Client Requested DHCPv6 Options
 
 
  The following default options are encapsulated by the DHCPv6 client when
   requesting DHCPv6 server.
    - OPTION_CLIENTID (code 1). The Client Identifier option is used to carry
     a DUID identifying a client between a client and a server.
- OPTION_SERVERID (code 2). The Server Identifier option is used to carry
     a DUID identifying a server between a client and a server. Note    OPTION_SERVERID option is included if DHCPv6 client is responding to a particular
      server. 
- OPTION_IA_NA (code 3). The client uses IA_NA options to request the assignment of
     non-temporary address assignment.
- OPTION_IAADDR (code 5). The IA_ADDR is used to specify the IPv6 addresses associated with
     IA_NA or IA_TA option. Note    OPTION_IAADDR is included only if the client lease is
      present. 
 Note    IAID is the last 4 bytes of the hardware address 
- OPTION_ORO (code 6). The Option Request option is used to identify a list of options in a
     message between client and server. A client includes an Option Request option in a Solicit,
     Request, Renew, Rebind, Confirm or Information-request message to inform the server about
     options the client is interested in.
 The following are the Default requested options included by the 
ExtremeXOS DHCPv6 client as
   part of Option Request Option (OPTION_ORO) option:
    - OPTION_DNS_SERVERS (code 23).
- OPTION_DOMAIN_LIST (code 24). Reference for above ORO options: http://tools.ietf.org/html/rfc3646.
- OPTION_ELAPSED_TIME(code 8). A client MUST include an Elapsed Time
          option in messages to indicate how long the client has been trying to complete a
            DHCP (Dynamic Host Configuration Protocol) message exchange.