Chapter 19: LLDP
260
Overview
The data sent and received by LLDP are useful for many reasons. The
switch can discover other devices directly connected to it. Neighboring
devices can use LLDP to advertise some parts of their Layer 2
configuration to each other, which may highlight inconsistencies in the
neighboring device’s configuration which can then be corrected.
LLDP is a “one hop” protocol; LLDP information can only be sent to and
received by devices that are directly connected to each other, or
connected via a hub or repeater. Devices that are directly connected to
each other are called neighbors. Advertised information is not forwarded
on to other devices on the network. LLDP is a one-way protocol. That is,
the information transmitted in LLDP advertisements flows in one direction
only, from one device to its neighbors, and the communication ends there.
Transmitted advertisements do not solicit responses, and received
advertisements do not solicit acknowledgements. LLDP cannot solicit any
information from other devices. LLDP operates over physical ports only.
For example, it can be configured on switch ports that belong to static port
trunks or LACP trunks, but not on the trunks themselves, and on switch
ports that belong to VLANs, but not on the VLANs themselves.
Each port can be configured to transmit local information, receive neighbor
information, or both. LLDP transmits information as packets called LLDP
Data Units (LLDPDUs). An LLDPDU consists of a set of Type-Length-
Value elements (TLV), each of which contains a particular type of
information about the device or port transmitting it.
Summary of Contents for AT-GS950/24
Page 12: ...Figures 12 ...
Page 14: ...List of Tables 14 ...
Page 18: ...Preface 18 ...
Page 60: ...Chapter 2 Basic Switch Configuration 60 ...
Page 68: ...Chapter 3 Port Configuration 68 ...
Page 74: ...Chapter 4 Port Mirroring 74 ...
Page 94: ...Chapter 5 Virtual LANs 94 ...
Page 102: ...Chapter 6 GVRP 102 ...
Page 132: ...Chapter 8 STP and RSTP 132 ...
Page 146: ...Chapter 9 Multiple Spanning Tree Protocol 146 ...
Page 156: ...Chapter 10 Static Port Trunking 156 ...
Page 178: ...Chapter 12 Quality of Service CoS 178 ...
Page 206: ...Chapter 13 Access Control Configuration 206 ...
Page 226: ...Chapter 15 MAC Address Table 226 ...
Page 238: ...Chapter 16 DHCP Snooping 238 ...
Page 244: ...Chapter 17 IGMP Snooping 244 ...
Page 288: ...Chapter 21 Simple Network Management Protocol SNMPv3 288 ...
Page 300: ...Chapter 22 RMON 300 ...
Page 322: ...Chapter 24 Management Software Updates 322 ...
Page 348: ...Appendix A MSTP Overview 348 ...
Page 366: ...Appendix A AT GS950 24 Default Parameters 366 ...