By using autonomous system, the amount of processor resources is reduced in EIGRP. The bandwidth use can be reduced significantly by the implementation of partial and incremental updates means that EIGRP sends routing information only when a topology change occurs. Instead, EIGRP always sources data packets from the primary address such that all routes are configured on a particular subnet with primary address that belongs to the same subnet. Well, this is one of the drawbacks of EIGRP that it does not support secondary addresses as the routers does not form EIGRP neighbors over secondary networks. Hence, EIGRP authentication is configurable on a pre-interface basis for safety. EIGRP supports this message digest authentication to prevent the interface of any unauthorized information from unacknowledged devices. This key is used to generate and verify a message digest which is a one-way function that gets attached to common network for each packet. Thus for security reasons, only those packets are allowed by devices that have same pre-shared authenticated key. The neighbor uses unicast to communicate. It is to be noted that the devices accepts packets only from devices that know the pre-shared authentication key as each packet that is exchanged between neighbors is authenticated. But when unacknowledged packets are pending, multicast packets are quickly sent by the reliable transport protocol. The EIGRP sends a single multicast hello packet that need not to be acknowledged as it has indication in the packet to inform a receiver. Some Enhanced Interior Gateway Routing Protocol (EIGRP) must be sent reliably to all neighbors. And the neighbor devices can exchange routing information after the status of the neighbor is determined. The working or functioning of the neighbor can be determined as long as hello packets are achieved. When devices periodically send small hello packets to each other with low overhead, neighbor relationship maintenance can be achieved. The device should be able to have knowledge about its neighbors being unreachable or inoperative. The process that devices use to dynamically lean of other devices on their direct attached networks is the neighbor relationship maintenance. Neighbor Relationship and its authentication EIGPR relies on four fundamental concepts that are neighbor tables, topology tables, route states and route tagging. It supports multiple routed protocols through protocol dependent modules. It has faster convergence than any other IGP.
EIGRP uses a more gradual version of IGRP's metrics that is 32 bits v. Both query and reply packets are transmitted reliably. Reply packets are unicast to the originator of the query. Reply packets are sent in response to query packets to instruct the originator not to recomputed the route because feasible successors exist. Query and reply packets are sent when a destination has no feasible successors. In other cases, such as a link cost change, updates are multicast.
Eigrp ip fast reroute update#
When a new neighbor is discovered, unicast update packets are sent so that the neighbor can build up its topology table. Updates packets are used to convey reachability of destinations. Acknowledgement packets contain a non-zero acknowledgement number and always are sent by using a unicast address. An acknowledgement is a hello packet that has no data. Hello packets are multicast for neighbor recovery and do not require acknowledgement. In addition, EIGRP treats IGRP routes as external routes and provides a way for the network administrator to customize them.ĮIGRP uses the following packet types: Hello and acknowledge, Update, and Query and Reply. Because the metrics for both protocols are directly exchangeable, they are as easily comparable as if they were the routes that originated in their own Autonomous Systems. An automatic redistribution mechanism allows EIGRP routes to be imported into Enhanced IGRP and vice a versa, so it is possible to add EIGRP gradually into an existing IGRP network. It includes the diffusing update algorithm. Enhanced IGRP integrates the capabilities of link state protocols into distance vector protocols. The Enhanced Interior Gateway Routing Protocol (EIGRP) represents an evolution from its predecessor IGRP and this evolution is resulted from changes in networking and the demands of diverse, large scale internetworks.