TrainSignal Chapter 6, Lecture 10 - Route Reflector Lab
R4 is in AS4, and will advertise its loopback (4.4.4.4/32) into BGP
Straight away we can see an issue, whereby the R4's loopback network which is being advertised into BGP, and since R3 learned this via eBGP when it advertises this into its iBGP peers it will retain R4's Eth0 as the next-hop address ......
So lets apply the next-hop-self to R3 to correct this
(We could have configured dynamic routing or static routing to get a route to 4.4.4.4 in R1's IP routing table, or configure next hop self on R3 - as we did)
So, does R1 see any BGP routes ........ NO, no it does and why not? .....
Well it would of learnt this route (4.4.4.4) from another internal BGP speaker, then trying to advertise it to another iBGP peer ...... therefore BGP Split Horizon would stop this
The same is true if R2 wants to advertise its loopback (2.2.2.2/32) to R3
We can fix this by configuring R1 as a route reflector :0)
