- Bird-users - Mailing Lists

[PATCH] MRT: Add overwrite switch (default: off)
by Wydrych, Piotr 29 Mar '21

29 Mar '21

Hello, I was working recently with MRT dumps. I wrote a small patch that allows bird to overwrite the dump file. Piotr -- Piotr 'GhosT' Wydrych ........ Engineering Manager, SDN ......... Akamai ........................................................................ A: Because it messes up the order in which people normally read text. .. Q: Why is top-posting such a bad thing? ................................

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BGP connect retry time
by dev＠kou.li 29 Mar '21

29 Mar '21

Hello, I am running bird's BGP on a slower link with accounted data. I would like to lower connection attempt frequency when the peer is down. I found only two parameters mentioning connection delays: 'connect delay time' and 'connect retry time'. From documentation, I understood to change the 'connect retry time' to slow down failed connection attempts, but the bird seems to use 'connect delay time' repeatedly if the connection fails (test: bird 1.6.6, peer's firewall drops all BGP packets). So, what is the 'connect retry time' used for? Also, if I increase the 'connect delay time' to lower BGP data throughput in case the peer is offline, I introduce also unwanted delay when everything works and only the BGP protocol is restarted... I understand bird 1.6.6 is rather old to ask for any help here. However, it is such a basic functionality I do not believe it to have changed recently. Also, I found no mention of these parameters in the NEWS file. Milan

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BMP protocol support - request for review and merge
by Maslanka, Pawel 29 Mar '21

29 Mar '21

Hi BIRD devs, Akamai team have implemented basic subset of BMP (BGP Monitoring Protocol) specification for BIRD project (according to RFC 7854). We are happy to share our work with BIRD community and would ask for review patch. Please feel free for modify this patch to meet BIRD source code requirements for merge it to BIRD mainline code since we post this patch under to GPLv2+ license (please look at |proto/bmp/LICENSE|). It worth to note that there are few minor unimplemented things from RFC 7854, but the most important are: - not implemented Route Mirroring message - not implemented Stats Report message This implementation has been tested with open source BMP collectors like OpenBMP and pmacct. This patch is compatible with BIRD v2.0.7 release. Additionally I would like to take the opportunity to thank Ondrej Zajicek for hints to contribution of this patch according to BIRD project specification. Thanks, Pawel Maslanka Software Engineer at Akamai Technologies, Inc.

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Incorrect setting of BGP Path Attribute Extended Length flag breaks MRT output
by Simon Marsh 28 Mar '21

28 Mar '21

Hi, i run bird as a route collector in DN42 and so get a variety of different BGP daemons peering with and passing routes to the collector. We recently ran in to an issue where MRT dumps from bird were not readable by any of the common MRT parsers and, on investigation, found a bug in how bird handles the BGP Path Attribute Extended Length flag. The issue occurred because peers using the FRR daemon set the Extended Length flag on the AS PATH attribute by default, regardless of the actual data length. When bird re-encodes the AS Path (for example as part of the MRT dump) it correctly re-calculates whether to use an 8 bit or 16 bit length field for the attribute, but simply copies the flags and does not reset the Extended Length flag in the 8 bit case. This results in an AS PATH attribute being output that has the Extended Length flag set but with the actual length field being only 8 bits. Of course, any parsers trying read this get very confused. A simple fix is to ensure the Extended Length flag is cleared when encoding the 3 byte attribute header: diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c index 6752cb7f..5c7b4fdd 100644 --- a/proto/bgp/attrs.c +++ b/proto/bgp/attrs.c @@ -118,7 +118,7 @@ bgp_set_attr(ea_list **attrs, struct linpool *pool, uint code, uint flags, uintp static inline int bgp_put_attr_hdr3(byte *buf, uint code, uint flags, uint len) { - *buf++ = flags; + *buf++ = flags & ~BAF_EXT_LEN; *buf++ = code; *buf++ = len; return 3; Cheers Simon

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A ifname counterpart for the "from" attribute
by Marcel Krüger 26 Mar '21

26 Mar '21

Hi, is there any way to identify in a filter the interface the route was learned from? So basically an attribute which relates to "from" like ifname and ifindex relate to "gw"? This would be particularly useful when "from" is a link lcal address and therefore might not be enough to identify the source. If this doesn't exists, is there another way to enforce that the "gw" is always on the same interface the route was learned on whithout having to use interface specific configuration (e.g. customized filters or special igp tables in BGP). (I am mostly interested in BGP, but I guess that most solutions would apply more gnerally) If not, would a patch implementing such an route attribute have a chance of being merged? Best regards, Marcel

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Re: Foreign upstream gateway for remote maintenance
by Bernd Naumann 26 Mar '21

