I learned from the shoulders of giants that multi-area OSPF is the right way to build networks when moving from the Core to the Distribution network.
The classic solution is to divide the network into areas of routers that are relatively related through topology or latency zones, enabling the small area network to converge quickly and only flood a single summary LSA with the result. This limits the risk inherent with link state protocols whereas link flaps could cause OSPF to rapidly execute Dijkstra SPF, leading to OSPF storms. This storm risk grows with the size of a particular area.
Lately, I've encountered engineers who run very large networks with everything in Area 0. They cite modern improvements to router CPUs that can handle mesh environments that widely exceed the guidance of up to 50 routers per area. A very important but secondary concern is the understanding by the staff required to maintain single area OSPF is a much lower bar. I believe that I've also heard about additional complexities with MPLS / LDP in multi-area OSPF.
I'd love to hear other's thoughts on this concept.
The classic solution is to divide the network into areas of routers that are relatively related through topology or latency zones, enabling the small area network to converge quickly and only flood a single summary LSA with the result. This limits the risk inherent with link state protocols whereas link flaps could cause OSPF to rapidly execute Dijkstra SPF, leading to OSPF storms. This storm risk grows with the size of a particular area.
Lately, I've encountered engineers who run very large networks with everything in Area 0. They cite modern improvements to router CPUs that can handle mesh environments that widely exceed the guidance of up to 50 routers per area. A very important but secondary concern is the understanding by the staff required to maintain single area OSPF is a much lower bar. I believe that I've also heard about additional complexities with MPLS / LDP in multi-area OSPF.
I'd love to hear other's thoughts on this concept.
Statistics: Posted by Spudrageous — Wed Dec 27, 2023 11:53 pm