MPLS and Label Switching Networks, 2nd Edition

Description

Whether you're in an enterprise network or service provider environment, MPLS and Label-Switching Networks, Second Edition is the authoritative resource you need to understand MPLS technologies -- and implement them for competitive advantage. Writing specifically for network and communications professionals, renowned communication specialist Uyless Black illuminates the final MPLS standard through practical examples and realistic configuration diagrams. Black introduces every fundamental concept and protocol, explaining how MPLS works and how it can be applied in both IPv4 and IPv6 environments. This book's in-depth QoS coverage shows how to use MPLS to combat network latency and jitter; how to build more resilient service provider and ISP backbones; and how to configure networks for rapid service restoration. Black also presents in-depth coverage of MPLS-based VPNs, including security issues. Black introduces the new Generalized MPLS (GMPLS) protocol for optical networking, which extends MPLS to time, wavelength, and space-based switching domains. He also introduces Resource Reservation Protocol for Traffic Engineering (RSVP-TE), showing how to use it to maximize network reliability and utilization.

Sample Content

Online Sample Chapter

Using MPLS to Improve Network Performance

Table of Contents

Preface.


1. Introduction.

What is Label Switching? Why Use Label Switching? Speed and Delay. Scalability. Simplicity. Resource Consumption. Route Control (Control of the Forwarding Path). Route Control Using. The ZIP Code Analogy. Why a Label Is Not an Address. How Label Switching is Implemented and How it Came About. Clarification of Terms. The Need for a QOS-based Internet. Label Switching and QOS. The Contribution of Label Switching. Label SwitchingÕs Legacy: X.25 and Virtual Circuits. The Logical Channel Number: Precursor to the Label. Frame Relay and ATM: A Rose by Any Other Name Is Still a Rose. MPLS: Status and Concepts. Examples of Label and QOS Relationships. Determination of the Physical Path Through the Network: The Label Switched Path (LSP). Summary.

IP and MPLS Control and Data Planes. IP Control and Data Planes. MPLS Control and Data Planes. The Forwarding Equivalence Class. Scalability and Granularity. Granularity in Terabit Networks. Information Used in the Forwarding Decision. Label Allocation Methods. Local and Remote Binding. Downstream and Upstream Binding. Control Operations Followed by Data Operations. Label Space and Label Assignments. Execution of the Control Planes in a Label Switching Domain. Scenarios for Label Assignments. Relationships Between IP and MPLS Control Planes. Examples of FEC and Label Correlations: The Label Switching Tunnel. Alternatives for Carrying the Label. Label Swapping. Summary.

A Taxonomy of Switching and Forwarding Networks. Layer 2 Switching. Layer 3 Routing (Actually, Forwarding). Problem with IP Forwarding Operations. Layer 3 Switching. Cache-Assisted Switching. Distributed Switching. Example of Layer 3 Switching. Layer 4 Switching. Label Switching/Swapping/Mapping. Layer 3 to Layer 2 Mapping. At the Ingress LSR. At an Intermediate (Interior) LSR. At the Egress LSR. MPLS's Relationship to These Operations. IP Switching. Architecture of the IP Switch. Route-Server-Based Relaying. Route-Server-Based Operations. Multiprotocol Over ATM (MPOA) and Next Hop Resolution Protocol (NHRP). Tag Switching. Forwarding Component. Tag Encapsulation. Control Component. Tag Switching with ATM. Quality of Service. Examples of Tag Switching Operations. Border (Edge) TSRs. Flow Classification. IPv6 Flow Operations. IPv4 Codepoint Operations. MPLS and LDP. IPv6 Label Operations. Summary.

