BGP – Advertising IPv4 and IPv6 in a single BGP session!

First we’re going to be creating a eBGP session with IPv4 and then we will advertise routes for IPv6 Prefixes over that session. R2 is in AS 1. R3 is in AS 2. R2 has a L00pback interface with an IPv6 address of 2002:2::2/128 R3 has a L00pback interface with an IPv6 address of 2003:3::3/128 …

BGP – How to configure basic Multipath/Load balancing

As you may know BGP HAS to pick a best route, and that is the route that will be put into our global routing table. Recall that our IGPs have a maximum-paths command that state how many paths can be in the routing table? BGP supports the “maximum-paths” command, however it behaves differently than it …

BGP – Changing MED/Metric to Influence Inbound Routing with Lab Examples

The reason I decided to make this post is because all other MED/Metric changing tutorials out there only include an example of one prefix. I wanted to make one that looked more realistic. Before we begin let’s overview the BGP MED attribute: MED/Metric are synonymous MED influences how your eBGP neighbors should enter your autonomous …

Cisco – Basic Policy Based Routing

Link between R1-2 is 10.0.0.0/30 link between R1-4 is 10.0.1.0/30 Link between R2-4 is 10.0.2.0/30 Link between R2-3 is 10.0.3.0/30 R1 has a loopback of 1.1.1.1/32 R3 has a loopback of 3.3.3.3/32 We want our traffic to go from router 3 (far right) to router 4, then to router 1. We need to apply this …

BGP – Using the next-hop-self command to provide Transit

yes, I see I spelled Colorado wrong. In this topology:   Denver is AS1 Chicago to Colorado is AS 2 Virginia and everything to the right is AS3   First we configure our links with /30s, then I give denver a lo0 of 1.1.1.1 and Chicago a l0 of 2.2.2.2, then configure eBGP between the …

Calculating EIGRP Metric with real world examples

Although not required by the CCNA it’s good to know how to calculate EIGRP metrics to really understand distance. I haven’t found any great guides on teaching this so I thought I’d take a stab at it. Since the only values we use are K1 and K3 by default (Bw and Delay) Here is how …