HP Cisco Nexus 5000 Cisco MDS 9000 Family CLI Configuration Guide - Release 4. - Page 393

Chapter 15 Configuring Generation 2 and Generation 3 Switching Modules Buffer Credit Allocation Send documentation comments to [email protected] • Extended BB_Credits, page 15-22 Buffer Pools In the architecture of Generation 2 and Generation 3 modules, receive buffers shared by a set of ports are called buffer groups. The receive buffer groups are organized into global and local buffer pools. The receive buffers allocated from the global buffer pool to be shared by a port group are called a global recieve buffer pool. Global receive buffer pools include the following buffer groups: • Reserved internal buffers • Allocated BB_credit buffers for each Fibre Channel interface (user configured or assigned by default) • Common unallocated buffer pool for BB_credits, if any, to be used for additional BB_credits as needed • Performance buffers (only used on 12-port 4-Gbps and 4-port 10-Gbps switching modules) Note The 48-Port and 24-Port 8-Gbps modules have dual global buffer pools. Each buffer pool in the 48-port modules support 24 ports and in the 24-port modules each buffer pool supports 12 ports. Figure 15-1 shows the allocation of BB_credit buffers on linecards (24-port and 48-port 4-Gbps line cards). Figure 15-1 Receive Buffers for Fibre Channel Ports in a Global Buffer Pool Reserved Internal Buffers (not user configurable) Performance Buffers (Shared Pool) Common unallocated buffer pool for BB_credits Allocated BB_credit buffers 1 23 for each front panel FC ports N Maximim Receive buffers Total BB_credit buffers 185164 OL-18084-01, Cisco MDS NX-OS Release 4.x Cisco MDS 9000 Family CLI Configuration Guide 15-9