Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 123)

NOTE
You cannot use the -buffers option with the -distance option or the -frameSize option.
switch:admin> portcfglongdistance 2/35 LS 1 -buffers 400
Reserved Buffers = 420
Configuring buffers using frame size
You can configure the number of buffers by using the -frameSize option of the portCfgLongDistance
command along with the -distance option. Fabric OS calculates the number of buffers from the -
frameSize option value according to the following formula:
buffers_required = (2048/framesize) * data_vc_credits
If you enter the average frame size of 1024, Fabric OS will allocate almost twice as many buffers as for
the maximum frame size of 2048.
The -frameSize option value is persistent across reboots and HA failover.
Example
switch:admin> portcfglongdistance 2/35 LS 1 -distance 100 -framesize 1024
Calculating the number of buffers required given the distance, speed,
and frame size
If you know the distance, speed, and frame size for a given port, you can use the portBufferCalc
command to calculate the number of buffers required. If you omit the distance, speed, or frame size, the
command uses the currently configured values for the port. Given the buffer requirement and port
speed, you can use the same distance and frame size values when using the portCfgLongDistance
command.
To determine the number of buffers required, complete the following steps:
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the portBufferCalc command and provide values for the distance, port speed, and frame size.
The following example calculates the number of buffers required for an 8-Gbps port on a 100-km link
with an average frame size of 512 bytes.
switch:admin> portbuffercalc 9/4 -distance 100 -speed 8 -framesize 512
1606 buffers required for 100km at 8G and framesize of 512 bytes
Allocating buffer credits for F_Ports
The default configured F_Port buffer credit is fixed at eight buffers. You can use the
portCfgFPortBuffers command to configure a given port with the specified number of buffers.
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the portCfgFPortBuffers command.
switch:admin> portcfgfportbuffers --enable 2/44 12
Configuring buffers using frame size
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