Setting sensible max-prefix limits

Jared Mauch jared at
Wed Aug 18 13:53:57 UTC 2021

> On Aug 18, 2021, at 9:38 AM, John Kristoff <jtk at> 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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