Bounded updates
Distance vector protocol, RIP sends the periodic updates to maintain the routing table. Unlike the RIP, EIGRP does not send the periodic updates, it sends the bounded updates means EIGRP send updates when the topology changes or the metric for that route is change. When any router to be add or removed, EIGRP send an update only the information about that route instead of the entire table and this information send only to router that need it.
EIGRP send the updates that are-
1. Nonperiodic, because they are not send updates on regular basis as in RIP.
2. Partial updates, because EIGRP send updates when there is any change in the topology that effect the routing information.
3. Bounded updates, because EIGRP send the updates to router only that need the information.
Trigger updates-
RIP uses trigger updates for the fast convergence when there is a topology changes. A trigger update is a routing table update that is sent quickly in response to a routing change. Trigger update not wait for the update timer to expire. Trigger updates are sent when-
1. An interface of the router changes up or down.
2. A route is entered to unreachable state.
3. A new route is installing in the routing table.
However trigger updates are used for the fast convergence but there are two problems with this-
1. The packets containing the updates can be drop.
2. The packets containing the updates can be damage be some other link in the network.
Random jitter-
Sending the updates at the same time known as synchronization of updates. When multiple routers sending the routing updates at the same time on the LAN segment, the update packet can collide and produce delay or consume more bandwidth. In distance vector routing protocol synchronization can become a problem because of periodic updates. If more routers timer synchronized, more collisions of updates and more delay will occur in the network. In the starting when the router start to send updates that will not be synchronized but over the time, the timers across the network become globally synchronized.
To prevent the synchronization of updates, Cisco IOS uses a random jitter, which adds a variable amount of time to the update interval for the every router in the internerwork.The ranges of variable amount of time, from 0 to 15 percent of the update interval. The update interval varies in a range of 25 to 30 seconds for the default is 30 seconds interval.
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