Routing – Page 3 – ShortestPathFirst

December 3, 2009

Book Review :: IS-IS: Deployment in IP Networks

IS-IS_Deployment IS-IS: Deployment in IP Networks
by Russ White, Alvaro Retana
Hardcover: 320 pages
Publisher: Pearson Education
ISBN-13: 978-0201657722

Better off choosing an alternative selection

As IS-IS is one of the more esoteric protocols, understood only by a few people in large scale ISP environments, I thought this book would be a welcome addition to my library as there isn’t much else on the market covering this protocol. There are of course ISO 10589 and RFC 1195 which covers these protocols, but seeing as this is a short book I thought it might be able to shed some light on an otherwise complex protocol.

In reviewing this book I’ve come up disappointed in general. There are certainly a few golden nuggets and I give the book a couple of stars just for attempting to bridge the gap between the purely theoretical and the purely vendor specific. However, the book comes up short on most other points. Often times I found myself wanting to scrap this book in favor of some of the other selections on the market, but since I have respect for these authors I read the whole book hoping that they might be able to redeem themselves by the time I finished.

Obviously the authors have a great deal of knowledge about the subject, and I don’t fault them entirely. The quality of the editing is poor with many grammatical and syntactical errors littered throughout the text. There are abundant instances throughout the book where the diagrams used do not match the text describing them. I was rather disappointed because I usually find that Addison-Wesley publishes some of the best texts on the market.

All in all, I thought this book could have been a lot better than it was. After all, these authors have several other titles under their belt, most notably “Advanced IP Network Design”. But in this case, I would say that you are better off looking for other similar titles available on the market, such as Jeff Doyle’s “Routing TCP/IP Volume 1” or “The Complete IS-IS Routing Protocol” by Hannes Gredler and Walter Goralski.

November 30, 2009December 3, 2009

Book Review :: MPLS-Enabled Applications: Emerging Developments and New Technologies

MPLS-Enabled Applications: Emerging Developments and New Technologies
by Ina Minei, Julian Lucek
Paperback: 526 pages
Publisher: Wiley
ISBN-13: 978-0470986448

Excellent coverage of VPLS, and Multicast over Layer 3 VPNs

Recently I had to work on a project which involved demonstrating Multicast over Layer 3 VPN interoperability between Cisco and Juniper. I spent several days reading through all the RFCs and working-group drafts which pertained to this subject matter, after which I still had many unanswered questions. In order to round out my understanding, I decided to order the Second Edition of ‘MPLS-Enabled Applications’. Looking back, I wish I had read this book instead of wasting my time reading the various RFCs and working-group drafts. This book answered all of my questions and went above and beyond to give me a solid understanding of the concepts and their application. As other reviewers have pointed out, often one needs to read a book to understand the technology basics, and then refer to RFCs or working-group drafts in order to keep abreast of the latest changes. Not so with this book… In fact, this book is so current that reading the working-group drafts is largely unnecessary. It is incredibly comprehensive, concise, and gives the reader a thorough understanding of the business drivers. Furthermore, it illustrates the various ways in which MPLS services can be offered and outlines the pros and cons of each approach so that the network designer can make intelligent decisions with regards to implementation.

In addition to the great coverage that was provided by the First Edition, the Second Edition has updated the text to reflect newer trends and applications such as the transport of IPv6 over an IPv4 MPLS core, and detailed coverage of end-to-end and local protection schemes in MPLS networks. Likewise, the chapter previously called “Point-to-Multipoint LSPs” has now been renamed to “MPLS Multicast”, with much more detailed coverage of the P2MP hierarchy and the forwarding-plane and control-plane operation. The biggest value for me was the addition of a completely new chapter on “Multicast over Layer 3 VPNs” which provided comprehensive coverage of this emerging technology and fully illustrates the full gamut of operation of either the PIM/GRE approach, or the NG-VPN approach utilizing BGP and P2MP LSPs. Finally, the addition of a chapter on “MPLS in Access Networks” was well deserved seeing as Ethernet is quickly becoming the access technology of choice and MPLS will likely be utilized as an overlay in order to realize the full potential of Ethernet in these environments.

This book has earned a spot on my bookshelf as one of my most coveted resources, and I refer to it quite often to refresh my memory on the myriad workings of various functions within MPLS. I wish I could give this book a rating higher than five stars! I can’t overemphasize how exceptional this book is. If you are in the market for a book covering MPLS and emerging applications offered on MPLS networks, this single book should be at the top of your list!

November 15, 2009January 19, 2017

An Overview of BGP FlowSpec

I have given this presentation a few times in the last year and was asked to make this available for public consumption. Essentially, this is a brief overview of RFC 5575, entitled “Dissemination of Flow Specification Rules”, written by Danny McPherson, Jared Mauch, and others.

This standard had somewhat of a rocky beginning as there was limited vendor support, but as of recently it appears to have picked up quite a bit of steam with Cisco announcing support for the protocol in the very near future.

The benefit of BGP Flow Spec is that it allows BGP speakers to use a new BGP NLRI defining flow filter information which can then be advertised to upsteam neighbors via BGP. The primary and immediate motivation of this protocol is to provide intra and inter provider distribution of traffic filtering rules to filter DoS and DDoS attacks, however it can be used for a wide variety of applications in which filtering information must be dynamically distributed throughout a network.

I will probably make additional modifications to these slides as the protocol gains more significant foothold throughout the vendor community and as Service Providers gain more practical deployment experience. As with my other presentations, I will eventually add a voice-over to turn this into a slide-cast.

November 13, 2009January 19, 2017

IP Routing Tutorial

I’ve given this tutorial quite a few times now and several people have asked me to make it publicly available. This is very much geared towards non-technical folks who would like to have a better understanding of how routing in the Internet works.

