How to apply policy on vlan in cisco switch

Applying policies (such as QoS or security) to a VLAN on a Cisco switch involves defining the policy map and applying it under the VLAN configuration mode or to the Switch Virtual Interface (SVI). Use service-policy type qos input <policy-name within vlan configuration <vlan-id or apply ACLs to the SVI for layer 3 control. 

Key Steps and Commands:

• Define Class Map: Identify the traffic to be controlled

switch(config)# class-map match-all CLASS_NAME
switch(config-cmap)# match access-list

Create Policy Map: Define actions for the traffic.

switch(config)# policy-map POLICY_NAME
switch(config-pmap)# class CLASS_NAME
switch(config-pmap-c)# police conform-action exceed-actionswitch(config)# policy-map POLICY_NAME
switch(config-pmap)# class CLASS_NAME
switch(config-pmap-c)# police conform-action exceed-action

Apply to VLAN (Nexus/Specific Platforms):

switch(config)# vlan configuration
switch(config-vlan)# service-policy type qos input POLICY_NAME

Apply to SVI (Layer 3 Interface):

switch(config)# interface vlan
switch(config-if)# ip access-group in

Important Notes:

• Precedence: Interface policies take the highest precedence, followed by VLAN QoS policies, and then system QoS policies.
• Requirements: A VLAN must have at least one active member port for a service policy to be applied.
• Verification: Use show policy-map interface to verify applied policies.