Dell Force10 MXL Blade MXL 10/40GbE Switch IO Module Configuration Guide - Page 660

www.dell.com | support.dell.com Deciding to Tune Buffers Dell Force10 recommends exercising caution when configuring any non-default buffer settings, as tuning can significantly affect system performance. The default values work for most cases. As a guideline, consider tuning buffers if traffic is very bursty (and coming from several interfaces). In this case: • Reduce the dedicated buffer on all queues/interfaces. • Increase the dynamic buffer on all interfaces. • Increase the cell pointers on a queue that you are expecting will receive the largest number of packets. Buffer Tuning Commands To tune the buffers, use the following commands: Task Define a buffer profile for the FP queues. Define a buffer profile for the CSF queues. Change the dedicated buffers on a physical 1G interface. Change the maximum amount of dynamic buffers an interface can request. Change the number of packet-pointers per queue. Apply the buffer profile to a CSF to FP link. Command buffer-profile fp fsqueue buffer-profile csf csqueue buffer dedicated buffer dynamic buffer packet-pointers buffer csf linecard Command Mode CONFIGURATION CONFIGURATION BUFFER PROFILE BUFFER PROFILE BUFFER PROFILE CONFIGURATION FTOS Behavior: If you attempt to apply a buffer profile to a non-existent port-pipe, FTOS displays the following message. However, the configuration still appears in the running-config. %DIFFSERV-2-DSA_BUFF_CARVING_INVALID_PORT_SET: Invalid FP port-set 2 for linecard 2. Valid range of port-set is Configuration changes take effect immediately and appear in the running configuration. Because under normal conditions all ports do not require the maximum possible allocation, the configured dynamic allocations can exceed the actual amount of available memory; this is called oversubscription. If you choose to oversubscribe the dynamic allocation, a burst of traffic on one interface might prevent other interfaces from receiving the configured dynamic allocation, which causes packet loss. You cannot allocate more than the available memory for the dedicated buffers. If the system determines that the sum of the configured dedicated buffers allocated to the queues is more than the total available memory, the configuration is rejected, returning a syslog message similar to the following. Table 39-3. Buffer Allocation Error 00:04:20: %S50N:0 %DIFFSERV-2-DSA_DEVICE_BUFFER_UNAVAILABLE: Unable to allocate dedicated buffers for stack-unit 0, port pipe 0, egress port 25 due to unavailability of cells 658 | Debugging and Diagnostics