Fix Stuck Application Server in Cisco ISE

Once in a while the Cisco ISE web service doesn’t start after a reboot of the server, and though less frequent, sometimes the service just stops in a running production server. This means the Admin portal is unavailable, though ISE may be working properly otherwise. In this post I’ll go over a couple commands that can help.

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Troubleshooting DTLS Handshake Error Joining Cisco 2702i Access Point to 9800 Wireless Controller

Recently I tried to join a Cisco 2702i access point to a 9800-CL wireless controller but found an issue that needed to be fixed prior to it joining successfully. I also recently joined a Catalyst 9115 access point right out of the box and experienced no issue at all, so my theory is that the 2702i had config still on it from when it was previously joined to a 5508 WLC. In this post I’ll go through the few steps I took to fix the issue and successfully join the 2702i to the 9800-CL.

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Deploying and Configuring the Cisco 9800 Virtual Wireless Controller for the First Time

Deploying the new Cisco 9800-CL wireless controller is fast and easy, and by using the built-in workflows, a new wireless network can be deployed in only a few minutes. In this post, I’ll review how to deploy the virtual wireless LAN controller in VMware ESXi and stand up a very simple WLAN. We’ll also take a look at some potential gotchas and some noteworthy differences between how the new WLC is configured compared to the AireOS WLC.

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Hopeful with a Dash of Skepticism: Cisco 9800 Wireless Controllers

Only a few years ago, Cisco tried their hand at a converged access wireless platform with, among other devices, the Cisco 5760 Wireless LAN Controller. To this day, I have nightmares about that box. It wasn’t fully functional, and it had huge code issues. Today, in spite of AireOS being a stable, highly functional, and well-known WLC platform, Cisco is trying it again with a range of WLCs in the 9300 and 9800 series.

However, will this brave attempt prove to have the same fate as the 5760?

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Bridging the Gap Between the Classroom and Real-World IT

This week I taught my last class as a part-time adjunct instructor at a community college. I’ve been there for six years – 12 consecutive semesters. Each term, alongside the actual curriculum, I incorporated my work experiences and lessons learned about the reality of working in IT. Making the class meaningful from a real-world perspective was very important to me.

For my very last class, I chose not to cover anything in the textbook or any of the bullets on the syllabus. Instead, I introduced my students to systems and network automation. What may seem old news to you and me was brand-new to my class, and I don’t believe this is the exception.

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Engage with the Networking Community

I’ve been an active part of the networking community on social media for only a few years. Before that I was a passive consumer of tweets, blogs, and videos. A previous manager inspired me to be more active, and very quickly after engaging directly with bloggers, podcasters, and engineers, the value of being an active participant became very clear to me.

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Locating Wireless Clients and Location History in Cisco Prime with CMX

Locating a wireless client in real time and viewing its location history in Cisco Prime Infrastructure is a little bit different with CMX than with MSE. In this post we’ll walk through the few steps to locate a wireless client among all your maps and then view its location history.

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Whitebox Switching at the Access Layer

Whitebox switches make use of generic and generally inexpensive hardware along with a network operating system that can be purchased and installed separately. Often the hardware and software come from different vendors, and there are several reasons this practice is becoming more common especially in the data center. What I’m interested in lately is how this is relevant to the non-webscale enterprise.

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BGP Default Route Failover Using Reachability

Sometimes political, financial, or logistical hurdles determine how we solve networking problems. In these tricky situations we may not be able to solve the problem the way we’d prefer, but we still need to solve the problem.

In this post I’m going to look at how we can solve a WAN failover scenario when we have a default route learned from both of our service providers and a reachability problem via our primary ISP.

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Amazon S3 Outage: We’ve All Been There

I’ve been thinking a little bit about the Amazon S3 incident. Not really the incident, actually, but the responses to it. More than once I read something along the lines of “I’m sure that guy got fired” with regard to the engineer who entered the fatal command.

Sure, that’s kind of funny for a quick tweet or in the greater context of a blog post on change control, but for me, I’m not sitting at my desk shaking my head right now. Instead, I’m reminded about the times I did the exact same thing (on a much smaller scale) and will probably do it again.

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How Do You Know That’s True?

About a thousand years ago, rather than configure routers, I taught high school English.

One day, instead of unpacking our favorite Shakespearean sonnet, I was sidetracked by a student who asked me how we know anything about electrons and how they orbit the nucleus of an atom. Apparently he asked his physics teacher the period before and got a pithy “electrons are the essence of a negativity.”

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Apstra: The Intent-Driven Cure for Network Blindness

Apstra, Incorporated isn’t focused on new features, more advanced silicon, or some new widget. Instead, they’re offering a different way to look at networking. Apstra offers an early form of intent-driven networking that abstracts network programmability and allows network engineers to configure intent rather than device features. We expect the network to behave in a specific way, so we configure our intent accordingly. I was very excited to meet the Apstra team at Networking Field Day 13, and they didn’t disappoint.

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