[c-nsp] BGP maximum-prefix on ASR9000s

Mark Tinka mark.tinka at seacom.mu
Mon Jan 27 02:14:03 EST 2020

On 27/Jan/20 08:05, Hank Nussbacher wrote:

> As many of us run full routing tables on our ASR9000s, we have just
> found popping up in our logs:
> gp[1058]: %ROUTING-BGP-5-MAXPFX : No. of IPv4 Unicast prefixes
> received from xxx.xxx.220.91 has reached 786433, max 1048576
> Reference:
> https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k_r5-3/routing/configuration/guide/b_routing_cg53xasr9k/b_routing_cg53xasr9k_chapter_010.html
> The undefined default for maximum-prefix on ASR9000s (IOS-XR) is 1048576.
> Recommendation: increase maximum-prefix to 1500000

Known issue since IOS XR launched back in the day.

For as far back as I can remember (probably 2010 or earlier), we always
had the below line as standard configuration in all our IOS XR platforms
for BGP sessions that did not require a prefix limit:

       maximum-prefix 4294967295 75

Doesn't affect only the ASR9000, but all IOS XR platforms.


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