#Bgp route reflector full

So they looked into BGP Confederation and BGP RR’s as possible ways to solve this problem and chose BGP RR over confederation for simplicity reasons. Additionally, with this many numbers the memory needed to store Adj-rib-in will be huge. This large number of iBGP sessions create problems not only from an iBGP session management perspective, but also from an operational perspective as the addition or removal of a router needs an operator to touch all the PE routers in the mesh which is a very costly operation.

#Bgp route reflector full

They would also like to achieve Fast-Recovery and multi-pathing for BGP learned prefixes.Īs you can see that the number of PE routers in ACME network is around 1200.Running 1200 routers in an iBGP full mesh leads to a total of 719,400 (N* (N-1) / 2) iBGP sessions. ACME had already implemented MPLS-TE to achieve FRR (and maximize link utilization) in the Core and IP FRR in the POP’s. ACME runs a BGP free core and PE routers are running BGP for providing various services like 元VPN, L2VPN or Internet. ACME guidelines for Routing is to exit the traffic as soon as possible aka Hot Potato Routing. Out of 6 PE’s in each POP, 2 PE’s are dedicated to VPN (元VPN, L2VPN etc.) functionality and 4 PE’s are for Internet Services. ACME runs a flat single Level IS-IS (Level2) domain for the IGP. Each Core location consists of 2 Core Routers (CR) and each POP (connected to a core location) consists of 6 Provider Edge (PE) bringing the total number of routers to 1300 (100+1200).

It has around 200 POPs and 50 core locations. Setting the StageĪCME is a communications company providing communications and data services to residential, business, governmental and wholesale customers. As usual, I am assuming that the reader has familiarity with BGP and basic RR concepts. In this post we will be looking at large scale RR design by using a fictional ISP ACME as a reference.