The blog post is sort of "How to ...?"
Some time ago I needed to prepare a lab environment where I should have to simulate a huge amount of BGP updates between routers. How can we arrange that? The main thing is how to generate a lot of BGP updates? As I see we have two ways:
Today I’m going to talk about Segment Routing, especially SR-MPLS. Exactly the best source of theoretical information is RFC. But Segment Routing is a huge topic and it's difficult to sort things out. I will provide basic concepts of SR-MPLS and we will go through basic control plane and data plane tasks of SR.
A good network engineer always tries to optimize network, operation tools and workflow. And I’m sure, engineers who develop Segment Routing concepts follow the same idea.
Why do I think so? Look SR-MPLS short facts:
SR is an alternative of main label distribution protocols - LDP and RSVP.
SR decreases control plane entities because it’s a part of IGP protocols (IS-IS or OSPF)
SR uses stateless paradigm unlike RSVP (It helps to reduce CPU consumption)
Let’s investigate basic SR concepts.
Segment and routing. Take the first definition. What is a "segment"? What types of segments do we have?
Segments are instructions. Head-end encodes these instructions into MPLS headers. It's an interesting concept. We can steer traffic flow by data plane units that contain a stack of MPLS labels - stack of instructions. It helps to eliminate states for every MPLS LSP on Continue reading
Troubleshooting network issues is one of the common skills of every network engineer. And usually, we don’t think about it. We don’t study and train this skill especially. I tell about troubleshooting as a formal process. We just get experience from our daily routine or follow company workflow. I will try to formalize some basic notions. Hope it will be helpful.
Of course, it depends on the situation and business constraints but when we try to resolve some issue we should follow the next steps:
Preparing -> Information-gathering -> Isolating -> Resolving -> Escalating
Let's look at every step.
Every network has infrastructure tools (monitoring, inventory, etc), but we should continuously improve and keep up to date them. Try to develop and integrate a new one. This stack of tools is our source of truth. If we have it, we can easily fetch a full amount of information before, during, and after problems. It’s an enormous topic but without these tools, we can’t successfully troubleshoot our network.