QoS Policy-Map Inbound vs Outbound

When applying a policy-map to a network interface, the choice of doing so in an inbound or outbound direction largely depends on the network's intended outcomes. For traffic classification purposes, such as marking Telnet messages for example, whether the policy is applied inbound or outbound generally has minimal impact, as the core objective is to ensure proper marking for network-wide transit.

However, if Quality of Service (QoS) priorities have been configured, applying the policy in an inbound direction can ensure that these priorities are respected as packets exit the device. Consequently, the direction of application influences the order of operations concerning additional features like routing or Network Address Translation (NAT), making this consideration relevant when specific processing preferences are required.

https://networklessons.com/quality-of-service/qos-marking-cisco-ios-router