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

3. July 29, 2000 TECON 20002 Agenda MPLS - The Motivation How MPLS Works ! MPLS Technology MPLS Application

4. July 29, 2000 TECON 20003 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.

5. July 29, 2000 TECON 20004 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)

6. July 29, 2000 TECON 20005 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

7. July 29, 2000 TECON 20006 Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application

8. July 29, 2000 TECON 20007 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

9. July 29, 2000 TECON 20008 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

10. July 29, 2000 TECON 20009 MPLS Cloud LSR LER LSR LER IP Packet IP Packet w/ Label L3 Routing Label Swapping LER L3 Routing

11. July 29, 2000 TECON 200010 MPLS Link Layers & Label Encapsulation ATMFR Ethernet PPP VPIVCI DLCI“Shim Label” Layer2 “Shim header” ……. IP | PAYLOAD

12. July 29, 2000 TECON 200011 Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application

13. July 29, 2000 TECON 200012 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.

14. July 29, 2000 TECON 200013 Ingress LabelFECEgress Label 6138.120.6/24 - xxxx9 Ingress LabelAttributeFECEgress Label Ingress LabelFECEgress Label 6138.120.6/24 - xxxx9 Attribute A 6138.120.6/24 - 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

15. July 29, 2000 TECON 200014 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 1-115 (i.e. 0/25)F49 (i.e. 101)5-1 FR Gig Eth5-17F122 (i.e. 4/65)3-4 ATM

16. July 29, 2000 TECON 200015 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

17. July 29, 2000 TECON 200016 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

18. July 29, 2000 TECON 200017 Label Switched Path 5 12 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120 312 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120x 4 5 3 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x 138.120 MPLS switch 1 2 3 12 3 1 2 3 4 1 2 3 138.120 192.168 127.20

19. July 29, 2000 TECON 200018 MPLS switch 1 2 3 12 3 1 2 3 4 1 2 3 138.120 192.168 127.20 138.120.6.12 ?? 138.120.6.12 Default3 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x None ?? 138.120.6.12 ?? 138.120.6.12 Default Ingress Interface Ingress Label FECEgress Interface Egress Label 1 None 3 ?? 138.120.6.12 ?? 138.120.6.12 Default Ingress Interface Ingress Label FECEgress Interface Egress Label 1 Nonex 4 ?? 138.120.6.12 Hop by Hop IP forwarding

20. July 29, 2000 TECON 200019 5 12 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120 312 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120x 4 5 3 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x 138.120 MPLS switch 1 2 3 12 3 1 2 3 4 1 2 3 138.120 192.168 127.20 138.120.6.12 IP forwarding using LSP

21. July 29, 2000 TECON 200020 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

22. July 29, 2000 TECON 200021 Downstream stream on demand Mapping 12 Mapping 5 5 12 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120 3 12 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120x 4 5 3 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x 138.120 Request 138.120 MPLS switch 1 2 3 12 3 1 2 3 4 1 2 3 138.120 192.168 127.20 The label is requested by the upstream node and the downstream node defines the label used.

23. July 29, 2000 TECON 200022 Unsolicited Downstream MPLS switch 1 2 3 12 3 1 2 3 4 1 2 3 138.120 192.168 127.20 Mapping 12 Mapping 5 5 12 5 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120 3 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 138.120x 43 Ingress Interface Ingress Label FECEgress Interface Egress Label 1 x 138.120 The downstream node defines the label and advertises it to the upstream node.

24. July 29, 2000 TECON 200023 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

25. July 29, 2000 TECON 200024 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

26. July 29, 2000 TECON 200025 Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application

27. July 29, 2000 TECON 200026 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

28. July 29, 2000 TECON 200027 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

29. July 29, 2000 TECON 200028 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 !!

30. July 29, 2000 TECON 200029 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.

31. July 29, 2000 TECON 200030 MPLS VPN : MPLS topology Site A 138.120.8.0/24 VPN 2Site B 138.120.6.0/24 VPN 2 ISP Backbone LSR Site A 138.120.8.0/24 VPN 1 Site B 138.120.6.0/24 VPN 1 LSP 32 LSP 47

32. July 29, 2000 TECON 200031 MPLS - Some Major Vendors Alcatel Cisco Juniper Networks Nortel Lucent

33. July 29, 2000 TECON 200032 MPLS - More Information @ MPLS Charter http://www.ietf.org/html.charters/mpls-charter.html MPLS Resource Center http://www.mplsrc.com MPLS Forum http://www.mplsforum.org

34. Any Questions ? Thanks for your time ! Email Pramoda.Nallur@ind.alcatel.com

35. July 29, 2000 TECON 200034 MPLS - An Analysis UDP Rate (in Mbps) Throughput (in Mbps) TCP 1 UDP TCP 2 TCP & UDP Flows without MPLS

36. July 29, 2000 TECON 200035 MPLS - An Analysis UDP Rate (in Mbps) Throughput (in Mbps) TCP 1 UDP TCP 2 TCP & UDP Flows with MPLS Trunks (LSPs)