From: Ethan Katz-Bassett (ethan@cs.washington.edu)
Date: Sun Nov 14 2004 - 23:32:34 PST
In the paper, the authors present their Internet Indirection Infrastructure,
an overlay to provide rendezvous-based communication on the Internet. As we
have seen in class, the Internet protocols were designed for unicast
point-to-point communication between fixed endpoints. Because of this
design focus, the protocols are not ideal for dealing with other situations,
such as multicast. Solutions to problems such as multicast have required
some amount of jerry rigging, with researchers either arguing for changes to
the underlying protocols or giving schemes implemented in end hosts or by
overlays. Generally, these solutions do not attempt to be general purpose.
The Internet Indirection Infrastructure is a general overlay service (on top
of IP) that can be used to solve many of these problems. Basically,
receivers tell the service to send packets with specific IDs to its address,
and senders give the service ID and data packet pairs. The service then
sends (over IP) the data to the addresses of any hosts interested in that
ID. The system also allows for ID stacks and for partial matching of IDs.
They then describe how this simple system enables multicast, mobility of
hosts, and other services. For instance, the system does not need to
explicitly implement multicast trees; ID stacks can be used for this goal.
I found the explanation of service composition to be particularly
interesting; I had not thought about this problem before.
The authors did a great job of addressing most of the concerns I had while
reading the paper. I have numerous questions written in the margins, then
scribbled out as they were answered in later questions: how the random IDs
work, whether or how nodes pick nearby i3 servers, what happens when an i3
server goes down, etc. The sampling scheme to pick a nearby server seemed
somewhat clumsy, but, otherwise, I was impressed with how they cleanly
addressed so many issues. Latency stretch occurred, but was limited.
The Internet Indirection Infrastructure has a simple design that seems
capable of offering clean solutions to many Internet problems. I am curious
to see what other services it can enable and also what it is incapable of.
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