Setting sensible max-prefix limits
Jared Mauch
jared at puck.nether.net
Wed Aug 18 13:53:57 UTC 2021
> On Aug 18, 2021, at 9:38 AM, John Kristoff <jtk at dataplane.org> wrote:
>
> Maybe because there isn't a simple, universal approach to setting it.
> Probably like a lot of people, historically I'd set it to
> some % over the current stable count and then manually adjust when the
> limits were about to be breached, or often was the case when they were
> and I wasn't ready for it. Not ideal.
>
> I've never felt the automation of this setting however was worth the
> effort. Of course I am not usually responsible for hundreds of routers
> and thousands of peering sessions.
We did a variant of this at NTT, with certain baseline settings. Sometimes networks would advertise more routes because they onboarded a large customer and it would cause manual updates to be necessary.
Polling daily and snapshotting these values is important to understand what is changing. The reason I just posted a message about Akamai max-prefix is we have been giving some general guidance that is out of line/norm compared to what perhaps what we want. This won’t cause a service outage per-se but will cause suboptimal routing as we continue to make improvements and upgrades to our network.
- Jared
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