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FTOS Configuration Guide for the C-Series - Force10 Networks

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Chapter 14 Link Layer Discovery Protocol<br />

Link Layer Discovery Protocol is supported only on plat<strong>for</strong>ms: c e s<br />

This chapter contains <strong>the</strong> following sections:<br />

• 802.1AB (LLDP) Overview on page 283<br />

• TIA-1057 (LLDP-MED) Overview on page 286<br />

• Configuring LLDP on page 290<br />

802.1AB (LLDP) Overview<br />

Link Layer Discovery Protocol (LLDP)—defined by IEEE 802.1AB—is a protocol that enables a LAN<br />

device to advertise its configuration and receive configuration in<strong>for</strong>mation from adjacent LLDP-enabled<br />

LAN infrastructure devices. The collected in<strong>for</strong>mation is stored in a management in<strong>for</strong>mation base (MIB)<br />

on each device, and is accessible via SNMP.<br />

Protocol Data Units<br />

<strong>Configuration</strong> in<strong>for</strong>mation is exchanged in <strong>the</strong> <strong>for</strong>m of Type, Length, Value (TLV) segments. Figure 185<br />

shows <strong>the</strong> Chassis ID TLV.<br />

• Type—The kind of in<strong>for</strong>mation included in <strong>the</strong> TLV<br />

• Length—The value, in octets, of <strong>the</strong> TLV after <strong>the</strong> Length field<br />

• Value—The configuration in<strong>for</strong>mation that <strong>the</strong> agent is advertising<br />

Figure 185 Type, Length, Value (TLV) Segment<br />

TLV Type<br />

(1-127)<br />

TLV Header<br />

7 bits 9 bits<br />

TLV Length Value<br />

0-511 octets<br />

Chassis ID Sub-type<br />

Chassis ID<br />

1 octet 1- 255 octets<br />

fnC0057mp<br />

TLVs are encapsulated in a frame called an LLDP Data Unit (LLDPDU) (Figure 186), which is transmitted<br />

from one LLDP-enabled device to its LLDP-enabled neighbors. LLDP is a one-way protocol.<br />

LLDP-enabled devices (LLDP agents) can transmit and/or receive advertisements, but <strong>the</strong>y cannot solicit<br />

and do not respond to advertisements.<br />

<strong>FTOS</strong> <strong>Configuration</strong> <strong>Guide</strong>, version 7.7.1.0 283

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