September 2021 - Bird-users

OSPF route in database not imported in table
by Joachim Desroches 16 Sep '21

16 Sep '21

Ave, I am observing behavior that I do not understand on two of our bird instances, maybe you guys can help me make sense of it. I'll start by giving you an overview of our setup, then I'll describe the problem and paste some configuration snippets. We have three pairs of routers connected over a meshed VPN, each pair being in a different physical location. These routers are connected to the wider internet, to the inter-location mesh VPN and to stub networks to whom they provide connectivity. We use BGP sessions at each site with our local upstream to obtain and export routes, and OSPF over the mesh VPN for internal routing. Everything is dual-stacked, but the issue I am observing is only over IPv4, so let us only consider IPv4. Calling the three locations A, B and C, I have the following problem: C exports a /30 prefix via OSPF (gathered by the automagic generation of stub networks). A and B correctly recieve it and display it in the `birdc show ospf state <ospf ipv4 name>` map, but while it is correctly imported into the master4 table in B, it does not appear in the master4 table in A. Both configurations are, as far as I can tell, identical for all relevant purposes. Versions of bird, operating system and kernel are the same. Relevant birdc output: ``` show ospf state ospf4: [...] router 0.0.2.1 distance 10 network [0.0.2.1-6] metric 10 stubnet xx.xxx.xxx.x/30 metric 10 ``` ``` show route table master4 protocol ospf4: Table master4: [...] ``` where the second output does not contain the required /30. Relevant configuration: ``` protocol ospf v3 ospf4 { description "backbone OSPF v4"; instance id 64; ipv4 { import all; export none; }; area 0 { interface "tun0"; interface "vlan10"; }; } ``` The main difference between A and B are the routes that they recieve over BGP from our upstreams: one of them contains a 0.0.0.0/0 default route (A) and the other does not, only the list of IPv4 routes. I am at loss as to why the route is not imported into the master table, so any advice or suggestions would be very welcome. Vale, -- Joachim Desroches

1 0

BGP "import table"
by Lutz Preßler 09 Sep '21

09 Sep '21

Hello, https://bird.network.cz/?get_doc&v=20&f=bird-6.html#bgp-import-table states import table switch A BGP import table contains all received routes from given BGP neighbor, before application of import filters. It is also called Adj-RIB-In in BGP terminology. BIRD BGP by default operates without import tables, in which case received routes are just processed by import filters, accepted ones are stored in the master table, and the rest is forgotten. Enabling import table allows to store unprocessed routes, which can be examined later by show route, and can be used to reconfigure import filters without full route refresh. Default: off. (and following "export table"). Haven't checked the filter reconfiguration/rpki_reload aspect of the feature or looked into that part of the code yet. But I cannot find a way with 2.0.8 to "examime by show route unprocessed routes". What do I miss? Regards, Lutz Preßler (SerNet GmbH)

2 3

Next bird release timeframe
by Etienne Champetier 08 Sep '21

08 Sep '21

Hello, Is there a rough estimate of when the next release of bird will be cut ? (I'm interested in the OSPF + /32 fixes) Thanks Etienne

1 0

default protocol preference values
by Kseniya Blashchuk 07 Sep '21

07 Sep '21

Hello! I could not find any information about default protocol preference values (administrative distance) for bird. Can anybody please help with it? Are there any default values for OSFP, BGP, static, etc.? Or is it better to configure each value explicitly?

3 3

When router becomes ABR, ospf is restarted
by Senthil Kumar Nagappan 06 Sep '21

06 Sep '21

Hi, While adding an area and if the router becomesABR, entire ospf protocol is restarted which deletes all the neighbors and adjacencies. can we not do this gracefully with the minimum disturbance toprotocol, like resending the router lsa with B bit enabled, redoing summary-lsasand route calculation? Thanks and Regards,Senthil

5 8

BFD and Juniper SRX inter-op issue
by Justin Cattle 02 Sep '21

02 Sep '21

Hi, I have encountered what seems to be a bug of sorts in the Juniper implementation of BFD in at least their SRX340. We have no issues with the QFX series, where BFD seems to work as expected with bird. I'm wondering if there is anything we can do to handle this issue on the bird side, or if anyone has any insight that may shed some light on the behaviour we are seeing. Here is the issue summary: - BFD timers are set quite conservatively - interval 4000 ms - multiplier 6 - A BFD session between a bird endpoint and a juniper endpoint is up and running at the start - all fine - If the you stop bird on the server, after the Detection time [ currently 24 secs ], the BFD messages from the Juniper show status as Down with the Diagnostic message Control Detection Time Expired. You can then start bird on the server again, and the two sides will agree session info and BFD status goes Up. - This is expected. - However, if you stop bird, but start it again before the Detection time [ currently 24 secs ], like for a service restart, the BFD messages from the Juniper never show as Down, and the two sides never agree on a BFD session and BFD remains Down on the server but Up on the Juniper. - Should a new session be established at this point ? - Once the Juniper gets stuck in the BFD status Up state, then you can stop the bird for a long time [ over an hour at least ] , and the Juniper never seems to notice [ the BFD packets still show state Up ]. - This seems to be a bug n the juniper end - why should it never go Down in this state ? - If the BFD session info is reset on the Juniper side, then the two sides will agree session info and BFD status goes Up. Does anyone have any thoughts ? Is there a packet bird can send, gratuitous or not, that can make the juniper end realise it MUST reinitialize ? Any config that can be tweaked to help ? Cheers, Just -- Notice: This email is confidential and may contain copyright material of members of the Ocado Group. Opinions and views expressed in this message may not necessarily reflect the opinions and views of the members of the Ocado Group. If you are not the intended recipient, please notify us immediately and delete all copies of this message. Please note that it is your responsibility to scan this message for viruses. References to the "Ocado Group" are to Ocado Group plc (registered in England and Wales with number 7098618) and its subsidiary undertakings (as that expression is defined in the Companies Act 2006) from time to time. The registered office of Ocado Group plc is Buildings One & Two, Trident Place, Mosquito Way, Hatfield, Hertfordshire, AL10 9UL.

3 4