Characterisation of "Local" Networks
Kapil Bajaj,
M.Tech,
03,
52 pp.
Department of
Computer Science and Engineering
Indian Institute of Technology Bombay,
Powai, Mumbai 400 076.
Supervisor(s):
D. Manjunath, G.Sivakumar
Characterisation of ``local Internet'' and ``local
network'' as a whole involves analysis of traffic patterns, construction
of topology for both Internet and Intranet, measurement and estimation
of parameters which characterise links and paths in the topology. This
characterisation is important for pathological analysis of networks. Because
of hierarchical management of Intranet in a typical organisation, there
is a need for top level managers to be aware of the link layer topology at
lower levels for identifying and locating failures. But, most of the tools
available in the public domain discover Intranet topology up to the network
layer level. In this thesis, we propose algorithms for discovering detailed
topology of Intranet up to the link layer using SNMP. The network layer topology
discovery finds the devices in the subnet. The link layer discovery is to
detail the connection among the link layer devices and the active spanning
tree. An important characteristic of link layer discovery algorithm is that
it does not require the forwarding database to be complete and it can discover
existence of non-SNMP device between two SNMP enabled link layer devices.
There has been extensive studies to characterise paths in Internet using
round trip measurements. Since, routing in the Internet is asymmetric, there
is a need for {\em one way} end-to-end characterisation. In this thesis we
propose algorithm to obtain {\em one way} bandwidth characteristics of Internet
paths in the forward and reverse direction from a measuring node to target
Internet host. A {\em non-cooperative} framework is assumed where the target
host is not aware of the measurement process. Bandwidth measurements use
the well known packet-train method. The thesis also describes \textsf{Arrowsmith},
a network analysis tool developed by us which analyse traffic, displays traffic
pattern, determine landmark sites and generate topology for the landmark
sites obtained. {\tt traceroute} is used for construction of topology. \textsf{Arrowsmith}
incorporates the Intranet topology discovery and end-to-end measurements.
It also make use of {\tt ping} for round-trip path parameters.