T (MULTI-PROTOCOL LABEL SWITCHING)

IP Hop-by-hop 3 (IP)

IP

Multi-Protocol Label Switching (labels) 2 & 3 (data link & network) 2 3

MPLS Forwarding & Control (1/2) MPLS . MPLSATM (VPI/VCI) / FRAME RELAY (DLCI) /TDM (timeslot) / X25 (LCN)Data LinkLayerNetwork LayerIPLDP/CR-LDPTE-RSVPMPLS forwardingBGPIS-ISOSPFRIP

MPLS Forwarding & Control (2/2)

IP MPLS : , 2

Label Switching Routers - (Label-Switching Routers, LSRs). Label Edge Routers (LER) Edge LSRLabel Switching Routers (LSRs)

MPLSLabel Switching RouterForwarding Equivalence Class (FEC) LabelLabel Switched Path () Label Swap Operation LSRsLabel Information Base (LIB) LSRLabel Distribution Protocol (LDP) ( LIB)

Forwarding Equivalence Class (FEC)A group of IP packets which are forwarded in the same manner (e.g., over the same path, with the same forwarding treatment) (RFC3031 Definition)IP2IP3IP1IP1IP2IP3

LabelA short fixed length physically contiguous identifier which is used to identify a FEC, usually of local significance (RFC3031 Definition)

Label StackLayer 2 HeaderLabel 3IP PacketLabel 2Label 1MPLS Domain 1MPLS Domain 2MPLS Domain 3

Position of MPLS Label

LDP & LIB47.147.247.3123121233MPLS Label Distribution based on routing tableLDP: ( LIB)

Intf

In

Label In

Dest

Intf Out

3

0.40

47.1

1

Intf

In

Label In

Dest

Intf Out

Label Out

3

0.50

47.1

1

0.40

Intf

In

Dest

Intf Out

Label Out

3

47.1

1

0.50

LSP47.147.247.3121233123MPLS SwitchingLSP:

Intf

In

Label In

Dest

Intf Out

3

0.40

47.1

1

Intf

In

Label In

Dest

Intf Out

Label Out

3

0.50

47.1

1

0.40

Intf

In

Dest

Intf Out

Label Out

3

47.1

1

0.50

Label Swap123

Intf

In

Label In

Dest

Intf Out

Label Out

3

0.70

47.2

2

0.80

3

0.50

47.1

1

0.40

MPLS control process (1 of 4)User PlaneControl PlaneRouting TablePacket ClassificationNext Hop + PortQueuing and Schedule rulesOutput QueueConventional IP forwarding

MPLS control process (2 of 4)User PlaneControl PlaneClassification to FECNext Hop + Port Queuing and Schedule rulesOutput QueueFECMPLS Ingress NodeLabelPush

MPLS control process (3 of 4)User PlaneControl PlaneNext Hop + Port Queuing and Schedule rulesOutput QueueLabelSwapMPLS Intermediate Node

MPLS control process (4 of 4)User PlaneControl PlaneNext Hop + Port Queuing and Schedule rulesOutput QueueMPLS LabelLabelPopMPLS Egress Node

(Label Distribution) LIB LSR { , } { , } :downstream unsoliciteddownstream on-demand LSP ,

(Explicit Routes) : / : ( )

E (Label Distribution Protocol, LDP) LSRs LSPs LSR LDP TCP, LSRs Downstream Unsolicited Downstream On demand ...

LSP -. :

Constraint Routed LDP, CR-LDP

RSVP , RSVP-TE

CR-LDP LDP . TCP LSRs CR-LDP LSPID: (-tunnel)ER: ( IP )Resource Class ( Color): Peak Rate, Committed rate, Excess Burst size, Variable Delay

CR-LDP LSPLSP LSR A LSR C LSP LSR B. O LSR A LABEL_REQUEST (B, C). LSR A LSP, LSR B TCP.O LSR B , LABEL_REQUEST LSR C. LSR C LSP. LSP LSP B LABEL_MAPPING LSR B , , LSP, LIB LSR LABEL_MAPPING LSR A , LSR A LSR LSR LSP

RSVP-TE RSVP : . : PATH RESV LDP PATH :LABEL_REQUEST & EXPLICIT_ROUTE RESV :LABEL_MAPPING: LSP LSR A LSR C CR-LDP: RESV

CR-LDP RSVP-TE

& LSP LSP . (explicit route) LSR . LSP LSP CR-LDP RSVP RSVP: (refresh) Path LSP. time-out (: ) CR-LDP & RSVP: Makebeforebreak: . LSR (: ) LSP

MPLS IP connectionless connection-oriented 2 LSP (scalable) IP ATM IP-over-SONET VPNs

- Go to IETF MPLS WG for RFCs and Ids: http://www.ietf.org/html.charters/mpls-charter.htmlRFCsRFC2702 Requirements for Traffic Engineering Over MPLSRFC3031 MPLS ArchitectureRFC3032 MPLS Label Stack EncodingRFC3036 LDP SpecificationInternet-Drafts (IDs)draft-ietf-mpls-generalized-signaling-02.txt (GMPLS)MPLS resourcesMPLS Resources Center http://www.mplsrc.com/MPLS Forum http://www.mplsforum.com/The Internet Protocol Journal, Cisco, Volume 4, Number 3, September 2001http://www.cisco.com/ipj