HP Cisco MDS 9120 Cisco MDS 9000 Family Fabric Manager Configuration Guide, Re - Page 433

Chapter 22 Configuring Generation 2 Switches and Modules Buffer Credit Allocation Send documentation comments to [email protected] The following considerations apply to BB_credit buffers on 12-port 4-Gbps switching modules: • 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)). Note Extended BB_credits are allocated across all ports on the switch. That is, they are not allocated by port group. 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. 4-Port 10-Gbps Switching Module BB_Credit Buffers Table 22-9 lists the BB_credit buffer allocation for 4-port 10-Gbps switching modules. Table 22-9 4-port 10-Gbps Switching Module BB_Credit Buffer Allocation Defaults BB_Credit Buffer Allocation Type BB_Credit Buffers Per Module User configurable BB_credit buffers 5488 Performance buffers 512 (shared) 1. ISL = E port or TE port. 2. Ports on the 4-port 10-Gbps cannot operate in FL port mode. BB_Credit Buffers Per Port Defaults Dedicated Rate Mode 4-Gbps Speed ISL1 F port2 250 16 145 12 Note The ports in the 4-port 10-Gbps switching module only support 10-Gbps dedicated rate mode. FL port mode and shared rate mode are not supported. The following considerations apply to BB_credit buffers on 4-port 10-Gbps switching modules: • 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. OL-16184-01, Cisco MDS SAN-OS Release 3.x Cisco MDS 9000 Family CLI Configuration Guide 22-13