About this task
Create a DHCPv6 Guard policy to provide Layer 2 security to DHCPv6
                                                clients by protecting them against rogue DHCPv6
                                                servers.
Procedure
- 
        Enter Global Configuration mode:
        
          enable configure
              terminal 
 
- 
                                                Enter DHCP Guard mode with the DHCPv6 Guard policy name (dhcpv6g_pol_1). The DHCPv6 Guard policy for the interface is connected to a
                                                  router. 
                                                
                                                  ipv6 fhs dhcp-guard policy
                                                  dhcpv6g_pol_1 
 
- Configure the source
IPv6 access list to allow only a DHCPv6 server replies that originate
from the IPv6 address fe80:0:0:0:cef9:54ff:feb4:9481/128 and check
the preceding IPv6 ACL configuration for ipv6_acl_1 list.
match server access-list ipv6_acl_1 
 
- Verify the prefixes sent in the DHCPv6 server reply message
so that the ipv6_acl_2 IPv6 ACL configuration allows only the prefix
1000::1/64.
match reply prefix-list ipv6_acl_1