LDP autodiscovery Slide 1

1
IETF63 ParisL2VPN WG LDP Autodiscovery
LDP-based Autodiscoverydraft-stein-ldp-auto-00.t
xtjoint work with Simon Delord
2
Access Network Architecture
MPLS-enabled Access Network
Core Network
there may also be combined multiservice access
nodes
3
Access Network Characteristics
ACCESS NETWORK simple tree (or ring)
topology (may be redundant links) limited BW
limited computational power 1000s of access
nodes no BGP, may not be IGP LDP for access LSP
setup
CORE NETWORK rich topology huge BW strong
computational power smaller number of routers BGP
LDP
4
MS-VPLS
access network
core B
access network
core A
access network
core C
access network
MS-VPLS supported by MS-PWs
PE not in Vset
PE in Vset
PE joining Vset
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Service Discovery

• network elements and links (in both access and
  core networks)
• are relatively static (perhaps add or change 1 or
  2 elements per day)
• hence network discovery is not an operational
  burden
• manual provisioning of LDP sessions between PEs
  is reasonable
• services are by their nature dynamic
• (perhaps add several users per day to each set of
  services)
• manual provisioning of services is a logistical
  nightmare
• for scalability need service discovery
• when BGP is available (i.e. in core network)
• it can be used for autodiscovery of all types
• when only LDP is available
• need to have an LDP-based technique

6
Autodiscovery possibilities

• central server holding Vset (single point of
  failure)
• each PE in Vset periodically advertises the fact
  (very chatty)
• PW wanting to join Vset sends label mapping to
  all PEs
• (thousands of un-necessary mapping messages and
  perhaps bindings)
• PE wanting to join Vset inquires and initiates PW
  setup
• (w/o central server needs to send inquiry
  messages and collect responses
• and then one PE needs to initiate setup of
  many MS-PWs)
• PE wanting to join Vset announces (join messages)
• and Vset members initiate PW setup

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JOIN Message
core B
core A
core C
NB SPE used for JOIN message is not necessarily
used by PW
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PW Setup
core B
core A
core C
PW setup uses whatever MS-PW mechanism PWE3
decides upon