IT Archives - Nate15329's Blog

Choosing Network Patch Cable Lengths

Setting up a computer network requires careful planning, and one important decision you’ll need to make is selecting the right patch cable lengths for the job. Patch cables are used to connect devices within a rack or between different racks, and choosing the right cable length is crucial to ensuring an efficient and easy-to-troubleshoot network.

When choosing patch cable lengths, it’s important to keep them short but not too short. For instance, 6-inch patch cables are ideal for connecting devices/patch panel ports within a single rack unit (U), which is 1.75 inches tall. Longer cables will create clutter and strain on the cable. A 1-foot patch cable is usually sufficient for as many as six rack units.

However, calculating the appropriate cable length can be more complex when the path goes in different directions or depths within the rack. In such cases, you’ll need to calculate the cable length based on the total inches required for the path. For instance, if the path goes in either horizontal direction, add 19 inches to the total vertical inches, then divide by 12 inches to obtain the cable length in feet. If the path goes from the front of the rack to the back, you’ll need to add the equipment depth to the total inches before calculating the cable length in feet.

Depending on the existing rack layout, it may also be necessary to add a service loop of 2-3 feet (24-36 inches) to allow for flexibility and future maintenance. Once you’ve determined the total cable length in feet, round up to the nearest foot. In some cases, it may be necessary to round up to the nearest foot ending with 5 or 0 when there is no pre-made cable length available that matches your requirements.

By following these guidelines, you can select the appropriate patch cable length for your computer network setup. This can help ensure optimal performance, efficiency, and easy maintenance, which are crucial for a successful network.

TLDR: Fast Formulas

Total Estimated Min Length (inches) = 1.75″ * (Rack U Height to Travel) + (if destination is not directly vertical from source in same rack, 19″) + (Device depth, if going from front to back of rack, commonly 21″) + (Any service loop required)

Total Min Length (Feet) = Round Up (Total Estimated Min Length (inches)/12)

UniFi – Log4j Vulnerability Notice

Update: 15 December 2021 – version 6.5.54 and earlier is vulnerable. Please update Unifi Controller again.

With the recent Log4j vulnerability, CVE-2021-442228, UniFi controller version 6.5.54 and earlier is vulnerable.

Jacobalberty has backported the fix to v6.0.45 and v5.14.23 for those whom are on the older hardware or controller versions.

For ours, we will be migrating to the latest v6 build by changing out Docker tag to “jacobalerty/unifi:v6” instead of “jacobalerty/unifi:stable-6” by following UniFi Controller – Docker Tag Change again with the tag changed.

References:

UniFi Controller – Docker Tag Change

While checking up on our UniFi controller image for updates, the tag “jacobalberty/unifi:stable” is no longer valid. There are 2 new tags instead, “jacobalerty/unifi:stable-5″ and ” jacobalerty/unifi:stable-6″. We will be upgrading to UniFi controller 6 with the tag “jacobalerty/unifi:stable-6.

WARNING: Upgrading the controller may invoke device provisioning, which may disrupt current service/s.

As a precaution, download a backup of the controller by going to Settings > Backup > Download Backup.

In our previous post UniFi Controller – Self Hosted Docker, our UNIFI_UID and UNIFI_GID were 1001, update the below ID numbers as required.

docker stop unifi
docker update --restart=no unifi
docker rename unifi unifi.old
docker run -d --restart=always --net=host --name=unifi -e RUNAS_UID0=false -e UNIFI_UID=1001 -e UNIFI_GID=1001 -v /var/docker_storage/unifi:/unifi jacobalberty/unifi:stable-6

After a minute of executing the last command, check the Unifi Controller web interface and everything works. Devices will start to re-provision.

If this is successful, run the below command for cleanup

docker rm unifi.old

If this fails, suggest starting over and restore the controller docker image with the backup that was downloaded at the beginning. Be sure to clean up the docker storage folder on the host prior.