Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual page 403

Chapter 15 Configuring Generation 2 and Generation 3 Switching 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
Table 15-13
BB_Credit Buffer Allocation Type
Total number of BB_credit buffers per module
Total number of performance buffers per module
1. ISL = E port or TE port.
The following considerations apply to BB_credit buffers on 12-port 4-Gbps switching modules:
•
•
•
•
Note
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.
OL-18084-01, Cisco MDS NX-OS Release 4.x
12-Port 4-Gbps Switching Module BB_Credit Buffer Allocation
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)).
Extended BB_credits are allocated across all ports on the switch. That is, they are not allocated
by port group.
BB_Credit Buffers Per Port
Dedicated Rate Mode
4-Gbps Speed
1
ISL Fx Port
5488
512 (shared)
Cisco MDS 9000 Family CLI Configuration Guide
Buffer Credit Allocation
15-19