McDATA 4314 Manual Do Utilizador

The switch module supports class 2 and class 3 Fibre Channel service with a 
maximum frame size of 2148 bytes at transmission rates of 1-Gbps or 2-Gbps. 
An external port adapts its transmission speed to match that of the device to 
which it is connected prior to login when the connected device powers up. 
Related performance characteristics include the following:

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•

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Consider the physical distribution of devices and switches in the fabric. 
Choose SFP transceivers that are compatible with the cable type, distance, 
Fibre Channel revision level, and the device host bus adapter. Refer to 

 for more information about cable types and transceivers.

Each Fibre Channel port is supported by a data buffer with a 16 credit 
capacity; that is, 16 maximum sized frames. For fibre optic cables, this enables 
full bandwidth over the following approximate distances:

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26 kilometers at 1-Gbps (0.6 credits/Km)

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13 kilometers at 2-Gbps (1.2 credits/Km)

Beyond these distances, however, there is some loss of efficiency because the 
transmitting port must wait for an acknowledgement before sending the next 
frame.

Longer distances can be spanned at full bandwidth by extending credits to 
G_Ports, F_Ports, and E_Ports. Each port can donate 15 credits to a pool from 
which a recipient port can borrow. The recipient port also loses a credit in the 
process. For example, you can configure a recipient port to borrow 15 credits 
from one donor port for a total of 30 credits (15+15=30). This will support 
communication over the following approximate distances:

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50 Km at 1-Gbps (30÷0.6) 

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25 Km at 2-Gbps (30÷1.2)

You can configure recipient and donor ports using the EFCM BASIC 
application or the Set Config command. Refer to the McDATA 4314 Command 
Line Interface Guide for information about the Set Config command.

Bandwidth is a measure of the volume of data that can be transmitted at a 
given transmission rate. A Fibre Channel port can transmit or receive at 
nominal rates of 1-Gbps or 2-Gbps depending on the device to which it is 
connected. This corresponds to actual bandwidth values of 106 MB and 212 
MB. Multiple source ports can transmit to the same destination port if the 
destination bandwidth is greater than or equal to the combined source 
bandwidth. For example, two 1-Gbps source ports can transmit to one 2-Gbps 
destination port. Similarly, one source port can feed multiple destination