There are several ways to troubleshoot DHCP issues. One could verify that DHCP scope is good, verify if the DHCP relay configuration is configured correctly, etc. Today, this blog post will cover a possible solution for DHCP issues that one might encounter. Though, this might be unlikely to happen in some networks. Of course, that depends on the environment.
I was looking at Nexus 3064-T for one of the projects that I was involved in that required 10GBASE-T but while I was waiting for a demo unit I was tasked to play with the Quanta T3040-LY3. I’ve worked with them a little bit since some of our clients have them deployed and sometimes I get phone calls about helping them to get it working. Technically, I didn’t have to but I didn’t want to be the guy who doesn’t try help.
The Quanta’s syntax is almost identical to IOS which is not a surprise since there are vendors out there copy the CLI commands. Only one I’ve encountered so far that is completely different from IOS is Junos OS. Having said that, it was quite easy to convert my template to Quanta equivalent commands. However, I did have to read the docs when I had questions on how to do a specific command on their OS.
I first learned about 802.1X when I was studying for one of the CCNP exams, the BCMSN exam (SWITCH equivalent), at Ohlone College. At the time, I assumed that the short material covered in the book was all of it. Of course, that was a bad assumption in my part. That’s probably a normal assumption of someone who at the time just finished Cisco Network Academy Program CCNA 1 to 4 and newly minted CCNA with no professional experience.
What is 802.1X?
Essentially, 802.1X is a security feature that provides a mechanism to authenticate devices before it can access network resources. While it’s a good idea to have this security feature implemented, I’ve worked for companies who didn’t have this feature or similar implemented or it’s on their roadmap. It’s a shame that it wasn’t on their roadmap a long time ago since it was ratified in 2001. Then again, implementing technologies have its challenges.[Read more…] about Implementing Wired 802.1X
Several months ago, sFlow became instrumental in figuring out the issue with HP switches that we inherited. Just to give you an idea of what the issue was, the HP switches would sporadically drop off the network but the user data traffic was still flowing. Good thing it was only the management traffic that was dropping and not user traffic. With the help of sFlow collector, I was able to correlate the timestamps of when several HP switches went down and I found out that MLD (Multicast Listener Discovery) was the culprit. Tried to search the web for some answers but no luck. I upgraded the code of the switches but still no luck. Finally, I decided to contact HP Tech Support since they offer a lifetime warranty on hardware and software. When the tech support asked for the config, he saw that igmp querier was turned on and when we turned it off the problem never came back. Since we’ve been replacing the HP switches with Cisco Catalyst switches, I wanted to replicate some level of the sFlow functionality. Luckily, the Catalyst 2960-X supports NetFlow-Lite.
Yes, it’s not the best practice to put both data and voice traffic in the same VLAN and subnet, but I’ve recently encountered it in production and caused us some head scratching scenario. While it was probably best to redesign the whole thing since it doesn’t follow best practices, it was not going to fly in this case.