Getting pretty close to default IPv4 route maximum for 6500/7600 routers.

Łukasz Bromirski lukasz at
Tue Jun 10 18:07:35 UTC 2014

On 10 Jun 2014, at 19:39, Blake Hudson <blake at> wrote:

>> And yes, you’re 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.
> Please correct me if I'm wrong, but if the BGP table contains ~500k prefixes, which are then summarized into ~300k routes (RIB), and the FIB contains only the "best path" entries from the RIB, wouldn't the FIB be at or below 300k?

Because you need to do your own summarization or ask your upstreams
to do it for you. Until then, most of transit accepts loosely
prefixes in exact length but also longer (i.e. /24 but also both /25s).

You’ll see more and more deaggregation with the rise of smaller
entities fighting for chance to do some traffic engineering, so be
prepared to constant rise of prefixes overall.

"There's no sense in being precise when |               Łukasz Bromirski
 you don't know what you're talking     |      jid:lbromirski at
 about."               John von Neumann |

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