MPLS and Label Switching Networks

by Black, Uyless N.

• ISBN13: 9780130358196
• ISBN10: 0130358193
• Edition: 2nd
• Format: Paperback
• Copyright: 2002-04-09
• Publisher: Prentice Hall

Summary

The authoritative, practical introduction to the final MPLS standard! Fully updated to cover the final, official MPLS standard Presents detailed enterprise and service provider example scenarios Includes up-to-the-minute coverage of QoS and MPLS-based VPNs Introduces the new Generalized MPLS and RSVP-TE protocols MPLS will be at the heart of tomorrow's flexible, manageable, and cost-effective networks. MPLS and Label Switching Networks, Second Edition is the authoritative resource you need to understand MPLS technologies-and implement them for competitive advantage. Renowned communications consultant Uyless Black illuminates the final MPLS standard through practical examples and detailed diagrams, offering start-to-finish guidance on using MPLS to maximize network reliability, utilization, and performance. Coverage includes: Integrating MPLS into ATM and Frame Relay networks-and both IPv4 and IPv6 environments Traffic engineering-including RSVP-TE and CR-LDP Building more resilient service provider and ISP backbones Configuring MPLS-based networks for rapid service restoration Deploying and securing MPLS-based VPNs GMPLS for optical networks: accelerating service deployment and improving operational efficiency Whether you're in an enterprise or service provider environment, MPLS and Label Switching Networks, Second Edition gives you insight and clarity for planning, deploying, and succeeding with MPLS technologies-starting today.

Author Biography

Uyless Black is a widely respected telecommunications consultant and lecturer with extensive operations and implementation experience in both public and private networks

