RE: Received route with strange next-hop
Hi Ondrej, It took me a while to continue this work, but the patch works flawlessly. Our "alien" routing protocol removes nexthop routes which become unavailable so the behavior you implemented is correct for us. Thanks for your help, Niels -Original Message- From: Ondrej Zajicek Sent: Thursday, May 16, 2019 5:43 PM To: Adrichem, N.L.M. (Niels) van Cc: bird-users@network.cz Subject: Re: Received route with strange next-hop On Wed, May 15, 2019 at 09:09:34AM +, Adrichem, N.L.M. (Niels) van wrote: > Hello, > > Additionally, the bird.log file throws the following error: > 2019-05-15 10:27:21.869 Started > 2019-05-15 10:27:21.902 Missing broadcast address for interface > vxlan0 > 2019-05-15 10:27:29.329 KRT: Received route 10.0.1.3/32 with > strange next-hop 10.0.1.4 > > It may be that kernel protocol rejects the route because the next-hop > is not in the interface its regular netmask (which is set to /32), > though I am not familiar enough with the source code to determine the > exact cause except that the error gets thrown from > sysdep/linux/netlink.c line 1643. However, I think the line should be > accepted since there is another routing rule confirming that the > next-hop is directly attached to device eth1. Given the explicit error > I don't think this is a configuration error (though I am open to learn > more), so I hope BIRD can be patched to solve this. Hello BIRD generally expects that next hop is resolvable through an address range associated with interfaces, not just through another direct/device route. This is limitation compared to the Linux kernel which allows next hop resolvable through another direct/device route (but not through another regular route with next-hop). We have some plans to redesign it in a more generic manner, but it is not a simple fix. As a workaround, attached patch (untested) should disable next hop checking for all alien routes. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santi...@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." This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages.
Re: Received route with strange next-hop
On Wed, May 15, 2019 at 09:09:34AM +, Adrichem, N.L.M. (Niels) van wrote: > Hello, > > Additionally, the bird.log file throws the following error: > 2019-05-15 10:27:21.869 Started > 2019-05-15 10:27:21.902 Missing broadcast address for interface vxlan0 > 2019-05-15 10:27:29.329 KRT: Received route 10.0.1.3/32 with strange > next-hop 10.0.1.4 > > It may be that kernel protocol rejects the route because the next-hop > is not in the interface its regular netmask (which is set to /32), though > I am not familiar enough with the source code to determine the exact > cause except that the error gets thrown from sysdep/linux/netlink.c line > 1643. However, I think the line should be accepted since there is another > routing rule confirming that the next-hop is directly attached to device > eth1. Given the explicit error I don't think this is a configuration > error (though I am open to learn more), so I hope BIRD can be patched to > solve this. Hello BIRD generally expects that next hop is resolvable through an address range associated with interfaces, not just through another direct/device route. This is limitation compared to the Linux kernel which allows next hop resolvable through another direct/device route (but not through another regular route with next-hop). We have some plans to redesign it in a more generic manner, but it is not a simple fix. As a workaround, attached patch (untested) should disable next hop checking for all alien routes. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santi...@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." diff --git a/sysdep/linux/netlink.c b/sysdep/linux/netlink.c index d773743d..d5d64b6b 100644 --- a/sysdep/linux/netlink.c +++ b/sysdep/linux/netlink.c @@ -1632,7 +1632,7 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h) if ((i->rtm_family == AF_INET6) && ipa_in_netX(ra->nh.gw, (net_addr *) &sit)) return; - if (i->rtm_flags & RTNH_F_ONLINK) + if ((i->rtm_flags & RTNH_F_ONLINK) || (krt_src == KRT_SRC_ALIEN)) ra->nh.flags |= RNF_ONLINK; neighbor *nbr;
Received route with strange next-hop
Hello, I'm trying to redistribute routes from another routing daemon through synchronization of the kernel table using the kernel protocol in BIRD 2.0.4. However, I run into some problems that not all routes are imported by the BIRD router. The kernel routing table contains the following routing table: # ip route 10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.1 10.0.1.3 via 10.0.1.4 dev eth1 proto zebra metric 2 10.0.1.4 dev eth1 proto zebra scope link metric 1 10.0.4.0/24 via 10.0.0.2 dev eth0 proto bird metric 32 The interface eth1 has the address 10.0.1.1/32 in an ad-hoc routing domain, through OSPF-MDR (which is an extension of Quagga) it finds the direct neighbor 10.0.1.4 which is added as "10.0.1.4 dev eth1 proto zebra scope link metric 1". The neighbor 10.0.1.4 advertises that it can forward to 10.0.1.3 which is added as "10.0.1.3 via 10.0.1.4 dev eth1 proto zebra metric 2". The routing of OSPF-MDR