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مشاهدة النسخة كاملة : What is Goodput?



A7med Baraka
04-15-2009, 08:49 PM
When ATM is used to tranasport cells originating from higher-level
protocols (HLP), an important consideration is the impact of ATM cell loss
on that protocol or at least the segmentation processs. ATM cell loss can
cause the effective throughput of some HLPs to be arbitrarily poor depending
on ATM switch buffer size, HLP congestion control mechanisms, and packet size.

This occurs because during congestion for example, and ATM switch buffer can
overflow which will cause cells to be dropped from multiple packets, runining
each such packet. The preceding and the remaining cells from such packets,
which are ultimately discarded by the frame reassembly process in the receiver,
are nevertheless transmitted on an already congested link, thus wasting
valuable link bandwidth.

The traffic represented by these "bad" cells may be termed as BADPUT.
Correspondingly, the effective throughput, as determined by those cells which
are successfully recombined at the receiver, can be termed as GOODPUT.