Building Network Design Skills

How do you learn how to do network design well? NetCraftsmen does Network Assessments, as well as other types of assessments. We frequently get asked about design skills and sources of best practices. In addition, I’ve been mulling over how to best internally build junior engineers’ skills in design.

Here are several ways to build your network design skills:

• Read everything you can get on the topic with a critical eye. Determine what is trustworthy, what is marketing pushing an agenda, what is overly complex, what is good for the customer.
• Read the Cisco Press ARCH book. Now. It ties to the CCDP exam, and certainly doesn’t hurt if you’re doing the CCDE written (from experience). I’ve been involved with the second and third editions, and can vouch that there is lots of good design content. The updated fourth edition came out in December 2016. I now have a copy, but haven’t read/skimmed it, so I can’t comment on it yet. The table of contents indicates some timely updates, including some added case studies at the end. Good idea!
• Read the CCDE suggested reading list — you need to know various approaches, their technical capabilities, limitations, pros, and cons. You may find the CCDE Study Guide useful (good content, many typos). It does include Service Provider and MPLS topics, which might be deferred if you’re primarily interested in enterprise design.
• Read the Cisco Validated Design (CVD) documents. They’re mostly really good content. A few are shallow or have an agenda. In general, I find any given CVD about 95% bang on, with minor differences over some of the ancillary details. There are some major exceptions, ones that I consider poor ideas/overly complicated.
• Get into a job position where you can see and analyze many networks, regarding both business requirements and technical design. Consulting (internal or external) and design reviews are one way to do that. Question everything. Think outside the box. Solve business problems for the customer.
• Practice design write-ups and simple clean diagramming. Presenting a design to the customer is important. Did I say “PowerPoint”? Definitely a required skill!
• Practice critical thinking. How could this be done differently? What are the pros and cons of each alternative? Over time, you should build up mental or notes-based lists of alternatives for various design situations (campus, datacenter, WLAN, WAN, small/medium/large sites, etc.). Example: datacenter design with two core switches, or three different flavors of spine-leaf with Nexus 9Ks.
• Practice your PowerPoint and/or Visio skills. They’re essential for presenting a design, and darn useful for showing the stages of a migration or new technology deployment.

Exercising design skills

As an example, consider campus network segmentation, a topic that doesn’t get widely discussed. I’m using it for precisely that reason: Thinking through new situations builds skills.

I’ve seen the following alternative approaches. A terse pros/cons analysis is included. I’m not claiming its 100% perfect; I’m just trying to provide a meaningful example, one where I’ve seen a lot of rigid design thinking (that is, picking one of the below approaches where I’d have picked another, generally because it was simpler or less costly and met the requirements).

>This can work; I have done it at 100+ building hospital and medium-sized government agency scale.Simple, low-tech for operations

NEXT page: A closer look at campus network segmentation options.