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?
Sean.