From: dmk@uask4it-95 (David Kahn)
Date: Wed, 10 Sep 1997 18:52:09 -0700
Subject: Item #423: OBP-TFTP RP: /chosen/bootreply-packet ...


P1275 Openboot Working Group Proposal -- Proposal #:423 Ver <dmk-01>

Title:          Boot Reply Packet should be MAC independent

Author:         David Kahn (For Michael.Carney@East.Sun.Com)

Date:           Wed Sep 10 18:37:01 PDT 1997

Ed/Tech:        Technical

Synopsis:       The /chosen/bootreply-packet property should
		exclude the encapsulating MAC and protocol
		dependent packet info.

Doc & Version:  OBP-TFTP RP, draft ver 0.6

Problem:        MAC-layer independent software shouldn't have to
		know about the protocol layer encapsulation of
		the bootp bootreply packet ... it should be able
		to interpret the contents without knowing or
		caring about the encapsulating MAC layer prototocol
		headers.

		The "load" method specifically states that the 
		/chosen/bootreply-packet include the "entire packet".

		The BOOT Protocol (and DHCP by inheritance) is designed
		to include enough (and no more) information required
		by an implementation to operate without violating any
		of the protocol layering. That's why the BOOTP header
		contains such fields as hardware type (htype), hardware
		address len (hlen), flags, and client hardware address
		(chaddr). They allow an implementation above the UDP
		layer to effectively address, send, and receive BOOT
		protocol datagrams by permitting such functions as
		updating the ARP table (chaddr + ciaddr) such that a
		server can unicast a response to a client. We don't
		need the data in the link-layer, IP, or UDP headers
		to do this, and to expose these headers needlessly exposes
		link-layer and IP layer (IP options) dependencies.

Proposal:       


  Direct the editor to inlcude the following change in the next version of the
  document and publish this proposal as an addenda/errata to version 0.6
  on the recommended practices page of the web site.

  Replace this text in the "load" method definition
  on  page 7 of obp-tftp RP, draft version 0.6:

    If a BOOTP sequence is performed and succeeds, the BOOTP BOOTREPLY packet
    shall be reported by creating a "bootreply-packet" property under the
    "/chosen" node. The entire packet (including hardware addresses) shall be
    reported, encode as with encode-bytes.

  With this text:

    If a BOOTP sequence is performed and succeeds, the BOOTP[3] BOOTREPLY packet
    shall be reported by creating a "bootreply-packet" property under the
    "/chosen" node. The contents of this property are encoded as 'encode-bytes',
    and contain only the BOOTP[3] packet, with the encapsulating UDP[4], IP[8],
    and link-layer headers omitted.

  Add the following reference to the references section:

    [8] RFC 791, Internet Protocol, IETF, J. Postel. Sep-01-1981.


[ P1275 Item #423 -- Received: Wed Sep 10 18:53:18 PDT 1997 ]