Networking And Routing

In the previous post, we spoke about how a network packet gets from a computer to another device, possibly thousands of kilometers away. Knowing what form of transport a packet takes is one thing, but how does it know how to get there?

Workstation

Your Workstation, be it Windows, MacOS, or Linux doesn’t know anything more about its surroundings than its local address. If the packet is not local, it sends it instead to a network router. The router is the key to the whole journey.

Router

A router receives a packet and inspects it for the destination address. In the same way a postman might not know exactly how to get from Cairns to Albury. They may know they first need to go to the main sorting office in Cairns and knows where that is. A router will send it to the next part of the network, which is often the ISP’s own routers. As it reaches each router that device determines the next step, based on a huge lookup table called a Route Table.

The contents of the route table are updated and managed by different mechanisms and these ensure that the network remains resilient in the event that routes become unavailable, similar to how modern navigation systems can pick the best way to get from location to location based on the road closures, etc…

The process continues all the way to the end destination, where the packet is delivered to the device it was intended for.

Due to the dynamic way route tables are updated and maintained and the various weights and variables that routers may place on certain paths, it’s possible for two packets from the same network to take different paths to the same destination. As each ISP or network provider manages their own routers and might choose to send information a particular way. The shortest way to get to a destination might not be the path your packet takes. This can lead to an increase in latency or the round trip time.

This variability is why privately managed networks are still widely used by enterprises. Telcos such as Telstra maintain a private network that ensures that network packets always take the best and most efficient path in their network. If you are on a Telstra Managed network and have two offices connected by the network, you can assume that your packet will be delivered to the destination in the most efficient way possible.

Whilst this is desirable for many organisations, the private nature of the network and its low utilisation or contention rate does mean that it is more expensive to access than the public internet. If access to a private network is not possible, chose a quality network provider (ISP) who manages the elements of the network that they control in the most effective manner possible. A good Managed Service Provider should be able to help you identify such a network provider and the most appropriate plan for your organisation.

If you’re having any issues with your network, talk to the team at Future IT Services today and we’ll be happy to assist you!