Cisco CCNP / BSCI Tutorial: The BGP Attribute

Cisco CCNP / BSCI Tutorial: The BGP Attribute

When you"re learning for the BSCI test on the method to gaining your CCNP certification, you"ve surely got to learn the use of BGP attributes. These features allow you to manipulate the road or paths that BGP will use to attain certain destination when multiple paths to that destination occur.

Within this free BGP training, we are going to have a look at the NEXT_HOP feature. This pictorial linklicious wp plugin use with has a pile of impressive cautions for how to consider it. Maybe you are thinking "hey, how complicated may this attribute be?" It"s not to difficult 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 IP address that should be taken to reach a spot. In the following illustration, R1 is a heart hub and R3 and R2 are spokes. This engaging senukex xindexer encyclopedia has a pile of pictorial warnings for the purpose of this belief. All three routers are in BGP AS 100, with R1 having a connection with both R2 and R3. If people choose to be taught further on what is linklicious, there are many online resources people should consider investigating. There is no BGP peering between R2 and R3. Should people require to discover more about linklicious free, there are many libraries you might consider pursuing.

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

The matter with the next-hop attribute is available in if the route is marketed to BGP peers. If R3 were in another AS from R1 and R2, R1 would then advertise the course to R2 using the next-hop attribute set to 172.12.123.3. Whenever a BGP speaker advertises a path to iBGP friends that has been originally learned from an eBGP expert, the value is stored.

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

R2#show ip bgp



There will be no next-hop attribute for the route on R2, because the route will not appear on R2. Automagically, a route will not be advertised by a BGP speaker to iBGP neighbors when the route was learned from another iBGP neighbor.

Fortunately for us, there are lots of ways around this concept. The most typical is the usage of route reflectors, and we"ll look at RRs in another free BGP tutorial..

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