EIGRP stands for Enhanced Interior Gateway Routing Protocol which is one of the routing protocol released by Cisco which is an open standard and available to use it with no licences associated. To understand EIGRP, get an understanding of RIP. We are not covering RIP in this article. Like RIP, below rules apply for EIGRP. This is also well-known as hybrid vector protocol
- Split Horizon
- Route Poisoning
- Poison Reverse
These routers will send the hello packet to other routers and establish neighboring. These neighbors will exchange routing information which gets saved in the EIGPR topology table. Post which, the shortest path or the best path from the topology table will be copied in the routing table. To calculate the shortest path, protocol uses set of metrics like bandwidth, delay, load, and reliability, these parameter values will be substituted into formula to calculate the shortest distance.
Features of EIGRP
- Fixed distances defined based on Internal (routers connected in the same autonomous) or External. The values are 90 and 170 respectively.
- This protocol uses DUAL (Diffusing update algorithm) algorithm to calculate and choose the best path from source to destination.
- As mentioned above this is well known to be hybrid protocol, with properties of Distance Vector and link state routing protocol.
- Provides support for cashless routing, automatic and manual summarization on an EIGRP enabled interface.
- Multicasting is supported on EIGRP router and updates each other through multicast IP 184.108.40.206
- It uses MD5 authentication mechanism for hashing the data and have a tightly coupled security on data exchange.
- It provides support for IP, IPX, AppleTalk and IPV6, which are well known network protocols.
- EIGRP is a condition driven topology to establish neighboring. Below is the list of conditions.
- Routers that are meant to be routing should be available in the same IP subnet
- Numbers of autonomous system should match to connect
- K series numbers should match between both the neighbor routers
- In EIGRP there is a limitation on hop count which is 255 but the default value set is 100
- For storing the details on neighboring devices its uses three different tables.
- Neighboring table
- This table contains the information about the neighboring devices.
- Topology table
- This table stores all the paths to destination networks known by the EIGRP neighbor routers
- Routing table
- This table stores the currently used routes path for sending packets to destination network.
- It has the load balancing capability on equal and non-equal cost paths.
- Neighboring table
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