Campus Segmentation and Beyond

Security is top of mind for most companies today. And for good reasons. Every day new major security incidents hit both the private and public sectors. We’re no longer dealing with curious geeks, script kiddies, and smaller groups of cyber criminals. Hacking used to be a niche thing. Today state-sponsored hackers are a reality. Although you cannot guarantee protection from these malicious events, you can try to limit the risk and possibility of their success.

VRF-aware RADIUS with DNAC

DNAC is currently not designed to be VRF-aware with its Network Settings. The AAA server settings are configured with global context regardless of the device management IP being in a VRF. Here is what DNAC provisions for RADIUS: aaa new-model aaa authentication login default local aaa authentication login dnac-cts-list group dnac-client-radius-group local aaa authentication dot1x default group dnac-client-radius-group aaa authorization exec default local aaa authorization network default group dnac-client-radius-group aaa authorization network dnac-cts-list group dnac-client-radius-group aaa accounting Identity default start-stop group dnac-client-radius-group aaa accounting update newinfo periodic 2880 !

Jinja Templates in DNAC

In this post I will show you some examples of Jinja templates that might inspire you to create your own. As always my focus is centered on how stuff works rather than how you use the product. I will provide a breif overview of the Template Editor, though. For a user guide, please have a look at the official doc: Create Templates to Automate Device Configuration Changes One of the main advantages of DNAC is its ability to help you automate certain tasks within your network.

DNAC Code Names

DNA Center has a versioning scheme that uses four digits. At the time of writing the recommended DNAC version is  2.b.c.d - The first digit is the major release which introduces “significat market value, including infrastructure and architectural changes”  a.2.c.d - The second digit is a minor version that includes “new functions and features in the platform”. It is categorized as a “new market value” release and also an anchor point for long-lived releases

CCDE Journey

CCDE is one of the most sought-after and valuable IT certifications today. It used to be very service provider focused. The current version, CCDEv3, was launched November 2, 2021 and it changed radically in terms of technology coverage. Also, this version adds the AoE (Area of Expertise) scenarios of choice, meaning you can choose one scenario based on three different technology areas: Large Scale Networks On-Prem and Cloud Services Workforce Mobility To become a CCDE you must pass a written exam and a practical exam - respectively in that order.

MPLS VPNs vs. VRF-lite

Segmentation is becoming more and more critical as part of securing a network. In this article I will compare MPLS VPNs to VRF-lite. Both are ways to segment a network logically at L3 using VNs (VRFs). Many years ago when I was new to networking technologies I had some fear of “MPLS”. I was biased and I though of MPLS as something insanely complicated that only service providers used in their network to magically inter-connect large companies.

DNAC - NIC Bonding

If you are looking to configure NIC bonding for DNAC, this post will show the currently available options for the DN2-HW-APL appliance running DNAC version and newer. Only 10G interfaces are addressed for NIC bonding in this post. If you want to play with 1G interface NIC bonding, have a look at the official documentation NOTE! NIC bonding is not supported for the DN1-HW-APL (1st gen DNAC appliance). An apparent reason for this is that the DN1 appliance only comes with a single NIC adapter with two 10G interfaces.

Practice Documentation

Introduction We all know how daunting it can be to create and maintain documentation. Yet, when it is missing, we get frustrated. There is a standing joke regarding documentation: Documentation is like sex. When it's good, it's very good. When it's bad, it's still better than nothing. Nevertheless I believe we can all agree that documentation is a requirement for any system. Having good up to date documentation provides the following benefits:

DNAC LAN Automation vs. PnP

The Challenge Operating a network can be a daunting task. Especially when you find yourself manually repeating ordinary work on a regular basis. As a network engineer you are likely to enjoy challenges with protocols and designs rather than unboxing, mounting, and installing hardware. The time spent on this everyday work should be kept at a minimum. In a streamlined network design, the configuration of new equipment should be based on a template with few variables, such as hostname and IP addressing.


Introduction ISIS is the routing protocol preferred for SD-Access (SDA). Roughly said, SDA is somewhat similar to routed access. We can think of fabric edge nodes as access switches when comparing them to our traditional flat networks. Many companies buy multiple switches and deploy them in stacks using Cisco StackWise technology. This has the usual benefits of stacking, namely collapsing all of the switches in the stack into just one management and control plane.