works, in the sense that 10.0.1.1 can reach 10.0.1.3 and 10.0.1.4. However, when we try to import these routes from the protocol kernel into the Bird routing table, only the directly connected route to 10.0.1.4 shows while the route to 10.0.1.3 are not imported: # birdc show route BIRD 2.0.4 ready. Table master4: 10.0.1.4/32 unicast [kernel1 10:27:29.329] (10) dev eth1 10.0.4.0/24 unicast [babel1 10:27:23.461 from fe80::200:ff:feaa:4] (130/96) [00:00:00:00:0a:00:00:02] via 10.0.0.2 on eth0 10.0.0.0/24 unicast [direct1 10:27:21.870] * (240) dev eth0 unicast [babel1 10:27:23.461 from fe80::200:ff:feaa:4] (130/96) [00:00:00:00:0a:00:00:02] via 10.0.0.2 on eth0 Additionally, the bird.log file throws the following error: 2019-05-15 10:27:21.869 Started 2019-05-15 10:27:21.902 Missing broadcast address for interface vxlan0 2019-05-15 10:27:29.329 KRT: Received route 10.0.1.3/32 with strange next-hop 10.0.1.4 It may be that kernel protocol rejects the route because the next-hop is not in the interface its regular netmask (which is set to /32), though I am not familiar enough with the source code to determine the exact cause except that the error gets thrown from sysdep/linux/netlink.c line 1643. However, I think the line should be accepted since there is another routing rule confirming that the next-hop is directly attached to device eth1. Given the explicit error I don't think this is a configuration error (though I am open to learn more), so I hope BIRD can be patched to solve this. I have attached the bird.conf file, as well as an image of the example topology. Above snippets and config file are taken from node n1 which is running both the OSPF-MDR router based on Quagga and BIRD Router. Any help would be much appreciated. Thanks in advance, Niels van Adrichem [cid:image001.png@01D50B0D.4706B540] This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages. bird.conf Description: bird.conf
Re: KRT: Received route with strange next-hop
On 12/5/2015 9:54 AM, Ondrej Zajicek wrote: On Sat, Nov 28, 2015 at 04:16:54PM -0500, Brian Rak wrote: Sorry for late answer, 'device route' i call a route for directly attached network prefix, with associated iface but without associated gateway IP. Perhaps there is a better / more established term for such routes. Sorry, my spam filter was delaying this. That's what I have I think? I have the '45.63.4.188 dev veth0 scope link' route, I'm not aware of any other way to add this (and it doesn't use a gateway IP). Well, the recommended way is to add ptp address: ip addr add A.B.C.D peer 45.63.4.188 dev veth0 instead of just the route (when ptp address is added, the route is also added by the kernel) The host end of the interface does not have an IP address, so using 'ip addr add' won't really work. A peer address won't really work, this isn't a /30 (the 45.63.4.188 IP is assigned to a virtual machine, and is part of a bigger /23, we're using proxy ARP to get traffic to/from the VM).
Re: KRT: Received route with strange next-hop
On Sat, Nov 28, 2015 at 04:16:54PM -0500, Brian Rak wrote: > >Sorry for late answer, 'device route' i call a route for directly > >attached network prefix, with associated iface but without associated > >gateway IP. Perhaps there is a better / more established term for such > >routes. > > > Sorry, my spam filter was delaying this. > > That's what I have I think? I have the '45.63.4.188 dev veth0 scope link' > route, I'm not aware of any other way to add this (and it doesn't use a > gateway IP). Well, the recommended way is to add ptp address: ip addr add A.B.C.D peer 45.63.4.188 dev veth0 instead of just the route (when ptp address is added, the route is also added by the kernel) -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santi...@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." signature.asc Description: Digital signature
Re: KRT: Received route with strange next-hop
On 11/25/2015 5:51 AM, Ondrej Zajicek wrote: On Thu, Nov 19, 2015 at 08:25:01AM -0500, Brian Rak wrote: Generally, BIRD expects that the next hop address is reachable by interface address prefix. In your case you just add device route for 45.63.4.188/32 instead of adding peer address of 45.63.4.188 to veth0. It is true that for the kernel the difference does not matter in this regard and that the warning is not important in this case. What do you mean by 'device route'? I'm not sure how that differs from what I have, and not finding a lot of references to that phrase online. Hi Sorry for late answer, 'device route' i call a route for directly attached network prefix, with associated iface but without associated gateway IP. Perhaps there is a better / more established term for such routes. Sorry, my spam filter was delaying this. That's what I have I think? I have the '45.63.4.188 dev veth0 scope link' route, I'm not aware of any other way to add this (and it doesn't use a gateway IP). Are you talking about the '216.155.132.254 via 45.63.4.188 dev veth0 proto bird' route? If so, I have no way to change that. BIRD itself is adding that route based on information from BGP. AFAIK, there is no way to specify the next hop is an interface via BGP.
