GarrettCom CSG14 - Manual (Page 38)

CSG14 Series Gigabit Converter Switch Installation and User Guide (09/09)
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2.3 Frame Buffering and Latency
The Magnum CSG14 Series Converter Switches are store-and-forward switches.
Each frame (or packet) is loaded into the Switch’s memory and inspected before forwarding
can occur. This technique ensures that all forwarded frames are of a valid length and have
the correct CRC, i.e. they are good packets. This eliminates propagation of bad packets,
enabling all of the available bandwidth to be used for valid information.
While other switching technologies such as "cut-through" or "express" impose
minimal frame latency, they will also permit bad frames to propagate out to the Ethernet
segments connected. The "cut-through" technique permits collision fragment frames,
which are a result of late collisions, to be forwarded to add to the network traffic. Since
there is no way to filter frames with a bad CRC (the entire frame must be present in order
for CRC to be calculated), the result of indiscriminate cut-through forwarding is greater
traffic congestion, especially at peak activity. Since collisions and bad packets are more
likely when traffic is heavy, the result of store-and-forward operation is that more
bandwidth is available for good packets when the traffic load is greatest.
To minimize the possibility of dropping frames on congested ports, each