Service Provider Core


The documents on this page pertain mostly to technologies like MPLS, iBGP, overlay technologies (like PBB-EVPN and VxLAN), Route Reflection and Confederations.

  • VPLS, PBB, EVPN and VxLAN Diagrams: These diagrams give an overview of the different overlay and L2VPN technologies currently used. Whilst not comprehensive, these diagram will help the understanding how they work and interrelate.


  •  Pseudowire Overview: Shows an conceptual overview of what an MPLS pseudowire (or xconnect) is, as well how it is signaled.



  • VRF Route Leaking using Import and Export maps: This documents shows how traffic passes from one VRF to another and where all the config sits, using import and export maps.


  • SSO, GR, NSF and NSR: These terms are often  used for High Availability feature of devices in a Service Provider Core. This quick reference has been created in an attempt to clarify these often ambiguous or confusing features.


  • BGP Route Dampening: BGP Route Dampening is commonly used in Service Provider environments to protect the core network from BGP reconvergence events caused by unstable BGP routes. This document details how it works.



  • Route Reflection Rules: A quick reference guide to the principle and rules involved in route reflection.


  • 6to4 Tunnelling: A visual guide to 6to4 Automatic Tunnels, breaking down details like how IPv4 addresses are embedded in IPv6 addresses and how tunnels are formed.


  • Router Tables and Databases: This diagram, whilst not exhaustive, gives an overview of the tables and databases that you would encounter when looking at a router within a service provider network. It also provides the corresponding Cisco IOS commands.


  • Inter-AS MPLS Options: MPLS communications between Autonomous Systems can be achieved a number of ways and can sometimes be confusing to get your head around. This document outlines the different possibilities, giving diagrams of the overall concepts as well as CLI output from GNS3 labs that can be downloaded from here.


  • MPLS TE Database and RSVP Process: This document shows three basic concepts of MPLS Traffic Engineering: (1) How the Topology Database is populated, (2) How the RESV and PATH messages are used to signal an MPLS TE tunnel and (3) The contents of the RSVP messages.


  • MPLS DiffServ Tunnelling Models: Very quick reference document showing the Pipe, Short Pipe and Uniform Tunnelling Models.