Bandwidth - EMC Connectrix EC-1200 Planning Manual

Fibre Channel Switching Concepts
2

Bandwidth

All Connectrix products are fully nonblocking, which means that any
random set of port pairs can each operate at 100 MB/s or 200 MB/s
full duplex without contention for resources or interference from the
other port pairs. Whether the ports are on the same port card or are
physically spread apart on the unit there will be no effect on
throughput.
Bandwidth across an ISL is effected by the physical length of the ISL.
This is most likely to be a consideration with DWDM (Dense
Wavelength Division Multiplexing) equipment. Each port on each of
the Connectrix products can be configured for extended distance,
which provides up to 60 Buffer-to-Buffer Credits (BB_Credits) on
each port. Table 2-2 and Figure 2-3 show the effect of BB_Credit as a
function of distance for a link of 1 Gb/s; Table 2-3 and Figure 2-4
show similar information for a link of 2 Gb/s.
With insufficient BB_Credit there is a dropoff (known as droop in
ESCON) in throughput.
The speed of light is 5 microseconds/km in glass. As a general rule of thumb:
2 km/buffer at 1 Gb/s.
2-17

Bandwidth