RIPng

RIPng stands for Routing Information Protocol Next Generation. Plain distance-vector protocol utilizing UDP as its transport protocol using port number 521 instead of 520 (to avoid conflict with the existing RIPv1 & RIPv2). Wide adoption of RIP and support over a wide variety of CISCO routers as well as other different vendors prompted the creation of an IPv6 version of RIP called as RIPng. It is built on top of RIPv2 (RIP version 2 for IPv4). The destination IPv6 address for multicast RIPng advertisements is FF02::9. Many operations of RIPng are similar to RIPv2.

METRIC in RIPng:

It is based on hop counts. The metric is incremented by the receiver of RIPng advertisements.

metric =15 being the maximum
metric =16 representing infinity 
(as RIP/ RIPng is suitable for small office
/home office (SOHO) routers and simple networks)

Pre-requisites: Routing Information Protocol (RIP), Routing Information Protocol (RIP) V1 & V2, Implementation of RIP Routing 

Routing Information Protocol (RIP) is a dynamic routing protocol that applies hop count as a routing metric to find the best path between source and destination networks. It is a distance vector routing protocol with an AD value of 120 and operates on the network layer of the OSI model. RIP uses port number 520.