Troubleshooting MPLS VPN

As I had promised in my post “Non-Technical Tips for CCIE Lab Troubleshooting”, I am back with a series on troubleshooting different networking technologies centering around CCIE Lab. In this post I will be talking about MPLS VPN. For an average person working in Computer Networks, MPLS seems to be a topic which seems to be most scary. Even if their project involves just an MPLS circuit between 2 locations, the word “MPLS” still scares them although there is not much difference between it and a layer 2 circuit. I have received International calls from many of my friends and colleagues who were overwhelmed by MPLS. This could stem from lack of knowledge on MPLS or the way many people teach MPLS. I have seen many guys teaching MPLS by jumping straight to configuration. This teaching method even overwhelmed me, so I tore apart MPLS VPN to understand it better and if you see the concept first and then individual protocols, it might not seem that difficult. In this post, I will not explain MPLS VPN but help develop a strategy to troubleshoot MPLS VPN. It is expected that you know MPLS beforehand to make sense of it or at least have partial knowledge. As I had mentioned in my previous blog about the disadvantages of “Show Run”, so I would be concentrating on using debugs and show commands rather than show run for troubleshooting. Continue reading

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MPLS VPN Torn apart

MPLS is one of the topic where there is too much entry barrier as far as information is concerned. You have to deal with new protocols, different label types, MP BGP, VRFs, etc. on top of the fact that we don’t get exposure to it in our day to day networking (except if you work for an ISP). When I was taught MPLS the first time, it was very difficult for me to visualize (I rely heavily on visualization to understand a topic) the flow as labels had been flying all over the place and pushed and popped and what not. So this is my attempt to explain MPLS VPN by tearing open the packets and showing you what takes place across the network. I will try my best to make it as graphical as possible. Continue reading

MPLS VPN QoS with GNS3 and Virtualbox

The integration of Virtualbox with GNS3 has driven me crazy as simulations you can do with it are limitless. When QoS over MPLS is concerned, not many websites are available explaining it in simple terms. The vast majority of results you might get on google would refer to Cisco documentations. It gives me chills to refer to Cisco documentations as it is just too vast and the thought of it overwhelms me. So in this blog, we will see how QoS works in an MPLS environment and the various types and options available with it. We will make a vanilla MPLS setup so that we can concentrate more on QoS. Continue reading