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Transcript of © 2006 Cisco Systems, Inc. All rights reserved. MPLS v2.2—1-1 MPLS Concepts Introducing Basic...
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v2.2—1-1
MPLS Concepts
Introducing Basic MPLS Concepts
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v2.2—1-2
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 v2.2—1-3
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 v2.2—1-4
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 v2.2—1-5
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 v2.2—1-6
Benefits of MPLS
• MPLS supports multiple applications including:
–Unicast and multicast IP routing
–VPN
– TE
–QoS
–AToM
• MPLS decreases forwarding overhead on core routers.
• MPLS can support forwarding of non-IP protocols.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v2.2—1-9
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 v2.2—1-10
Label Switch Routers: Architecture of LSRs
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v2.2—1-11
LSR Architecture Example
MPLS router functionality is divided into two major parts: the control plane and the data plane.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v2.2—1-13
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 v2.2—1-14
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.