[Babel-users] High CPU usage & instability with full IPv6 table

[Toke Høiland-Jørgensen]

"Steven Honson" <babel-users at steven.honson.au> writes:

> Thank you for such a prompt reply Toke!

You're welcome :)

> On Fri, 10 Jun 2022, at 11:34 PM, Toke Høiland-Jørgensen wrote:
>>> At the moment I am using Bird 2 to handle both BGP and Babel, and it
>>> barely breaks a sweat, but would like to use babeld for the Babel
>>> component so to be able to leverage some of the additional features
>>> that the Bird implementation lacks.
>>
>> Which feature(s) are you missing in Bird? :)
>
> The two that I'd like to use are IPv4 with IPv6 next-hop (RFC 9229),
> mainly to keep my network as IPv6 single stack as possible, with just
> IPv4 mainly on loopbacks, and delay based metrics
> (draft-jonglez-babel-rtt-extension-02), as in my case some Internet
> routing quirks mean that least-hops isn't always the lowest latency
> path between my hosts.
>
> Neither are critical, and bird is doing a wonderful job, so it isn't a
> big issue if I just keep forgoing these.

Both of these have actually been implemented in Bird, just not merged
yet... :)

v4-via-v6:
https://bird.network.cz/pipermail/bird-users/2022-April/016046.html

RTT extension:
https://github.com/tohojo/bird/tree/babel-rtt-01

Would be awesome if you could test one or both and provide feedback!

>>> Any clues what sort of limit I may have reached or how to mitigate
>>> this? Is the CPU being eaten up constantly monitoring and filtering
>>> route changes in my kernel routing table due to the constant churn of
>>> the global IPv6 table?
>>
>> Sounds like you could be hitting the same issue as described in this
>> thread?
>>
>> https://alioth-lists.debian.net/pipermail/babel-users/2022-February/003884.html
>
> That does indeed look like the same issue, thank you for the
> reference, I've been subscribed to this list for quite a while now and
> somehow missed that. That helps me understand what is going on a lot
> better.

Well, it's a somewhat obscure issue, certainly :)

-Toke