Traffic routing: Network operators vs. user's perspective
1. Algorithm overview
The objective of this project is to find optimal control variables
allocating traffic to various links connecting source
S
with destination
D.
We will consider two cases. In the first one the goal is to find an
optimal solution for a network operator, in the second, an individual
user's interest is the top priority. In both cases the traffic routing
strategies are delay-related. We assume that an average delay
experienced by a packet is
d=1/(c-f)
, where
c
denotes capacity of a link
and
f
is intensity of traffic offered to this link. This formula results from
the theory of stochastic service systems.
2. Optimal strategy for a network operator
A packet can be routed from source
S
to destination
D
over one of two
different links, whose capacities are
c
1
and
c
2
. A network operator makes
a decision which link is selected for each incoming packet. What delay
related quality criterion
J
n
(a
1
,a
2
,c
1
,c
2
,A)
is the best from the network
operator's perspective? Find control variables
a
1
and
a
2
, resulting from
optimization of
J
n
, that allocate the total traffic
A
from
S
to
D
to both
links
f
1
=a
1
A
and
f
2
=a
2
A
. What is the corresponding optimal value of the
proposed quality criterion
J
n
?
Assume
A
=10,
c
1
=16,
c
2
=4.
Optimal strategy for an individual user
The topology of our simple network is slightly modified, i.e. source
S
is
connected with destination
D
with three different links (not two as in
Section 2) of capacities
c1
,
c2
and
c3
. Now every incoming packet (not
the network operator) chooses for itself a path from
S
to
D
. What delay-
related decision criterion
Jp
should be applied by each individual
packet? Is this criterion identical to
Jn
? Find the corresponding optimal

traffic control variables
a1
,
a2 , a3
and the numerical value of
Jp
.
Assume
A
=20,
c1
=16,
c2
=4,
c3
=6.