Cisco CCNP / BSCI Tutorial: The BGP Attribute NEXT_HOP abc

When you are learning for the BSCI test on the solution to making your CCNP certification, you've surely got to master the use of BGP attributes. These capabilities allow you to adjust the path or paths that BGP will use to attain certain destination when multiple paths to that destination exist.

In this free BGP article, we are going to take a peek at-the NEXT_HOP attribute. You might be thinking "hey, how difficult can this attribute be?" It is not so complex at all, but this being Cisco, there is 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 address that needs to be taken to achieve a destination. In the following example, R1 is a heart hub and R3 and R2 are spokes. Linklicious.Me Discount contains more concerning the inner workings of this viewpoint. All three routers are in BGP AS 100, with R1 having a relationship with both R3 and R2. Reviews On Linklicious contains supplementary info about the inner workings of it. There's no BGP peering between R2 and R3.

R3 is advertising the network 33.3.0.0 /24 via BGP, and the importance of the feature on R1 is the IP on R3 that is utilized in the peer relationship, 172.12.123.3.

The problem with the next-hop credit comes in if the route is advertised to BGP peers. Dig up new information on our related encyclopedia - Navigate to this hyperlink: linklicious review. If R3 were in a separate AS from R1 and R2, the route would be then advertised by R1 to R2 with the attribute set to 172.12.123.3. The next-hop value is retained, when a BGP speaker advertises an approach to iBGP friends which was initially learned from an eBGP peer. Learn further on linklicious wiki by navigating to our refreshing paper.

Here, all three routers are in AS 100. What'll the characteristic be set to when R1 advertises the path to its iBGP friend R2?

R2#show ip address bgp

< no result >

There will be no next-hop capability for the route on R2, because the route will not look on R2. Automatically, a BGP speaker won't promote a to iBGP neighbors when the route was initially learned from another iBGP neighbor.

Fortuitously for all of us, there are many ways around this rule. The most frequent is the usage of route reflectors, and we'll look at RRs in another free BGP article..