The Cidr Report

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

  ! 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?