Once you’re getting ready to pass the BSCI exam and earn your CCNP certification, one among the biggest challenges is Understanding BGP. BGP is totally unique from any protocol you figured out to gain your CCNA certification, and one of several distinctions is the fact that BGP works by using path characteristics to favor just one path above A further when many paths to or from the desired destination exist.
Discover I reported “to or from”. In earlier free of charge BGP tutorials, I talked about the BGP attributes “weight” and “neighborhood choice”. These attributes are used to favor 1 route to the place around another; for example, if BGP AS one hundred has two paths 토토사이트 into a place in AS 200, both of these attributes is often established in AS a hundred to favor just one route over Yet another. But Let's say AS 100 wants to inform the routers in AS 200 as to which path it should use to reach a presented location in AS 100?
That’s where by the BGP attribute “Multi-Exit Discriminator”, or MED, comes in. The MED price is usually established in AS a hundred to tell AS 200 which route it ought to use to achieve a given community in AS 100.
Just like quite a few BGP characteristics, the MED is often set by using a route-map. What you should check out is that there's no “set med” worth in route maps. To change the MED of the route, you might want to change the metric of that path. Enable’s say there are two entry paths for AS 200 to employ to reach destinations in AS a hundred. You'd like AS two hundred to make use of the a hundred.one.1.0/24 route over the one hundred.2.2.0/24 path. Very first, discover the two paths with two individual ACLs.
R1(config)#entry-record 22 allow one hundred.1.1.0 0.0.0.255
R1(config)#accessibility-checklist 23 permit one hundred.two.two.0 0.0.0.255
Following, publish a route-map that assigns a lower metric to the more-fascinating route.
R1(config)#route-map PREFER_PATH allow ten
R1(config-route-map)#match ip address 22
R1(config-route-map)#established metric http://www.thefreedictionary.com/토토사이트 100
R1(config-route-map)#route-map PREFER_PATH permit 20
R1(config-route-map)#match ip deal with 23
R1(config-route-map)#set metric 250
Ultimately, use the route-map on the neighbor or neighbors.
R1(config-route-map)#router bgp a hundred
R1(config-router)#neighbor 22.two.2.two route-map PREFER_PATH out
The main element details to remember is the fact even though a lot of BGP attributes prefer a greater value, the MED is essentially an external metric – plus a decreased metric is preferred, equally as Along with the protocols you’ve now analyzed to gain your CCNA certification.