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Link Layer Discovery Protocol
Emergency Services Workshop, NY
Oct 5-6, 2006
Manfred Arndt ([email protected])
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Scope
IEEE 802.1AB Link Layer Discovery Protocol (LLDP)
A standard and extensible multi-vendor protocol and managementelements to support network topology discovery and exchange
device configuration and capabilitiesDeveloped and maintained by IEEE 802.1, planned for revision
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Objectives
Widespread industry adoptionSimple and leveraged design increases chances of vendor adoption
Simple design leads to low development cost
Interoperability with many endpoint device types
Low complexity higher interoperability potential
Must be practical for both cost-restrained and feature rich endpoints
High reliability, critical to Emergency Call Service scenarios
Low complexity with fewest possible moving parts
Location always provided immediately on connection of move
Easily extensible for future needs
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LLDP Overview
Basic Functions (IEEE 802.1AB-2005*):
Simple one-way neighbor discovery protocol with periodic transmissions
LLDP frames are not forwarded, but constrained to a single point to point link
LLDP frames contain formatted TLVs (type, length, value)
Globally unique system and port identification
Time-to-Live information for ageing purposes
Optional system capabilities (e.g. router, IP phone, wireless AP)
Optional system name, description, and management address
Organizational extensions
Receiver stores information in a neighbor database, accessible via SNMP MIB
Receiver ages MIB to
insure only valid network data is available
Management applications can harness the power via SNMP
* Currently planned for revision, PAR submitted for targeted Nov 06 approval
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All LLDP Entities contain1 or more LLDP Agents
LLDP operates above theMAC Service Layer
LSAP = Link service access point
MSAP = MAC service access point
LLDP Entities & AgentsA peak under the hood*
Local MIBs: Holds locally
configured data Data may be
supplied/modifiedby managementapplications
Remote MIBs: Holds and ages received data
from far end Available for management
applications use
Entity Management MIBs: Common data, of use to
LLDP and others Not directly part of LLDP
LLDP State machine Controls Tx and Rx of frames Contains state machine control
variables
* Animated Slide
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Easy to define organizational extensions
There are currently three organizational extensions:
1. IEEE 802.1
Port VLAN, Port & Protocol VLANs, VLAN Name, Protocol Entity2. IEEE 802.3
MAC/PHY configuration, PoE Power, Link Aggregation, Maximum Frame Size
3. TIA - IP Telephony Infrastructure (LLDP-MED)
VLAN & QoS auto-config, Physical Location Discovery, Detailed Inventory, Fine Grain PoE Power
LLDP TLV Extensibility
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802.1AB Revision Proposal (Nov 06)
Currently planned project revision considerations include: Supporting the needs of 802.3at (PoE Plus), including:
Ongoing dynamic fine-grain power negotiation (e.g. video call in process)
Power priority (e.g. must keep red phone alive)
Backup power conservation (e.g. extend UPS battery life during disasters)
Provide support for rapid fast start TLV exchange
Required for power negotiation and to quickly discover Audio Visual Bridgeand Congestion Management interconnectivity boundaries
Define additional destination addresses such that the propagation of
LLDP frames across specific transparent devices can be achieved Certain TLVs, like PoE power and speed/duplex, must never be forwarded
Some TLVs need to traverse transparent links (e.g. across provider bridges)
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References & Contacts
The formal LLDP specification is freely available for download at:
http://standards.ieee.org/getieee802/download/802.1AB-2005.pdf
Useful links:
http://en.wikipedia.org/wiki/LLDP
http://wiki.ethereal.com/LinkLayerDiscoveryProtocol
Contacts:
Paul Congdon ([email protected]); project leader of IEEE 802.1AB-2005 (LLDP)and vice-chair of IEEE 802.1 Working Group
Manfred Arndt ([email protected]); co-author of ANSI/TIA-1057 (LLDP-MED)
http://standards.ieee.org/getieee802/download/802.1AB-2005.pdfhttp://en.wikipedia.org/wiki/LLDPhttp://wiki.ethereal.com/LinkLayerDiscoveryProtocolmailto:[email protected]:[email protected]:[email protected]:[email protected]://wiki.ethereal.com/LinkLayerDiscoveryProtocolhttp://en.wikipedia.org/wiki/LLDPhttp://standards.ieee.org/getieee802/download/802.1AB-2005.pdfhttp://standards.ieee.org/getieee802/download/802.1AB-2005.pdfhttp://standards.ieee.org/getieee802/download/802.1AB-2005.pdf7/31/2019 Esw06 - Ieee Lldp Overview
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Backup Slides
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Discovery MIB
Discovery MIB
How Does LLDP Work?
PSTN
Im an
IP-PhoneIm a PC
Im anIP-Phone
Im an
IP-Phone
Im a
switch
Im a
switch
Im a VoIP Gateway / Server
Im a
switch Im a
switch
Im a
switch
Im a
switch
Im a
switch
port device info
A4 IP-phone xxxx
A4 PC xxxx
B6 PC xxxx
B21 Switch xxxx
port device info
A19 Switch xxxx
C2 IP-Phone xxxx
D2 IP-Phone xxxx
F3 VoIP Gateway xxxx
Im a PC
Im a PC
Management App
Topology discovery,
location, inventory &more
SNMP
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LLDP Frame Format
IEEE 802.3 LLDP frame format
LLDP Multicast = 01-80-C2-00-00-0E (same as Spanning Tree except for last octet)
LLDPDU format
Each TLV (Type, Length, Value) contains a set of useful attributes
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Is LLDP a stateless protocol?
IEEE 802.1AB-2005: LLDP updates are limited to no faster than 1 per second
Intended as one-way advertisements, without req / acks
Dramatically simplifies implementations
Bounds performance requirements for scalability
On occasion, the management entity may see a change in state of apeer and perform some local database maintenance operation
By definition, anytime a local value changes, LLDP sends a frame thustriggering a packet in reverse (limited to once per second)
The protocol itself is stateless, but the management entity above isrequired to maintain state and may act on information from peers
LLDP-MED (ANSI/TIA-1057) follows these same principals.