RIP query

[abhimanyashpal]

Hi all,

I just wanted to know as to why the count to infinity value was decided as 16 in RIP.

[pkhatri]

Hi,

This is because the designers of RIP considered that a network with a diameter greater than 16 was not suitable for RIP. This is because of the distance-vector nature of RIP. That is why 16 hops is considered unreachable in RIP.

Hope that helps - pls rate the post if it does.

Paresh

[pkhatri]

Here's a quote from RFC1058:

"If a network becomes completely inaccessible, we want counting to infinity to be stopped as soon as possible. Infinity must be large enough that no real route is that big. But it shouldn't be any bigger than required. Thus the choice of infinity is a tradeoff between network size and speed of convergence in case counting to infinity happens. The designers of RIP believed that the protocol was unlikely to be practical for networks with a diameter larger than 15."

Paresh

[abhimanyashpal]

Hi Paresh,

Thank you for the reply.

Is there any pointer as to how did they came out with this figure, because DVMRP which is also a Distance Vector based protocol has the count to infinity as 32.

If Distance Vector limits the boundary then it should have been 16 for DVMRP as well. Isn't it?

Abhiman

[pkhatri]

I don't have any such documentation, I'm afraid. While both DVMRP and RIP are distance-vector protocols, they are aimed at quite different purposes, so there is no reason why they should both use the same hop limit. In fact, OSPF and ISIS are both link-state protocols and yet they use completely different metric ranges !

Paresh