TIE Breaking: Tunable Interdomain Egress Selection    

    

Renata Teixeira	Timothy G. Griffin	Mauricio G. C. Resende	Jennifer Rexford
UC San Diego	University of Cambridge	AT&T Labs-Research	Princeton University
La Jolla, CA	Cambridge, UK	Florham Park, NJ	Princeton, NJ
teixeira@cs.ucsd.edu	Timothy.Griffin@cl.cam.ac.uk	mgcr@research.att.com	jrex@cs.princeton.edu

Abstract:

The separation of intradomain and interdomain routing has been a key feature of the Internet's routing architecture from the early days of the ARPAnet. However, the appropriate ``division of labor'' between the two protocols becomes unclear when an Autonomous System (AS) has interdomain routes to a destination prefix through multiple border routers--a situation that is extremely common today because neighboring domains often connect in several locations. We believe that the current mechanism of early-exit or hot-potato routing--where each router in an AS directs traffic to the ``closest'' border router based on the intradomain path costs--is convoluted, restrictive, and sometimes quite disruptive. In this paper, we propose a flexible mechanism for routers to select the egress point for each destination prefix, allowing network administrators to satisfy diverse goals, such as traffic engineering and robustness to equipment failures. We present two example optimization problems that use integer-programming and multicommodity-flow techniques, respectively, to tune our mechanism to satisfy network-wide objectives. Experiments with traffic, topology, and routing data from two backbone networks demonstrate that our solution is both simple (for the routers) and expressive (for the network administrators).