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
14-13
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
The following considerations apply to BB_credit buffers on 12-port 4-Gbps switching modules:
•
BB_credit buffers for ISL connections can be configured from a minimum of 2 buffers to a
maximum of 250 buffers.
•
BB_credit buffers for Fx port mode connections can be configured from a minimum of 2 buffers to
a maximum of 250 buffers.
•
By default, 512 performance buffers are preallocated and are shared by all the ports. These buffers
are configurable and the buffers are assigned to the port based on the availability of the buffers in
the shared pool.
•
There are 2488 extra buffers available as extended BB_credit buffers after allocating all the default
BB_credit buffers for all the ports in ISL mode (5488 - (250 * 12)).
Note
Extended BB_credits are allocated across all ports on the switch. That is, they are not allocated
by port group.
Note
By default, the ports in the 12-port 4-Gbps switching modules come up in 4-Gbps dedicated rate mode
but can be configured as 1-Gbps and 2-Gbps dedicated rate mode. Shared mode is not supported.
4-Port 10-Gbps Switching Module BB_Credit Buffers
Table 14-9
lists the BB_credit buffer allocation for 4-port 10-Gbps switching modules.
Table 14-8
12-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
ISL
1
1.
ISL = E port or TE port.
Fx Port
User configurable BB_credit buffers
5488
250
16
Performance buffers
512 (shared)
145
12
Table 14-9
4-port 10-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
ISL
1
1.
ISL = E port or TE port.
F port
2
2.
Ports on the 4-port 10-Gbps cannot operate in FL port mode.
User configurable BB_credit buffers
5488
250
16
Performance buffers
512 (shared)
145
12
