Dell Force10 S55T S55 Configuration Guide FTOS 8.3.5.3 - Page 516

www.dell.com | support.dell.com 1. the power-inline mode: static or auto, 2. the power-inline priority configuration, 3. the LLDP-MED priority sent by the PD in the Extended Power-via-MDI TLV, 4. and the port's slot and port number. FTOS maintains a sorted list of PoE ports based these four parameters. Static ports have a higher weight than auto mode ports, so all static ports always stay on top of all auto ports regardless of the other 3 parameters. Within the set of static ports, FTOS attempts to order them based on the second parameter power-inline priority, the default of which is "Low". If FTOS finds multiple ports with the same power-inline priority, it breaks the tie using the third parameter, the LLDP-MED Priority advertised by the PD, which like power-inline priority could be "Critical," "High," or "Low". After this, if FTOS still finds a tie, priority is based on the fourth parameter which is the ports position in the chassis; there cannot be a tie based on this parameter. This sorted list is dynamically updated by FTOS when: • a user changes the power-inline mode or priority • the PD advertises a different LLDP-MED priority • the PD is connected or disconnected FTOS always uses this sorted list of ports for allocation. When an additional PSU is added, additional ports are powered based on this list, and PSU is removed, this same list is used to remove power from the lowest priority ports. power-inline mode FTOS allows ports to be configured in one of two modes: auto and static. auto: Ports configured for auto mode manage the power allocation by themselves. There is no prior reservation of power made on these ports. When no PD is connected on this port, the power allocated is zero. Once a PD is connected, FTOS detects its PoE class dynamically and the maximum power for its class is allocated to the port. The PD then boots using this allocated power. After bootup, if the PD is LLDP-MED capable, it might send in Extended Power via MDI TLV to the system. In this case, the Dell Force10 switch revises the power allocation to the value that the PD requests via LLDP-MED. The advertised Power Requirement from the PD could be less than or greater than the currently allocated value. Ports configured for auto mode with the max_milliwatts option allocate power the same way, but the allocation never exceeds the specified maximum. If max_milliwatts is greater than the PoE class maximum the system allocates only the class maximum. Note that if a PD has class maximum that is greater than max_milliwatts, the system allocates no power, and the PD does not power up. static: Ports configured in static mode reserve a fixed power allocation whether a device is connected or not. By default 15.4W is allocated, but this is user-configurable with the max_milliwatts option. No dynamic PoE class detection is performed on static ports, and Extended Power via MDI TLVs have no effect. 516 | Power over Ethernet