Cisco CCNP BSCI Tutorial: The BGP Attribute NEXT HOP 33869

When you are learning for the BSCI exam on the way to making your CCNP accreditation, you have got to learn the use of BGP attributes. Browsing To company website probably provides warnings you might tell your mom. These attributes enable you to manipulate the trail or paths that BGP use to reach a given destination when numerous paths to that destination exist.



Within this free BGP guide, we're planning to take a look at-the NEXT_HOP credit. Perhaps you are considering "hey, how complicated could this characteristic be?" It's not so complicated at all, but this being Cisco, there is got to be at least one unusual aspect about it, right?

The NEXT_HOP attribute is simple enough - this attribute indicates the next-hop INTERNET protocol address that should be taken to attain a destination. Within the following illustration, R1 is a heart modem and R2 and R3 are spokes. All three routers come in BGP AS 100, with R1 having a relationship with both R2 and R3. There's no BGP peering between R2 and R3.

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

The problem with the feature will come in when the route is marketed 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 next-hop attribute set to 172.12.123.3. When a BGP speaker advertises an approach to iBGP peers which was actually learned from an eBGP fellow, the next-hop value is retained. To read additional information, you are asked to view at: website.

Here, all three routers are in AS 100. What will the next-hop attribute be set to when R1 advertises the path to its iBGP neighbor R2?

R2#show ip address bgp



There will be no credit for the route on R2, as the route will not appear on R2. By default, a route won't be advertised by a BGP speaker to iBGP neighbors when the route was initially learned from another iBGP neighbor.

Fortunately for all of us, there are numerous ways around this principle. The most common is the usage of route reflectors, and we'll look at RRs in another free BGP tutorial..

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