December 2018 - Bird-users

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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[PATCH] feature to keep protocol's state while configuring
by Alexander Zubkov 29 Jan '23

29 Jan '23

Hello. I have created a patch (attached) with new protocol option: disabled keep on|off. To keep the protocol's state while loading new config. It is useful when protocols disabled manually in the runtime, but we want to keep that state when loading new config. Patch is attached. I have made it against the current int-new branch.

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Bug: BFD confuses sessions with identical IPv6 link-local addresses
by Julian Brost 14 Jan '21

14 Jan '21

Hi, I just tried to enable BFD for some OSPF and BGP connections and ran into an issue which BFD sessions flapping up and down and Bird logging many messages like these: bfd1: Bad packet from fe80::2 - unknown session id (130079069) bfd1: Bad packet from fe80::2 - unknown session id (3102513000) bfd1: Bad packet from fe80::2 - unknown session id (3650438750) bfd1: Bad packet from fe80::2 - unknown session id (1597034259) This presumably happens due to this piece of code in bfd_rx_hook() in proto/bfd/packets.c: s = bfd_find_session_by_addr(p, sk->faddr); I use fe80::1/fe80::2 as addresses for most of my IPv6 peering connections and sk->faddr is just a 128 bit value, so it contains no interface identifier, which likely leads to Bird confusing multiple BFD sessions. Regards, Julian

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[PATCH] babel: Set onlink flag for IPv4 routes with unreachable next hop
by Toke Høiland-Jørgensen 14 Apr '20

14 Apr '20

If the next hop of a route is not a reachable address, the route should be installed as onlink. This enables a configuration common in mesh networks where the mesh interface is assigned a /32 and babel handles the routing by installing onlink routes. Signed-off-by: Toke Høiland-Jørgensen <toke(a)toke.dk> --- proto/babel/babel.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/proto/babel/babel.c b/proto/babel/babel.c index 88c4711e..4fd88042 100644 --- a/proto/babel/babel.c +++ b/proto/babel/babel.c @@ -640,6 +640,13 @@ babel_announce_rte(struct babel_proto *p, struct babel_entry *e) .nh.iface = r->neigh->ifa->iface, }; + /* If we cannot find a reachable neighbour, set the entry to be onlink. This + * makes it possible to, e.g., assign /32 addresses on a mesh interface and + * have routing work. + */ + if (!neigh_find2(&p->p, &r->next_hop, r->neigh->ifa->iface, 0)) + a0.nh.flags = RNF_ONLINK; + rta *a = rta_lookup(&a0); rte *rte = rte_get_temp(a); rte->u.babel.seqno = r->seqno; -- 2.17.0

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Bird 1.6.3 removing IPv6 device routes on Linux (3.10.0)
by Ben Arblaster 12 Oct '19

12 Oct '19

Hi, I’m seeing an issue with bird 1.6.3 where IPv6 device routes are unexpectedly removed from the kernel table on Linux (3.10.0, CentOS 7) when bird removes a matching route learned via another protocol (in this case OSPF). To reproduce, I’ve rigged up a very simple test with two bird6 instances running OSPF in a single area 0 over a ptp tunnel. Configs are here - https://gist.github.com/andatche/ca5b5ac120e09b6b8171ec5ca95d2e25 If I add an address/network (e.g. fd00::1/64) to an interface (dummy0) on host A, the route is flooded by A, learned by B and correctly installed in the kernel table on B: fd00::/64 via fe80::5efe:ae2:b006 dev tun0 proto bird metric 1024 If I then add the same address/network (e.g. fd00::1/64) to an interface (dummy0) on host B, at that instant a device route is installed in the kernel table alongside the existing route on host B and it now looks like this: fd00::/64 dev dummy0 proto kernel metric 256 fd00::/64 via fe80::5efe:ae2:b006 dev tun0 proto bird metric 1024 Shortly after, bird picks up the new address/network on dummy0, recalculates the area and correctly selects the connected route as the new best. It then removes the old route via host A from the kernel table, as expected: kernel1 < removed fd00::/64 via fe80::5efe:ae2:b006 on tun0 However, this causes both the route via host A *and* the device route to be removed from the kernel table, leaving the kernel table on host B with no route to fd00::/64 at all. # ip -6 route show fd00::/64 # This is a change in behaviour from 1.4.5 and seems like a bug, rather than the expected behaviour? Regards, Ben -- Ben Arblaster e: ben(a)andatche.com t: +447943860840 w: https://andatche.com

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For developer, required some explanation on code with timer and BGP
by Mattia Milani 06 Apr '19

