HP 9124 - Cisco MDS Fabric Switch, Configuration Manual

Page: 391 / 1444

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
14-11
Cisco MDS 9000 Family CLI Configuration Guide
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Chapter 14 Configuring Generation 2 Switches and Modules
Buffer Credit Allocation
Note For an example of the configuration of the this example, see “Configuring a 48-port 4-Gbps Fibre
Channel Switching Module Example” section on page 14-37 .
Figure 14-4 Example Speed and Rate Configuration on a 48-Port 4-Gbps Switching Module
24-port 4-Gbps Fibre Channel Module BB_Credit Buffers
Table 14-7 lists the BB_credit buffer allocation for 24-port 4-Gbps Fibre Channel switching modules.
The following considerations apply to BB_credit buffers on 24-port 4-Gbps Fibre Channel switching
modules:
• BB_credit buffers for ISL connections can be configured from a minimum of 2 buffers to a
maximum of 250 buffers for dedicated rate mode or 16 buffers for shared rate mode.
•
BB_credit buffers for Fx port mode connections can be configured. The minimum is 2 buffers and
the maximum of 250 buffers for dedicated rate mode or 16 buffers for shared rate mode.
• Performance buffers are not supported on this module.
Each port group on the 24-port 4-Gbps Fibre Channel switching module consists of six ports. The ports
in shared rate mode have bandwidth oversubscription of 2:1 by default. However, some configurations
of the shared ports in a port group can have maximum bandwidth oversubscription of 4:1 (considering
that each port group has 12.8-Gbps bandwidth). The following example configurations are supported by
the 24-port 4-Gbps Fibre Channel switching modules:
• Six ports with shared rate mode and 4-Gbps speed (2:1 oversubscription) (default)
2-Gbps
2-Gbps
2-Gbps
2-Gbps
2-Gbps
2-Gbps
Dedicated
Dedicated Dedicated Dedicated
Dedicated Dedicated
1-Gbps
Shared
1-Gbps
Shared
1
2
3
4
5
7
9 11
6
8 10
12
1-Gbps
Shared
1-Gbps
Shared
Out of
Service
Out of
Service
144859
Table 14-6 24 Port 4-Gbps Switching Module BB_Credit Buffer Allocation Defaults
BB_Credit Buffer Allocation Type
BB_Credit
Buffers Per
Module
BB_Credit Buffers Per Port Defaults
Dedicated Rate Mode
4-Gbps Speed Shared Rate Mode
4-Gbps Speed
ISL
1
1. ISL = E port or TE port.
Fx Port ISL
1
Fx Port
User configurable BB_credit buffers 6000 250 16 16 16