HP Cisco MDS 9120 Cisco MDS 9000 Family Fabric Manager Configuration Guide - R - Page 493

Chapter 22 Configuring Generation 2 and Generation 3 Switching Modules Buffer Credit Allocation Send documentation comments to [email protected] Table 22-12 24 Port 4-Gbps Switching Module BB_Credit Buffer Allocation BB_Credit Buffer Allocation Maximum BB_credit buffers Total number of BB_credits buffers per module 1. ISL = E port or TE port. BB_Credit Buffers Per Port Dedicated Rate Mode 4-Gbps Speed ISL1 Fx Port Shared Rate Mode 4-Gbps Speed Fx Port 250 250 16 6000 The following considerations apply to BB_credit buffers on 24-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 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: • 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 Figure 22-10) Figure 22-10 Example Speed and Rate Configuration on a 24-Port 4-Gbps Switching Module 1 4-Gbps 2 4-Gbps Dedicated Dedicated 3 4-Gbps Dedicated 4 1-Gbps Shared 5 1-Gbps Shared 6 1-Gbps Shared 144857 18-Port Fibre Channel/4-Port Gigabit Ethernet Multiservice Module BB_Credit Buffers Table 22-12 lists the BB_credit buffer allocation for 18-port 4-Gbps multiservice modules. OL-17256-03, Cisco MDS NX-OS Release 4.x Cisco MDS 9000 Family Fabric Manager Configuration Guide 22-19