Troubleshooting Network Connectivity Issues

In a real-time environment, I am pretty sure that 99% of network administrators have had a chance to troubleshoot network cable connectivity.  Most of the troubles might have shown different indications and you would have fixed it after spending a lot of time towards this. Let us see some of the most common symptoms that we may face.

·      Maybe you’re getting no connection at all.

·      You’re not able to see the network and obviously not able to connect to anything over the network. 

·      Maybe you have a connection but the data that you’re sending is very slow. 

·      You’re getting very bad throughput when you’re trying to transfer information through the network. 

·      Maybe your connection is telling you that you’re connected, and then it’s telling you that you’re not connected, then it’s telling you you’re connected again. 

These are obviously indicative of some kind of network problem. 

The moment that you identify that you are having some kind of network cable issue. What would be the first step? The best option would be to replace the network cable(copper/fiber). Yeah, we are right about it. But is this the best approach? there are many cases where you cannot do this or not even required to replace the cable. For example, when the distance of cabling is so long, If it’s a fiber cable then the cost would be much higher, If this is being affected for one or more devices and so on.

The very first thing that you need to do is understand the exact nature of the issue. Let’s understand some of this in network cabling based(physical aspects and we are not going to cover logical aspects of this article).

Network cable testing Tools

If you ever suspecting that it could be the network cable issue. The most easiest way confirm this is by the use of simple network testing tools. There are many testing tools available today and I believe that this is one of the most handy tool that is required by all networking guys. 

·      General cable continuity tester for RJ45/RJ11 – Which are cheapest and best solution available in market. This will really help you to identify the continuity of the cable just within few minutes and replace the cable  if required.

·      Fluke Networks are having many products that is optimized for fiber optics cable and twisted paid cable. These are highly recommended when you need to have a detailed report on signal strength, exact view of errors etc.

If you don’t have any of this testing tools. Then the below steps will give you much more ideas on identifying exact error.

If we’re not connected at all, then we need to look at what the cable situation is. 

·      Is there a link light that we’re able to see? Network adapters typically have one or two LED lights that display that an established connection exists and transmission activity is occurring on the line. A network connection is indicated by the network adapter's Link LED. After plugging the cable into the network adapter, the Link LED should come on or start flashing to indicate a connection was made. If the LED doesn't light up or flash, there is likely a problem with the cable or its connector, or both.

·      Do we have a crimp in the cable and is it properly done?

·      Bad connectors - It is important to audit the connector to ensure that the connectors are not broken or cracked for copper and fiber connections.

·      Is it punched down incorrectly? 

·      Do we have the wires in the wrong place inside of the connector? This is especially common if it’s a new installation. 

·      Check the interconnecting cables and patch panel ports are working well?

·      Maybe it would be better to swap out all of the cables that we have, it’s certainly a very quick check to see if the problem might resolve itself that way.

·      Is your cable is selected or crimped as per your current need? Is this a cross over connection or straight through connection that you need to use?

·      Check your cabling switch port or network device ports and make sure the port is working fine.

·      Is there any Network Administrative restriction for this device or interconnected port? Identify that with the respective team.

·      Try to change the network or fiber cables that are used to establish the connection.

If we’re getting very slow throughput,

That means that we’ve got a link light, we might even see some activity lights that are flashing, but we’re still not getting very good throughput. 

·      So we may want to check to see if the cable might be damaged. 

·      There might be a crimp, or a bend, in the cable itself. 

·      If you are using fiber connectors, or using things like SFPs or GBICs, you may want to pull out those connectors and replace them with a brand new set.

·      Is there any chance that your cable is interfering with electromagnetic signals? Make sure you are avoiding this as much as possible.

·      Distance - It is essential to decide which cable has to use based on network topology and distance between those components. For example, when we use CAT 6 cables, the maximum allowed length of a CAT 6 cable is 100 meters or 328 feet. This consists of 90 meters (300 ft) of solid "horizontal" cabling between the patch panel and the wall jack, plus 10 meters (33 ft) of stranded patch cable between each jack and the attached device. If you are lying the cable for a longer than it’s designed capacity you will face network interim issues.

If the connectivity is connected and then not connected, and you’re having this intermittent connectivity issue. 

·      Then, it’s probably best that you swap the cable completely and throw the old cable away. It’s a very quick fix, and it might be able to resolve these intermittent problems.

Sometimes the problem might be more difficult to identify. 

If the cables were manually crimped, there are some most common issues that would occur something like a split pair, Open pair, Miss wire, Crossed wires or Shorted pair. This picture is self-explanatory for you to understand these wiring problems.

It’s a wiring problem, and it’s a very common mistake, but one of the challenges is that if you were to do a simple wire map, it would look like it was perfectly normal. But you’re going to have problems, because there will be a lot of Near-End Crosstalk, and this is why you will get bad throughput, even though a simple cable map is showing you that everything is wired properly. It’s all about the twist of the twisted pair. We want to make sure the pairs of twisted pairs are all kept together. If we’re splitting off any of these pairs, we’re going to have performance problems. The best way to avoid this wiring problem would be to use factory-made network cables. These are available in the market on different sizes and colors of your choice.

Now the best way to confirm a network cable issue is by using various tools available in the market. We will look into those tools and methods in the next article.

Have a comment or points to be reviewed? Let us grow together. Feel free to comment.