not managed to identify these points. Is anyone here able to give some pointers as to where in the code we could place these markings to measure this? Other comments and insights are also welcome. Kind regards, Patrick

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Next-hop check not needed?
by Vincent Bernat 28 Jun '17

28 Jun '17

Hey in netlink.c, there is this piece of code: #v+ if (a[RTA_GATEWAY]) { neighbor *ng; ra->dest = RTD_ROUTER; memcpy(&ra->gw, RTA_DATA(a[RTA_GATEWAY]), sizeof(ra->gw)); ipa_ntoh(ra->gw); #ifdef IPV6 /* Silently skip strange 6to4 routes */ if (ipa_in_net(ra->gw, IPA_NONE, 96)) return; #endif ng = neigh_find2(&p->p, &ra->gw, ra->iface, (i->rtm_flags & RTNH_F_ONLINK) ? NEF_ONLINK : 0); if (!ng || (ng->scope == SCOPE_HOST)) { log(L_ERR "KRT: Received route %I/%d with strange next-hop %I", net->n.prefix, net->n.pxlen, ra->gw); return; } } #v- In turns, it calls neigh_find2() which delegates the decision to if_connected(). if_connected() will return an error if it thinks that the gateway is not part of the prefix of one of the configured IP addresses. This means that if I have the following setup: ip route add 203.0.113.4/32 dev vnet2 ip route add 203.0.113.15/32 via 203.0.113.4 dev vnet2 BIRD will complain about "strange next-hop" while the setup is perfectly valid. I don't need an IP address on an interface to route traffic on it. I would think the check should just be removed. If the kernel says this is a valid gateway, it likely is. However, I can't find the reason the check was added. In the past, this was just a warning: #v+ + ng = neigh_find(&p->p, &ra.gw, 0); + if (ng) + ra.iface = ng->iface; + else + /* FIXME: Remove this warning? */ + log(L_WARN "Kernel told us to use non-neighbor %I for %I/%d", ra.gw, net->n.prefix, net->n.pxlen); #v- (commit aa64578641c15b137172acc927d9d7af5914576b) But this was made an error in commit 9d4d38d1a5d67f5485d2b2fa439c879583dfdcb0. #v+ - ng = neigh_find(&p->p, &ra.gw, 0); + ng = neigh_find2(&p->p, &ra.gw, ifa, 0); if (ng && ng->scope) + { + if (ng->iface != ifa) + log(L_WARN "KRT: Route with unexpected iface for %I/%d", net->n.prefix, net->n.pxlen); ra.iface = ng->iface; + } else - /* FIXME: Remove this warning? Handle it somehow... */ + { log(L_WARN "Kernel told us to use non-neighbor %I for %I/%d", ra.gw, net->n.prefix, net->n.pxlen); + return; + } #v- Commit message says "Fixes some problems related to link-local routes in KRT interface". Does this ring any bell? -- Avoid temporary variables. - The Elements of Programming Style (Kernighan & Plauger)

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Structured output
by Darren O'Connor 26 Jun '17

26 Jun '17

Hi all. I currently use the unix socket to communicate with bird. the issue is that the data I get back is unstructured text. I have quite a bit of code parsing all that data into usable structs. Would it not be possible to add the ability to request structured data back? i.e. receive a response with the data encoded in json, protobuf, or even xml. Thanks Darren

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