Fundamentals of MPLS LSPs
One of the items that often trips folks up with MPLS is the concept of label switched paths or LSPs. We’ve talked about them extensively before in many of the blog posts here and I’ve described them a couple of different ways. Many people look at an LSP as a sort of unidirectional tunnel. In fact, most network diagrams aiming to describe an LSP often show it just as that – a tunnel. It’s an easy thing to visualize especially when you start talking about nested tunnels or LSPs inside of LSPs, but I also think it can be rather confusing. This becomes even more confusing when people start talking about end to end LSPs or how a service label is the same end to end as traffic traverses an LSP. What does that mean? Where does an LSP start or stop? Is it really a tunnel? How far can an LSP reach? What if we run different label distribution protocols? In this post, and perhaps the next, I hope to address these questions as well as talk about how we can solve some of the common problems that are often encountered with LSPs.
So let’s dive right in and Continue reading
