[c-nsp] An observation: 512k default max-prefix in IOS-XR

[Will Hargrave]

Configuring some ASR9ks, and I noticed:

http://www.cisco.com/en/US/docs/routers/asr9000/software/asr9k_r4.2/routing/configuration/guide/b_routing_cg42asr9k_chapter_00.html#con_1088375

""" To prevent a peer from flooding BGP with advertisements, a limit is placed on the number of prefixes that are accepted from a peer for each supported address family. The default limits can be overridden through configuration of the maximum-prefix limit command for the peer for the appropriate address family. The following default limits are used if the user does not configure the maximum number of prefixes for the address family:
	• 512K (524,288) prefixes for IPv4 unicast """

524288 is also default setting for 6500/7600 PFC3BXL 'mls cef maximum routes'.


As usual when wondering about DFZ growth, one reaches for Geoff Huston's excellent presentations:
https://ripe64.ripe.net/presentations/25-2012-04-16-bgp2011.pdf

So around 2015 or perhaps before, careless operators of both IOS-XR and 7600 boxes may have a shock. :-)


You may wish to manually set max-prefix to something higher on your transit provider sessions. And, look at those -3BXL boxes too.

-- 
Will