  During the design of ABR traffic management at the ATM Forum, we performed
several analyses to ensure that the ABR service will operate efficiently over
satellite links. In the cases where the performance was unacceptable, we
suggested modifications to the traffic management specifications. This paper
describes one such issue related to the count of missing resource management
cells (Crm) parameter of the ABR source behavior. The analysis presented here
led to the changes which are now part of the ATM traffic management (TM 4.0)
specification. In particular, the size of the transient buffer exposure (TBE)
parameter was set to 24 bits, and no size was enforced for the Crm parameter.
This simple change improved the throughput over OC-3 satellite links from 45
Mbps to 140 Mbps.
