and Computer Networks
Visualization of QoS-Based Routing Algorithms via Java
The routing decisions in current Internet routing protocols
are made without awareness of network resource availability and
Quality-of-Service (QoS) requirements.
This results in routes that cannot adequately support real-time
applications involving audio and video traffic,
although alternate routes with sufficient resources
may actually be available. In this regard, QoS-based routing algorithms
are desirable. The goals of QoS-based routing algorithms
should be to compute routes that satisfy the QoS requirements
as well as to improve the total network throughput
(or in other words to optimize network resource usage).
In the last few years, a few QoS-based routing algorithms have been proposed.
We have created a Java-Applet to visualize some of these proposed
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- The shortest-widest path algorithm: compute a path
with the maximum bandwidth among all feasible paths. If there are
several such paths, the one with the smallest propagation delay is
chosen (see: Z. Wang and J. Crowcroft, Quality-of-Service Routing
for Supporting Multimedia Applications, IEEE Journal on
Selected Areas in Communications, 14(7), pp.1228-1234, September 1996).
- The widest-shortest path algorithm: compute
a path with the minimum hop count among all feasible paths. If
there are several such paths, the one with the maximum available
bandwidth is selected (see: R. Guerin, S. Kamat, A. Orda,
T. Przygienda and D. Williams,
QoS Routing Mechanisms and OSPF Extensions,
Internet Draft, draft-guerin-qos-routing-ospf-00.txt,
March 25, 1997).
- The bandwidth-constrained least hop-count
algorithm: compute the least hop-count path with
bandwidth constraint (see: Z. Zhang, C. Sanchez, B. Salkewley and E. Crawley,
Quality of Service Extension to OSPF,
Internet Draft, draft-zhang-qos-ospf-01.txt, September, 1997).
- The bandwidth-constrained least-cost path
algorithm: compute a least-cost path with bandwidth
constraint where the path cost is the sum of the costs of all links
along the path and the cost of a link is defined to be the inverse
value of the available bandwidth of the link (see:
Q. Ma and P. Steenkiste, On Path Selection for Traffic with Bandwidth
Guarantees, in IEEE International Conference on Network Protocols,
Atlanta, Georgia, October 1997).
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