Major Attributes of MPLS. Terminology. Network Model for Examples. Types of MPLS Nodes. Uniqueness of Labels. MPLS Startup. Assigning Labels to FECs. Independent Control. Ordered Control. Unsolicited and Solicited Label Distribution. Example of the Label Information Base (LIB). Example of the Label Forwarding Information Base (LFIB). Liberal and Conservative Retention Modes. How MPLS can Recover from Link or Node Failures. Discovery of Inoperability. Problem with the Topology in the Network Model. The MPLS Header. The Label Stack. Stacking Rules for the Label Switched Path. Penultimate Hop Popping. Stacks and Encapsulations. Reserved Label Values. MPLS terms for LIB and LFIB. The Next Hop Label Forwarding Entry (NHLFE). FEC-to-NHLFE Map (FTN). Incoming Label Map (ILM). Aggregation. Label Merging. Scope and Uniqueness of Labels in a Label Space. Hop-by-Hop and Explicit Routing. Review of the Label Retention Mode. Advertising and Using Labels. The Downstream LSR (Rd) Procedures. The Upstream LSR (Ru) Procedure. NotAvailable Procedure. Release Procedure. Label Use Procedure. Summary.

The Issue of Label Granularity. Methods for Label Distribution. Advertising and Distributing Aggregated FECs. Ru Has Finer Granularity Than That of Rd. Ru Has Coarser Granularity Than That of Rd. Introduction to LDP. LDP Messages. FECs, Label Spaces, and Identifiers. Mapping Rules. Label Spaces and Identifiers. LDP Sessions. Sessions Between Indirectly Connected LSRs. How LSRs Know About Other LSRs. LDP Label Distribution and Management. Independent Control Mapping. Ordered Control Mapping. Downstream-on-Demand Label Advertisement. Problem Management for the First Three Distribution Methods. Downstream Unsolicited Label Advertisement. LDP Messages. The LDP Header. Type-Length-Value (TLV) Encoding. The LDP Message Format. TLVs: Formats and Functions. The LDP Messages: Formats and Functions. Loop Detection and control. Buffer Control. Time to Live (TTL). Path Vectors. Colored Threads. RSVP and Label Distribution. Aspects of RSVP Pertinent to MPLS. The Flow Descriptor. Interworking Concepts for MPLS and RSVP. More Information About RSVP Extensions. BGP and Label Distribution. Summary.

Aspects of ATM of Interest to MplS. Virtual Circuits. VPIs and VCIs. The ATM Cell Header. Permanent Virtual Circuits and Switched Virtual Calls. Other Important Fields in the ATM Cell. ATM and MPLS: Similarities and Differences. Scaling IP/ATM Overlay Networks. Principal Traffic Management Issues in and between ATM-LSRs. MPLS and ATM Interworking. Difficulty of Interleaving AAL5 Traffic. VC and VP Merging. The Merging Process. Reversing the Process with an MPLS Backbone. Mapping the MPLS Labels To ATM Vpis/VCIs. Types of Merging (or Nonmerging). Interoperation of VC Merge, VP Merge, and Non-merge. The Virtual Circuit ID. Notification Operation. VPI/VCI Values. Encapsulation And TTL Operations. Aspects of Frame Relay of Interest to MPLS. Virtual Circuits and DLCIs. The Frame Relay Header. Permanent Virtual Circuits and Switched Virtual Calls. Running ATM, Frame Relay and Others over MPLS. Summary.

Traffic Engineering Defined. Traffic-Oriented or Resource-Oriented Performance. The Congestion problem. Problem Description. Two Scenarios of Congestion. Services Based on QOS Needs and Classes of Traffic. Traffic Engineering and Traffic Shaping. Queuing the Traffic. Problems with Existing Routing Operations. The Overlay Network Approach. Induced MPLS Graph. Traffic Trunks, Traffic Flows, and Label Switched Paths. Attractiveness of MPLS for Traffic Engineering. Link Capacity: The Ultimate Arbiter. Load Distribution. Traffic Trunk Attributes. Attributes of Traffic Trunks for Traffic Engineering. Constraint-Based Routing (CR). Peak Rate. Committed Rate. Excess Burst Size. Peak Rate Token Bucket. Committed Data Rate Token Bucket. Weight. Differentiated Services, MPLS, and Traffic Engineering. Average Rate Meter. Exponential Weighted Moving Average Meter. Token Bucket Meter. Ideas on Shaping Operations. DS Guaranteed Rate. Assured and Expedited Forwarding PHBs. Examples of WFQ And MPLS Flows. Examples of MPLS Protection Switching. Using RSVP to Establish Alternate/Detour LSPs. Determining Which Path Protection Method to Use. Summary.

