From: Rosalia Tungaraza (rltungar@u.washington.edu)
Date: Tue Nov 02 2004 - 23:33:30 PST
In this paper, the authors tried to find out the causes of unnecessarily
long Internet paths. In their investigations they nailed down the problem
to interactions (or routing mechanisms) within and between Internet
domains specifically intra-domain, peering points, and inter-domain
routing. Among these, the Inter-domain routing contributed the most to
path inflation. They do so due to the policies used by ISPs to facilitate
routing from one domain to the other. Peering policies are the second
largest contributor to path inflation. It is argued that in both
situations ISPs lack good techniques/tools to opt for shorter routing
paths.
The authors report that commercial concerns are not the cause of the high
path inflation resulting from inter-domain routing policies. This is very
surprising because I expected much of these path inflation problems to be
a result of decisions made by ISPs based on how much profit they can make
rather than the underlying network topology. For instance, whenever the
no-valley and prefer-customer policy is used, paths through customers
should have the highest inflation followed by paths through peers, while
paths through providers should have the least. I would also imagine that
the shortest AS-path to be rarely used unless it is the same as the
longest path through customers. The paper contradicts my expectations by
showing that such policies do not contribute to path inflation.
In general I think the paper was well written. One of the successes of
this paper is the fact that the authors managed to neatly define/isolate
the causes of Internet path inflation into six categories and used those
to analyze the problem.
A minor improvement to this paper could be achieved by giving more
information about the tool that the authors believe ISPs need to
facilitate better peering point and AS-path selection. Hence, future work
could be geared towards researching how to design and implement such a
tool and how ISPs could use it to provide shorter paths for their traffic
while optimizing their profits.
This archive was generated by hypermail 2.1.6 : Tue Nov 02 2004 - 23:33:32 PST