HP Cisco MDS 9216i Cisco MDS 9000 Family Fabric Manager Configuration Guide, R - Page 426

About Generation 2 Modules and Switches Chapter 22 Configuring Generation 2 Switches and Modules Send documentation comments to [email protected] 2. By default, all ports in a 24-port 4-Gbps switching module operate in shared mode with administrative operating speed set to auto. All ports in a 24-port 4-Gbps switching module can operate in dedicated mode with a 2-Gbps operating speed. However, if you configure one or more ports to operate in 4-Gbps dedicated mode, some of the other ports in the module would have to operate in shared mode Note Port rate modes are supported on all Generation 2 modules and fabric switches. Port rate modes are not supported on the Cisco Fabric Switch for HP c-Class BladeSystem, and the Cisco Fabric Switch for IBM BladeCenter. Dedicated Mode When port rate mode is configured as dedicated, a port is allocated required fabric bandwidth and related resources to sustain line rate traffic at the maximum operating speed configured for the port. In this mode, ports do not use local buffering and all receive buffers are allocated from a global buffer pool (see the "Buffer Pools" section on page 22-8). Table 22-4 show the amount of bandwidth reserved for a configured port speed on 4-Gbps switching modules. Table 22-4 Bandwidth Reserved for the Port Speeds on 4-Gbps Switching Modules Configured Speed Auto 4-Gbps Auto with 2-Gbps maximum 2-Gbps 1-Gbps Reserved Bandwidth 4 Gbps 2 Gbps 1 Gbps Note 10-Gbps ports in auto mode only support auto speed mode at 10 Gbps. Shared Mode When port rate mode is configured as shared, multiple ports within a port group share data paths to the switch fabric so that fabric bandwidth and related resources are shared. Often, the available bandwidth to the switch fabric may be less than the negotiated operating speed of a port. Ports in this mode use local buffering for the BB_credit buffers. All ports in switching modules where bandwidth is shared support 1-Gbps, 2-Gbps, or 4-Gbps traffic. However, it is possible to configure one or more ports in a port group to operate in dedicated mode with 1-Gbps, 2-Gbps or 4-Gbps operating speed. Dynamic Bandwidth Management On port switching modules where bandwidth is shared, the bandwidth available to each port within a port group can be configured based on the port rate mode and speed configurations. Within a port group, some ports can be configured in dedicated mode while others operate in shared mode. 22-6 Cisco MDS 9000 Family CLI Configuration Guide OL-16184-01, Cisco MDS SAN-OS Release 3.x