Definition of ABR in OSPF on S series switches

Question: What is the definition of ABR? Is a device with more than two areas configured an ABR?

Answer: According to RFC 2328, an OSPF backbone area contains the ABRs of all areas. That is, an ABR must belong to a backbone area. If Area 2 and Area 3 are configured on a device with no interface in a backbone area, the device is not an ABR.
If two or more areas are configured on an S series switch supporting OSPF and one of these areas is a backbone area, the switch is an ABR. Not all these areas must have interfaces in the Up state.

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