08-12-2012, 02:41 PM
MPLS overview
MPLS-overview.pdf (Size: 3.35 MB / Downloads: 78)
Label Distribution Protocol
• Defined in RFC 3036 and 3037
• Used to distribute labels in a MPLS network
• Forwarding equivalence class
How packets are mapped to LSPs (Label
Switched Paths)
• Advertise labels per FEC
Reach destination a.b.c.d with label x
• Neighbor discovery
Basic and extended discovery
TDP and LDP
• Tag Distribution Protocol
Pre-cursor to LDP
Used for Cisco tag switching
• TDP and LDP supported on the same box
Per neighbor/link basis
Per target basis
RSVP and Label Distribution
• Used in MPLS traffic engineering
• Additions to RSVP signaling protocol
• Leverage the admission control mechanism
of RSVP
• Label requests are sent in PATH messages and
binding is done with RESV messages
• EXPLICT-ROUTE object defines the path over which
setup messages should be routed
• Using RSVP has several advantages
BGP-Based Label Distribution
• Used in the context of MPLS VPNs
• Need multi-protocol extensions to BGP
• Routers need to be BGP peers
Works in both RR and non-RR environment
• Label mapping info carried as part of NLRI
(Network Layer Reachability Information)