MultiProtocol Label Switching (MPLS) July 29, 2000TECON 2000 Pramoda Nallur Alcatel Internetworking Division

July 29, 2000 TECON Agenda MPLS - The Motivation How MPLS Works ! MPLS Technology MPLS Application

July 29, 2000 TECON MPLS - The Motivation IP Protocol Suite - the most predominant networking technology. Voice & Data convergence on a single network infrastructure. Continual increase in number of users. Demand for higher connection speeds. Increase in traffic volumes. Ever-increasing number of ISP networks.

July 29, 2000 TECON MPLS Working Groups and Standards Standardized by the IETF - currently in Draft stage. MPLS recommendations are done by IP players for IP services MPLS core components are generic MPLS doesn’t use specific technology process (e.g. ATM/FR signaling protocol PNNI or ATM OAM flow)

July 29, 2000 TECON MPLS and ISO model PPP Physical (Optical - Electrical)1 2 IP3 4 Applications 7 to 5 Frame Relay ATM (*) TCPUDP PPPFRATM (*) MPLS (*) ATM overlay model (without addressing and P-NNI) is considered as an ISO layer 2 protocol. IETF main goal is that when a layer is added, no modification is needed on the existing layers. All new protocol must be backward compatible

July 29, 2000 TECON Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application

July 29, 2000 TECON MPLS Architecture Routing protocol OSPF Attributes PrecedenceLocal table Label table Local table LSP Label swappingLabel removal Classification Label assignment Ingress Node Core Node Egress Node Label Switch Layer 2 Layer 1 Layer 2 Layer 1 Layer 2 Layer 1 Layer 2 Layer 1 Layer 2 Layer 1 FEC table Local table

July 29, 2000 TECON Label swapping Label removal Classification Label assignment Label swapping Label removal Classification Label assignment OSPF / RIP / IS-IS Label Switch Path Label table Ingress Node Core Node Egress Node Layer 2 Layer 1 Layer 2 Layer 1 Layer 2 Layer 1 Precedence Label table Layer 2 Layer 1 Layer 2 Layer 1 FEC MPLS process

July 29, 2000 TECON MPLS Cloud LSR LER LSR LER IP Packet IP Packet w/ Label L3 Routing Label Swapping LER L3 Routing

July 29, 2000 TECON MPLS Link Layers & Label Encapsulation ATMFR Ethernet PPP VPIVCI DLCI“Shim Label” Layer2 “Shim header” ……. IP | PAYLOAD

July 29, 2000 TECON Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application

July 29, 2000 TECON Some MPLS Terms... LER - Label Edge Router LSR - Label Switch Router FEC - Forward Equivalence Class Label - Associates a packet to a FEC Label Stack - Multiple labels containing information on how a packet is forwarded. Shim - Header containing a Label Stack Label Switch Path - path that a packet follows for a specific FEC LDP - Label Distribution Protocol, used to distribute Label information between MPLS-aware network devices Label Swapping - manipulation of labels to forward packets towards the destination.

July 29, 2000 TECON Ingress LabelFECEgress Label /24 - xxxx9 Ingress LabelAttributeFECEgress Label Ingress LabelFECEgress Label /24 - xxxx9 Attribute A /24 - xxxx12B FECs are manually initiated by the operator A FEC is associated at least one Label A packet can be mapped to a particular FEC based on the following criteria: destination IP address, source IP address, TCP/UDP port, in case of inter AS-MPLS, Source-AS and Dest-AS, class of service, application used, … any combination of the previous criteria. FEC Classification

July 29, 2000 TECON What is a Label ? A short, fixed length, locally significant identifier used to identify a FEC. The label can be identified by the L2 technology identifier (e.g. VPI/VCI for ATM, DLCI for FR or MPLS label for PPP/Ethernet). L2 Type Port Ingress LabelEgress LabelFEC ATM1-112 (i.e. 4/65)F122 (i.e. 5/65)3-4 ATM (i.e. 0/25)F49 (i.e. 101)5-1 FR Gig Eth5-17F122 (i.e. 4/65)3-4 ATM

July 29, 2000 TECON MPLS Label Assignment Schemes Topology Driven –Label assignment in response to routing protocols (OSPF and BGP) updates Control Driven –Label assignment in response to RSVP, CR- LDP requests Traffic Driven –Label assignment in response to flow detection & triggering

July 29, 2000 TECON The MPLS Shim Header The Label (Shim Header) is represented as a sequence of Label Stack Entry Each Label Stack Entry is coded by 4 bytes (32 bits) as described 20 Bits is reserved for the Label Identifier (also named Label) Label (20 bits) Exp (3 bits) S (1 bit) TTL (8bits) Label : Label value (0 to 15 are reserved for special use) Exp : Experimental Use S : Bottom of Stack (set to 1 for the last entry in the label) TTL : Time To Live