Table of Contents

Preface	xxi
Introduction	1	(20)
What is Label Switching?	1	(1)
Why Use Label Switching?	2	(5)
Speed and Delay	2	(1)
Scalability	3	(1)
Simplicity	3	(1)
Resource Consumption	4	(1)
Route Control (Control of the Forwarding Path)	4	(1)
Route Control Using IP	5	(2)
The ZIP Code Analogy	7	(1)
Why a Label Is Not an Address	8	(3)
How Label Switching is Implemented and How it Came About	11	(1)
Clarification of Terms	11	(1)
The Need for a QOS-based Internet	12	(2)
Label Switching and QOS	13	(1)
The Contribution of Label Switching	14	(1)
Label Switching's Legacy: X.25 and Virtual Circuits	14	(2)
The Logical Channel Number: Precursor to the Label	15	(1)
Frame Relay and ATM: A Rose by Any Other Name is Still a Rose	16	(1)
MPLS: Status and Concepts	16	(1)
Examples of Label and QOS Relationships	17	(2)
Determination of the Physical Path Through the Network: The Label Switched Path (LSP)	19	(1)
Summary	20	(1)
Label Switching Basics	21	(17)
IP and MPLS Control and Data Planes	21	(3)
IP Control and Data Planes	22	(1)
MPLS Control and Data Planes	23	(1)
The Forwarding Equivalence Class	24	(3)
Scalability and Granularity	25	(1)
Granularity in Terabit Networks	25	(1)
Information Used in the Forwarding Decision	26	(1)
Label Allocation Methods	27	(1)
Local and Remote Binding	27	(1)
Downstream and Upstream Binding	27	(1)
Control Operations Followed by Data Operations	28	(1)
Label Space and Label Assignments	29	(1)
Execution of the Control Planes in a Label Switching Domain	30	(4)
Scenarios for Label Assignments	32	(2)
Relationships Between IP and MPLS Control Planes	34	(1)
Examples of FEC and Label Correlations: The Label Switching Tunnel	34	(1)
Alternatives for Carrying the Label	35	(1)
Label Swapping	35	(2)
Summary	37	(1)
Switching and Forwarding Operations	38	(31)
A Taxonomy of Switching and Forwarding Networks	38	(2)
Layer 2 Switching	40	(1)
Layer 3 Routing (Actually, Forwarding)	41	(1)
Problem with IP Forwarding Operations	41	(1)
Layer 3 Switching	42	(2)
Cache-Assisted Switching	42	(1)
Distributed Switching	42	(1)
Example of Layer 3 Switching	42	(2)
Layer 4 Switching	44	(1)
Label Switching/Swapping/Mapping	44	(1)
Layer 3 to Layer 2 Mapping	44	(3)
At the Ingress LSR	45	(1)
At an Intermediate (Interior) LSR	46	(1)
At the Egress LSR	47	(1)
MPLS's Relationship to These Operations	47	(1)
IP Switching	47	(4)
Architecture of the IP Switch	48	(3)
Route-Server-Based Relaying	51	(3)
Route-Server-Based Operations	51	(1)
Multiprotocol Over ATM (MPOA) and Next Hop Resolution Protocol (NHRP)	52	(2)
Tag Switching	54	(13)
Forwarding Component	55	(1)
Tag Encapsulation	56	(1)
Control Component	56	(3)
Tag Switching with ATM	59	(1)
Quality of Service	60	(1)
Examples of Tag Switching Operations	60	(2)
Border (Edge) TSRs	62	(4)
Flow Classification	66	(1)
IPv6 Flow Operations	66	(1)
IPv4 Codepoint Operations	67	(1)
MPLS and LDP	67	(1)
IPv6 Label Operations	67	(1)
Summary	68	(1)
MPLS Key Concepts	69	(33)
Major Attributes of MPLS	69	(1)
Terminology	70	(1)
Network Model for Examples	71	(2)
Types of MPLS Nodes	73	(1)
Uniqueness of Labels	74	(1)
MPLS Startup	75	(1)
Assigning Labels to FECs	75	(3)
Independent Control	75	(2)
Ordered Control	77	(1)
Unsolicited and Solicited Label Distribution	78	(1)
Example of the Label Information Base (LIB)	78	(1)
Example of the Label Forwarding Information Base (LFIB)	79	(1)
Liberal and Conservative Retention Modes	80	(1)
How MPLS Can Recover from Link or Node Failures	80	(2)
Discovery of Inoperability	80	(2)
Problem with the Topology in the Network Model	82	(1)
The MPLS Header	82	(1)
The Label Stack	83	(4)
Stacking Rules for the Label Switched Path	87	(2)
Penultimate Hop Popping	87	(1)
Stacks and Encapsulations	88	(1)
Reserved Label Values	89	(1)
MPLS terms for LIB and LFIB	89	(2)
The Next Hop Label Forwarding Entry (NHLFE)	90	(1)
FEC-to-NHLFE Map (FTN)	90	(1)
Incoming Label Map (ILM)	91	(1)
Aggregation	91	(1)
Label Merging	92	(1)
Scope and Uniqueness of Labels in a Label Space	93	(1)
Hop-by-Hop and Explicit Routing	94	(1)
Review of the Label Retention Mode	95	(1)
Advertising and Using Labels	95	(6)
The Downstream LSR (Rd) Procedures	96	(3)
The Upstream LSR (Ru) Procedure	99	(1)
NotAvailable Procedure	100	(1)
Release Procedure	100	(1)
