Please see the new BRITE release
at http://www.cs.bu.edu/brite
BRITE: Boston university
Representative Internet Topology gEnerator
A Flexible Generator
of Internet Topologies
Alberto Medina
Ibrahim Matta
John Byers
amedina@cs.bu.edu
matta@cs.bu.edu
byers@cs.bu.edu
QoS Networking
Laboratory
Computer Science Department
Boston University
BRITE is a parametrized topology generation tool, which can be used
to flexibly control various parameters (such as connectivity and growth
models) and study various properties of generated topologies (such power
laws, average path length, etc).
Overview
BRITE is a parametrized topology generator that can be used to
study the relevance of possible causes for power laws and other metrics
recently observed in Internet topologies. Different combinations of possible
causes can be tested. In this version, we consider four possible causes:
preferential connectivity, incremental growth, node placement, and connection
locality. For each combination, the generated topologies can be analyzed
in terms of power laws and other metrics observed in real networks. The
following table lists the various parameters of BRITE. We describe
each parameter next.
Table: Parameters of BRITE
Parameter 
Meaning 
Values 
HS 
Size of one side of the plane 
Integer > 1 
LS 
Size of one side of a highlevel square 
Integer >= 1 
NP 
Node Placement 
0: Random, 1: HeavyTailed 
m 
Number of links added per new node 
Integer >= 1

PC 
Preferential Connectivity 
0: NONE, 1: ONLY, 2:
BOTH 
IG 
Incremental Growth 
0: INACTIVE, 1: ACTIVE 
The Plane:
The nodes of the generated topology are distributed in a plane divided
into HS x HS squares. Each one of these highlevel squares is
further subdivided into smaller LS x LS lowlevel squares.
Each lowlevel square can be assigned at most one node.
Node Assignment:
A Random placement of nodes in the plane is achieved by simply
selecting a lowlevel square randomly and dropping a node there while avoiding
collisions. To achieve a HeavyTailed distribution of nodes, for
each one of the highlevel squares, the generator picks a number of nodes
to be assigned to that square according to a bounded Pareto distribution.
A node is then placed randomly in one of the LS x LS lowlevel
squares while avoiding collisions.
Number of Links for a New Node:
The parameter m controls the number of neighbor nodes to which
a new node connects when it joins the network (or in other words, the number
of new links to be added to the topology). The greater the value of m,
the denser the generated topology. We refer to the set of nodes from which
a neighbor is selected for a new node as the candidate neighbor set.
Incremental Growth:
This parameter controls incremental growth and can take one of two values:

INACTIVE places all nodes at once in the plane before adding any
link. In this case, a new node considers all other nodes as candidate
neighbors when joining the network.

ACTIVE places nodes in the plane gradually one at a time as they
join the network. In this case, a new node considers as candidate neighbors
only those nodes that have already joined the network (i.e. nodes that
are already connected to some other node(s)).
Initially, before operating in either INACTIVE or ACTIVE
mode, the generator generates a small randomly connected backbone of m_{0}
nodes. The remaining nodes are then connected.
Preferential Connectivity:
This parameter controls the activation or deactivation of preferential
connectivity. There are three possible values for this parameter:

NONE indicates that preferential connectivity is turned off. In
this case, a new node connects to a candidate neighbor node using Waxman's
probability function. This process is repeated to connect the new node
to m nodes.

ONLY means that preferential connectivity is turned on. In this
case, from the set of candidate neighbor nodes, a new node joining the
network selects with high probability a node with a high outdegree. This
process is repeated to connect the new node to m nodes.

BOTH combines preferential connectivity and connection locality.
In this case, for a new node, the probability of connecting to a candidate
neighbor node is a function of bothWaxman's probability and outdegree.
This process is repeated to connect the new node to m nodes.
Papers
Alberto Medina, Ibrahim Matta, and John Byers. On
the Origin of Power Laws in Internet Topologies. ACM Computer Communication
Review, 30(2), April 2000. Also, BUCSTR20000004, January 21, 2000.
Alberto Medina, Ibrahim Matta, and John Byers. BRITE:
A Flexible Generator of Internet Topologies. BUCSTR2000005.
Software
Please see the new BRITE release
at http://www.cs.bu.edu/brite
Download BRITE version 1.0. Please read copyright
notice.
We apologize BRITE is not available for downloading at this time as
we prepare the new version.
Please send us email and we will notify you once the new version is
released (expected end of March 2001).
Please send comments and suggestions to Alberto
Medina, Ibrahim Matta, John Byers.
Created on 01/21/2000
Last updated 03/23/2001