[dhcwg] Re: Last call for <draft-ietf-dhc-csr-05.txt>

Stuart Cheshire <cheshire@apple.com> Tue, 28 August 2001 02:24 UTC

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From: Stuart Cheshire <cheshire@apple.com>
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Subject: [dhcwg] Re: Last call for <draft-ietf-dhc-csr-05.txt>
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>But you can't specify that with the static routes option!   This is
>why we need the CSR option - because you can't specify a CIDR route
>such as the one you just mentioned using the existing static routes
>option.

10/8 is NOT a CIDR route. Net 10 is a common private network, and 10/8 is 
the standard classful interpretation.

>The client probably won't *get* all three options!  The server will
>likely leave one out due to lack of space, and there is no reason to
>believe that the one it will drop will be the static routes option.

I didn't say I expected the server to send all three options.
I said the client has to *ask* for all three options, because it doesn't 
know what the server is configured for.

A typical server will most often be configured to send either (a) only 
CSR, or (b) only Router and Static Routes.

The problem is that the client doesn't know which until it asks.

>>     * Can anyone give any technical reason why it is          *
>>     * necessary for *this* document to prohibit clients       *
>>     * from requesting DHCP option number 6 (static routes)?   *
>
>Because both options are likely not to fit in a packet.

The Mac OS DHCP client sets the DHCP Maximum Message Size Option to 1500 
bytes.

The Static Routes option for a single Net 10/8 entry is ten bytes.

The CSR option for a single Net 10/8 entry is eight bytes.

I think a 1500-byte packet has space for eighteen bytes, even if the 
server were configured to send both, which as I said above, it probably 
won't.

Stuart Cheshire <cheshire@apple.com>
 * Wizard Without Portfolio, Apple Computer
 * Chairman, IETF ZEROCONF
 * www.stuartcheshire.org



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