How to Configure BGP Weight Attribute

Lessons Discussion
106

Hello Gilang

The direction that is specified in the command does not refer to the direction of user traffic and how it is to be routed. It refers to the direction of the BGP updates upon which you want to apply the change in weight.

So this particular route map will change the weight of the routes learned via BGP that come from R3 to R1 inbound. So specifically:

  • R3 sends an update to R1 containing the 22.22.22.0/24 prefix
  • This update enters the R1 router via Fa1/0 in an inbound direction
  • R1 has a route-map that will act upon this update in an inbound direction
  • the Weight is changed, and installed in the BGP table with the newly modified weight

Thus, from here on in, outbound user traffic destined to 22.22.22.0/24 will have a weight of 400.

Take a look at this NetworkLessons note on BGP attributes and route-map directions for more information.

I hope this has been helpful!

Laz

107

R1(config-router)#neighbor 192.168.13.3 route-map SETWEIGHT in

in this statement the " in " menas traffic cominf in R1 that time this accesslist verify or check ? pleasse clarify i have doubt on tis

108

Hello Alpesh

The in keyword here referrs to the direction of the BGP Update message and not user traffic. What this is saying is that the route map will be applied to the routes found within the BGP update that is received from that neighbor (in an inward direction). The weight will be adjusted for those routes that match the statements in the route map.

Take a look at this NetworkLessons note on the topic for more information.

I hope this has been helpful!

Laz

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