Tag Archives: design

Snagless RJ45 connectors – How To Make Network Cables Snagless

Patch Panel

Snagless RJ45 Connectors – the Odd Request

Snagless RJ45 connectors are that odd request that my department makes from time to time. Why do you need RJ45 connectors anyway, it’s the invariable answer from supervisors, and the typical reminder: “You have all sorts of patchcords, all dimensions…” Well, first of all, we sysadmins never have all the patchcords dimensions available. The IT racks should be something that should be kept as tidy as possible, and one way is to have custom length of the patchcords.

Depending on your infrastructure, you might want or might not want to use handmade patchcords in your racks; however, in many cases this is totally acceptable. You can probably make a Cat 5 patchcord, but you won’t be able to make a Cat 6 one. In other words your hand made patchcords will be able to run at Gigabit speeds, but not at 10 Gigabit speeds, even with the proper connectors and cables. Having said that, most of the equipment in a business server room is connected into a Gigabit switch or at lower speeds, so this would not be a problem.

Custom Patchcords – Always Broken Lokcing Tabs

The major problem with all the handmade Ethernet patchcords and cables is that the locking tab is breaking. I probably don’t have to explain why broken tabs are bad; they will not be secured into the equipment’s jack, resulting in intermittent data loss, or even disconnection.

There are two reasons for the locking tabs breaking so often. Firstly, the little locking tab is very fragile, and we can’t change that, it is fragile to keep the costs down. The other reason is the design, the locking tab sticks out, and it is very easy to get snagged and broken off. All store-bought cables come with a snagless boot; it’s the standard these days. All the cables with broken locking tabs don’t have the boots, because they are terminated in place, by either a datacom tech, or an admin.

These plugs from Panduit are the best snagless RJ45 connectors.

The connectors are meant for patch cords, and they are rated as providing Category 5e performance.

The patented tangle-free plug latch prevents snags, hence breaking.

They are easy release, unlike some snagless boots, and they save time on frequent moves, adds, and changes.

The design facilitates easy insertion and termination of wires

What Is the Solution for Broken RJ45 Connectors

One of the solutions to fix the snagging network cables is to install a "snagless" boot over the cable, before crimping the connector. After crimping, just push the boot over the connector and the boot will protect the little tab.

My preferred way to fix this is to use snagless RJ45 connectors, and a boot. This ensures the plug will not break ever, unless you purposely do it. You can also use just the snagless connectors, they are very good, and I do it very often, but if I have both the snagless connectors and the snagless boots, I will use both for optimization. The snagless plugs are slightly more expensive than the regular ones, but when you draw the line, and consider the troubleshooting needed on the long term, and the fact that sooner or later those RJ45 connectors will break and will need to be replaced, the additional cost is worth paying.

Like I already mentioned before, with the low prices for commercial made patchcords, and the quality ensured by a machine made ethernet cable, there is no need to make your own, it's just not practical.

This cables are made in a commercial facility, they are tested, and they come in a variety of lengths, just choose the one that is right for you. You can even get  to choose the color, so you can color code your patch panel connections, so everything looks tidy, and easy to follow.

Troubleshoot a Slow Network – The entire Network is Slow

The Entire Network is Slow

If the entire network or a part of the network is slow, this could be a strong suggestion for a faulty switch or a miss-configuration.

Poor network equipment
Usage of hubs is not recommended, (hubs are prone to collisions by design)
Cheap switches that cannot handle the total needed bandwidth. The switch’s chip can handle 100Mb/s for 12 ports, but the switch has 24 ports and all are connected. For low network usage this is not a problem, but if your network usage spikes, your switch will not be able to handle the bandwidth. The quick fix in such situation is to power off the switch for a few minutes and then power it back on.

Loopback
A loopback is a network cable that has both ends connected to the same switch. If it’s a managed switch activating loop protection on all the ports could fix the problem. You can look on the switch’s log file for excessive broadcasts and isolate the two ports that are in loop. If you don’t have managed switches you can use a packet sniffer to determine if there’s a loop. A wrongly configured Spanning tree could cause a loopback.
FIX: Check all the patch-cord connections in the faulty switch. Check for patch-cords that have both ens into the same switch. Check for more than one patch-cord connecting the same two switches.
If you have cascaded switches it is normal to be slower for the devices in the cascaded switch but is not normal for the devices that are not cascaded. Check if any cascaded device is not connected on two ports on the wall, (usually the ports on the wall go to the network room). Your cascaded switch makes a loop into the upper level switch.

