Maximum number of layer 3 switch in a single ospf area

[sarb_sharmin]

please let me know the maximum number of layer 3 switch in a single ospf area?

[Peter Paluch]

Hello,

If you are asking about the maximum number of OSPF routers in a single OSPF area, technical limits are in orders of thousands. With today's routers whose CPUs and memory have enough processing power and capacity, the old tales of "no more than 50 routers per OSPF area" do not hold anymore.

How many routers/L3 switches speaking OSPF do you expect to have in a single area? What counts more is how often does the topology or the addressing change in this area, because each such change leads to a new SPF computation on all routers in the area.

Best regards,

Peter

[Joseph W. Doherty]

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Posting

Practical maximums vary.  Depends much on the complexity of your topology, its stability, your needs for convergence speed, etc. With newer IOSs (e.g. those that support ISPF) you might go even larger.

An old recommendation was no more than 50 routers per OSPF area, but I've worked with OPSF areas containing (low) hundreds of L3 switches within the same OSPF area.