Port 4-Gbps Fibre Channel Module Bb_Credit Buffers - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

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

24-Port 4-Gbps Fibre Channel Module BB_Credit Buffers

Table 15-11
Table 15-11
BB_Credit Buffer Allocation
Default BB_credit buffers
Maximum BB_credit buffers
Total number of BB_credits buffers per module
1. ISL = E port or TE port.
The following considerations apply to BB_credit buffers on 24-port 4-Gbps Fibre Channel switching
modules:
•
•
•
Each port group on the 24-port 4-Gbps Fibre Channel switching module consists of six ports. The ports
in shared rate mode have a bandwidth oversubscription of 2:1 by default. However, some configurations
of the shared ports in a port group can have a 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:
•
•
•
•
•
For detailed configuration steps of this example, see the
Note
Switching Module Example" section on page
OL-18084-01, Cisco MDS NX-OS Release 4.x
lists the BB_credit buffer allocation for 24-port 4-Gbps Fibre Channel switching modules.
24 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 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.
Six ports with shared rate mode and 4-Gbps speed (2:1 oversubscription) (default)
Two ports with dedicated rate mode and 4-Gbps speed plus
four ports with shared rate mode and 4-Gbps speed (with 4:1 oversubscription)
One port with dedicated rate mode and 4-Gbps speed plus
three ports with dedicated rate mode and 2-Gbps speed plus
two ports with shared rate mode and 4-Gbps speed (4:1 oversubscription)
Six ports with dedicated rate mode and 2-Gbps speed
Three ports with dedicated rate mode and 4-Gbps speed plus
three ports with shared rate mode and 1-Gbps speed (see
BB_Credit Buffers Per Port
Dedicated Rate Mode
4-Gbps Speed
1
ISL Fx Port
250 16
250 250
6000
Figure 15-8)
"Configuring a 24-Port 4-Gbps Fibre Channel
15-53.
Cisco MDS 9000 Family CLI Configuration Guide
Buffer Credit Allocation
Shared Rate Mode
4-Gbps Speed
Fx Port
16
16
15-17