Dell Force10 S25N-S50N FTOS Configuration Guide FTOS 8.4.2.7 E-Series TeraScal - Page 785

36 Power over Ethernet c s Power over Ethernet (PoE) is supported only on platforms: This chapter contains the following major sections: • Configuring Power over Ethernet on page 786 • Power Additional PoE Ports on the S-Series on page 794 • Deploying VOIP on page 795 FTOS supports Power over Ethernet (PoE), as described by IEEE 802.3af . IEEE 802.3af specifies that a maximum of 15.4 Watts can be transmitted to Ethernet devices over the signal pairs of an unshielded twisted pair (UTP) cable. PoE is useful in networks with IP phones and wireless access points because separate power supplies for powered devices (PD) are not needed. Table 36-2 describes the classes of powered devices defined by IEEE 802.3af: Table 36-1. PoE Classes of Powered Devices Class 0 1 2 3 4 Power Range (Watts) 0.44 to 12.95 0.44 to 3.84 3.84 to 6.49 6.49 to 12.95 Reserved Classification Current (mA) < 5.0 10.5 18.5 28 40 Note: FTOS treats Class 0, Class 3, and Class 4 powered devices the same. Class 4 is meant for IEEE802.3at compliant devices which require >12.95 Watts. Currently FTOS treats Class 4 devices as Class 3. FTOS supports PoE on all copper ports on the C-Series and on the S25V and S50V models of the S-Series. The C-Series and S-Series transmit power to connected IEEE 802.3af-compliant powered devices through ports that have been configured to supply PoE. Those platforms also support the protocols LLDP and LLDP-MED, which help optimize power distribution to PoE devices. See Chapter 46, Link Layer Discovery Protocol, on page 861. Power over Ethernet | 785