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| 4.1 |  | RIP v2 Overview |
| 4.1.8 |  | Limitations of RIP v2 |

Despite its overhaul, RIP v2 could not compensate for all its predecessors limitations. In fairness to the creators of RIP v2, they did not seek to make RIP v2 anything but a modernized RIP. This included maintaining its original purpose as an Interior Gateway Protocol (IGP) for use in small networks or autonomous systems. Therefore, all the original functional limitations designed into RIP also apply to RIP v2. A critical difference is that RIP v2 can be used in networks that require either support for authentication and variable-length subnet masks.

Some of the more significant limitations that were inherited by RIP v2 include the following:

- Lack of alternative routes – RIP v2 continues to maintain a single route to any given destination in its routing tables. In the event a route becomes invalid, the RIP v2 node does not know any other routes to the destination of the failed route. Consequently, it must wait for a routing update before it can begin to assess potential alternative routes to that destination. This approach to routing minimizes the size of routing tables but can result in the temporary unreachability of destinations during a link or router failure.
- Counting to infinity – RIP v2 continues to rely on counting to infinity as a means of resolving certain error conditions within the network. One such error condition would be a routing loop. RIP v2 remains dependent on timers to generate updates. Therefore, it is also relatively slow to converge on a consensus of the network topology following any change to that topology. The more time that it takes to converge, the greater the opportunity for obsolete information to be mistakenly propagated as current information. The result could be a routing loop.
- 15-hop maximum – Perhaps the single greatest limitation that RIP v2 inherited from RIP is that its interpretation of infinity remained at 16. After a route cost is incremented to 16, that route becomes invalid, and the destination is considered unreachable. This limits the use of RIP v2 to networks with a maximum diameter of 15 or fewer hops.
- Static distance vector metrics – Another inherited limitation is found in the RIP v2 static cost metrics. The default value of 1 is just like RIP. However, the default value can be manually adjusted by the network administrator. This metric remains constant, and can only be changed by the administrator. Therefore, RIP v2 remains unsuited for network environments that require routes to be selected in real-time based on either delay, traffic loads, or any other dynamic network performance metric.