Current time: 05-20-2018, 07:50 PM Hello There, Guest! (LoginRegister)


Post Reply 
 
Thread Rating:
  • 0 Votes - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Cisco CCNP / BSCI Tutorial: The BGP Attribute NEXT_HOP
04-16-2018, 06:32 PM
Post: #1
Big Grin Cisco CCNP / BSCI Tutorial: The BGP Attribute NEXT_HOP
When you're studying for the BSCI test on the method to gaining your CCNP accreditation, you've got to learn the usage of BGP attributes. These capabilities permit you to adjust the trail or paths that BGP use to reach certain destination when multiple paths to that destination exist.

Within this free BGP guide, we're going to have a look in the NEXT_HOP attribute. You may be thinking "hey, how complicated can this capability be?" It's not to 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 straightforward enough - this attribute indicates the next-hop IP address that should be taken to attain a destination. My cousin learned about remove frames by searching books in the library. In case people require to dig up further about http://linklicious.me/, we know about lots of online libraries people should think about investigating. Within the following example, R1 is a centre modem and R3 and R2 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 feature on R1 is the IP on R3 that's utilized in the peer relationship, 172.12.123.3.

The issue using the attribute comes in if the route is marketed to BGP peers. Identify further on our favorite related use with by visiting partner sites. If R3 were in a different AS from R1 and R2, R1 would then advertise the route to R2 with the next-hop attribute set to 172.12.123.3. When a BGP speaker advertises a path to iBGP peers that has been actually learned from an eBGP peer, the value is retained.

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

R2#show ip address bgp

< no productivity >

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

Luckily for all of us, there are lots of ways around this rule. The most common is the usage of route reflectors, and we'll look at RRs in a future free BGP training.. Be taught more on this partner essay by visiting better than linklicious.
Find all posts by this user
Quote this message in a reply
Post Reply 


Forum Jump:


User(s) browsing this thread: 1 Guest(s)


Contact Us | Your Website | Return to Top | Return to Content | Lite (Archive) Mode | RSS Syndication