What are Common Routing Issues and How to resolve them

Certification: Cisco CCIE Routing and Switching - Cisco Certified Internetwork Expert Routing and Switching


The process of routing is extremely important in networking. There is a lot of flow of data over a network. Data needs to be sent and received continuously without any issue and problem. In fact, one of the most essential functions performed by a network is to ensure that each data packet reaches its destination without any modification or deletion. In this regard, the process of routing comes into existence.

The process of routing ensures that the data reaches its exact destination. This process comes into being during the layer 3 of OSI model. It is quite essential that data packets have specific routes which they can follow to reach their destination. In this regard, the map of the whole network is stored beforehand in each router which makes use of it to send data packets on appropriate routes. However, any issue in this integral process of routing can lead to the breaking down of the network. In this regard the data packets might get deleted or modified, the flow of data might get slow or the connection might get lost. These issues need to be dealt with seriousness and they should be resolved as soon as possible. Following are one of the most common issues with routing and ways in which they can be resolved.

Improper port Configuration

Whenever a router is set in a network to carry out the process of routing, there are a number of configuration settings which need to be done on the router. Among these settings, the configuration of ports is very important. Sometimes, misconfigured ports lead to the unusual flow of data packets. The data packets might be transferred to the wrong destination or might be amended as well. In this regard, it is important to check all of these configurations before setting up a network.

Bad Cables

The process of routing is quite delicate and it requires all the cables in the network to be perfect. This is because the data has to be sent out these cables generally and any problem in these cables could lead to issues in the process of routing. These problems could lead to connection problems as well as loss of data packets. In addition to this, it could also lead to interference of electrical signals which might modify or delete the data packets. Hence, it is important to replace all the bad cables covered with insulated material which will be able to carry the data packets efficiently.

Mismatched Maximum Transmission Unit (MTU)

Maximum Transmission Unit (MTU) determines the largest data packet which could be transferred over the network. It is quite important that the interfaces and the devices are configured with the same MTU. It the MTU is not same, then the data packets might be dropped which could lead to incomplete data reaching the destination. Hence, whenever you figure out that the data packets are being lost during the process of routing, you should consider reconfiguring the MTU on the devices.

Power Failure

All of the devices in a network are powered on electricity. However, in case there is a power failure, there is no way in which these routers could remain running to carry out the process of routing. This means that whole of the network will come to a halt in case of a power failure. In order to avoid this, it is essential that these devices have got a backup power plan for them. This power plan could be a generator which turns on immediately in case of a power failure. This will ensure that the process of routing does not stop in any condition.

Incorrect or Damaged Routing Tables

When each router in a network is configured, it is provided with a routing table. This routing table contains details regarding all the routers which are in the network and their distances between each other. This enables the routers to determine the routes on which the data is to be sent. However, if these tables are incorrect or there is any missing information in them, this could lead to the incorrect routing of data packets. The router will not be able to figure out the correct path to send the data packets and this might even result in loss of data. Hence, it is important to make sure that the routing tables are correct. Whenever you experience such problems, you should immediately check the routing tables and ensure that they are accurate. You should also make sure that they are updated because the routers should know the latest routes in the networks to carry the process of routing.

Incorrect subnet mask

The subnet mask is a part of the IPv4 addresses. In order to get the exact position of a client, the router needs to know the subnet mask. However, sometimes the wrong subnet mask is entered which leads to the incorrect routing of data packets. In fact, the router will not even get to know the exact destination without the subnet mask. Hence, it needs to be ensured that the subnet mask is correct.

Duplicate IP Addresses

IP Addresses are unique addresses assigned to each device in a network. These IP Addresses are unique identifiers which make sure that data gets to the right destination. However, sometimes the problem of duplicate IP Addresses arises which means that the router will now not be able to identify the correct path over which the data has to be sent. In this regard, it becomes quite essential to make sure that the IP Addresses are unique and are not duplicated. The problem arises when the IP Addresses are assigned manually without catering to the issue of duplicated IP addresses. Thus, it is advised to use a DHCP server which allocates the IP Addresses automatically to devices.


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