Recovering Guaranteed Performance Service Connections
                 from Single and Multiple Faults


                        Anindo Banerjea,
                        Colin J. Parris,
                               and
                        Domenico Ferrari.


                           Tenet Group
             Computer Science Division, UC Berkeley
                               and
            International Computer Science Institute,
                   1947 Center St. , Suite 600
                    Berkeley, CA 94704-1105.
             Tel: (510)-642-8919 Fax:(510)-643-7684
          E-mail: {banerjea,parris}@tenet.berkeley.edu


                            ABSTRACT

Fault recovery techniques must be reexamined in the light of  the
new  guaranteed  performance services that networks will support.
We investigate the rerouting of  guaranteed  performance  service
connections  on  the  occurrence of link faults, focussing on the
aspects of route selection and establishment in the network. In a
previous  investigation, we explored some components of rerouting
in the presence of single link faults in the  network.   In  this
paper  we study the behavior of our techniques in the presence of
multiple link faults in the network, and also examine  the  tech-
nique  of  retries  to  improve  the  success  of rerouting.  Our
schemes are simulated on a cross-section  of  network  workloads,
and  compared  using the criteria of the fraction of the affected
traffic that could be rerouted,  the  time  to  reroute  and  the
amount  of resources consumed in the network. A novel metric, the
Queueing Delay Load Index, which captures both the bandwidth  and
delay  demands  made  on  the network by a connection, is used to
present and analyze the results.