Re: KRT: Received route with strange next-hop
On Thu, Nov 19, 2015 at 08:25:01AM -0500, Brian Rak wrote: > >Generally, BIRD expects that the next hop address is reachable by > >interface address prefix. In your case you just add device route for > >45.63.4.188/32 instead of adding peer address of 45.63.4.188 to veth0. It > >is true that for the kernel the difference does not matter in this > >regard and that the warning is not important in this case. > > What do you mean by 'device route'? I'm not sure how that differs from what > I have, and not finding a lot of references to that phrase online. Hi Sorry for late answer, 'device route' i call a route for directly attached network prefix, with associated iface but without associated gateway IP. Perhaps there is a better / more established term for such routes. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santi...@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." signature.asc Description: Digital signature
Re: KRT: Received route with strange next-hop
On 11/19/2015 2:52 AM, Ondrej Zajicek wrote: On Wed, Nov 18, 2015 at 01:01:44PM -0500, Brian Rak wrote: I'm trying to figure out why BIRD is throwing this error every time it scans the kernel routing table: KRT: Received route 216.155.132.254/32 with strange next-hop 45.63.4.188 Netlink: File exists I have two routes relevant to this one: # ip route | grep 45.63.4.188 45.63.4.188 dev veth0 scope link 216.155.132.254 via 45.63.4.188 dev veth0 proto bird The 45.63.4.188 route was added by me (manually), the 216.155.132.254 was added via BIRD (BIRD learned it via BGP). Hi Generally, BIRD expects that the next hop address is reachable by interface address prefix. In your case you just add device route for 45.63.4.188/32 instead of adding peer address of 45.63.4.188 to veth0. It is true that for the kernel the difference does not matter in this regard and that the warning is not important in this case. What do you mean by 'device route'? I'm not sure how that differs from what I have, and not finding a lot of references to that phrase online.
Re: KRT: Received route with strange next-hop
On Wed, Nov 18, 2015 at 01:01:44PM -0500, Brian Rak wrote: > I'm trying to figure out why BIRD is throwing this error every time it scans > the kernel routing table: > > KRT: Received route 216.155.132.254/32 with strange next-hop > 45.63.4.188 > Netlink: File exists > > I have two routes relevant to this one: > > # ip route | grep 45.63.4.188 > 45.63.4.188 dev veth0 scope link > 216.155.132.254 via 45.63.4.188 dev veth0 proto bird > > The 45.63.4.188 route was added by me (manually), the 216.155.132.254 was > added via BIRD (BIRD learned it via BGP). Hi Generally, BIRD expects that the next hop address is reachable by interface address prefix. In your case you just add device route for 45.63.4.188/32 instead of adding peer address of 45.63.4.188 to veth0. It is true that for the kernel the difference does not matter in this regard and that the warning is not important in this case. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santi...@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." signature.asc Description: Digital signature
KRT: Received route with strange next-hop
I'm trying to figure out why BIRD is throwing this error every time it scans the kernel routing table: KRT: Received route 216.155.132.254/32 with strange next-hop 45.63.4.188 Netlink: File exists I have two routes relevant to this one: # ip route | grep 45.63.4.188 45.63.4.188 dev veth0 scope link 216.155.132.254 via 45.63.4.188 dev veth0 proto bird The 45.63.4.188 route was added by me (manually), the 216.155.132.254 was added via BIRD (BIRD learned it via BGP). So, to me this looks like bird adding the route to the kernel, then getting confused why the route exists. Aside from this warning, everything appears to be working fine. Linux routes the traffic properly, BIRD readvertises this route properly. Any thoughts here? I think I can probably suppress this warning by removing the 'ng->scope == SCOPE_HOST' check from netlink.c, but I'm not entirely sure why that's there to begin with.