Label Use Procedure	101	(1)
Summary	101	(1)
Label Distribution Operations	102	(36)
The Issue of Label Granularity	102	(1)
Methods for Label Distribution	103	(1)
Advertising and Distributing Aggregated FECs	104	(2)
Ru Has Finer Granularity Than That of Rd	104	(1)
Ru Has Coarser Granularity Than That of Rd	105	(1)
Introduction to LDP	106	(1)
LDP Messages	107	(1)
FECs, Label Spaces, and Identifiers	107	(2)
Mapping Rules	108	(1)
Label Spaces and Identifiers	108	(1)
LDP Sessions	109	(1)
Sessions Between Indirectly Connected LSRs	109	(1)
How LSRs Know About Other LSRs	110	(1)
LDP Label Distribution and Management	110	(4)
Independent Control Mapping	111	(1)
Ordered Control Mapping	111	(1)
Downstream-on-Demand Label Advertisement	112	(1)
Problem Management for the First Three Distribution Methods	113	(1)
Downstream Unsolicited Label Advertisement	113	(1)
LDP Messages	114	(12)
The LDP Header	114	(1)
Type-Length-Value (TLV) Encoding	115	(1)
The LDP Message Format	115	(1)
TLVs: Formats and Functions	116	(3)
The LDP Messages: Formats and Functions	119	(7)
Loop Detection and Control	126	(3)
Buffer Control	127	(1)
Time to Live (TTL)	127	(1)
Path Vectors	127	(1)
Colored Threads	127	(2)
RSVP and Label Distribution	129	(7)
Aspects of RSVP Pertinent to MPLS	130	(2)
The Flow Descriptor	132	(1)
Interworking Concepts for MPLS and RSVP	133	(2)
More Information About RSVP Extensions	135	(1)
BGP and Label Distribution	136	(1)
Summary	137	(1)
MPLS and ATM and Frame Relay Networks	138	(24)
Aspects of ATM of Interest to MPLS	139	(8)
Virtual Circuits	139	(1)
VPIs and VCIs	139	(2)
The ATM Cell Header	141	(2)
Permanent Virtual Circuits and Switched Virtual Calls	143	(1)
Other Important Fields in the ATM Cell	143	(2)
ATM and MPLS: Similarities and Differences	145	(2)
Scaling IP/ATM Overlay Networks	147	(2)
Principal Traffic Management Issues in and between ATM-LSRs	149	(2)
MPLS and ATM Interworking	149	(1)
Difficulty of Interleaving AAL5 Traffic	150	(1)
VC and VP Merging	151	(3)
The Merging Process	151	(2)
Reversing the Process with an MPLS Backbone	153	(1)
Mapping the MPLS Labels To ATM VPIs/VCIs	154	(1)
Types of Merging (or Nonmerging)	155	(1)
Interoperation of VC Merge, VP Merge, and Non-merge	155	(1)
The Virtual Circuit ID	156	(1)
Notification Operation	157	(1)
VPI/VCI Values	158	(1)
Encapsulation And TTL Operations	158	(1)
Aspects of Frame Relay of Interest to MPLS	159	(2)
Virtual Circuits and DLCIs	159	(1)
The Frame Relay Header	160	(1)
Permanent Virtual Circuits and Switched Virtual Calls	161	(1)
Running ATM, Frame Relay and Others Over MPLS	161	(1)
Summary	161	(1)
Traffic Engineering	162	(32)
Traffic Engineering Defined	162	(1)
Traffic-Oriented or Resource-Oriented Performance	163	(1)
The Congestion Problem	163	(2)
Problem Description	163	(1)
Two Scenarios of Congestion	164	(1)
Services Based on QOS Needs and Classes of Traffic	165	(1)
Traffic Engineering and Traffic Shaping	166	(1)
Queuing the Traffic	167	(1)
Problems with Existing Routing Operations	168	(1)
The Overlay Network Approach	169	(1)
Induced MPLS Graph	170	(1)
Traffic Trunks, Traffic Flows, and Label Switched Paths	171	(1)
Attractiveness of MPLS for Traffic Engineering	171	(1)
Link Capacity: The Ultimate Arbiter	172	(1)
Load Distribution	172	(1)
Traffic Trunk Attributes	173	(5)
Attributes of Traffic Trunks for Traffic Engineering	173	(5)
Constraint-Based Routing (CR)	178	(3)
Peak Rate	179	(1)
Committed Rate	179	(1)
Excess Burst Size	179	(1)
Peak Rate Token Bucket	179	(1)
Committed Data Rate Token Bucket	180	(1)
Weight	180	(1)
Differentiated Services, MPLS, and Traffic Engineering	181	(1)
Average Rate Meter	181	(1)
Exponential Weighted Moving Average Meter	181	(1)
Token Bucket Meter	181	(1)
Ideas on Shaping Operations	182	(3)
DS Guaranteed Rate	182	(2)
Assured and Expedited Forwarding PHBs	184	(1)
Examples of WFQ And MPLS Flows	185	(2)
Examples of MPLS Protection Switching	187	(6)
Using RSVP to Establish Alternate/Detour LSPs	191	(2)
Determining Which Path Protection Method to Use	193	(1)
Summary	193	(1)
OSPF in MPLS Networks	194	(17)
Review of IP-Based Routing Protocols	194	(1)
Routing Domains	195	(2)
Route Advertising	195	(1)
Routing Domains and the ``Flat Network'' Problem	196	(1)
Autonomous Systems	197	(2)
