BGP attribute

[R Manjunatha]

Hi

 Normally we use local preference and weight to influence outgoing traffic with the same destination multiple paths. so incoming traffic is preferred to MED. Can I use the local preference and weight attribute for incoming traffic as well?

[M02@rt37 · Accepted solution]

Hello @R Manjunatha,

The local preference and weight attributes are typically used to influence outgoing traffic in BGP. They are not commonly used for influencing incoming traffic.

For incoming traffic, the MED attribute is often used to provide hints to neighboring ASes about the preferred entry point for traffic into your network. If you're looking to influence incoming traffic, other methods such as manipulating AS path prepending or communities might be more appropriate.

[David Ruess]

You can set the local preference and or weight on incoming prefixes to control outbound policy. However the reason these attributes are used for outgoing traffic is it’s not sent to eBGP neighbors. Weight is only local to the same router it’s applied on since the weight attribute is not sent with BGP prefixes (non transitive attribute). So no other devices will know about it. Local preference is sent within the iBGP domain so it won’t be learned by eBGP neighbors. Therefore it cannot influence anything but your local domain teaffic.

Hope that helps

-David

[Joseph W. Doherty]

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@R Manjunatha wrote:

Can I use the local preference and weight attribute for incoming traffic as well?

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No.

@David Ruess further explains why not.

M02@rt37 mentions ways to influence eBGP ingress traffic.