HP Cisco MDS 9020 - Fabric Switch Configuration Manual page 407

Chapter 14 Configuring Generation 2 Switches and Modules
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
By default, all 48-port and 24-port 4-Gbps Fibre Channel switching modules have restrictions on
oversubscription ratios enabled.
As of Cisco SAN-OS Release 3.1(1) and later, you can disable restrictions on oversubscription ratios.
All ports in 48-port and 24-port modules can be configured to operate at 4 Gbps in shared mode–even if
other ports in the port group are configured in dedicated mode–regardless of available bandwidth.
However, when oversubscription ratio restrictions are enabled you may not have all shared ports
operating at 4 Gbps. For example, oversubscription ratios are enabled, and you have configured three 4
Gbps dedicated ports in one port group, no other ports in the same port group can be configured to
operate at 4 Gbps.
switch# show port-resources module 8
Module 8
Available dedicated buffers are 5478
Port-Group 1
Total bandwidth is 12.8 Gbps
Total shared bandwidth is 0.8 Gbps
Allocated dedicated bandwidth is 12.0 Gbps
--------------------------------------------------------------------
Interfaces in the Port-Group
--------------------------------------------------------------------
fc8/1
fc8/2
fc8/3
fc8/4 (out-of-service)
fc8/5 (out-of-service)
fc8/6 (out-of-service)
For dedicated ports, oversubscription ratio restrictions do not apply to the shared pool in port groups. So
if oversubscription ratio restrictions are disabled, and you've configured three 4 Gbps dedicated ports in
one port group, then you can configure all other ports in the same port group to operate at a shared rate
of 4 Gbps. In the following example, a 24-port module has a group of 6 ports–3 dedicated ports are
operating at 4 Gbps, and 3 shared ports operating at 4 Gbps:
switch# show port-resources module 8
Module 8
Available dedicated buffers are 5382
Port-Group 1
Total bandwidth is 12.8 Gbps
Total shared bandwidth is 0.8 Gbps
Allocated dedicated bandwidth is 12.0 Gbps
--------------------------------------------------------------------
Interfaces in the Port-Group
--------------------------------------------------------------------
fc8/1
fc8/2
fc8/3
fc8/4
fc8/5
fc8/6
Port-Group 2
Total bandwidth is 12.8 Gbps
Total shared bandwidth is 0.8 Gbps
Allocated dedicated bandwidth is 12.0 Gbps
--------------------------------------------------------------------
Interfaces in the Port-Group
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Configuring Generation 2 Module Interface Shared Resources
B2B Credit Bandwidth
Buffers (Gbps)
16 4.0
16 4.0
16 4.0
B2B Credit Bandwidth
Buffers (Gbps)
16 4.0
16 4.0
16 4.0
16 4.0
16 4.0
16 4.0
B2B Credit Bandwidth
Buffers (Gbps)
Cisco MDS 9000 Family CLI Configuration Guide
Rate Mode
dedicated
dedicated
dedicated
Rate Mode
dedicated
dedicated
dedicated
shared
shared
shared
Rate Mode
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