Updated: Oct 26, 2020
Written by: Andrew Connnely
I was recently at a client site, bootstrapping a new network. The requirements called for a Cisco SG350 POE switch and a Ruckus R510 to provide the WIFI (amongst other devices, like firewalls and servers). The install went smoothly and everything was finished in one overnight work-a-thon. I left the site, flew home (yes, it was far away) and caught up on sleep.
Over the next few days, I remotely connected to complete the final parts of the configuration and noticed a few issues. The first was that the Cisco switch was generating errors in the log. The second had to do with the Ruckus WIFI, and was a bit more elusive.
Just browsing the internet, there weren’t any issues with the WIFI. But once there were more users, or higher bandwidth requirements, the WIFI would have major issues and sometimes, cut out altogether. During speed tests (speedtest.net), the upload portion of the test would fail with Latency issues.
The first thought was that there might be a cable issue in the ethernet cable that ran from the patch panel to the Ruckus, which was mounted on the ceiling. Not being onsite, though, I had to start my troubleshooting elsewhere.
I looked at the Cisco switch first due to the event log being filled with errors – the two issues could be related. My troubleshooting methodology is to basically try one thing at a time, then retest the issue. This is definitely the long way of doing things, but isolating the problem to one specific change allows you to understand the root cause of the problem.
The first thing I tried was updating the firmware. It was a new switch, but sometimes these switches sit in a distribution center for a few months and the firmware becomes outdated. I updated the firmware, applied the image and rebooted the switch. Same issue.
Next, I started disabling unused or unnecessary features. It’s surprising how many functions are turned ON by default in SG series switches.
Smart port was first. I’ll let Cisco describe what SmartPort is: Auto Smartports macros dynamically configure ports based on the device type detected on the port. When the switch detects a new device on a port, it applies the appropriate macro. When there is a link-down event, the switch removes the macro. For example, when you connect a Cisco IP phone to a port, Auto Smartports applies the IP phone macro. Same problem.
Next, I disabled Energy Efficient Ethernet (EEE). Again, I’ll give you Cisco’s official description: 802.3az EEE is designed to save power when there is no traffic on the link. In Green Ethernet, power is reduced when the port is down. With 802.3az EEE, power is reduced when the port is up, but there is no traffic on it.