Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com The Complete IS-IS Routing Protocol Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Hannes Gredler and Walter Goralski The Complete IS-IS Routing Protocol 123 Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Hannes Gredler, MA, Schwaz, Austria Walter Goralski, Professor, Phoenix, AZ, USA British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Gredler, Hannes. The complete IS-IS routing protocol / Hannes Gredler, Walter Goralski. p. cm. Includes bibliographical references and index. ISBN 1-85233-822-9 (pbk. : alk. paper) 1. IS-IS (Computer network protocol) 2. Routers (Computer networks) I. Goralski, Walter. II. Title TK5105.5675.G74 2004 004.6′2 dc22 2004049147 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or trans- mitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. ISBN 1-85233-822-9 Springer-Verlag London Berlin Heidelberg Springer Science+Business Media springeronline.com © Hannes Gredler 2005 The use of registered names, trademarks etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the information con- tained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Typesetting: Gray Publishing, Tunbridge Wells, Kent, UK Printed and bound in the United States of America 34/3830-543210 Printed on acid-free paper SPIN 10962268 Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com To Caroline, for making sense of it all. Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Walter J. Goralski is a Senior Member of Technical Staff with Juniper Networks Inc. and an Adjunct Professor of Computer Science at Pace University Graduate School in New York. He has spent more than 30 years in the data communications field, including 14 years with AT&T, and is the author of several books on DSL, the Internet, TCP/IP and SONET, as well as of articles on data communications and other technology issues. Hannes Gredler is a Professional Services Consultant at Juniper Networks Inc., where he is deploying/advising for numerous carriers and ISPs running the IS-IS, BGP and MPLS suite of protocols in their core backbones. He has been in the telecom industry for 7 years and holds a Master’s degree for Manufacturing and Automation from the Technical University of Graz (Austria). Hannes holds a CCIE certification (#2866) since 1997 as well as JNCIE (#22) certification since 2001. Besides his engagement at Juniper Networks, Inc., Hannes is actively involved in Open-Source Developments of networking decoders, where he contributed large parts of the Routing and Signaling Protocol Engines for tcpdump/libpcap http://www.tcpdump.org/ and Etherreal http://www.ethereal.com. Hannes currently lives near Innsbruck, Austria. He is married and has three daughters. Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Foreword IS-IS has always been my favourite Interior Gateway Protocol. Its elegant simplicity, its well-structured data formats, its flexibility and easy extensibility are all appealing – IS-IS epitomizes link-state routing. Whether for this reason or others, IS-IS is the IGP of choice in some of the world’s largest networks. Thus, if one is at all interested in routing, it is well worth the time and effort to learn IS-IS. However, it is hazardous to call any routing protocol “simple”. Every design decision, be it in architecture, implementation or deployment, has consequences, some unantici- pated, some unknowable, some dire. Interactions between different implementations, the dynamic nature of routing, and new protocol features all contribute to making routing protocols complex to design, write and deploy effectively in networks. For example, IS-IS started as a link-state routing protocol for ISO networks. It has since evolved signifi- cantly: IS-IS has IPv4 and IPv6 (and IPX) addressing; IS-IS can carry information about multiple topologies; link attributes have expanded to include traffic engineering parame- ters; a new methodology for restarting IS-IS gracefully has been developed. IS-IS even has extensions for use in “non-packet networks”, such as SONET and optical networks, as part of the Generalized Multi-Protocol Label Switching (G-MPLS) protocol suite. Understanding all of what IS-IS offers and keeping abreast of the newer protocol fea- tures is a weighty endeavour, but one that is absolutely essential for all serious network- ing engineers, whether they are developing code or running networks. For a long time, there were excellent books on OSPF, but very little on IS-IS. This encyclopaedic work changes that. Now, at last, there is a book that does IS-IS justice, explaining the theoret- ical aspects of IS-IS, practical real-life situations, and quirks in existing implementa- tions, and gives glimpses into some troubleshooting tools. You couldn’t ask for a better-matched pair of guides, either. Hannes: intense, passionate, expert; and Walter: