Re: [dhcwg] Comments on 22 rev of the draft

Vijay Bhaskar A K <> Wed, 23 January 2002 16:15 UTC

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From: Vijay Bhaskar A K <>
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Subject: Re: [dhcwg] Comments on 22 rev of the draft
Date: Wed, 23 Jan 2002 21:41:10 +0530
In-Reply-To: <66F66129A77AD411B76200508B65AC69B4CDC9@EAMBUNT705> from Bernie Volz at Jan "21, " 2002 "01:28:33" am
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> VB3> Here, i have another doubt. Assume the following scenario. 
> Assume the Relay agent has addresses from two prefix A and B
> in the link attached to the client. Client has some addresses of
> prefix A. It has  been rebooted now. So, it sends the confirm packet.
> The confirm is received in the relay agent's interface. Now, what 
> prefix it has to put in the link-address field. If it chooses to put B,
> then the addresses assigned to client becomes invalid. In what 
> basis, the Relay agent chooses the prefixes, if the interface
> attached to the client's link has more than one prefixes?
> BV4> You have misconfigured your DHCP environment. Fix the configuration so that either
> the relay always supplies the correct prefix or configure the DHCPv6 server to know about
> both prefixes.

No, both the server and relay  knows  about both  prefixes A and B.  The
problem here is, choosing the prefix.  If the relay's  link  attached to
the  client has both the  prefixes,  the what will the relay  choose?  I
feel like, here the subnet  selection option is really needed.  This can
be useful in two ways.

i) the client can says its prefered prefix in the SOLICIT/REQUEST message.
ii) it can say  about  the  prefix  it was  allocated  to it in  Confirm
meessage.  This  prefix  (say  3ffe::/64)  will  be  compared  with  the
prefixes in the relay's  link  attached to the client.  If the relay has
addresses  with 2 prefixes  3ffe::/64  and  5ffe::/64  in the  interface
attached to client's link, then it puts the  link-address  as 3ffe::/64.
This info will be used by server to check whether the client  resides in
the valid link.

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