Link Layer Discovery Protocol Emergency Services Workshop, NY Oct 5-6, 2006 Manfred Arndt ([e-mail])

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Link Layer Discovery ProtocolEmergency Services
Workshop, NYOct 5-6, 2006Manfred Arndt
(manfred.r.arndt_at_hp.com)
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Scope

• IEEE 802.1AB Link Layer Discovery Protocol
  (LLDP)
• A standard and extensible multi-vendor protocol
  and management elements to support network
  topology discovery and exchange device
  configuration and capabilities
• Developed and maintained by IEEE 802.1, planned
  for revision

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Objectives

• Widespread industry adoption
• Simple 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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LLDP Entities AgentsA peak under the hood

• Remote MIBs
• Holds and ages received data from far end
• Available for management applications use

LLDP operates above the MAC Service Layer

• Local MIBs
• Holds locally configured data
• Data may be supplied/modified by management
  applications

• LLDP State machine
• Controls Tx and Rx of frames
• Contains state machine control variables

LSAP Link service access point MSAP MAC
service access point
All LLDP Entities contain 1 or more LLDP Agents

• Entity Management MIBs
• Common data, of use to LLDP and others
• Not directly part of LLDP

Animated Slide
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LLDP TLV Extensibility

• Easy to define organizational extensions
• There are currently three organizational
  extensions
• 1. IEEE 802.1
• Port VLAN, Port Protocol VLANs, VLAN Name,
  Protocol Entity
• 2. 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

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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 Bridge and 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/LinkLayerDiscoveryProtoco
  l
• Contacts
• Paul Congdon (paul.congdon_at_hp.com) project
  leader of IEEE 802.1AB-2005 (LLDP) and vice-chair
  of IEEE 802.1 Working Group
• Manfred Arndt (manfred.r.arndt_at_hp.com) co-author
  of ANSI/TIA-1057 (LLDP-MED)

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Backup Slides
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How Does LLDP Work?
Management App Topology discovery, location,
inventory more
port device info
A19 Switch xxxx
C2 IP-Phone xxxx
D2 IP-Phone xxxx
F3 VoIP Gateway xxxx
PSTN
SNMP
port device info
A4 IP-phone xxxx
A4 PC xxxx
B6 PC xxxx
B21 Switch xxxx
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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 a peer and perform some local
  database maintenance operation
• By definition, anytime a local value changes,
  LLDP sends a frame thus triggering a packet in
  reverse (limited to once per second)
• The protocol itself is stateless, but the
  management entity above is required to maintain
  state and may act on information from peers
• LLDP-MED (ANSI/TIA-1057) follows these same
  principals.