MPLS Concepts Introducing Basic MPLS Concepts 2006 Cisco

Outline • Overview • What Are the Foundations of Traditional IP Routing? • Basic MPLS Features • Benefits of MPLS • What Are the MPLS Architecture Components? • What Are LSRs? • Summary © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -2

Foundations of Traditional IP Routing • Routing protocols are used to distribute Layer 3 routing information. • Forwarding decision is made based on: – Packet header – Local routing table • Routing lookups are independently performed at every hop. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -3

Traditional IP Routing • Every router may need full Internet routing information. • Destination-based routing lookup is needed on every hop. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -4

Basic MPLS Features • MPLS leverages both IP routing and CEF switching. • MPLS is a forwarding mechanism in which packets are forwarded based on labels. • MPLS was designed to support multiple Layer 3 protocols • Typically, MPLS labels correspond to destination networks (equivalent to traditional IP forwarding). © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -5

Benefits of MPLS • MPLS supports multiple applications including: – Unicast and multicast IP routing – VPN – TE – Qo. S – ATo. M • MPLS decreases forwarding overhead on core routers. • MPLS can support forwarding of non-IP protocols. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -6

MPLS Architecture: Control Plane © 2006 Cisco Systems, Inc. All rights reserved. MPLS v

MPLS Architecture: Data Plane © 2006 Cisco Systems, Inc. All rights reserved. MPLS v

MPLS Devices: LSRs • The LSR forwards labeled packets in the MPLS domain. • The edge LSR forwards labeled packets in the MPLS domain, and it forwards IP packets into and out of the MPLS domain. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -9

Label Switch Routers: Architecture of LSRs © 2006 Cisco Systems, Inc. All rights reserved.

LSR Architecture Example MPLS router functionality is divided into two major parts: the control

LSRs: Architecture of Edge LSRs © 2006 Cisco Systems, Inc. All rights reserved. MPLS

Basic MPLS Example • MPLS core routers swap labels and forward packets based on simple label lookups. • MPLS edge routers also perform a routing table lookup, and add or remove labels. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -13

Summary • Traditional IP routing forwards packets based on the destination address. • MPLS forwards packets based on labels. • MPLS supports multiple applications. • MPLS has two major architectural components: – Control plane (exchanges routing information, exchanges labels) – Data plane (forwards packets) • LSRs implement label exchange protocols and primarily forward packets based on labels. The role of Edge LSRs is primarily to forward packets into and out of the MPLS domain. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 1 -14