Again, the routing is relatively simple in a slightly more complex data pipe with two routers.
If the router knows that the destination address is directly connected, it can send the traffic.
It must be connected to the other router if its not directly connected.
once you nail more than two routers in a internet, things become more complicated.
This is especially the case when there is also access to the Internet.
Contents
Routing Tables
This is where routing tables come in.
A routing table stores a list of which connected routers the router can forward specific traffic to.
In small, simple networks, this could be hard coded by hand.
Note:A routing table is always concluded with a default route.
On startup, and then every 30 seconds, give or take an up to five-second random variation.
Connected routers respond by providing their routing tables.
Note:End-user devices, such as computers, are configured in silent mode.
This prevents them from responding with their routing tables, which would be useless to the router.
While the hop count for directly connected devices can be as low as 0.
RIP has a maximum number of 15 hops.
A hop count of 16 is treated as infinite as if the link is down.
Potential Issues With RIP
There are several potential issues with this approach.
The first potential issue is the Split-Horizon problem.
In RIP, this is handled in two ways.
First, only the smallest number of hops to a destination is ever kept.
Another potential issue is what to do when a route is down for whatever reason.
This is handled with route poisoning.
In Cisco routers, this functionality is further enhanced with a hold-down timer.
The hold-down timer does, however, increase the time it takes for a RIP connection to achieve convergence.
That is when the routing tables of all devices are stable.
RIPv2
RIPv2 maintains full backward compatibility with RIPv1.
However, it addresses some of its issues.
In reality, this change allowed for subnet masks to also be transmitted along with an IP address.
RIPv2 reduced this effect somewhat by changing from broadcast to multicast.
The use of broadcast meant that end devices saw the traffic spike.
Another version of RIP is standardized as RIPng.
RIPv1 and RIPv2 both only cover IPv4 addresses.
RIPng is designed for IPv6 addresses.
The ng in RIPng stands for next generation.
Timers In RIP
There are four timers associated with the RIP protocol.
The Invalid timer defines how long a route will be held as valid without another router updating the entry.
This means that the Flush timer must always be greater than the Invalid timer.
The hold-down timer is an addition to the standard by Cisco.
The default duration is 180 seconds.
Conclusion
RIPv2 is a simple routing protocol for IPv4 networks.
It calculates the number of routers between the current router and the destination.
This makes it easy to set up and configure.
RIPv2 was popular in enterprise web link environments but has since been replaced by more advanced protocols.
A key feature in its loss of popularity was the limitation to a maximum hop count of 15.
