EIGRP is an meaningful factor of real-world networking as fit as someone a great content on the 642-901 CCNP BSCI communicating. As beside any networking topic, until that time you try to master mediate and advanced skills, you must artist the bedrock. It doesn't get any more than connecting than the EIGRP adjacency formula - and it doesn't get any more important, because without that adjacency, we don't have an EIGRP deployment!
In today's CCNP tutorial, we'll occupation beside R1 and R2, two Cisco routers communicating complete a serial interface. EIGRP is once moving on R2's sequent interface, but was righteous enabled on R1's sequent surface. The EIGRP contiguousness modus operandi begins with R1 sending an EIGRP Hello parcel to the multicast computer address 224.0.0.10 in an endeavor to insight eventual neighbors.
R2 will receive this Hello aggregation and come back with next to a Hello aggregation as in good health as an EIGRP Update package. This assemblage will comprise all the EIGRP routes R2 knows of, as durable as the conception of divide up visible horizon is not desecrated. (Split skyline dictates that a path cannot be publicised out the aforesaid interface that has normative an trailer for that one and the same tour.)
Oddly enough, the EIGRP Update aggregation transmitted by R2 will be a unicast packet, not a multicast. EIGRP Update packets are roughly multicast to 224.0.0.10, but during the original rotate of routes next to a new neighbor, the Update packet is unicast.
In response, R1 will dispatch an EIGRP ACK, epigrammatic for recognition. That lets R2 cognize that R1 received the EIGRP routes. R1 will likewise dispatch an unicast Update collection to R2, which R2 will admit.
A crucial divergence linking EIGRP and OSPF adjacencies is that EIGRP speakers do not have to agree on hello and deathly times, wherever an OSPF adjacency will never outline linking routers mistreatment assorted greeting and motionless nowadays. However, EIGRP speakers must agree on the Autonomous System (AS) amount as well as the metric linear unit weight belief. We have an adjacency involving R1 and R2, but what happens to that contiguousness if the metrical weights are denaturised on R2?
R2(config)#router eigrp 100
R2(config-router)#metric weights 0 1 1 1 1 1
R2#show ip eigrp neighbor
IP-EIGRP neighbors for action 100
R2# (Nothing to see here!)
The closeness is worn down! If we changed the metric linear unit weights on R1 or removed that ending pattern from R2, the adjacency would come in subsidise up. You should have a extraordinarily angelic source to fine-tuning the EIGRP metrical weights in the premier place, but if you do tuning them on one EIGRP utterer in an AS, you well again do so on all the other speakers in the AS as ably. And if you do so, corroborate them with attest ip eigrp neighbor!
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