26 Mar '21

Good morning Nils, On 26.03.21 08:47, Nils van Lück wrote: > Hello! > > I am using the latest Bird version from the git repo under Debian. I > have one dedicated NIC for the LAN, one dedicated NIC for BGP sessions > and one NIC with an IP from a foreign ASN for remote maintenance. How > can I make the routed traffic go through Bird but still connect to a > foreign gateway via SSH through another NIC? Also the operating system > updates (apt-get) should run over the third NIC and not over the bird > routes. > > NIC 1: LAN / OSPF > NIC 2: BGP / Peering / routed traffic over bird > NIC 3: foreign gateway fo remote maintenance of the routers debian instance > > Regards, > > Nils van Lück I'm not 100% sure... but I see two two ways, but both with limitations. Maybe someone can comment on these approaches, or provide an alternative better idea. 1) Use different routing tables. This way you can ensure that traffic which hits nic3 goes out of nic3 then. See https://tldp.org/HOWTO/pdf/Adv-Routing-HOWTO.pdf Section 4.2.1. Split access for the general setup But I do not know how you would /tell/ `apt` to use that table or a specific source address (so its traffic would then go out of nic3). However, bird is able to use different tables. 2) Using namespaces Start `sshd` in a separate namespace, and call `apt` also only from within this namespace. This namespace would only have `lo` and `nic3`. See for instance https://lwn.net/Articles/580893/ While using a namespace for sshd and apt, you would not need to configure bird / tell bird about it. Hope this helps somehow. Best, Bernd

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Foreign upstream gateway for remote maintenance
by Nils van Lück 26 Mar '21

26 Mar '21

Hello! I am using the latest Bird version from the git repo under Debian. I have one dedicated NIC for the LAN, one dedicated NIC for BGP sessions and one NIC with an IP from a foreign ASN for remote maintenance. How can I make the routed traffic go through Bird but still connect to a foreign gateway via SSH through another NIC? Also the operating system updates (apt-get) should run over the third NIC and not over the bird routes. NIC 1: LAN / OSPF NIC 2: BGP / Peering / routed traffic over bird NIC 3: foreign gateway fo remote maintenance of the routers debian instance Regards, Nils van Lück

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recursive next-hop from filter
by Manon Goo 25 Mar '21

25 Mar '21

Hallo, Is it possible to set or modify a recursive next-hop and the loop-up table for a route from a filter or function ? Kind regards, Manon

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CentOS to Debian migration issue
by Pavlo Astakhov 22 Mar '21

22 Mar '21

Hello, all I got a weird question. We recently migrated two our routers from CentOS 7 to Debian 10, installed Bird, placed config files back - and since then we are observing BGP flaps. Moreover, flaps are observed on IPv6 peers only: Name Proto Table State Since Info device1 Device --- up 2021-03-18 15:42:27 direct1 Direct --- up 2021-03-18 15:42:27 kernel1 Kernel master4 up 2021-03-18 15:42:27 kernel2 Kernel master6 up 2021-03-18 15:42:27 static1 Static master4 up 2021-03-18 15:42:27 static2 Static master6 up 2021-03-18 15:42:27 UPLINK BGP --- up 2021-03-18 15:42:31 Established UPLINKv6 BGP --- up 2021-03-22 21:11:12 Established AR1 BGP --- up 2021-03-18 15:42:31 Established AR1v6 BGP --- up 2021-03-19 23:42:55 Established AR2 BGP --- up 2021-03-18 15:42:28 Established AR2v6 BGP --- up 2021-03-20 15:37:38 Established BR2 BGP --- up 2021-03-18 15:42:28 Established BR2v6 BGP --- up 2021-03-21 11:03:33 Established ospf4 OSPF master4 up 2021-03-18 15:42:27 Running ospf6 OSPF master6 up 2021-03-18 15:42:27 Running Flaps are unregular, currently we saw no coincedences with anything. The network is stable, our and peers configs were not changed, Bird version too (2.0.7 on both CentOS and Debian). The only message about this in logs is hold-related: 2021-03-22 21:01:10 <WARN> Kernel dropped some netlink messages, will resync on next scan. 2021-03-22 21:04:33 <WARN> Kernel dropped some netlink messages, will resync on next scan. 2021-03-22 21:06:10 <WARN> Kernel dropped some netlink messages, will resync on next scan. 2021-03-22 21:10:12 <RMT> UPLINKv6: Error: Hold timer expired 2021-03-22 21:10:13 <WARN> Kernel dropped some netlink messages, will resync on next scan. 2021-03-22 21:10:15 <WARN> Kernel dropped some netlink messages, will resync on next scan. 2021-03-22 21:10:16 <WARN> Kernel dropped some netlink messages, will resync on next scan. 2021-03-22 21:10:16 <WARN> Kernel dropped some netlink messages, will resync on next scan. Could you please suggest some way to go except of returning to CentOS? Thank you in advance. _--

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Bird Centos 8 Replacement recommendations request
by W Templeton 18 Mar '21

18 Mar '21

Hiya Guys, Apologies if not the right approach/ protocol, do let me know what is if required. Asks: Pls provide.... 1.Details of what OS and version supported by Bird 2.Any OS preferences or best choice of useful. 3.Any views thoughts on below useful Our draft shortlist is Debian 10.7 Buster Ubuntu 20.04 LTS Leap 15.3 Note did not consider any of the BSD variants, which is an oversight so should be included Background We were close to productionising a network stack around number of sites using Bird2.07 as the Routing daemon on Centos 8. In light of the Centos changes are now looking for a replacement and would like to confirm what is supported by Bird as this is a mandatory prerequisite. Happy for call etc if easier. Thks in advance FYI -I did look at wiki FAQs and was semi generic and possibly not up to date Thks Will +44(0)7967 464459

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