Buffer Credit Allocation
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
In the architecture of Generation 2 modules, receive buffers shared by a set of ports are called buffer
groups. The receive buffer groups are organized into global and local buffer pools.
The receive buffers allocated from the global buffer pool to be shared by a port group are called a global
buffer pool. Global receive buffer pools include the following buffer groups:
In some modules, performance buffers are not supported.
The minimum BB_credits required to bring up a port is two buffers.
Cisco MDS 9000 Family CLI Configuration Guide
Reserved internal buffers
Allocated BB_credit buffers for each Fibre Channel interface (user configured or assigned by
Common unallocated buffer pool for BB_credits, if any, to be used for additional BB_credits as
Performance buffers (only used on 12-port 4-Gbps and 4-port 10-Gbps switching modules)
shows the allocation of BB_credit buffers on linecards (24-port and 48-port line cards).
Receive Buffers for Fibre Channel Ports in a Global Buffer Pool
Reserved Internal Buffers (not user configurable)
Performance Buffers (Shared Pool)
Common unallocated buffer pool for BB_credits
shows the default BB_credit buffer allocation model for 24-port 4-Gbps switching modules.
BB_Credit Buffer Allocation in 24-port 4-Gbps Switching Modules
Allocated BB_credit buffers
for each front panel FC ports
Configuring Generation 2 Switches and Modules
OL-16184-01, Cisco MDS SAN-OS Release 3.x