Subject: [dhcwg] [Question] Question about length of link-layer address in DUID

From: Hideshi Enokihara <[email-masked]>
Date: Wed, 26 Oct 2005 16:37:20 +0900

Hi all,

I have a question about DUID-LLT and DUID-LL.

The format of DUID-LLT and DUID-LL is as follows. 

DUID-LLT

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               1               |    hardware type (16 bits)    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        time (32 bits)                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .             link-layer address (variable length)              .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

DUID-LL

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               3               |    hardware type (16 bits)    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .             link-layer address (variable length)              .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

And RFC3315 says,

                        The hardware type MUST be a valid hardware type
   assigned by the IANA as described in RFC 826 [14].  Both the time and
   the hardware type are stored in network byte order.  The link-layer
   address is stored in canonical form, as described in RFC 2464 [2].

In both DUID, I think that length of link-layer address field changes depending
on the hardware type.
If hardware type is Ethernet(1), length of link-layer address field should be
48 bits(link-layer address/MAC address), I think.

So, if DHCPv6 client that uses Ethernet  sends Solicit message, 
length of link-layer address field in this message should be 48 bits.

Is my understanding correct or not?

Best Regards,
-- 
*************************************
Hideshi Enokihara
IPv6 Business
Network & Software Development Dept.
Yokogawa Electric Corporation

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From: Ted Lemon <[email-masked]>
Date: Wed, 26 Oct 2005 01:24:40 -0700

> Is my understanding correct or not?

Sounds right to me!