Subject: [midcom] I-D ACTION:draft-ietf-midcom-semantics-00.txt

From: [email-masked]
Date: Fri, 01 Nov 2002 08:43:09 -0500

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Middlebox Communication Working Group of the IETF.

	Title		: MIDCOM Protocol Semantics
	Author(s)	: M. Stiemerling et al.
	Filename	: draft-ietf-midcom-semantics-00.txt
	Pages		: 55
	Date		: 2002-10-31
	
This memo specifies semantics for a Middlebox Communication (MIDCOM)
protocol to be used by MIDCOM agents for interacting with
middleboxes, such as firewalls and NATs.  The semantics discussion
does not include any specification of a concrete syntax or a
transport protocol.  However, a concrete protocol is expected to
implement the specified semantics or a superset of it.  The MIDCOM
protocol semantics is derived from the MIDCOM requirements, from the
MIDCOM framework, and from working group decisions.

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From: Juergen Quittek <[email-masked]>
Date: Fri, 01 Nov 2002 18:23:49 +0100

Dear all,

The announced document is based on
draft-stiemerling-midcom-semantics-02.txt
and contains a lot of improvements by Tom.

It describes the semantics of a midcom protocol meeting the
requirements, but it is still open to the selection of a
Midcom protocol. All four protocol candidates can implement
this semantics.

The semantics is structured into three groups of transactions:
session control transactions, policy rule transactions, and
policy rule group transactions. For each of the transaction
groups, a very simple state machine is defined. A concrete
protocol will probably extend the number of states, the number
of transactions, and/or the number of parameters for some
transactions. But Regardless of such extensions, the semantics
provide the minimum necessary subset of what must be implemented.

After describing the the semantics, conformance statements for
implementations are given. These statemets cover conformance with
the semantics. A concrete protocol will need to extend them by
by protocol specific statements.

Two usage example covering many of the transaction illustrate
the use of a protocol based on this semantics.

Finally, compliancy of the semantics with the Midcom requirements
is explained for each individual requirement.

Tom, Martin, and I see three major areas where the document
needs improvement:

  - The group transactions need to be re-designed. They are
    based on the assumption that groups can be instatiated
    independent of policy rules. This is different to the
    result of our WG discussion at Yokohama (no groups timers!).
    We want to simplify the group concept by only having
    logical groups that are implicitly instanciated by policy
    rule transactions.
    All three of us agree on this, but becasue time was lacking to
    apply all required changes consistently to the document, we
    did not start this work. We see this as a major subject of
    change for the next version.

  - We also did not have sufficient time for developing the
    wildcarding semantics thoroughly. We believe that the
    current one is not mature and probably needs improvement.

  - The major configuration of firewalls and NATs is covered
    by two transactions: the optional policy reserve rule
    transaction (PRR) and the mandatory policy enable rule
    transaction (PER). PER handles all configuration concerning
    packet treatment at the middlebox. PRR is only rerquired in
    some cases, when an agent needs to reserve addresses and
    port numbers at the middlebox, before it can enter a PER
    transaction. We are still discussing, to what extend the
    PER transaction should perform reservations.

Further subjects of potential improvement are listed at the end
of the document in the Open Issues section.

    Juergen
-- 
Juergen Quittek     [email-masked]     Tel: +49 6221 90511-15
NEC Europe Ltd.,    Network Laboratories     Fax: +49 6221 90511-55
Adenauerplatz 6, 69115 Heidelberg, Germany   http://www.ccrle.nec.de

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