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In Layer 2 connected subscriber sessions, the first hop security needs to be enabled which is the key requirement for ISG IPv6 Layer 2 connected subscriber sessions. On configuring control policy on the interface, ISG will enable FHS snooping policy.

ISG does not get information on any other control packets for session initiation.

Existing FHS behavior is modified and programmed to snoop DHCPv6 prefix.

IPv6 ND sends multicast Router Advertisement (RA) at regular intervals and on receiving Router Soliciation (RS) from the host on bootup with all IPv6 prefixes. The interaction between IPv6 ND and ISG happens with ISG integration, where IPv6 ND sends unicast RA, instead of multicast RA, with prefixes assigned to the subscriber.

Incase of DHCPv6, unicast RA is not advertised to client containing the prefix, to support this feature. Based on the type of the session (SLAAC or DHCPv6) ISG would enable or disable RA session respectively.

To support ISG dual stack sessions with DHCPv6, an interface is configured with ISG and FHS is programmed for prefix-glean snooping policy. After the DHCPv6 handshake, a prefix is allocated to the CPE. Binding for the assigned prefix is created in FHS and a notification is sent to the IPSUB along with the prefix.

To support DHCPv6, ISG session initiator unclassified-mac is used. After the DHCPv6 handshake is complete, a binding is created in FHS and a notification is sent to IPSUP to trigger session creation.

Based on the configuration on the interface, ISG configuration handler will program FHS for SLAAC or DHCPv6 based sessions.

For DHCPv6, ISG session is provisioned for MAC-address of the CPE and the prefix is allocated via DHCPv6. So the DHCP session is provisioned for the CPE MAC and DHCPv6. Packets flowing from the clients allocated ip address through this delegated prefix is accounted for this session.

Perform the following task to configure DHCPv6 support for ISG.

interface Port-channel8.10 
    encapsulation dot1Q 10 primary GigabitEthernet1/1/0 
    ip address 192.168.11.1 255.255.255.0 
    ipv6 address 3002::1/64 
    ipv6 enable ipv6 nd managed-config-flag 
    ipv6 nd other-config-flag 
    ipv6 dhcp relay destination 201:201:201:201::2
    service-policy type control GX_TEST 
    ip subscriber l2-connected 
        initiator unclassified mac-address 
        initiator dhcp