Summary: The Effects of Temporary Sessions on Network Performance
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April 23, 1999
We consider a packet network, in which packets are injected in sessions along fixed paths.
Packet movement is restricted by link bandwidth. In case of contention, a contention resolution
protocol determines which packets proceed. In the permanent session model, every session can
inject packets at all times. In the temporary session model, sessions come and go and can only
inject packets during their active time. In this paper we compare network performance in these
two models in terms of stability and endtoend delay.
We provide the first separation of the two models in terms of stability. In particular, we show
that Generalized Processor Sharing (GPS) can be unstable with temporary sessions, whereas
GPS is known to be stable and have polynomial delay bounds with permanent sessions.
We also observe that the relative performance of protocols can differ in the two models. For