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14 July 2022

What is IP Routing?

IP routing is the application of routing methodologies to IP networks. IP networks use the internet protocol suite, which is a set of communication protocols used in the internet and computer networks. An IP router, or IP network node, is an element that determines a suitable path for a network packet to traverse the IP network from its source to its destination. Although a router is physically connected to fiber optics, copper-based cabling or wireless media, IP routing is essentially about computing a route and transporting the digital bits across an IP network.

The network industry uses something called the OSI stack to conceptualize the seven layers that contribute to the act of communication. The physical layer or layer one (L1) comprises the physical media (e.g., copper cable). The data link layer (L2) establishes and terminates the link between two nodes (e.g., Ethernet). IP operates at the network layer or L3, which presupposes that L1 and L2 are in place and doing their jobs. The router’s job is to determine the route and forwarding path of the data bits.

When we talk about ‘data’, we generally mean user data, which can be any kind of digital information from any application. For instance, the data could be coming from an email application, a video conferencing application, or a voice application. It could also be data used to control a relay in an electrical transmission network or to tell an autonomous mining truck to stop. There are literally millions of applications that currently use IP to move their application-specific data across the network. 

IP performs two functions with this user application data. First it encapsulates it into packets. The packet is made up of the ‘payload’, which is the user data, and a header, which has the destination address information. Think of the latter like the information form you might fill out at UPS when sending a package. It has the addresses that the packet comes from and where it is going, as well as other information related to the ‘payload’ contents. 

Routing protocols are used to dynamically configure packet-forwarding tables to direct the IP packets to the next available IP router or network node on its path to the desired destination. To coordinate these actions, the IP routers talk to one another over what is often called the control plane. One way to think of it is that the control plane performs routing, while the data plane performs the forwarding.

IP was initially designed as a “best-effort” protocol, where quality of service (QoS) was not seen as critical. This made IP ideal for applications where latency isn’t critical, such as sending an email. It was less suitable for latency-sensitive applications such as a telephone conversation, where skips and stutters caused by late arriving packets degrade the experience, or a mission-critical application such as an autonomous vehicle or an electrical relay which cannot safely suffer from latency or delay.

“Best effort” was initially sufficient given the nature of the traffic transitioning the internet or computer networks. However, as applications have evolved with the introduction of more and more real-time traffic and interactive applications, QoS cannot be ignored. Services cannot be offered without the guarantee of QoS. This has led to the development of QoS mechanisms and protocols that enable IP networks to support the demanding needs of the multimedia and cloud services era.

Everything connected to everything else

As we look forward to services and applications only limited by human imagination, the reliance on our IP networks will only increase. As more and more applications share the same network infrastructure and are increasingly delivered using highly scalable clouds, the network needs to become much more agile, scalable, and resilient. 

One of the focuses for IP networks is the continued shift to mission-critical and business-critical vertical applications. Access will be from evolving wireless and wireline access networks, which will connect to powerful IP edge routers that connect edge clouds and central clouds using data center interconnection services. 

This means that IP routers must become faster, handling data center interconnection services at 400 and 800 Gbs, something that is beginning to happen today. This requires highly specialized network processors like the Nokia FP5 to analyze incoming packets, manage services and add encryption at very high line speeds while reducing the power they use.

Whatever the future brings, IP routing is here to stay.

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