Controlling Route Advertisement

Answer - A.

This is also mentioned in the AWS Documentation.

BGP Communities.

AWS Direct Connect supports a range of BGP community tags to help control the scope (regional or global) and route preference of traffic.

Scope BGP Communities.

You can apply BGP community tags on the public prefixes you advertise to Amazon to indicate how far to propagate your prefixes in the Amazon network-for the local AWS Region only, all regions within a continent, or all public regions.

You can use the following BGP communities for your prefixes.

7224:9100-Local AWS Region.

7224:9200-All AWS regions for a continent (for example, North America-wide)

7224:9300-Global (all public AWS Regions)

All other options are invalid since you need to use BGP communities.

For more information on routing and BGP communities, one can visit the below URL.

https://docs.aws.amazon.com/directconnect/latest/UserGuide/routing-and-bgp.html

When using AWS Direct Connect and a public VIF, BGP (Border Gateway Protocol) is used to exchange routing information between the on-premises data center and the AWS cloud.

BGP allows you to control how far your routes get advertised by using a feature called route propagation, which helps you to advertise only the routes that you intend to advertise.

To control the advertisement of your routes, you can use BGP communities. BGP communities are groups of routes that have some common properties, such as the origin or the path the route has taken. Communities can be used to tag your routes, and you can then use these tags to control how your routes are propagated through the network.

For example, you can use communities to restrict the advertisement of your routes to specific regions or to specific providers.

BGP headers are not used to control the advertisement of your routes. Instead, BGP headers are used to exchange information between BGP peers, such as the type of message being sent or the IP address of the sender.

AS_PATH prepending is a technique used to influence the inbound traffic flow to your network by manipulating the length of the AS_PATH attribute in BGP updates. This technique is used to make your network appear less attractive to inbound traffic, and it is not used to control the advertisement of your routes.

ME is not a valid option in this context and is not a feature of BGP or AWS Direct Connect.

Therefore, the correct answer to the question is A. Use BGP communities.