Tli asked:

| Exercise for the reader: If prefixes of length F and longer are filtered, | and a domain has a prefix of length N, how many prefixes can they propagate | into the backbone? How many before people start proxy aggregating them?

A/ (2 ** F) - 1. [assuming nobody imposes exact-match prefix filters]

B/ When we can easily do:

"router bgp N proxy-aggregate route-map Lazy-Types

I may be misunderstanding, but does this (proposed) config statement automaticly suppress (aggregate) any prefixes that are exactly the same as another prefix except in the length? For example given 128.8.0.0/16 128.8.0.0/24 128.8.1.0/24 the last two would not be propogated? That would be cool! Erik

! exceptions route-map Lazy-Types deny 10 match as-path 100

! the rule route-map Lazy-Types permit 20 match originated-prefix-count 16"

then the number 16 strikes me as a starting point, although I probably want to re-read Dennis's comments from a few years ago.

Do I pass?

Sean.