Subject: Re: Re: [dhcwg] draft-zi-dhc-agent-request-multi-pool-00.txt

From: zikang <[email-masked]>
Date: Thu, 20 Oct 2005 17:19:43 +0800

> Ted Lemon wrote:
> > There are a couple of problems with this draft.
> >   First, it changes the meaning of the subnet selection option. This is
easy
> > to deal with - just use a different option code.
> >
> >   Second, though, and more serious, it doesn't explain what it's trying
to
> > do. What is the server supposed to do? It sounds like you want the
server to
> > allocate two or more IP addresses, but you don't explain how the server
will
> > return these IP addresses to the client. If you want to allocate more
than
> > one IP address, the only way that I think you can really do it is to
either
> > use a different protocol (that is, not DHCP), or do more than one DHCP
> > packet exchange, using a different client identifier for each desired IP
> > address.
> I got the impression that the draft is trying to address the issue where
the
> Relay agent is unable to determine which of a multitude of subnets a
client
> is originating from.
Yes, this draft is trying to address the issue where the Relay agent is
unable
to determine which of a multitude of subnets a client is originating from.
But the Relay agent konws the subnets.

> >   While this is not explicitly allowed in RFC2131/2132, a conforming
DHCP
> > server will treat a client that identifies itself with two separate IP
> > addresses as two separate clients, and as a result a DHCP client that
wants
> > more than one IP address can, in practice, use two DHCP client
identifiers
> > and thereby get two IP addresses.
>
> Note that this is specifically used in the CableHome specifications. The
> CableHome device has multiple "personalities" each distinguished by a
> different ClientID.
> >   If what you want isn't for the client to get two IP addresses, then
you
> > need to explain what you do want.

The client don't need to get two IP addresses.

>
>
> However, having said that, DHCP Servers today can deal with this issue by
> some mechanism of grouping together various subnets at the DHCP server,
> offhand this draft seems to be a solution in search of a problem....
>
>

Only the DHCP Server can adjust alloc from which subnet for the client, but
the DHCP Server also need to know which subnets the Relay agent can support.
So, the DHCP Server can select one subnet form the subnets the Relay agent
tell it.

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