In this article, we are going to understand the role of IPv6 Segment Routing Header (SRH) in SRv6.
Imagine IPv6 as the digital highway for your internet traffic. It’s like a map that guides your data from start to finish. Now, think of Segment Routing Header (SRH) as a supercharged version of this map. It’s like GPS for your data packets, showing them the exact route to follow.
Here’s what you need to know about SRH
Routing Type: This is like a special signal that tells your data packet, “Hey, I’m an SRH packet!” It’s set to 4 to make this clear.
Segment List: This is the heart of SRH. It’s a list of all the stops your data packet will make on its journey. Each stop is like a checkpoint, and this list guides your packet through them.
Segments Left (SL): This is like a counter that keeps track of where your packet is in the journey. It starts at the beginning and counts down as your packet moves along the path.
Visualizing SRH
To make it easier to understand, let’s use an analogy. Think of your data packet as a traveller on a road trip. The “Segment List” is like the itinerary, showing all the places the traveller will visit. The “Segments Left” is like a countdown, indicating how many stops are left.
Processing SRH
Now, let’s see how this works in action. As your data packet travels through the network, it follows the itinerary in the “Segment List.” The “Segments Left” counter decreases with each stop, just like ticking off places on a travel checklist.
- When “Segments Left” is n, your packet is at the nth stop.
- When it’s n – 1, your packet is at the (n – 1)th stop.
- And so on…
If a network node doesn’t support SRv6, it acts like a traveler without a detailed itinerary. It consults a regular routing table to decide where to send the packet next, following basic routing rules.
But here’s the cool part: SRv6 makes the network operate in a unique way. It’s like building a route from the bottom up, unlike traditional methods.
Now, let’s talk about another difference between SRv6 and the older SR-MPLS (MPLS stands for Multi-Protocol Label Switching).
In SRv6, we don’t remove segments as the packet moves along. Here’s why:
- The original design of IPv6 didn’t have much to do with MPLS, so we couldn’t plan for segment removal back then.
- SRv6 segments are embedded within the SRH, which is part of the IPv6 header. They can’t be easily detached like MPLS labels, which sit separately on the packet.
- Keeping the segments in place allows us to retain crucial path information. It’s like having breadcrumbs to follow back, and it also opens up exciting possibilities for new features by using these segments creatively.
Conclusion
So, in a nutshell, SRv6 enhances IPv6 by giving your data packets a clear path to follow, almost like a GPS for the internet. It’s all about making your online journeys smoother and more efficient!