Subject: [PWE3] FW: I-D ACTION:draft-roth-pwe3-fc-encap-00.txt

From: "Moran Roth" <[email-masked]>
Date: Thu, 14 Jul 2005 07:22:55 +0200

I have submitted the internet-draft specified below for consideration by
the PWE3 Working Group.
We intend to present the draft at the upcoming IETF meeting in Paris.

Regards,
Moran

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Subject: I-D ACTION:draft-roth-pwe3-fc-encap-00.txt 

A New Internet-Draft is available from the on-line Internet-Drafts
directories.

	Title		: Encapsulation Methods for Transport of Fibre
                          Channel frames Over MPLS Networks
	Author(s)	: M. Roth, et al.
	Filename	: draft-roth-pwe3-fc-encap-00.txt
	Pages		: 9
	Date		: 2005-7-7
	
A Fibre Channel Pseudowire (PW) is used to carry Fibre Channel frames
over an MPLS network. This enables service providers to offer ^emulated^
Fibre Channel services over existing MPLS networks. This document
specifies the encapsulation of Fibre Channel PDUs within a pseudowire.
It also specifies the procedures for using a PW to provide a Fibre
Channel service.

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From: Stewart Bryant <[email-masked]>
Date: Mon, 25 Jul 2005 17:37:38 +0100

Some comments on draft-roth-pwe3-fc-encap-00.txt

- Stewart

4. Encapsulation

    This specification provides port to port transport of FC encapsulated
    traffic. The following FC connections are supported over the MPLS
    network:
        - N-Port to N-Port
        - N-Port to F-Port
        - E-Port to E-Port

SB> Where are these types defined?

4.1. The Control Word

    The Generic PW control word, as defined in "PWE3 Control Word" [PW-
    CW] MAY be used for FC PW. The structure of the control word is as
    follows:

SB> Do you mean MAY or MUST.

                         1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 0|0 0 0 0|FRG|  Length   | Sequence Number               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 3 - Control Word structure for the one-to-one mapping mode

    The Flags bits are not used for FC. These bits MUST be set to 0 by
    the ingress PE, and MUST be ignored by the egress PE.

    The FRG bits are used for PW PDU fragmentation as described in [PW-
    CW] and [FRAG].

    The length field can be used to remove any padding added by the PSN.
    Its processing must follow the rules defined in [PW-CW].

    The use of the sequence number is optional, and the processing must
    follow the rules as in [PW-CW].

SB> No, you have to describe the rules here.

4.2. MTU Requirements

    The network MUST be configured with an MTU that is sufficient to
    transport the largest encapsulation frames.

SB> So you don't need frag you can say that the bits MUST be 00

    When MPLS is used as the
    tunneling protocol, for example, this is likely to be 12 or more
    bytes greater than the largest frame size. The methodology described
    in [FRAG] MAY be used to fragment encapsulated frames that exceed the
    PSN MTU. However if [FRAG] is not used then if the ingress router
    determines that an encapsulated layer 2 PDU exceeds the MTU of the
    PSN tunnel through which it must be sent, the PDU MUST be dropped.

SB> But now you say can use frag. Did you meant to say SHOULD above?

5. Security Considerations

    This document specifies only encapsulations, and not the protocols
    used to carry the encapsulated packets across the PSN. Each such
    protocol may have its own set of security issues [PW-MPLS] [RFC3985],
    but those issues are not affected by the encapsulations specified
    herein. Note that the security of the emulated service will only be
    as good as the security of the PSN.

SB> Aren't FC apps a bit more sensitive to security than most apps?
SB>
SB> I think that you should consider writing an applicability section
SB> I would imagine that FC has quite stringent requirements on
SB> delay misordering latency etc. Would you consider it suitable
SB> for ruuning over the pblic Internet?

6. IANA considerations

    A new PW type, named "FC Port Mode" is requested from IANA. The next
    available value of 0x0021 is requested.

SB> The next available is 1F. But I don't think that you should quote a
SB> value.