EIGRP stands for Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary routing protocol , based on the original IGRP.
EIGRP is also advanced distance-vector routing protocol with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router.
Routing optimizations are based on the DUAL (Diffusing Update Algorithm) which is a guarantees loop-free operation as well as for fast convergence mechanism.
EIGRP is also advanced distance-vector routing protocol with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router.
Routing optimizations are based on the DUAL (Diffusing Update Algorithm) which is a guarantees loop-free operation as well as for fast convergence mechanism.
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said this on 14 Mar 2008 11:30:53 PM EDT
Basically, EIGRP operates on 4 technologies..
(1) Neighbor Discovery
Will use periodic hello packets so that the neigbor routers will know they are available.With multipoint network, speed lower than T1 , packets unicast in 60secs.
On LAN, 15 secs.
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-(2) Reliable Transport Protocol
Ensuring EIGRP updates infact reaching the neigboring routers.It is sent out as multicast 224.0.0.10. When neigboring Router receives, it requires ack to be sent out.
(3) DUAL( DIffusing Update Algorithm)
to ensure that the loop is free route advertised by the neighbors and it convergence fast enough for advertised routers.It is known to use the lowest calculated metric to know the best path to the destination which is also called the feasible distance.
(4) Protocol Modules
EIGRP have capabilities to route different routing protocols.One of the examples is like redistributing IGRP routes into EIGRP.
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said this on 14 Mar 2008 11:52:50 PM EDT
Routers that advertise a lower metric than the feasible distance (FD) are known as feasible successors,in which the route will hop to.
When changes on the network happens, it will use the next best feasible successors and in the case where the all metrics higher than the FD, EIGRP will need to recompute the route.
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said this on 15 Mar 2008 11:21:42 AM EDT
Another important note,
Static routes advertised by EIGRP automatically if next hop interface which it is covered by the network statement.
Distribution list usually used to prevent this.
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