calm, clear, expert. Between the two, they have produced a compre- hensive, up-to-date text that can be used for in-depth protocol study, as a reference, or to catch up with the latest developments in IS-IS. Happy reading! Kireeti Kompella Distinguished Engineer, Juniper Networks Inc. Common Control and Measurement Plane (ccamp) IETF Working Group Chair vii Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Credits and Thanks The authors would specifically thank the following individuals for their direct or indirect support for this book: Walter First of all, thanks to Hannes for giving me the opportunity to be involved in this project. What I know about IS-IS, I have learned from the Master. Patrick Ames made this book a reality, and Aviva Garrett provided inspired leadership. My wife Camille provided support, comfort, and the caring that all writers need. Hannes My biggest personal thank-you goes to my beloved wife Caroline. While she did so many good things for me, most importantly she created the environment for me that allowed me to write. Without her ongoing, loving support this book would never have been written up and finally published. Patrick Ames has left a profound footprint on that book. While he had possibly the hardest job on earth (chasing part-time authors for manuscripts beyond due dates) he always kept calm, professional and provided care and input on all stages of this book. Without him this book would not have made its way. Next I want to thank probably the best review team on IS-IS in the industry: first, the Juniper Engineering Team, most notably Dave Katz, Ina Minei, Nischal Sheth, Kireeti Kompella and Pedro Marquez who always took time and answered my questions in great detail. Tony Przygienda kept an eye from the IETF perspective on content accuracy and gave numerous suggestions to improve the text. The Service Provider Reviewing Team (Dirk Steinberg, Markus Schumburg, Ruediger Volk/Deutsche Telekom) and Nicolas Dubois (France Telekom) gave a lot of design inputs from the operational perspective. Finally, I want to thank my Home Base, the Juniper Customer Service Europe Team: Jan Vos who initially helped in advocating writing a book and generously donated Company Lab and Team Resources; Anton Bernal for teaching me a lot about ATM; Josef Buchsteiner supported my work everyday by several useful discussions and help with lab setups. Finally, my team mate, Peter Lundqvist, for sharing a lot of his vast knowledge with me and being always good for a good laugh. ix Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Contents Foreword vii Credits and Thanks ix 1 Introduction, Motivation and Historical Background 1 1.1 Motivation 1 1.2 Routing Protocols History in the 1990s 2 1.2.1 DECNET Phase V 2 1.2.2 NSFNet Phase I 3 1.2.3 OSPF 4 1.2.4 NLSP 5 1.2.5 Large-scale Deployments 6 1.2.6 IETF ISIS-WG 6 1.3 Sample Topology, Figures and Style 7 2 Router Architecture 11 2.1 Architecture and the Global Routing Paradigm 12 2.2 General Router Model 15 2.3 Routing and Forwarding Tables 17 2.3.1 Forwarding Plane Architectures 18 2.3.2 Control Plane Architectures 21 2.4 Router Technology Examples 26 2.4.1 Cisco 7500 Series 27 2.4.2 Cisco 7500 Series ϩ VIP Processors 29 2.4.3 Cisco GSR Series 30 2.4.4 Cisco IOS Routing Software 31 2.4.5 Juniper Networks M-Series Routers 31 2.4.6 JUNOS Routing Software 33 2.5 Conclusion 33 3 Introduction to the IOS and JUNOS Command Line Interface 35 3.1 Common Properties of Command Line Interfaces (CLI) 35 3.1.1 Operational Mode 36 3.1.2 Configuration Mode 39 3.1.3 Emacs Style Keyboard Sequences 40 3.1.4 Debugging 40 xi Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 3.1.5 IP Troubleshooting Tools 41 3.1.6 Routing Policy 41 3.1.7 Logging 41 3.2 Cisco Systems IOS CLI 42 3.2.1 Logging into the System, Authentication, Privilege Level 42 3.2.2 IS-IS-related Show Commands 43 3.2.3 Interface Name-space 44 3.2.4 Changing Router Configuration 47 3.2.5 IS-IS-related Configuration Commands 50 3.2.6 Troubleshooting Tools 50 3.2.7 Routing Policy and Filtering of Routes 55 3.2.8 Further Documentation 56 3.3 Juniper Networks JUNOS CLI 56 3.3.1 Logging into the System and Authentication 57 3.3.2 IS-IS-related Show Commands 59 3.3.3 Interface Name-space 60 3.3.4 IS-IS-related Configuration Commands 63 3.3.5 Changing the Configuration 65 3.3.6 Activating a Configuration 68 3.3.7 Troubleshooting Tools 69 3.3.8 Routing Policy 73 3.3.9 Further Documentation 77 3.4 Conclusion 77 4 IS-IS Basics 79 4.1 IS-IS and the OSI Reference Model 79 4.2 Areas 83 4.3 Levels 85 4.3.1 IS-IS Routing Hierarchy Rule 86 4.3.2 Route Leaking Between Levels 87 4.4 Area Migration Scenarios 90 4.4.1 Merging Areas 92 4.4.2 Splitting Areas 92 4.4.3 Renumbering Areas 92 4.5 Local SPF Computation 94 4.6 IS-IS Addressing 96 4.6.1 IP Addressing 96 4.6.2 IP Addressing Model 98 4.6.3 OSI Addressing 100 4.6.4 Examples of OSI Addressing 104 4.6.5 Configuring NETs 104 4.7 Names, System-, LAN- and LSP-IDs 105 4.8 Summary 107 xii Contents Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com [...]