3/20/2024 0 Comments Ibgp loopback to ebgp pingWhat we need to find out if the next-hop information from the local ISP passes the 'next-hop validation' process. Thus one of those BGP routers would receive routes from 2 providers and the next-hop information would be of each ISP instead of your peering iBGP - concept is clear. But that is no big deal because it will know how to get to it because router 2 will advertise a route to it through iBGP.īut the link I posted addresses the dilemma of the next hop not being reachable by an iBGP neighbor, so it says to run an IGP.Īgreed, I wanted to pointed out the main reason for running IGP on iBGP peering and the main reason is not due to the 'next-hop-self' but the loopback peering - I understand your point - well taken.īut, the fact of the matter is that, if I remove th enext hop self command, the internet routers will advertise the Internet routing table to each other, as well as the eBGP next hop, so they will know how to get to it and the next hop self command is not needed. If I dont have the next hop self command configured, each iBGP neighbor will have the eBGP ISP next hop as their next hop, but you dont have to be running an IGP for them to learn about how to reach that next hop.Įach router will advertise that directly connected subnet through iBGP.\\So, what Im saying is that if router 1 loses its eBGP connection to the ISP, it will learn all the internet routes through the iBGP connection and have router 2's eBGP next hop as its next hop. I have 2 internet routers running eBGP to their ISPs and iBGP between each other. We are told that you must run an IGP for the iBGP neighbor to learn about that next hop.īut that sounds incorrect, now that I actually have to make a decision as to whether to deploy the next hop self command. So, we know that if the iBGP neighbor does not have a route to the eBGP next hop, then it wont place the route in the BGP table. We know that iBGP passes the next hop information learned through eBGP to its iBGP neighbor. Lets do a little BGP 101 review, shall we?
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