Subject: Re: updates to IPv6 over PPP spec.

From: srihari varada <[email-masked]>
Date: Thu, 18 Mar 2004 19:06:54 -0500

Dear All:

Provided below is the *ratified *input received from the IPv6 community on the IPv6 over PPP spec. 
The modifications will be made as per the recommendations.

    * Relax the recommendation on the disabling of DAD, if the IPv6CP
      negotiates interface identifier with the peer

    "The Duplicate address detection shouldn't be recommended to be
    disabled, if the IPv6CP negotiates interface identifier with the
    peer. There is a train of thought that even if the interface
    identifier is negotiated, DAD is required on, for instance, global
    unicast address (assuming stateless address autoconfiguration) but
    not necessarily on Link-local address."

    * Review and clarify the IPv6 over PPP specification to match the
      current IPv6 addressing architecture as specified inRFC 3314.
    * Provide a big picture on how global unicast addresses are obtained
      to piece different aspects of addressing in an appendix
    * Identify an exception to consistent reproduction of interface
      identifier.

    "The Interface Identifier section should mention an exception (due
    to the need for privary addresses) to the suggestion of consistent
    reproduction of the interface identifier -- RFC 2472 states that the
    interface identifier is suggested to be consistently reproducable
    across initializations of the IPv6CP finite state machine (see
    section 4.1). The text should be elaborated to include an exception
    as identified by the Privacy Extensions for Stateless Address
    Autoconfiguration in IPv6 (RFC 3041)."

    * Clarify the use of interface identifier negotiated in IPv6CP in
      configuring global addresses

     "One thing related to 2472 came up during the discussions in the
    run up to RFC 3314. It wasn't clear to all  whether a host must use
    the IID that gets assigned in IPv6CP also to create a global address
    (stateless) and whether the host must only use that IID to configure
    global addresses.
    I believe neither are valid assumptions.

    Section 4.1 of 2472 says :
    The interface identifier MUST be unique within the PPP link; i.e.
    upon completion of the negotiation different Interface-Identifier
    values are to be selected for the ends of the PPP link. The
    interface identifier MAY also be unique over a broader scope.

    In Section 5:
    The Interface Identifier of IPv6 unicast addresses [6] of a PPP
    interface, SHOULD be negotiated in the IPV6CP phase of the PPP
    connection setup (see section 4.1).

    The spec doesn't seem to clarify the issue above unless I've missed
    something. So it may be a good idea to add some text to one of the
    above sections such as: It cannot be assumed that a host will use
    this interface identifier also for configuring global addresses
    using stateless address autoconfiguration. A host may generate one
    or more interface identifiers to autoconfigure one or more global
    addresses on its PPP interface using a method like [RFC3041]."

Regards,

Srihari Varada

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