Bad Network Configuration
DNS issues
can cause a lot of slowdowns.
One common error is to use your ISP’s DNS server inside your Active Directory network. Your Active Directory computer members will try to resolve internal names by querying your ISP’s DNS. Those records don’t exist outside of your network.
Fix: For all of your Active Directory network clients remove any entries for your ISP’s and use only internal DNS servers. Configure your ISP’s DNS server as a forwarder on your AD DNS servers.

Network switching equipment wrongly connected is the reason of slow network for many small networks. Typically this happens when a small switch is connected to the router. When the switch becomes too small for a growing network, the first impulse is to connect the computers into the router directly.
Fix
: Install a switch that will accommodate all of the computers in the network. Disconnect any computers connected directly into the router.
Note: It is normal for the wireless connected computers to have slower transfer rate than the wired ones. Most of the wireless routers and adapters function at 54Mb per second. If your router is a modern router, (100 Mb or faster), and you still don’t get the expected transfer rates, you should revise your configuration as above.

Broadcast storm
You can efficiently detect a broadcast storm using a packet sniffer or a managed switch. With a packet sniffer you need to look for large numbers of broadcast/multicast (more than 20% of the total traffic it is an alarm signal). Locate the retransmission packets and search for the source MAC address. Disconnect the problem host.
If you suspect a broadcast storm in your network and you don’t have a managed switch or a packet sniffer, you can run download and upload tests by systematically disconnecting all of your computers in the network one by one. This is only practical in small network environment.

Virus Attack
A lot of connections originating from the same MAC address, to the same destination port, but for different destination address, and in short intervals.
Fix: Determine the source address of these connections and disconnect the suspect hosts. Run an antivirus scan on the computer before plugging it back. There are a few ways to determine the source of a virus. Use a packet sniffer, look on your managed switch for the ports with the most traffic and confirm it on the suspected computer by issuing the command “netstat -a -b”, (on a Windows machine). The command will show you which ports are active and which program, (executable), is using the ports.

This article is part of a five posts series regarding Network Troubleshooting.

Computer Network – Tools and Supplies

Punch down tool

Punch down tool – The punch tool is used to insert the network cable in the patch panel or similar connection panels. For a small network up to 7 devices you might not need it as you can easily connect all of your devices directly into the switch.

Keystone module RJ45

Keystone Jacks – The RJ45 keystone jack is the female connector, usually immobile, part of a network connection that is mounted on the wall or similar. It provides a network connection close to the device to be connected. A patch-cord is used to connect the device to the keystone jack.

There are many types of RJ45 keystones, some require a punch down tool to be used, and some are tool-les, providing a lever for insertion and a retaining clip to secure the connection. The keystone is also produced for various categories, (Cat 3 – Cat 7), make sure you buy the correct one.


Deep Surplus
Wire Stripper Twisted Pair Cable

Wire stripper / Knife – I am not a fan of the wire stripper because it always cuts a little of the wires. Most of the times, the cut is superficial and it doesn’t get to the wire. But sometimes the stripper will scratch the wires. Using a utility knife or cutting pliers, is a little more laborious but I prefer it as I get more control. Moreover the many crimper tools come with a cable stripper. Don’t use that one, it doesn’t work for round cables, it only works for flat cables.

Simple Cable Tester

Network Tester – This is not a must, but if you are doing this for the first time, it will save you a lot of troubleshooting. For professional network cabling an expensive Network Tool that can measure attenuation, cable length, category supported, etc…, it’s a must. You need to give your client a report with your measurement results.
For small DIY jobs a simple tester will do it.


Patch Panel

Patch Panel – This is beyond the purpose of this article since it applies to bigger networks.

Network Switch

Network Switching device – The switching device switches packets between the different devices on your network. Modern switching devices can make a virtual map of all of the devices in your network and route packets according to this map.

Older connectivity devices, such as network hubs, used to indiscriminately broadcast the packets on all of the ports and only the device which the packet belonged to would have accepted it. This design creates a lot of collisions and saturates the network with unnecessary traffic.

Network hubs, (two or more ports), or repeaters, (only one port), are used to increase the maximum of 100m, (333 ft), between two devices connected on an Ethernet segment. Every repeater adds up another 100m.