By Daniel Muniz
There are 3 versions or variations on the RIP routing protocol, RIPv1, RIPv2, and RIPng.
All three versions of RIP fall under the category of “distance vector protocols”. Distance vector protocols (a vector contains both distance and direction), such as RIP, determine the path to remote networks using hop count as the metric.
A hop count is defined as the number of times a packet needs to pass through a router to reach a remote destination.
These three versions of RIP all are distinguished by (among other things) the use of the Bellman-Ford algorithm for computing routes, the sending of updates every 30 seconds (which contain the entire routing table), and the limitation of supporting a maximum hop count of 15.
Now let’s look at some differences between the different versions of RIP:
RIP v1 uses what is known classful routing. Classful addressing is the use of Class A, Class B, and Class C addresses. (Class D is reserved for multicasts, and Class E is reserved for future use.)
Class A, B, and C addresses define a set number of binary bits for the subnet portion. For example, a Class A network ranges from 1–127 and uses a subnet mask of 255.0.0.0.
A Class B network uses the mask 255.255.0.0, and Class C uses 255.255.255.0. RIP v1 does not support authentication of update messages (plain-text or MD5). RIP v1 is an older, no longer much used routing protocol.
RIP v2 is a classless protocol and it supports classful, variable-length subnet masking (VLSM), CIDR, and route summarization.
RIPv2 supports authentication of RIPv2 update messages (MD5 or plain-text). Authentication helps in confirming that the updates are coming from authorized sources. It also supports multicast routing updates to reduce resource consumption (as opposed to using broadcasting in RIP v1).
RIP v2 can be useful in small, flat networks or at the edge of larger networks because of its simplicity in configuration and usage.
RIPng works basically in the same manner as RIP v2 with one notable exception. RIPng can only run on IPv6 networks.
Additionally, it uses different IP address lengths, RIPng uses 128-bit IP addresses (to accommodate IPv6 128 bit addressing), compared with RIPv2’s 32-bit addresses.
Different packet lengths, a RIPv2 message carries up to 25 route entries, while the maximum number of RTEs in a RIPng packet depends on the IPv6 MTU of the sending interface. Lastly RIPng has a different packet format than its RIP v2 cousin.