It covers a brief history of the Internet and evolution of dynamic routing protocols, as well as high-level coverage of link-state vs. distance vector IGPs in addition to discussing EGPs and their role in the exchange of routing information between Autonomous Systems. It also has a few slides on QoS, MPLS, and IPv6.

I would still like to make some modifications to a few of the slides as well as adding more content around MPLS and the future of IP. I will also eventually add a voice-over to turn this into a true slide-cast. In the meantime, I’ve put it up on my slideshare account for those of you who would like to have access to it.

November 12, 2009November 13, 2009

Reflections on the Past :: ConneXions – The Interoperability Report

Way back in 1987, before there was the the “Internet Protocol Journal” and other notable publications which cover various aspects of Internet Technologies, there was “ConneXions – The Interoperability Report“. At the time, aside from reading RFCs or Internet-Drafts for more information on various protocols, this publication was the defacto resource for informative analysis of various protocols and their operation. A quick glance at the articles and you’ll see long-time industry heavy-hitters such as Doug Comer, Jon Postel, and Vint Cerf listed as the authors. This is an invaluable resource for those of you who want to understand the history and evolution of various Internet protocols commonly in use today.

February 5, 2009December 3, 2009

Book Review :: OSPF and IS-IS: Choosing an IGP for Large-Scale Networks

OSPF and IS-IS: Choosing an IGP for Large-Scale Networks
by Jeff Doyle
Paperback: 480 pages
Publisher: Addison-Wesley Professional
ISBN-13: 978-0321168795

A welcome addition to any networking library

If you consider yourself a student of routing protocols and enjoy coverage of graph theory from the perspective of its application to link-state routing protocols, this text will certainly be a welcome addition to your library. This book not only provides information regarding ‘how’ link-state routing protocols work, it also provides information regarding ‘why’ the link-state routing protocols behave as they do, and why the protocol designers made certain choices in the development of these protocols. While it might seem a daunting task especially to the novice reader to learn about two routing protocols side-by-side, it is this treatment which makes this text so worthwhile. Being able to compare these two protocols and identify their similarities and differences simultaneously will ultimately help the network designer pick the right protocol for the job in a given network environment.

This book goes beyond IGP fundamentals by giving practical advice to the network designer which can assist in the planning and implementation of a scalable IGP deployment. For example, in the chapter on Area Design, the author states that “a useful guideline when designing a network is that network control traffic should never exceed 5 percent of the available bandwidth of any link in the network, and in normal circumstances should not exceed 1 percent”. The author then presents various formulas which can be used to determine the amount of bandwidth used by the protocol control traffic based on the number and type of LSAs which are expected to be present in a given network. Arguably one of the best chapters in the book is the chapter on Scaling. This chapter has some of the best coverage of the various modifications which router vendors make to their link-state protocol implementations in order to make routers perform calculations more rapidly, enhance flooding of Link-State updates, and other changes designed to make the protocols scale to support very large networks.

I am a stickler for accuracy, especially when it comes to technical textbooks. I pride myself on my ability to spot technical and grammatical errors in texts such as these, however I must say as I read this book I was very impressed that I found very little errors beyond just the simple grammatical and typographical. Jeff Doyle is an experienced writer, and it should come as no surprise that the technical content in this book is extremely well-vetted, accurate, and error-free. Ultimately, if you are a network operator, designer or architect and are interested in broadening your understand of link-state protocols coupled with the ability to more fully understand the technical distinctions between OSPF and IS-IS, this book is without a doubt one of the best options on the market today.

December 17, 2008December 3, 2009

Book Review :: Designing and Developing Scalable IP Networks

Designing and Developing Scalable IP Networks
by Guy Davies
Hardcover: 302 pages
Publisher: Wiley
ISBN-13: 978-0470867396

Decent information with a hefty price tag…

The title of this book “Designing and Developing Scalable IP Networks” would lead one to believe that reading this book would give the reader special insight into certain architectural approaches that would enable the network designer to build very large and expansive networks. And while the book certainly did provide some useful information, I found it lacking somewhat in details. The author does not delve into the minutiae of the various protocols, such as message types, protocol interaction, etc. Instead, the author assumes the reader already has a solid understanding of the basic principles of IP networking and the protocols associated with IP routing and switching. The author states early on that the book is meant to “examine the architectural and design principles that can be applied to designing and building scalable IP and MPLS networks”, however after a thorough reading I did not find that I was substantially more educated in the subject matter. And herein lies the crux – this book, which is priced in at a whopping $130 – is far more expensive than other texts of a similar nature, some of which cover far more expansive material and cost considerably less. Furthermore, the book is too light on details to be sufficiently useful to someone who is new to the industry and looking to gain a better understanding of what is required to build large-scale networks, and is unlikely to provide the experienced network architect with useable knowledge beyond that which he or she may already possess.

That being said, there is decent treatment of MPLS and Generalized MPLS, MPLS VPNs, QoS, and IPv6. And there certainly are a few good nuggets of information to be found throughout the book. For example, there is very good information on route-reflection, such as the pro’s and con’s of using the same cluster-id on a pair of route-reflectors running in a pair. It also examines practical deployment information for such mechanisms as graceful-restart, citing the fact that enabling BGP graceful-restart without enabling a similar mechanism in the IGP is likely to reduce the benefit of enabling such a mechanism in the first place. And while this is one of the few texts that I have seen on the market that broaches the subject of graceful-restart, I welcome the author to include more information on this subject in subsequent editions.

All in all I would say that this is a good desk side reference if one wants a text which covers the main protocols and mechanisms in use in large Service Provider networks, but if you are looking for a text which will enable you to build large-scale networks you might be somewhat disappointed in the treatment, especially considering the hefty price tag of this item.

Category: Routing