September 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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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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[Bird2] Doubt about Route Server function and iBGP
by heisenbug at xpto 08 Oct '18

08 Oct '18

Hello Guys, On bird1.6, I have deployed our Route Servers using the below architecture to split the load from the control plane: Customer1 <-> RS1[pid0] <-> iBGP <-> RS2[pid1] <-> Customer2 And is working fine as RS until now [not inserting local AS on AS-PATH and not changing NH]. I'm planing to migrate to Bird2.0.2 with some new features, but when I do the same on Bird2.0.2, I have the AS from iBGP inserted on AS-PATH, just to let me know, this is an expected behavior on Bird2? I have tested in a lot of ways, but still the same results. []s

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MPLS LDP
by Danny Wensley 28 Sep '18

28 Sep '18

Hi all, I was wondering if anyone knows about improvements to MPLS support, specifically when it's going to be further integrated into BGP and when LDP will be added? Thanks, Danny.

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IPv6 next-hop with incorrect link-local address received
by Sebastian Neuner 27 Sep '18

27 Sep '18

Hi all, we currently have an issue, where Bird kind of misses the right config option to fix. So we have a Cisco (XR) router peering with Bird on a Linux server. It's an eBGP-Session though a /127 link. We're announcing a prefix from the Cisco to bird, which has a foreign next-hop (i.e. not in this /127). Cisco apparently misinterprets RFC2545 (or has a bug, I'm still discussing this with TAC) and adds the peering interfaces link-local address. So now the next-hop in the BGP update looks like this: > Next hop network address (32 bytes) > Next Hop: xxxx:xxxx:c02::28 > Next Hop: fe80::28a:96ff:fecc:c10 The GUA next-hop is correct and points to a VM on the server (i.e. not on the /127). The link-local next-hop points to the Cisco. Unfortunately, this is the one, bird uses to install the route in the kernel. Am I missing something? Can I work around this somehow? Or would it make sense for bird to have a switch for that? Similar to "missing lladdr ignore" which works outbound, it could be something like "next hop lladdr ignore"? Best regards, Sebastian

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Primary route confusion
by Kenth Eriksson 24 Sep '18

24 Sep '18

Hi! The primary route in BIRD, marked by '*', confuses me. Consider the following two default routes as displayed by BIRD (2.0.2) and the Linux kernel (4.14.51+). bird> show route Table master4: 0.0.0.0/0 unicast [ospf1 19:54:43.687] * E1 (110/350) [172.20.4.41] via 172.20.4.41 on p1-1-1-1-2 unicast [kernel1 19:47:39.563] (40) via 172.20.0.1 on eth1 # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 172.20.0.1 0.0.0.0 UG 0 0 0 eth1 0.0.0.0 172.20.4.41 0.0.0.0 UG 32 0 0 p1-1-1-1-2 BIRD shows that the OSPF route with administrative distance of 110 is primary, and not the kernel route with administrative distance of 40. When BIRD pushes the OSPF route to the kernel, it uses the metric 32 by default, whereas the default kernel route has metric 0. Both routes are installed to the FIB, but the kernel will elect the route via eth1. Why is not the default route over eth1 shown as primary in BIRD? Can we control if BIRD pushes the OSPF route into the kernel here? The kernel already has a more preferred default route. Thanks, Kenth

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Log length problem
by Mattia Milani 22 Sep '18

22 Sep '18

Hello everyone, I'm writing you because I recognize a strange problem when i log something, and I don't know if it is a bug or something wanted to work in this way. For a project i need to log some complex information, so i create a string with the info that I need and after that i log it with the command: log(L_INFO "...); But when the length of the string go over 1000 (I get the size with strlen) it is not printed on the log file. I was thinking to split the string to go over the problem, or there is another way? Thanks everyone Mattia

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