Tag Archives: machine

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 Computer Network – Your Computer is Slow and Not the Network

Slow Data Transfer is not Always caused by the Network

Slow data transfers are sometimes caused by a slow computer. Determine if the computer is the reason by comparing the transfer speed with a different computer connected on the same switch port. If the speed is the same, the problem is your network. If you get faster data transfers with a different computer then the problem is the computer.

A computer could be slow because of various reasons:

A bad network card. Troubleshoot: Swap the network card and test the data transfers afterwards.
The computer is outdated and it runs software that needs more resources. Troubleshoot: change the computer.
Slow hard-drive. The hard-drive will always be the computer’s bottle neck. It is the slowest part of a desktop computer. Old hard-disks are very often seen in new computers. Hard-disk fragmentation is a frequent reason for slow computers. Troubleshoot: Defragment often your hard-drive and reserve a 25% free space on the drive.
The computer might be infected with a virus or a Trojan. Troubleshoot: scan the computer for viruses. On a Windows machine run the command “netstat -a -b” to see what ports are being used and which program is using them. Use a network sniffer and monitor the network activity on the specific computer.
The transfer is intermittently slow, check what background processes are using the CPU, Memory, and hard-drives. Windows Vista can sometimes be a resources hog by allocating too many resources for background processes such as indexing and running the antispyware. Antivirus or other antimalware can consume a lot of the computers’ resources. Troubleshoot: Change the schedule for maintenance tasks to a time when you are not using the computer. Check what other programs are running in the background and configure accordingly. Some antivirus programs enable scanning the network drives by default.
A slow network printer. A slow network printer can be caused by the power save feature. If you use the printer very often you might consider turning off the power save.
A slow Network Attached Storage device. A slow NAS could be caused by improper SAMBA configuration or a disk power save feature. The power save feature is fairly easy to fix, just disable it if you find that you are using the drive very often. The SAMBA tune up is more difficult and usually it is complicated to have terminal access to the device itself. Many manufacturers do not allow direct access to the OS. SAMBA is a free implementation of Microsoft’s SMB protocol. SAMBA, SMB and CIFS offer file and print sharing services for Windows and Linux/Unix machines

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

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.