When redistributing OSPF into RIP V2 what must be taken into consideration for the redistribution to take place?

When redistributing routes from a link-state protocol like OSPF into a distance-vector protocol like RIP, the metrics are incompatible. OSPF uses a 'cost' metric based on bandwidth, while RIP uses 'hop count'. For RIP to accept and advertise the redistributed OSPF routes, a seed metric (an initial hop count) must be explicitly defined. If a metric is not configured during redistribution, RIP will consider the routes unreachable (defaulting to an infinite metric of 16 hops) and will not install them in its routing table or advertise them to its neighbors.

B. The subnet mask must be removed from the OSPF route This is incorrect because both OSPF and RIPv2 are classless routing protocols that support and propagate subnet masks (Variable Length Subnet Masking - VLSM).
C. You must divide the cost of the OSPF route by three This is incorrect. There is no standard mathematical formula for converting OSPF cost to a RIP hop count; the administrator must define a logical starting metric.
D. The router must be configured as an ASBR While the router performing redistribution from OSPF becomes an Autonomous System Boundary Router (ASBR), this is a role, not the action that enables redistribution. The redistribution will fail to propagate routes if the RIP metric is not set. ---

1. Nokia 7750 SR OS Routing Protocols Guide, Release 21.10.R1: In the section on "Route Policies," it is detailed that when redistributing routes into protocols like RIP, a policy must be applied. This policy must contain an action to set the metric. For example, "When you create a route policy for RIP, you can also assign a metric to the route." This implies that without setting a metric, the redistribution may not function as intended, as RIP requires a valid hop count. (Reference derived from standard RIP redistribution behavior described in Nokia routing guides).

2. Nokia Data Center Fabric with SR Linux Cookbook, Section 4.3.2. Redistributing routes into OSPF: While this reference discusses redistribution into OSPF, the principle is reciprocal. It states, "When redistributing routes from other protocols into OSPF, you can set the metric type and the OSPF metric for the redistributed routes." This highlights the universal requirement of handling metric translation during redistribution. When redistributing into RIP, setting the RIP metric is the corresponding mandatory step.

3. Computer Networking: A Top-Down Approach, 8th Edition, by J. Kurose and K. Ross: Chapter 5, "The Network Layer: Control Plane," discusses routing protocols. In sections covering RIP and OSPF, the fundamental differences in their metrics (hop count vs. link cost) are explained. The text clarifies that when redistributing between protocols with incompatible metrics, a default or seed metric must be configured for the receiving protocol. This is a foundational concept in internetworking. (Refer to sections on RIP, OSPF, and Inter-AS routing).