Subject: Q: EAP Message Format

From: Ricky Charlet <[email-masked]>
Date: Tue, 8 Jul 2003 15:22:41 -0700

Howdy,

	So, as currently specified in draft-08, the length field of the EAP 
message format may be either 2 or 4 bytes depending upon the type.  If 
the message does indeed have a 4 byte length and no type/type-data 
fields, then what does it look like? Perhaps the following?

                             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
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        !     Code      ! Identifier    !           Reserved            !
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        !                           Length                              !
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 25:  EAP Message Format

---
Ricky Charlet
[email-masked]
510.324.3163

---

From: "Yoav Nir" <[email-masked]>
Date: Wed, 9 Jul 2003 07:44:14 +0200

I'm confused.  Where did you get this 4-byte length field?  Current
technology does not allow 65536-byte frames, so what authentication type
would need a 4-byte length field?

To quote from -08:
   o  Length (two octets) is the length of the EAP message and MUST
      be four less than the Payload Length of the encapsulating
      payload.

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Ricky Charlet
Sent: Wednesday, July 09, 2003 12:23 AM
To: ipsec mailingList
Subject: Q: EAP Message Format

Howdy,

                             1                   2                   3

---
Ricky Charlet

---

From: Francis Dupont <[email-masked]>
Date: Wed, 09 Jul 2003 10:12:37 +0200

In your previous mail you wrote:

   	So, as currently specified in draft-08, the length field of the EAP 
   message format may be either 2 or 4 bytes depending upon the type.

=> no, the text in the draft is buggy but is simpler than your proposal.
Current text is:

   o  Type (one octet) is present only if the Code field is Request
      (1) or Response (2). For other types, the EAP message length
      MUST be four octets and the Type and Type_Data fields MUST NOT
      be present. ...

The fixed text should be:

   o  Type (one octet) is present only if the Code field is Request
      (1) or Response (2). For other codes, the EAP message length
                                     ^^^^^
      MUST be four octets and the Type and Type_Data fields MUST NOT
      be present. ...

So if the code is not Request or Response the length field *value* is 4
and there is nothing after the length field.

Regards

[email-masked]

---

From: Michael Richardson <[email-masked]>
Date: Sat, 19 Jul 2003 18:01:49 +0200

-----BEGIN PGP SIGNED MESSAGE-----

>>>>> "Yoav" == Yoav Nir <[email-masked]> writes:
    Yoav> I'm confused.  Where did you get this 4-byte length field?  Current
    Yoav> technology does not allow 65536-byte frames, so what authentication
    Yoav> type would need a 4-byte length field?

  HIPPI has long used 64K frames :-)
  It is my understanding that the research community is now using even 
longer frames as well.   

  As HIPPI is used in clusters and such, the likely hood of them needing
to run EAP is pretty low.

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