How Autonomous Systems Are Numbered	197	(1)
How a Host Is Made Known to Other Domains	198	(1)
Correlation (Binding) of the Prefixes to MPLS Labels	199	(1)
Multiple Routing Protocols	200	(1)
Overview of the Routing Protocols	201	(1)
Overview of OSPF	202	(4)
Role of the Router in OSPF	203	(1)
Directed Graphs	203	(1)
Key Operations	204	(1)
OSPF Areas	205	(1)
Packet Containment	205	(1)
Stub Areas	206	(1)
Revising OSPF to Support Constrained Routing and TE	206	(1)
General Idea of Using OSPF in MPLS Networks	207	(1)
Traffic Engineering Extensions to OSPF	208	(2)
The LSA TE Extension	208	(1)
The TLVs	209	(1)
Role of OSPF in VPNs	210	(1)
Summary	210	(1)
Constraint-Based Routing with CR-LDP	211	(10)
The Basic Concept	211	(1)
Explicit Routing	212	(1)
LDP and Constraint-based Routing	213	(1)
Strict and Loose Explicit Routes	213	(1)
Preemption	213	(1)
CR Messages and TLVs	214	(7)
Label Request Message	214	(1)
Label Mapping Message	215	(1)
Notification Message	216	(1)
Explicit Route TLV	216	(1)
Explicit Route Hop TLV	216	(1)
Traffic Parameters TLV	216	(2)
Preemption TLV	218	(1)
LSPID TLV	219	(1)
Resource Class TLV	220	(1)
Route Pinning TLV	220	(1)
CR-LSP FEC TLV	220	(1)
Summary	221	(1)
MPLS, Optical Networks, and GMPLS	221	(16)
WDM and Optical Networks	221	(3)
Relationships of Optical and MPLS Operations	222	(2)
Multiprotocol Lambda Switching (MPλS)	224	(3)
MPLS and Optical Wavelength Mapping	224	(2)
Failure of the Optical Connection	226	(1)
Views on the MPLS Control Plane and the Optical Switch	227	(1)
Control Adaptation	227	(1)
Generalized MPLS Use in Optical Networks	228	(7)
Considerations for Interworking Layer 1 Lambdas and Layer 2 Labels	229	(1)
Examples of GMPLS Operations	230	(4)
Suggested Labels for Wavelengths	234	(1)
Bidirectional LSPs in Optical Networks	235	(1)
Label Contention Resolution	235	(1)
Link Protection	235	(1)
Summary	236	(1)
VPNs with L2TP, BGP, OSPF, and MPLS	237	(15)
Overview of VPNs	237	(1)
Role of Tunnels in VPNs (by Use of L2TP)	238	(3)
Overview of BGP	241	(2)
BGP Neighbors	242	(1)
BGP Speakers	242	(1)
Communities	243	(1)
BGP Policy-Based Architecture	243	(1)
Path Selection with BGP	244	(1)
MPLS Label Stacking in the VPN	244	(1)
VPN Architecture	245	(2)
Customer Edge (CE) Devices	245	(1)
Multiple Forwarding Tables	246	(1)
Role of BGP in VPNs	247	(1)
The VPN-IP4 Address Family	247	(1)
Using BGP to Distribute the Address and the Label	247	(1)
Using Route Reflectors	248	(1)
Role of OSPF in VPNs	248	(2)
Disadvantages and Advantages of Using OSPF in the VPN	248	(1)
Principal Rules for Using OSPF in VPNs	249	(1)
Role of MPLS in VPNs	250	(1)
Keeping VPN Routers Out of P Routers	250	(1)
Isolating the VPNs	251	(1)
Summary	251	(1)
MPLS and DiffServ	252	(16)
Diffserv Concepts	252	(1)
Per-Hop Behavior	253	(1)
The Diffserv Domain	253	(1)
Types of Per-Hop Behaviors	254	(2)
MPLS and Diffserv Routers	256	(1)
Traffic Classification and Conditioning	257	(3)
DS Classifiers	258	(1)
Behavior Aggregates, Ordered Aggregates, and LSPs	258	(2)
Classification Operations	260	(1)
Metering Operations	261	(1)
The DS Codepoint Revisited	262	(2)
Codepoints for Assured Forwarding	264	(1)
DSCPs and LSR Use of MPLS Labels	264	(1)
The Ordered Aggregate and MPLS LSPS	265	(2)
EXP-Inferred-PSC LSPs	265	(1)
Label-Only-Inferred-PSC LSPs	266	(1)
Bandwidth Reservations for E-LSPs and L-LSPs	266	(1)
Summary	267	(1)
Appendix A Names, Addresses, Subnetting, Address Masks, and Prefixes	268	(23)
Principal Addresses Used in Internet and Intranets	269	(12)
MAC Address	270	(2)
Network Address	272	(2)
IP Address	274	(7)
Address Aggregation and Subnet Masks and Prefixes	281	(6)
Variable Length Submasks	287	(2)
High Overhead of IP Forwarding	289	(2)
Appendix B CR-LDP and Traffic Engineering and QOS	291	(8)
CR-LDP and ATM QOS	292	(3)
Parameters for ATM/CR-LDP Interworking	292	(2)
CR-LDP Parameters	294	(1)
CR-LDP Interworking with ATM QOS	295	(1)
CR-LDP and Frame Relay QOS	295	(1)
CR-LDP and RSVP Traffic Engineering (RSVP-TE)	295	(4)
References	299	(2)
Acronyms	301

Excerpts

PrefaceAs 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. Internet Drafts: Work in ProgressIn 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 copy; 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.