Networking

BGP Test Lab – Part 9 – Internal BGP (iBGP) – Three Router Configuration (Route Reflector, RR)

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We’re now going to investigate Route Reflectors and how and when they can be used. Route Reflectors are for use within iBGP only, they are never used for eBGP. A Route Reflector (RR) is: An iBGP router, that is specifically allowed to re-advertise iBGP-learned routes to other iBGP peers (within the AS), and is designed to remove the iBGP full-mesh requirement (amongst other things). If you … Read more

BGP Test Lab – Part 8 – Path Selection: BGP Communities

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In this article, we’re going to examine another mechanism of BGP, BGP Communities. These like MED are used to change/influence/direct how traffic will flow between different AS. Its just another mechanism like MED you could use, but has some advantages when compared to MED, namely it can be much more dictatorial rather than influencial and … Read more

BGP Test Lab – Part 4 – Internal BGP (iBGP) – Three Router Configuration (Interior Routing Protocol)

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In the previous article we discovered that iBGP requires a topology and usage that ensures that our exchange of routes between routers is not stopped by the iBGP rule: “A route learned via iBGP must not be advertised to another iBGP peer.” We came across this problem in the previous article where although in normal operational the routes were being … Read more

BGP Test Lab – Part 3 – Internal BGP (iBGP) – Three Router Configuration (next-hop-self)

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We’ll continue to explore Internal BGP (iBGP) in this next part of our deployment. We are going to be deploying another route in the AS Blue 65001. Remember that eBGP is used between AS and iBGP is used within an AS. Be aware however, that this lab topology is flawed in terms of its configuration, but it shows up … Read more

BGP Test Lab – Part 1 – Introduction and Basic Two Router Configuration

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The first part is a basic deployment of BGP between two routers (Router A and Router B) with a single point to point link. In this example, each router is within its own AS (Autonomous System). Therefore any routes exchanged between each AS are eBGP (external BGP) routes. Routes exchanged within an AS are known … Read more