July 29, 2000 TECON Label Switched Path 5 12 Ingress Interface Ingress Label FECEgress Interface Egress Label Ingress Interface Ingress Label FECEgress Interface Egress Label x Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x MPLS switch

July 29, 2000 TECON MPLS switch ?? Default3 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x None ?? ?? Default Ingress Interface Ingress Label FECEgress Interface Egress Label 1 None 3 ?? ?? Default Ingress Interface Ingress Label FECEgress Interface Egress Label 1 Nonex 4 ?? Hop by Hop IP forwarding

July 29, 2000 TECON Ingress Interface Ingress Label FECEgress Interface Egress Label Ingress Interface Ingress Label FECEgress Interface Egress Label x Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x MPLS switch IP forwarding using LSP

July 29, 2000 TECON MPLS Label Distribution Protocol LDP - a set of procedures by which one LSR informs the other of the FEC-to-Label binding it has made. Currently, several protocols used as Label Distribution Protocol (LDP) are available: –RSVP-TE (MPLS extension) –LDP and CR-LDP –BGP-4 MPLS extensions Label Distribution schemes

July 29, 2000 TECON Downstream stream on demand Mapping 12 Mapping Ingress Interface Ingress Label FECEgress Interface Egress Label Ingress Interface Ingress Label FECEgress Interface Egress Label x Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x Request MPLS switch The label is requested by the upstream node and the downstream node defines the label used.

July 29, 2000 TECON Unsolicited Downstream MPLS switch Mapping 12 Mapping Ingress Interface Ingress Label FECEgress Interface Egress Label Ingress Interface Ingress Label FECEgress Interface Egress Label x 43 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x The downstream node defines the label and advertises it to the upstream node.

July 29, 2000 TECON Edge LSR Features –Routing protocols –FEC Classification –Initiates LSP setup for Downstream On Demand method –Adaptation of non-MPLS data to MPLS data –Layer 2 translation for MPLS data –Terminated MPLS-VPN –At least one LDP protocol –Edge LSR is counted into the TTL count as a regular router

July 29, 2000 TECON Core LSR Features –Routing protocols –Propagates Downstream On Demand method (request and mapping) –Layer 2 translation –High speed label forwarding/switching –At least one LDP protocol

July 29, 2000 TECON Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application

July 29, 2000 TECON MPLS Advantages Simplified Forwarding Efficient Explicit Routing Traffic Engineering QoS Routing Mappings from IP Packet to Forwarding Equivalence Class (FEC) Partitioning of Functionality Common Operation over Packet and Cell media

July 29, 2000 TECON MPLS - the Future Who will use MPLS? –Large-scale data networks used by Enterprises, Carriers and ISPs. Why MPLS? –Delivers high speed L2 (really “Label”) switching at low cost vs. traditional L3 routing –Provides Traffic Engineering - allows the user to direct traffic based on network utilization and demand. –Ease of provisioning QoS –Support for VPNs

July 29, 2000 TECON Explicitly Routed LSP End-to-End forwarding decision determined by ingress node. Enables Traffic Engineering LER 1 LSR 2LSR 3 LER 4 Forward to LSR 2 LSR 3 LSR 4 LSR X Overload !!

July 29, 2000 TECON MPLS Traffic Engineering MPLS Traffic Engineering (TE) provides high quality IP service. TE defines : –LSP Admission Control (LAC) –IP traffic (policing or shaping) –IP service prioritization –Network capacity and growth capacity TE is primary done by external tools. This solution allows flexibility and customization.

July 29, 2000 TECON MPLS VPN : MPLS topology Site A /24 VPN 2Site B /24 VPN 2 ISP Backbone LSR Site A /24 VPN 1 Site B /24 VPN 1 LSP 32 LSP 47

July 29, 2000 TECON MPLS - Some Major Vendors Alcatel Cisco Juniper Networks Nortel Lucent

July 29, 2000 TECON MPLS - More MPLS Charter MPLS Resource Center MPLS Forum

Any Questions ? Thanks for your time !

July 29, 2000 TECON MPLS - An Analysis UDP Rate (in Mbps) Throughput (in Mbps) TCP 1 UDP TCP 2 TCP & UDP Flows without MPLS

July 29, 2000 TECON MPLS - An Analysis UDP Rate (in Mbps) Throughput (in Mbps) TCP 1 UDP TCP 2 TCP & UDP Flows with MPLS Trunks (LSPs)