... book about IS-IS, cover some recent routing protocol history and give an overview about various IS-IS development stages Finally, the chapter introduces a sample network and explains the style used in the figures throughout the book 1.1 Motivation One of the oddities of IS-IS is that there are hardly any materials available covering the entire protocol and how IS-IS is used for routing Internet Protocol. .. Protocol (IP) packets The base specification of the protocol was first published as ISO 10589 in 1987 and did not apply to IP packets at all From then on, however, most of the work on the protocol has been done in the IS-IS working group of the Internet Engineering Task Force (IETF) The IETF was responsible for two major changes to the OSI vision of IS-IS First, they extended the protocol by defining additional... details, and compare the overall implementation against the specification Furthermore, both IOS and JUNOS carry scalability improvements for IS-IS, which will be highlighted as well The purpose of this book is to provide a good start for the self-education of both the novice and the seasoned network engineer in the IS-IS routing protocol The consistent approach is to explain the theory and then show how things... on the LANs were servers) the TLVs from 190 to 196 have been allocated for Novell-specific routing needs Although NLSP looks largely the same as IS-IS, some of the mechanisms, particularly the “stickiness” of the DR election process, make NLSP incompatible with regular IS-IS routers Both the IP and the NSLP extensions demonstrate the flexibility built into IS-IS from the very start Adding another protocol. .. learning about the encoding style of the IS-IS protocol Too often the authors found the entire TLV and sub-TLV structure difficult to understand Figure 1.4 illustrates the shading style used to colour all protocolrelated illustrations The darker the background colour, the lower the field is located in the OSI protocol stack So the dark gray shading indicates link-layer encapsulation such as Ethernet or PPP... of the configuration file are propagated to the routing processes that “speak” router-to-router protocols like OSPF or IS-IS or Border Gateway Protocol (BGP) If the same routing protocol is provisioned on both ends of a direct router-to-router link, then the routers start to discover each other in their network Next, IP routing information is exchanged The remote network information is entered in the. .. of the OSI Data Link Layer protocol That makes the protocol inherently independent of any higher Network Layer Reachability Protocol In 1987, the International Organization for Standardization (usually abbreviated as ISO) adopted the protocols used in DECNET Phase V as the basis for the OSI protocol suite A whole array of networking protocols was standardized at the time A brief list of the adopted protocols... in and confused by the distinctions between the routing protocol definitions (IS-IS itself) and the higher-level network reachability definitions (known as the connectionless network protocol, or CLNP) and this makes differentiating IS-IS and CLNP more difficult Henk Smit, a well-respected implementer of the IS-IS protocol, once with Cisco Systems, noted on the NANOG Mailing List: IS-IS is defined in ISO... from the base protocol So IS-IS can be used for routing IP packets just as well as the other major link-state protocol, the Open Shortest Path First (OSPF) protocol But why bother having another link-state IGP for routing TCP/IP, especially if it is so similar to OSPF? At first sight, supporting both OSPF and IS-IS seems to be a double effort Only by looking back can it be easily understood why IS-IS. .. Transfer Protocol (SMTP) augments the stream with transport protocol level information like sequence numbers The augmented transport stream next is passed down the network protocol stack to the IP layer where each message segment is prepended with an IP header The packet then leaves the End System and is either sent directly to the receiving end system (if it is on the same network) or passed to the default . a good start for the self-education of both the novice and the seasoned network engineer in the IS-IS routing protocol. The consistent approach is to explain the theory and then show how things. http://www.simpopdf.com The Complete IS-IS Routing Protocol Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Hannes Gredler and Walter Goralski The Complete IS-IS Routing Protocol 123 Simpo. work on the protocol has been done in the IS-IS working group of the Internet Engineering Task Force (IETF). The IETF was responsible for two major changes to the OSI vision of IS-IS. First, they extended