[195691] in North American Network Operators' Group
Re: Max Prefix Out, was Re: Verizon 701 Route leak?
daemon@ATHENA.MIT.EDU (Randy Bush)
Sat Sep 2 03:27:09 2017
X-Original-To: nanog@nanog.org
Date: Sat, 02 Sep 2017 16:27:03 +0900
From: Randy Bush <randy@psg.com>
To: Job Snijders <job@instituut.net>
In-Reply-To: <CACWOCC-QCiQndmBBt5mSvYz3URn+fjLkyvc0pB+oZ6UxEby6xw@mail.gmail.com>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
>>>>> i have 142 largish bgp customers, a large enough number that the
>>>>> number of prefixes i receive from them varies annoyingly. how do
>>>>> i reasonably automate setting of my outbound prefix limit?
>>>>
>>>> First, it seems you know the inbound so automating the outbound is
>>>> simple arithmetic.
>>>
>>> I would have said the same... i ought to know high-water marks for
>>> your inbound peer count(s), and can work out a +20% outbound...
>>
>> you just assumed that the transitive closure of everybody's cones
>> implement and propagate count. ain't gonna happen.
>
> I am not sure what the issue here is. If I can tell my peering partner
> a recommended maximum prefix value for them to set on their side,
> surely I can configure that same value on my side as the upper
> outbound limit.
which is why i do not tell peers a max count.
this stuff works for small isps, in the lab, ... but not at scale;
especially when you have isps as customers. i wish it did.
bgp at scale is rather dynamic. i suspect your $dayjob's irr filters
being exact help a bit.
randy
