Cisco CCNP / BSCI Tutorial: The BGP Attribute NEXT_HOP

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When you're studying for the BSCI examination on the solution to gaining your CCNP accreditation, you've got to learn the usage of BGP attributes. These capabilities allow you to manipulate the trail or paths that BGP will use to achieve a given destination when multiple paths to that destination exist.

In this free BGP training, we are likely to take a look in the NEXT_HOP feature. You may be thinking \hey, how complicated can this feature be?\ It's not very difficult at all, but this being Cisco, there's got to be at least one unusual detail about it, right?

The NEXT_HOP attribute is easy enough - this attribute indicates the next-hop IP that should be taken to achieve a destination. Within the following illustration, R1 is a hub router and R3 and R2 are spokes. If people fancy to learn more about linkilicious.me, there are many resources you should investigate. Dig up further about linklicious free version by visiting our fine web site. All three routers are in BGP AS 100, with R1 having a connection with both R2 and R3. Browse here at the link linklicious youtube to compare the meaning behind this enterprise. There is no BGP peering between R3 and R2.

R3 is advertising the community 33.3.0.0 /24 via BGP, and the value of the next-hop characteristic on R1 is the IP on R3 that's used in the peer relationship, 172.12.123.3.

The issue with the attribute will come in once the route is advertised to BGP peers. If R3 were in another AS from R1 and R2, the route would be then advertised by R1 to R2 using the attribute set to 172.12.123.3. The next-hop value is stored, when a BGP speaker advertises a route to iBGP colleagues which was initially learned from an eBGP fellow.

Here, all three routers come in AS 100. What'll the feature be established to when R1 advertises the approach to its iBGP friend R2?

R2#show ip address bgp

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There will be no capability for the route on R2, since the route won't look on R2. By default, a BGP speaker won't advertise a to iBGP neighbors if the route was first learned from another iBGP friend. Visiting backlink booster maybe provides lessons you should use with your girlfriend.

Fortunately for all of us, there are lots of ways around this principle. The most frequent is the usage of route reflectors, and we'll look at RRs in the next free BGP article..