7.8.1.0 - Force10 Networks

Chapter 26 Power over Ethernet
Power over Ethernet (PoE) is supported only on platforms: c s
This chapter contains the following major sections:
• Configuring Power over Ethernet on page 576
• Deploying VOIP on page 583
• Deploying VOIP on page 583
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 49 describes the classes of powered devices defined by IEEE 802.3af:
Table 48 PoE Classes of Powered Devices
Class
Power Range
(Watts)
Classification
Current
(mA)
0 0.44 to 12.95 < 5.0
1 0.44 to 3.84 10.5
2 3.84 to 6.49 18.5
3 6.49 to 12.95 28
4 Reserved 40
Note: FTOS treats Class 0, Class 3, and Class 4 powered devices the same.
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 connections to PoE devices. See Chapter 46, Link Layer Discovery
Protocol, on page 861.
For the C-Series, FTOS requires that a minimum number of AC power supplies (PSU) be installed before
PoE can be enabled, and some PSUs are reserved for PoE redundancy, as described in Table 49.
Note: The C-Series can provide PoE only through its AC power supplies.
FTOS Configuration Guide, version 7.8.1.0 575