Certification Zone Zone Newsletter

Interview with the Author - Howard Berkowitz

Howard C. Berkowitz

CZ: Tell us a little bit about yourself and your current networking interests.

HB: I did my first networked communications around 1967. Contrary to current opinion, that was not all done with tin cans and strings. There were still a few legacy smoke signal systems, ancestors to the magic smoke in Cisco routers.

Throughout my career, I've been interested in the niches between different technologies -- typically the places where no job description or training programs have been defined. Above all, I'm self educated -- which includes learning how to study new fields quickly, always looking for the "what is the key concept". There usually is one, and once you grasp it, things fall into place. I'm not joking when I say I'm a Zen designer -- sometimes when I can't get a good grip on a concept, or a client problem, I literally go into a meditative or half-dreaming state and try to let the essence of the problem reveal itself to me.

These days, while I'm not a doctor, I do play one on computers. I'm doing a mixture of networking and medical computing, the latter including both clinical medicine and disaster preparedness. My technical interests in routing deal with Internet scalability, including such issues as BGP convergence. Hopefully, I have a BGP benchmarking document in the final stages of getting to the RFC Editor, http://www.ietf.org/internet-drafts/draft-ietf-bmwg-conterm-04.txt.

I'm also going through the new Cisco design methodology (SAFE, ECNM) and trying to find ways of making it friendlier.

And yes, the economy is as painful for me as for anyone else. We're all hunting for contracts.

CZ: How did you get interested in IPv4 and IPv6?

HB: Addressing is basic to networking, and it's historically been presented in a confusing manner. People assume that IP was developed at every step by someone with a clear purpose in mind, but the reality was that many steps were guesses by researchers.

When I was teaching introductory courses, I realized that a lot of historical nonsense about dotted decimal, classful concepts, etc., were obscuring the fundamental use of a 32-bit string.

The specific IPv4 and IPv6 tutorial, in many cases, uses IPv6 to explain what IPv4 was really trying to do. There aren't many things that IPv6 can do that you can't kludge in IPv4, but you can do them (usually) much more cleanly in IPv6 because the IPv6 architects had an opportunity to take a fresh look. Indeed, IPv6 has some problems of its own -- if you get into the confusion surrounding IPv6 multi-ISP multihoming, you'll see how things may be easier -- if less scalable -- in IPv4.

CZ: From your personal experience, what are the most important things to consider when dealing with IPv4 and IPv6?

HB: When you design a network, you are designing a city. The address structure starts with defining the streets, with the host address assignments giving the building numbers. Routing protocols define the traffic rules, but you can't have rules for streets that don't exist.

CZ: From your personal experience, what is the biggest challenge associated with IPv4 and IPv6?

HB: Remember that there can be a right way, a wrong way and a Cisco way. Especially on the lower-level Cisco certifications, there are oversimplifications or outright confusing things (like classful concepts being presented first) everywhere. Sometimes, you'll have to translate the right answer into what Cisco is looking for. Be ready to do that.

CZ: What advice can you give our audience of Cisco certification candidates when it comes to dealing with IPv4 and IPv6?

HB: Read or watch "The Exorcist," and recognize that classful addressing has possessed too many of us and needs to be driven out! :-)