In Cisco SD-WAN, data policies can influence the routing traffic flow, particularly when using BGP (Border Gateway Protocol) to manage the traffic from the LAN to the WAN. This involves route manipulation techniques such as AS-path prepending to influence path selection.
AS-Path Prepending:
AS-path prepending is a technique used to manipulate the path selection process in BGP. By adding extra AS numbers to the AS-path attribute, you make a particular route less preferred.
This can be useful in directing traffic to take a different path by making certain routes appear longer.
Option C Analysis:
Policy Definition: The policy named BGP-AS-PREPEND includes a sequence that sets the AS-path to prepend the AS numbers 10 and 20.
Application: The policy is applied in the outbound direction of BGP, which means it will influence the BGP routes being advertised from the LAN to the WAN.
This ensures that the traffic flow from the LAN to the WAN is influenced by the AS-path prepending, making certain paths less preferred.
Cisco SD-WAN Routing Configuration Guide
Cisco SD-WAN BGP Policy Configuration Documentation