[172282] in North American Network Operators' Group
Re: Getting pretty close to default IPv4 route maximum for 6500/7600
daemon@ATHENA.MIT.EDU (joel jaeggli)
Tue Jun 10 14:12:04 2014
X-Original-To: nanog@nanog.org
Date: Tue, 10 Jun 2014 11:10:53 -0700
From: joel jaeggli <joelja@bogus.com>
To: Blake Hudson <blake@ispn.net>, nanog@nanog.org
In-Reply-To: <539742E4.70108@ispn.net>
Errors-To: nanog-bounces@nanog.org
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On 6/10/14, 10:39 AM, Blake Hudson wrote:
>=20
> =C5=81ukasz Bromirski wrote the following on 6/10/2014 12:15 PM:
>> Hi Blake,
>>
>> On 10 Jun 2014, at 19:04, Blake Hudson <blake@ispn.net> wrote:
>>
>>> In this case, does the 512k limit of the 6500/7600 refer to the RIB
>>> or the FIB? And does it even matter since the BGP prefix table can
>>> automatically be reduced to ~300k routes?
>> Te 512k limit refers to FIB in the B/C (base) versions of 6500/7600
>> Supervisors and DFCs (for line cards). BXL/CXL versions have FIB for
>> 1M IPv4 prefixes.
>>
>> You can find more information here:
>>
>> http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-serie=
s-switches/117712-problemsolution-cat6500-00.html
>>
>>
>> And yes, you=E2=80=99re right - no matter how many neighbors you have,=
the FIB
>> will only contain best paths, so it will be closer to 500k entries in
>> total rather than N times number of neighbours.
>>
>=20
> Please correct me if I'm wrong, but if the BGP table contains ~500k
> prefixes, which are then summarized into ~300k routes (RIB),
Unlikely, just because prefixes could be cidr aggregated doesn't mean
they are. the more specifics exist for a reason, in the case of
deaggrates with no covering anouncement, well not much you're doing with
those.
your rib should be the sum of all received routes that you did not filter=
=2E
> and the FIB
> contains only the "best path" entries from the RIB, wouldn't the FIB be=
> at or below 300k?
a live example of rib size from a router with two transit providers.
bird> show route count
979842 of 979842 routes for 490932 networks
a live example of rib size from a router with one ibgp peer with addpath
and three upstream transit providers
bird> show route count
1471242 of 1471242 routes for 491977 networks
>=20
> --Blake
>=20
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