Intradomain Overlays: Architecture and Applications

We introduce an architecture for ``Intradomain Overlays'', where a subset of routers within a domain is augmented with a dedicated
host. These strategically placed hosts form an overlay network, and
we describe a number of applications for such
overlays. These applications include efficient network
monitoring, policy- and load-based packet re-routing, and network
resource accounting.

In this paper, we elaborate on the network monitoring application
and describe a distributed protocol for monitoring routers within an
AS which has been augmented with a few overlay nodes. The routers
and other infrastructure are unaware of the overlay nodes, and the
monitoring of individual elements is conducted using plain SNMP. We
describe techniques for efficiently synthesizing and transporting
the monitored SNMP data, and present results using trace data
collected from an AS with 400+ routers. Our results show that the
overlay-based monitoring reduces overheads by 2--4 orders of
magnitude, and thus enables much finer grained monitoring and
traffic engineering than is otherwise possible.
(UMIACS-TR-2003-70)