HP 9124 - Cisco MDS Fabric Switch, Configuration Manual

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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
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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
Buffer Pools
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:
• Reserved internal buffers
•
Allocated BB_credit buffers for each Fibre Channel interface (user configured or assigned by
default)
• Common unallocated buffer pool for BB_credits, if any, to be used for additional BB_credits as
needed
•
Performance buffers (only used on 12-port 4-Gbps and 4-port 10-Gbps switching modules)
Figure 14-1 shows the allocation of BB_credit buffers on linecards (24-port and 48-port line cards).
Note In some modules, performance buffers are not supported.
Figure 14-1 Receive Buffers for Fibre Channel Ports in a Global Buffer Pool
Figure 14-2 shows the default BB_credit buffer allocation model for 24-port 4-Gbps switching modules.
The minimum BB_credits required to bring up a port is two buffers.
Figure 14-2 BB_Credit Buffer Allocation in 24-port 4-Gbps Switching Modules
Re s erved Intern a l B u ffer s (not us er config u r ab le)
Perform a nce B u ffer s ( S h a red Pool)
Common u n a lloc a ted bu ffer pool for BB_credit s
1 2 3 N
Alloc a ted BB_credit bu ffer s
for e a ch front p a nel FC port s
M
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bu
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Tot
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