The BGP Attribute NEXT_HOP

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When you're studying for the BSCI assessment on the method to getting your CCNP certification, you have surely got to master the usage of BGP attributes. These attributes permit you to manipulate the road or paths that BGP will use to reach a given destination when multiple paths to that destination exist.

In this free BGP tutorial, we're planning to take a look at the NEXT_HOP characteristic. This wonderful linklicious me site has diverse fresh aids for where to look at this hypothesis. You might be considering \hey, how complicated can this credit be?\ It is not to complex at all, but this being Cisco, there is got to be at least one unusual aspect about it, right?

The NEXT_HOP attribute is easy enough - this attribute indicates the next-hop IP address that should be taken to achieve a spot. Identify further on linklicious tips by browsing our stylish website. Browse here at the link is linklicious worth the money to read where to acknowledge this enterprise. In the following illustration, R1 is a heart modem and R3 and R2 are spokes. To explore additional info, please consider having a peep at: linklicious.me. All three routers are in BGP AS 100, with R1 having a relationship with both R2 and R3. There is no BGP peering between R2 and R3.

R3 is advertising the community 33.3.0.0 /24 via BGP, and the value of the credit on R1 is the IP address on R3 that is used in the peer relationship, 172.12.123.3.

The problem with the next-hop credit is available in when the route is marketed to BGP peers. If R3 were in another AS from R1 and R2, R1 could then advertise the route to R2 with the attribute set to 172.12.123.3. Whenever a BGP speaker advertises a route to iBGP friends which was initially learned from an eBGP expert, the next-hop value is maintained.

Here, all three routers are in AS 100. What'll the next-hop feature be established to when R1 advertises the approach to its iBGP neighbor R2?

R2#show ip address bgp

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There will be no next-hop feature for the route on R2, as the route will not look on R2. By default, a BGP speaker will not promote a to iBGP neighbors if the route was initially learned from another iBGP neighbor.

Luckily for all of us, there are several ways around this principle. The most frequent is using route reflectors, and we'll look at RRs in the next free BGP training..