contributed articles
Doi: 10.1145/1538788.1538809
Network software adapts to user needs and
load variations and failures to provide reliable
communications in largely unknown networks.
BY eRoL GeLenBe
steps Toward
self-Aware
networks
tHe inForMation needed
to route packets in large
networks and in networks in which nodes join and
leave the network frequently or move in and out
of wireless range of each other can change more
frequently than the rate routing information is
updated throughout the network. In such a system
it becomes necessary to allow individual nodes to
proactively discover the presence of other nodes,
links, and paths (as needed and on demand), leading
to the design of self-aware networks. here, I focus on
experimental and theoretical research concerning the
technical steps leading to these networks.
The Internet Protocol offers an orderly update of
its status based on the shortest-path algorithm, 18
Distance Vector, 22 and Link State23 techniques so
routing algorithms operate seamlessly, despite
changes in network topology and conditions.
however, as computer networks become extremely
large, the information available concerning the
network state becomes uncertain. Link state changes
are more frequent in larger networks,
increasing the overhead and delay due
to updates throughout the network.
Consequently, information about the
network state, including connectivity,
condition of nodes, traffic conditions,
and quality of service (QoS), propagates more slowly than rate changes
occur. The need to convey time-sen-sitive information (such as voice and
media) also motivates investigation of
routing techniques based on user requirements and the network’s instantaneous state. Thus it is preferable that
nodes discover the network state autonomously, without having to rely on
an overall scheme that updates routing
tables systematically throughout the
network. Information updates can be
initiated by the nodes that need this
information at the time it is needed,
rather than throughout the network
and when changes occur.
We use the term “self-aware network,” or SAN, 11 for a system consisting
of nodes that can join and leave the network autonomously and discover paths
when the need to communicate arises.
The nodes in a SAN should sense the
status of other nodes, links, and paths,
including traffic level and congestion,
so as to update their own relevant information about the paths they need to
use, based on criteria specific to their
own needs. Each connection may then
use paths that optimize the connection’s own QoS criteria, rather than a
common criterion (such as the shortest
path) for all connections. These needs
might include user QoS requirements,
or performance, reliability, security,
defense against attacks, 9, 24 and power
utilization. 12 A SAN can be a wired, wireless, or a peer-to-peer system. A wireless
ad hoc network is a practical example
of a SAN that responds to time-varying
conditions related to the mobility of
nodes and changes in the conditions of
wireless links (such as noise and physical obstructions). Networks that must
operate autonomously and remotely
(such as sensor networks) also benefit
from self-aware capabilities.
Research on effective SAN architec-
DRAWING B Y EMMA McNALLY
