04-06-2013, 12:03 PM
MPLS Enhancements to Support Layer 2 Transport Services
MPLS.ppt (Size: 428 KB / Downloads: 75)
What is MPLS?
Multiprotocol Label Switching
Label switching mechanism with IP control plane initially designed to increase forwarding performance
Label stacking allows tunnel hierarchy for superior scalability
New signaling protocols (LDP, RSVP-TE, CR-LDP, and even mBGP)
First application - IP Traffic Engineering
Subsequently several new applications have been proposed
New applications for MPLS
MPLS has been viewed as an IP traffic engineering technology
Allows a carrier to increase operational efficiency, but service remains the same
Layer 2 transport is a new application of MPLS
MPLS becomes forwarding infrastructure for a number of services
IP services
Private Data (Frame Relay, ATM, Ethernet)
What problems are we solving?
Network consolidation
For carriers offering Private Data and IP services
Additional service revenue opportunities
For carriers currently only offering IP services
Scalability
Core switches MPLS tunnels and manages far fewer connections
Ease of provisioning
Touch only edge devices
Methods of providing layer 2 services over MPLS
MPLS-based Layer 2VPNs (L2VPN)
draft-kompella-mpls-12vpn-02.txt
L2VPN method eases provisioning of full mesh VPNs
Policies can be formed to provision hub and spoke topologies
Transport of Layer 2 frames over MPLS
draft-martini-l2circuit-trans-mpls-05.txt
Defines point-to-point transport using LDP
draft-martini-l2circuit-encap-mpls-01.txt
Defines encapsulations for multiple layer 2 services
Full or partial mesh provisioning requires automated management tools
Both techniques use label stacking for scalability
LDP in review
VC label established via indirect LDP session
New Virtual Circuit FEC element defined
Used in Label Mapping and Label Withdraw messages
PE binds VC label to VC Identifier(VCID) and advertises to remote peer
LDP message includes:
Local port identifier
VC type (FR, ATM, VLAN, etc)
Local MTU
Summary
L2 transport is a new application of MPLS
Not just for traffic engineering anymore
Allows a service provider to expand IP/MPLS network while offering Layer 2 services
MPLS label stacking mechanism allows for core network scalability
Far fewer connections to manage in core
Services provisioned at edge