Hange the EIGRP metric weights inside the first place, however if you do trade them on one EIGRP speaker in an AS, you better do so on all the other audio

EIGRP is an crucial a part of actual-global networking in addition to being a primary topic at the 642-901 CCNP BSCI examination. As with any networking subject matter, earlier than you try to master intermediate and advanced abilities, you should master the basics. It would not get any more essential than the EIGRP adjacency process - and it doesn't get any greater essential, due to the fact without that adjacency, we don't have an EIGRP deployment!

In trendy CCNP tutorial, we'll paintings with R1 and R2,  Cisco routers communicating over a serial interface. EIGRP is already jogging on R2's serial interface, however changed into just enabled on R1's serial interface. The EIGRP adjacency system begins with R1 sending an EIGRP Hello packet to the multicast address 224.0.0.10 in an try to find capacity buddies.

R2 will receive this Hello packet and reply with a Hello packet in addition to an EIGRP Update packet. This packet will include all the EIGRP routes R2 is aware of of, as long as the rule of break up horizon isn't always violated. (Split horizon dictates that a direction cannot be advertised out the same interface that has obtained an advertisement for that identical course.)

Oddly sufficient, the EIGRP Update packet transmitted with the aid of R2 will be a unicast packet, now not a multicast. EIGRP Update packets are typically multicast to 224.Zero.Zero.10, but during the primary exchange of routes with a new neighbor, the Update packet is unicast.

In response, R1 will send an EIGRP ACK, brief for acknowledgement. That we could R2 know that R1 acquired the EIGRP routes. R1 may even send an unicast Update packet to R2, which R2 will renowned.

A important distinction between EIGRP and OSPF adjacencies is that EIGRP speakers do no longer ought to agree on hiya and lifeless instances, wherein an OSPF adjacency will never form among routers using one of a kind hey and dead instances. However, EIGRP speakers should agree at the Autonomous System (AS) quantity in addition to the metric weight values. We have an adjacency between R1 and R2, but what occurs to that adjacency if the metric weights are modified on R2?

R2(config)#router eigrp one hundred

R2(config-router)#metric weights zero 1 1 1 1 1

R2#show ip eigrp neighbor

IP-EIGRP buddies for system one hundred

R2# (Nothing to see right here!)

The adjacency is torn down! If we modified the metric weights on R1 or eliminated that final configuration from R2, the adjacency might come again up. You ought to have a excellent motive to change the EIGRP metric weights inside the first place, however if you do trade them on one EIGRP speaker in an AS, you better do so on all the other audio system in the AS as properly. And in case you achieve this, verify them with display ip eigrp neighbor!

Chris Bryant, CCIE #12933, is the proprietor of The Bryant Advantage, domestic of over 200 loose certification exam tutorials, including CCNA certification training articles. His exclusive CCNA examine guide is likewise to be had!

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