Link Layer Discovery Protocol (LLDP)
Issue 5 April 2010 79
attempts occur using the stored 802.1X credentials, without prompting the user for ID and
password entry.
An IP telephone can support several different 802.1X authentication scenarios, depending on
the capabilities of the Ethernet data switch to which it is connected. Some switches may
authenticate only a single device per switch port. This is known as single-supplicant or
port-based operation. These switches typically send multicast 802.1X packets to authenticating
devices.
These switches support the following three scenarios:
●Standalone telephone (Telephone Only Authenticates) - When the IP telephone is
configured for Supplicant Mode (DOT1XSTAT=2), the telephone can support
authentication from the switch.
●Telephone with attached PC (Telephone Only Authenticates) - When the IP telephone
is configured for Supplicant Mode (DOT1X=2 and DOT1XSTAT=2), the telephone can
support authentication from the switch. The attached PC in this scenario gains access to
the network without being authenticated.
●Telephone with attached PC (PC Only Authenticates) - When the IP telephone is
configured for Pass-Through Mode or Pass-Through Mode with Logoff (DOT1X=0 or 1 and
DOT1XSTAT=0), an attached PC running 802.1X supplicant software can be
authenticated by the data switch. The telephone in this scenario gains access to the
network without being authenticated.
Some switches support authentication of multiple devices connected through a single switch
port. This is known as multi-supplicant or MAC-based operation. These switches typically send
unicast 802.1X packets to authenticating devices. These switches support the following two
scenarios:
●Standalone telephone (Telephone Only Authenticates) - When the IP telephone is
configured for Supplicant Mode (DOT1XSTAT=2), the telephone can support
authentication from the switch. When DOT1X is "0" or "1", the telephone is unable to
authenticate with the switch.
●Telephone and PC Dual Authentication - Both the IP telephone and the connected PC
can support 802.1X authentication from the switch. The IP telephone may be configured
for Pass-Through Mode or Pass-Through Mode with Logoff (DOT1X=0 or 1 and
DOT1XSTAT=1 or 2). The attached PC must be running 802.1X supplicant software.
Link Layer Discovery Protocol (LLDP)Release 1.1 1600 Series IP Telephones support IEEE 802.1AB. Link Layer Discovery Protocol
(LLDP) is an open standards layer 2 protocol IP Telephones use to advertise their identity and
capabilities and to receive administration from an LLDP server. LAN equipment can use LLDP
to manage power, administer VLANs, and provide some administration.
The transmission and reception of LLDP is specified in IEEE 802.1AB-2005. The 1600 Series
IP Telephones use Type-Length-Value (TLV) elements specified in IEEE 802.1AB-2005, TIA