Giant Yet Silent Changes of The Internet: The Emergence of Segment Routing
The Need for a Better Internet
The Internet can look quite simple when seen from afar. It’s just a network of networks all connected by wires. Originally run by BGP protocol, which was all about connectivity, the system ran well enough. But now we need networks that are much more reliable, secure and smarter. BGP protocol can’t provide us with that (here are all the reasons why). Because of the shortcomings of BGP, new concepts such as Software Defined Networks (SDN), Segment Routing (SR), and IPv6 are emerging.
The emergence of Software Defined Networks
One of the main drawbacks of BGP protocol is the way it routes traffic. In BGP, traffic always selects the shortest path. While this might seem logical, it can often lead to certain paths becoming congested with too much traffic, creating inefficiencies. Having the ability to predetermine how traffic moves across a network can solve this issue. SDN allows us to do just that — it’s a network that you can program. The nodes of such a network have built-in rules that are determined by the controller. These rules direct traffic. The operator of the network can now avoid paths that might be congested with traffic or simply have less capacity and speed.
Simplifying Networks Even Further
Segment Routing is well on its way to gaining popularity as a way to simplify networks. It has the benefits of interfacing with software-defined networks and allows for source-based routing. This technology is not new, but has only recently been embraced by all of the major equipment vendors.
In segment routing, two types of segments exist. The first type, a node segment identifies the shortest path to a destination node (e.g.,R1 to R3 in the diagram). This node segment is communicated throughout the network so that all remote nodes install the segment in their data planes. The second type, an adjacency segment represents a link between two nodes that are adjacent to each other (e.g.,R2 to R5).
Segments allow SR(Segment Routing) to ignore the shortest or lowest cost path preference. The operator gains the ability to steer traffic over different paths based on the requirements of the traffic and the state of the network.
One of the main applications of SR — to enable some kind of application controller to direct traffic over different paths. It finally provides network operators the ability to optimize their existing network infrastructure. Operators now have more control over network routes along with granular control over the traffic data.
Segment Routing Brings New Possibilities
In combination with a SDN Platform, SR can be used to provide value-added services such as bandwidth management, bandwidth calendaring, and bandwidth-on-demand.
SR can be used to help protect against distributed denial of service (DDoS) attacks. It can redirect traffic to a scrubbing device which cleans the traffic and re-injects it back into the network.
SR can be applied to the IPv6 architecture with a new type of routing header called the SR header (SRH). In this case, an instruction is associated with a segment and encoded as an IPv6 address.
What is IPv6?
The emergence of the Internet of Things has shown the need for way more IP addresses. IPv6 was created mainly for this purpose. With much longer addresses than IPv4, IPv6 provides network administrators with a lot more flexibility.
In addition, IPv6 will also be able to encode an instruction that is associated with a particular segment. In this manner, Segment Routing can be applied within the IPv6 architecture. That’s how SRv6 term comes into play.
SRv6 Interoperability
As Segment Routing is gaining more and more popularity and reaching the market adoption stage of “Early Majority”, a new wave of disruption is coming. It will change the way you design and engineer your network infrastructure. This wave is called Segment Routing IPv6 (SRv6).
IPv6 packet headers were originally designed with IPv6 Extension Headers. It didn’t seem like a big deal initially, but SRv6 is actually taking advantage of these Extension Headers by inserting Segment Routing Headers into IPv6 packets.
To make things simple, you have now the ability to code directly into each packet header where the traffic should be sent and how the traffic should be treated. It’s not only simple but also very scalable because you no longer have to maintain any states in the network.
SRv6 is a mindset shift. It makes your applications and your network interact in a completely different way. It’s no longer only about routing traffic from point A to point B. SRv6 goes one step further by enabling the infrastructure to perform actions on the applications themselves.
Our CDN architect Virginijus adds on:
During my 10 year experience working with Content Delivery Networks and Networks in general, I’ve been always obsessed with looking for the best solution that could provide the highest quality results. And I can assure you, IPv6 and Segment Routing will be the most influential changes that I’ve seen. These technologies are phenomenal because of their elegance and simplicity. Of course, CDNs can often be enough to solve the last mile’s delivery problem but there’s still a need to deliver the content from the origin to the edge. In this case, problems such as packet loss, jitter, and throughput rate arise. But the adoption of SRv6 can finally solve these issues. To put it more simply, you can now forget the buffering of videos or any latency in your online gaming experience.
A Tsunami Of Changes
IPv4 has not been updated since the 70s. That’s how monumental this change is. The capabilities that this tweak will enable, at the very fundamental level of the Internet, are just being explored but it’s already clear how massive the impact will be. Further combined with such concepts as Segment Routing, you can get “Programmable Networks”, or even “Programmable Internet”. But let’s save these subjects for future blogs.
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Originally published at noia.network on February 27, 2019.
