Chapter 4 Configuring Interface Buffers

Information About Interface Buffers

48-Port 4-Gbps Fibre Channel Module BB_Credit Buffers

Table 4-5lists the BB_credit buffer allocation for 48-port 4-Gbps Fibre Channel switching modules.

Table 4-5 48-Port 4-Gbps Switching Module BB_Credit Buffer Allocation

 

BB_Credit Buffers Per Port

 

 

 

 

 

Dedicated Rate Mode

Shared Rate Mode

 

4-Gbps Speed

 

4-Gbps Speed

 

 

 

 

BB_Credit Buffer Allocation

ISL1

Fx Port

Fx Port

Default BB_credit buffers

125

16

16

 

 

 

 

Maximum BB_credit buffers

250

250

16

 

 

 

 

Total number of BB_credit buffers per module

6000

 

 

 

 

 

 

1. ISL = E port or TE port.

The following considerations apply to BB_credit buffers on 48-port 4-Gbps Fibre Channel switching modules:

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.

Each port group on the 48-port 4-Gbps Fibre Channel switching module consists of 12 ports. The ports in shared rate mode have bandwidth oversubscription of 2:1 by default. However, some configurations of the shared ports in a port group can have maximum bandwidth oversubscription of 4:1 (considering that each port group has 12.8-Gbps bandwidth).

The following example configurations are supported by the 48-port 4-Gbps Fibre Channel switching modules:

Twelve ports with shared rate mode and 4-Gbps speed (4:1 oversubscription) (default)

One port with dedicated rate mode and 4-Gbps speed plus

11 ports with shared rate mode and 4-Gbps speed (5:1 oversubscription)

One port with dedicated rate mode and 4-Gbps speed plus

11 ports with shared rate mode and 2-Gbps speed (2.5:1 oversubscription)

Two ports with dedicated rate mode and 2-Gbps speed plus

10 ports with shared rate mode and 4-Gbps speed (5:1 oversubscription)

Two ports with dedicated rate mode and 2-Gbps speed plus

10 ports with shared rate mode and 2-Gbps speed (2.5:1 oversubscription)

Twelve ports with dedicated rate mode and 1-Gbps speed

Three ports with dedicated rate mode and 4-Gbps speed plus four ports with shared rate mode and 1-Gbps speed plus five ports put out-of-service (see Figure 4-6)

 

Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide

4-10

OL-29284-01, Release 6.x

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Cisco Systems DSC9148D8G48PK9 Dedicated Rate Mode, Gbps Speed, Port 4-Gbps Switching Module BBCredit Buffer Allocation