unstable BGP sessions after debian 10 -> 11 upgrade

[Alexander Shevchenko]

Hi.
We faced similar issues during memory pressure. Some app leaked and caused
intense swapping. You could check sar -B/sar -W if you have sysstat
installed.
WBR,
Alexander Shevchenko


вс, 24 окт. 2021 г., 17:26 Christoph <cm at appliedprivacy.net>:

> Hello,
>
> we upgraded our debian BGP routers from debian buster to bullseye.
>
> On debian 10 they used the repo https://bird.network.cz/debian/
> now they use the bird2 package directly from the official debian repos,
> both repos contain BIRD version 2.0.7.
>
>
> After upgrading and rebooting we noticed that iBGP sessions are
> constantly dying every few minutes.
>
>
> The logs also show multiple of these log entries:
>
> <WARN> Kernel dropped some netlink messages, will resync on next scan.
> <WARN> Event ... took 31415 ms
> <WARN> I/O loop cycle took 31529 ms for 9 events
> <WARN> Netlink: File exists
>
>
> Especially the warning "Kernel dropped some netlink messages" was not
> new but we previously solved them with these sysctl.conf settings:
>
>
> # solves the "Kernel dropped some netlink messages, will resync on next
> scan." BIRD Warnings
> # https://bird.network.cz/pipermail/bird-users/2017-September/011542.html
> # (we did not change the wmem_default since this is apparently not needed)
> net.core.rmem_max=4194304
> net.core.rmem_default=4194304
> net.core.wmem_max=4194304
>
>
> The most obvious change is the linux kernel version:
>   4.19.208 (buster)
>   5.10.70 (bullseye)
>
> To avoid constantly dying iBGP sessions we increased the keepalive and
> hold timers.
> Are you observing similar issues on your debian 11 systems?
> Does the newer kernel need higher rmem values?
>
> best regards,
> Christoph
>
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