> # Applying an IP-ACL to an Interface

> You can define IP-ACLs without applying them. However, the IP-ACLs will have no effect until they are applied to an interface on the switch. You can apply IP-ACLs to VSAN interfaces, the management interface, Gigabit Ethernet interfaces on IPS modules and MPS-14/2 modules, and Ethernet PortChannel interfaces.

> Tip Apply the IP-ACL on the interface closest to the source of the traffic.

> When you are trying to block traffic from source to destination, you can apply an inbound IPv4-ACL to M0 on Switch 1 instead of an outbound filter to M1 on Switch 3.

> The access-group option controls access to an interface. Each interface can only be associated with one IP-ACL per direction. The ingress direction can have a different IP-ACL than the egress direction. The IP-ACL becomes active when applied to the interface.

> Tip Create all conditions in an IP-ACL before applying it to the interface.

> Caution | If you apply an IP-ACL to an interface before creating it, all packets in that interface are dropped because the IP-ACL is empty.

> The terms in, out, source, and destination are used as referenced by the switch:

> - In—Traffic that arrives at the interface and goes through the switch; the source is where it transmitted from and the destination is where it is transmitted to (on the other side of the router).

> Tip The IP-ACL applied to the interface for the ingress traffic affects both local and remote traffic.

> - Out—Traffic that has already been through the switch and is leaving the interface; the source is where it transmitted from and the destination is where it is transmitted to.

> Tip The IP-ACL applied to the interface for the egress traffic only affects local traffic.

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