Multihomed ASes and traffic engineering


Q: Are extra routes introduced for traffic engineering?
A: Yes, but only a minority 
Multihomed ASes originating on one link
Nov.01, 2001, 26 tables; multiorigin prefixes are excluded
22.2% of all prefixes
15.8% of all top prefixes
28.6% of all more specifics
more specifics are announced on one link more frequently
6-12% more specifics may be traffic engineered splinter blocks
Majority of semiglobal prefixes are announced on all available connections
Largest groups:
On 1 connection  for singly homed AS,    22.6%
On 2 connections for doubly homed AS, 15.8%
On 3 connections for triply homed AS,     31.1%
On 2 connections for triply homed AS,       7.3%
(triply homed = indegree >= 3)