Configuring Option 82 handling

Option 82, or ‟Relay Information Option” is a field in DHCP messages used to identify the subscriber. The Option 82 field can already be filled in when a DHCP message is received at the router, or it can be empty. MAC learning must be enabled in the VPLS service, for DHCP snooping. If the field is empty, the router should add identifying information (circuit ID, remote ID or both). If the field is not empty, the router can decide to replace it.

The following is a sample partial BSA configuration output with Option 82 adding on a VPLS service. Note that snooping must be enabled explicitly on a SAP.

*A:7210SAS>config>service# 
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vpls 2 customer 1 create
            shutdown 
            stp
                shutdown
            exit
sap 1/1/12:100 create 
                dhcp                    //Configuration example to add option 82
                    option
                        action replace
                        circuit-id
                        no remote-id
                    exit
                    no shutdown
                exit
            exit
            no shutdown
        exit
----------------------------------------------

*A:7210SAS>config>service# 

The following is a sample partial BSA configuration output to remove the Option 82 on a VPLS service.

vpls 2 customer 1 create      
            stp
                shutdown
            exit
            sap 1/1/14:100 create      //Configuration example to remove option 82
                dhcp
                    snoop
                    no shutdown
                exit
            exit