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RE: [Geopriv] Confirmation of GEOPRIV IETF 68 Working Group Hums

2007-04-19 15:44:40
DHCP is a layer 3 technology that talks directly to layer 2.

This is entirely acceptable, useful and right for NETWORK configuration. DHCP 
is an entirely sensible means of obtaining an IP address and _proposals_ for 
domain name prefixes and DNS servers.

DHCP should not be used for any other purpose. In particular to make use of 
DHCP for application configuration is a layer violation. Layer 7 should NEVER 
communicate with Layer 2 directly. When that happens we lose all the power and 
flexibility built into the IP stack. 


To give a concrete example of the problems caused. I am currently typing on a 
VeriSign machine in an office in VeriSign corporate HQ. In that environment the 
local DHCP server could provide me with useful and valid suggestions for all 
manner of services. But its still the wrong technology.

The problem is that when I take the machine to the Hilton Garden Inn down the 
road where I am staying I explicitly DO NOT want the hotel network to provide 
any more than an IP address. I am not going to use their DNS server and I 
certainly don't want to make use of any email server, DNS prefix, GEOPRV or any 
other application layer feature they might want to foist onto me. 

I am using the Hilton Garden Inn LAN, I am not joining their network. The 
machine is remaining on the VeriSign network.


DHCP is a fine technology for the task DHCP is designed to do. It is an 
inappropriate technology for application or service configuration. The proper 
infrastructure to support those needs is DNS, supplemented if necessary by HTTP 
or LDAP backing store (i.e. either discover the services via DNS directly or 
use DNS to discover where the directory service is to be found).

Looking at the history of UPnP and Zero Config it strikes me that attempting to 
manage networks through peer to peer broadcast or multicast have been a bust 
precisely because of this layer violation.


-----Original Message-----
From: James M. Polk [mailto:jmpolk(_at_)cisco(_dot_)com] 
Sent: Thursday, April 19, 2007 5:31 PM
To: Dawson, Martin; John Schnizlein; Andrew Newton
Cc: GEOPRIV WG; ietf(_at_)ietf(_dot_)org; Allison Mankin
Subject: RE: [Geopriv] Confirmation of GEOPRIV IETF 68 
Working Group Hums

At 04:20 PM 4/19/2007, Dawson, Martin wrote:
"DHCP is not adequate because it doesn't meet multiple sets of 
requirements as documented multiple times ..."

bologna

"documented multiple times" means in individual submissions

of which, zero facts were presented to substantiate

If DHCP were so inadequate, why is the DSL forum now going to 
specify it? Why does PacketCable define it?  These were 
fairly recent moves...

And, how many times has HELD been presented as if it were a 
product of an IETF WG?

James


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