06 Apr '19

Hello all, this is a message for developer and who know how bird use timer, and buffer. Sorry for the length of this mail. For first, the protocol i want to modify and upgrade is BGP, i see that there isn't the timer MRAI implemented and it will be useful for some studies on information propagation, so i decided to develop a first version of it. The actual process to send any kind of pkt is to call the function bgp_fire_tx() and it's called by two other function respectively bgp_kick_tx() and bgp_tx() and the function bgp_fire_tx() take care to read from the buffer the message that has to be sent and send it. bgp_kick_tx() and bgp_tx() call bgp_fire_tx() while it don't return 0, so the clear all the buffer of the message that has to be sent. So my idea to introduce MRAI was that: Create a timer (for now I created it for connection, after like say RFC 4271 this timer has to be set for every route) and put it on the connection. Initialize it with the other timer of the conn when the state of the conn goes up i set it to some value and start the timer. when the timer finish i call the function MRAI_finish() that call the function bgp_fire_tx() while there is something to send more ore less like the while loop in bgp_kick_tx() and bgp_tx() when it's called bgp_fire_tx() on the update message part i written a check, if the timer isn't at 0 i can't send the update, because the function can be called from bgp_kick_tx() or bgp_tx(), but if it 0 it is finished so i can send the message When all the message had been send i reset the timer and start it again. But unfortunately i see something that doesn't make my code work. when something call bgp_kick_tx() or bgp_tx() the call bgp_fire_tx() and they clear all the buffer, including update message that wasn't sended so when the timer finish it didn't found anything on the buffer. Now how can i change that? My idea is to use a secondary buffer, when in bgp_fire_tx() i see that i can't send the update I will insert the pkt in this secondary buffer and consume the pkt on the main buffer. when bgp_kick_tx() or bgp_tx() have send all the messages I will transfer all the pkt in the secondary buffer into the main buffer. So I ask you it's possible that? there is something in the code already written that could help me? do you see another way to implement the MRAI timer? Thanks a lot to everyone, Mattia

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reorder BGP plink preference
by Eugene M. Zheganin 27 Jan '19

27 Jan '19

Hello, I have a bird router serving multiple BGP sessions with my AS uplinks, and now I need to create a more complicated thing, - I have several FIBs and I need to reorder the BGP link preference for a given FIB. Say, I have 3 uplinks, A/B/C, A is the most preferable one for default FIB, but I need B to be the most preferable one for FIB 1. I have some basic experience with multiple routing tables in bird, I'm successfully using two at the moment, but I just have no idea on how to do this. I mean I know how to make the B upstream the only channel for FIB 1 (without redundancy), but I have no idea on how to reorder the preference in order to keep the redundancy. Is there such a way ? Thanks. Eugene.

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Trouble with IPv6 and VRFs: Cannot assign requested address
by Ralf Jung 01 Jan '19

01 Jan '19

Hi all, I am playing around with VRFs in our network, and I am having trouble getting bird6 to establish its BGP sessions inside a VRF. Strangely, bird for IPv4 works with pretty much the same configuration. I have attached the full configuration. The (I think) interesting bits are > template bgp ffrl_uplink { > table ffrl; > vrf "vrf_freifunk"; > local as 64899; > import keep filtered; > import filter ebgp_ffrl_import_filter; > export filter ebgp_ffrl_export_filter; > next hop self; > direct; > }; > > protocol bgp ffrl_b_ak from ffrl_uplink { > source address 2a03:2260:0:195::2; > neighbor 2a03:2260:0:195::1 as 201701; > }; In the logs, all I get (with `debug all;` added) is > Dez 28 13:05:25 gw1.saar.freifunk.net bird6[24900]: ffrl_b_ak: Connecting to 2a03:2260:0:195::1 from local address 2a03:2260:0:195::2 > Dez 28 13:05:25 gw1.saar.freifunk.net bird6[24900]: ffrl_b_ak: Socket error: bind: Cannot assign requested address > Dez 28 13:05:25 gw1.saar.freifunk.net bird6[24900]: ffrl_b_ak: Connection closed > Dez 28 13:05:26 gw1.saar.freifunk.net bird6[24900]: ffrl_b_ak: Connect delayed by 5 seconds I tried adding `interface "tun-up-ffrl_b_ak";` (that's the interface which has the address 2a03:2260:0:194::2), to no avail. I also tried adding `interface "vrf_freifunk";`, which made the error messages go away but still no peer is listed in `birdc6 show route table ffrl`. My IPv4 configuration is almost the same, and yet there finding peers works. (Actually routing traffic doesn't work yet, but that may also be a problem with our NAT setup.) Note that I have very little experience with BGP, we use it only in an internal instance for peering with our uplink. >From some googling I found <https://bird.network.cz/pipermail/bird-users/2017-August/011440.html> which recommends adding `direct;`, but I already have that set. This is using bird 1.6.4, Linux 4.18, Debian stable. Any help would be greatly appreciated. Kind regards, Ralf

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Linux 4.20 / incomplete ipv4 addr list / RTM_GETADDR
by Arthur Gautier 31 Dec '18

31 Dec '18

Hello bird users, Today I tried to upgrade one of platform to from linux 4.19 to linux 4.20. I started noticing the bgp protocol could not start after this message: <TRACE> uplink: Waiting for 1.2.3.4 to become my neighbor The neighbor (directly connected on an interface) would never appear to bird (as in show interfaces) because the AF_INET/RTM_GETADDR reply from the kernel looks incomplete. It works fine in v6. The results from kernel are capped to 104 ip address (and we run servers with >700 ip address) on loopback. I confirm this behavour with nlmon / tcpdump / wireshark. Tested with bird v2.0.2 and v1.6.3 (debian stable). I haven't reproduced the behavior elsewhere than bird, but I believe this could prove useful to someone else. -- \o/ Arthur G Gandi.net

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Sync with userspace instead of kernel
by Cody Doucette 29 Dec '18

29 Dec '18

Is there any way in BIRD to sync the routing table directly with userspace instead of the OS kernel? We are managing forwarding tables in a userspace (DPDK) application instead of the kernel and want to avoid duplicating the table in both. I see a possible way of doing this with a patch to set `nl_pid` in nl_send() inside of sysdep/linux/netlink.c. But has anyone used BIRD for this use case before?

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