Review of IP-Based Routing Protocols. Routing Domains. Route Advertising. Routing Domains and the “Flat Network” Problem. Autonomous Systems. How Autonomous Systems Are Numbered. How a Host Is Made Known to Other Domains. Correlation (Binding) of the Prefixes to MPLS Labels. Multiple Routing Protocols. Overview of the Routing Protocols. Overview of OSPF. Role of the Router in OSPF. Directed Graphs. Key Operations. OSPF Areas. Packet Containment. Stub Areas. Revising OSPF to Support Constrained Routing and T. General Idea of Using OSPF in MPLS Networks. Traffic Engineering Extensions to OSPF. The LSA TE Extension. The TLVs. Role of OSPF in VPNs. Summary.

The Basic Concept. Explicit Routing. LDP and Constraint-based Routing. Strict and Loose Explicit Routes. Preemption. CR Messages and TLVs. Label Request Message. Label Mapping Message. Notification Message. Explicit Route TLV. Explicit Route Hop TLV. Traffic Parameters TLV. Preemption TLV. LSPID TLV. Resource Class TLV. Route Pinning TLV. CR-LSP FEC TLV. Summary.

WDM and Optical Networks. Relationships of Optical and MPLS Operations. Multiprotocol Lambda Switching (MPlS). MPLS and Optical Wavelength Mapping. Failure of the Optical Connection. Views on the MPLS Control Plane and the Optical Switch. Control Adaptation. Generalized MPLS Use in Optical Networks. Considerations for Interworking Layer 1 Lambdas and Layer 2 Labels. Examples of GMPLS Operations. Suggested Labels for Wavelengths. Bidirectional LSPs in Optical Networks. Label Contention Resolution. Link Protection. Summary.

Overview of VPNs. Role of Tunnels in VPNs (by Use of L2TP). Overview of BGP. BGP Neighbors. BGP Speakers. Communities. BGP Policy-Based Architecture. Path Selection with BGP. MPLS Label Stacking in the VPN. VPN Architecture. Customer Edge (CE) Devices. Multiple Forwarding Tables. Role of BGP in VPNs. The VPN-IP4 Address Family. Using BGP to Distribute the Address and the Label. Using Route Reflectors. Role of OSPF in VPNs. Disadvantages and Advantages of Using OSPF in the VPN. Principal Rules for Using OSPF in VPNs. Role of MPLS in VPNs. Keeping VPN Routers Out of P Routers. Isolating the VPNs. Summary.

Diffserv Concepts. Per-Hop Behavior. The Diffserv Domain. Types of Per-Hop Behaviors. MplS and Diffserv Routers. Traffic Classification and Conditioning. DS Classifiers. Behavior Aggregates, Ordered Aggregates, and LSPs. Classification Operations. Metering Operations. The DS Codepoint Revisited. Codepoints for Assured Forwarding. DSCPs and LSR Use of MPLS Labels. The Ordered Aggregate and MPLS LSPS. EXP-Inferred-PSC LSPs. Label-Only-Inferred-PSC LSPs. Bandwidth Reservations for E-LSPs and L-LSPs. Summary.

Principal Addresses Used in Internet and Intranets. MAC Address. Network Address. IP Address. Address Aggregation and Subnet Masks and Prefixes. Variable Length Submasks. High Overhead of IP Forwarding.

CR-LDP and ATM QOS. Parameters for ATM/CR-LDP Interworking. CR-LDP Parameters. CR-LDP Interworking with ATM QOS. CR-LDP and Frame Relay QOS. CR-LDP and RSVP Traffic Engineering (RSVP-TE).

Preface

Preface

As the name of this book implies, the focus is on the switching of traffic though a network or networks. The term switching is also known in some parts of the industry as forwarding, relaying, and routing.

In many of my explanations of label switching operations, I have relied on the Internet Request for Comments (RFCs) and draft standards, published by the Internet Society, and I thank this organization for making the RFCs available to the public. The draft standards are "works in progress," and usually change as they wind their way to an RFC (if indeed they become an RFC). A work in progress cannot be considered final, but many vendors use them in creating products for the marketplace. Notwithstanding, they are subject to change.

For all the Internet standards and draft standards the following applies:

Copyright © The Internet Society (1998). All Rights Reserved.

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.

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