AWS Certified Solutions Architect - Professional 2020

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How to use weighting to shift traffic? BGP?


An exam tip from the CSA Pro Course [in Networking and routing] indicated that we should understand "weighting to shift network traffic." Can you provide more context, reference guides, and a heads up as to what traffic flow is being weighted & shifted?

Is it traffic within VPC or traffic to-and-from the Customer Gateway? Was the instructor referring to BGP Communities? Were you referring to prioritizing Route Table traffic (Higher CIDR Prefix preferred over Static which is preferred over than DC/BGP)?  

 (Know we weren’t weighting Rt 53 traffic)

Anybody have any reference guides pertaining to this topic – and specific to that bullet?

Thank you.

1 Answers

Hi Martin,

Thanks for the question.   In broad strokes here, you might get a question on the exam about using routing to transition traffic from one connection to another connection…say Direct Connect to a VPN connection for example.

Most routers have some concept of weight or cost or metric that you can configure for certain routes that will direct the traffic to use a specific physical route even though there may be multiple ways to get to a destination.   This is what I meant for that exam tip…know that this is a thing and that when you hear terms like weight or metric, you’ll identify those with ways to control the flow of traffic.

Now, the CSAP won’t get into the detail that you might see in the Networking Specialty and there are many vendor-specific and provider-specific ways to setup route weights….the take away here for the CSAP exam is that this is a way you can transition traffic from a DC to a VPN connection and back without loosing connectivity.


Martin Leborgne

Thank you for the reply, Scott. Very much appreciated!

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