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


Agenda :July 29, 2000 TECON 2000 2 Agenda MPLS - The Motivation How MPLS Works ! MPLS Technology MPLS Application


MPLS - The Motivation :July 29, 2000 TECON 2000 3 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.


MPLS Working Groups and Standards :July 29, 2000 TECON 2000 4 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)


MPLS and ISO model :July 29, 2000 TECON 2000 5 MPLS and ISO model PPP 2 4 Frame Relay ATM (*) TCP UDP 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


Agenda :July 29, 2000 TECON 2000 6 Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application


Slide 7:July 29, 2000 TECON 2000 7 MPLS Architecture


Slide 8:July 29, 2000 TECON 2000 8 Label swapping Label removal Classification Label assignment Label swapping Label removal Classification Label assignment MPLS process


Slide 9:July 29, 2000 TECON 2000 9 MPLS Cloud LSR LER LSR LER IP Packet IP Packet w/ Label L3 Routing L3 Routing Label Swapping Label Swapping LER LER LER L3 Routing L3 Routing L3 Routing


Slide 10:July 29, 2000 TECON 2000 10 MPLS Link Layers & Label Encapsulation ATM FR Ethernet PPP VPI VCI DLCI “Shim Label” Layer2 “Shim header” ……. IP | PAYLOAD


Agenda :July 29, 2000 TECON 2000 11 Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application


Some MPLS Terms... :July 29, 2000 TECON 2000 12 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.


Slide 13:July 29, 2000 TECON 2000 13 FEC Classification


Slide 14:July 29, 2000 TECON 2000 14 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).


MPLS Label Assignment Schemes :July 29, 2000 TECON 2000 15 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


Slide 16:July 29, 2000 TECON 2000 16 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 : 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


Slide 17:July 29, 2000 TECON 2000 17 Label Switched Path MPLS switch MPLS switch MPLS switch MPLS switch 1 2 3 1 2 3 1 2 3 4 1 2 3 138.120 192.168 127.20


Slide 18:July 29, 2000 TECON 2000 18 Hop by Hop IP forwarding


Slide 19:July 29, 2000 TECON 2000 19 MPLS switch MPLS switch MPLS switch MPLS switch 1 2 3 1 2 3 1 2 3 4 1 2 3 138.120 192.168 127.20 IP forwarding using LSP


Slide 20:July 29, 2000 TECON 2000 20 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


Slide 21:July 29, 2000 TECON 2000 21 Downstream stream on demand Mapping 12 Mapping 5 5 12 12 5 Request 138.120 Request 138.120 The label is requested by the upstream node and the downstream node defines the label used.


Slide 22:July 29, 2000 TECON 2000 22 Unsolicited Downstream Mapping 12 Mapping 5 5 12 12 5 The downstream node defines the label and advertises it to the upstream node.


Slide 23:July 29, 2000 TECON 2000 23 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


Slide 24:July 29, 2000 TECON 2000 24 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


Agenda :July 29, 2000 TECON 2000 25 Agenda Motivation for MPLS How MPLS Works ! MPLS Technology MPLS Application


MPLS Advantages :July 29, 2000 TECON 2000 26 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


Slide 27:July 29, 2000 TECON 2000 27 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


Slide 28:July 29, 2000 TECON 2000 28 Explicitly Routed LSP End-to-End forwarding decision determined by ingress node. Enables Traffic Engineering LER 1 LSR 2 LSR 3 LER 4 Forward to LSR 2 LSR 3 LSR 4 LSR X Overload !! Overload !!


Slide 29:July 29, 2000 TECON 2000 29 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.


Slide 30:July 29, 2000 TECON 2000 30 MPLS VPN : MPLS topology ISP Backbone LSP 32 LSP 47


MPLS - Some Major Vendors :July 29, 2000 TECON 2000 31 MPLS - Some Major Vendors Alcatel Cisco Juniper Networks Nortel Lucent


MPLS - More Information @ :July 29, 2000 TECON 2000 32 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


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


MPLS - An Analysis :July 29, 2000 TECON 2000 34 MPLS - An Analysis UDP Rate (in Mbps) Throughput (in Mbps) TCP 1 UDP TCP 2 TCP & UDP Flows without MPLS


Slide 35:July 29, 2000 TECON 2000 35 MPLS - An Analysis UDP Rate (in Mbps) Throughput (in Mbps) TCP 1 UDP TCP 2 TCP & UDP Flows with MPLS Trunks (LSPs)