Information About Port Pacing
The Fibre Channel Port Pacer is supported only on Cisco MDS 9513 and MDS 9710 switches. The Port Pacer is designed to pace the number of mode F ports that come up simultaneously so that ports are brought up in a phased manner.
During an F port start up, the Port Pacer informs the F Port server that a port is starting up. The Port Pacer waits for the F port server to receive FLOGIs and FDISCs on that port. The Port Pacer attempts to bring up concurrent-ports number of ports simultaneously. However, after the F port server informs the Port Pacer that it has received FLOGI and FDISC for that port, and then the Port Pacer completes the port bring up and updates the port status as up. Subsequently, the next port is attempted for starting up.
By default, F port pacing is disabled. After enabling port pacing, number of FLOGI or FDISC received on the port are being tracked. In the case of all FLOGI or FDISC successfully logged in, which would take few seconds, another set of concurrent ports are brought up. At any given time, FLOGI is processed only for configured concurrent ports. This feature is useful in case of zero FLOGI retries in the hosts.