Subject: PMP> PortMon Mib question

From: [email-masked]
Date: Mon, 27 Jun 2005 21:05:19 -0400

Question/Issue from one of our dev's

For the variable ppmPortIEEE1284DeviceID, the MIB states:

        The value of this object MUST exactly match the IEEE 1284-2000
        Device ID string, except that the length field MUST NOT be
        specified.  The value MUST be assigned by the Printer vendor
        and MUST NOT be localized by the Print Service.

The definitition indicates that the size is 0-255. However, the actual 
1284 device ID can be much longer.

I think the length field of the 1284 string is two bytes (and the length 
includes the two bytes of length field).???

Jerry Thrasher

---

From: "McDonald, Ira" <[email-masked]>
Date: Mon, 27 Jun 2005 20:23:09 -0700

Hi Jerry,
 
The IETF SMIv2 and the IETF's best practices recommend that MIB string
objects longer
than 255 octets be avoided for interoperability reasons.  There are some
instances in
some modern IETF MIBs of strings with max lengths of 1023 octets (and
conformance
statements allowing a short length such as 255 octets).
 
We could certainly make the IEEE Device ID string longer.  Should we do so?
 
Cheers,
- Ira

Ira McDonald (Musician / Software Architect)
Blue Roof Music / High North Inc
PO Box 221  Grand Marais, MI  49839
phone: +1-906-494-2434
email: [email-masked] 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
[email-masked]
Sent: Monday, June 27, 2005 9:05 PM
To: [email-masked]
Subject: PMP> PortMon Mib question

The definitition indicates that the size is 0-255. However, the actual 1284
device ID can be much longer. 

Jerry Thrasher

---

From: [email-masked]
Date: Tue, 28 Jun 2005 11:32:51 -0400

Ira,

A 1284 ID length of 1023 octets would probably encompass the vast majority 
of strings in use today,  and
we(Lexmark) probably could live with 255 if that's what is decided, 
however we (PWG)  would still need to explain the 
truncation rules regardless of the length we decide (simple truncation at 
the final byte, or truncation at the last full key/value
pair before reaching the limit etc....).

JT

"McDonald, Ira" <[email-masked]>
Sent by: [email-masked]
06/27/2005 11:23 PM

        To:     "[email-masked]'" <[email-masked]>, [email-masked]
        cc: 
        Subject:        RE: PMP> PortMon Mib question

Hi Jerry,

We could certainly make the IEEE Device ID string longer.  Should we do 
so?

Cheers,
- Ira

-----Original Message-----

1284

Jerry Thrasher

---

From: "McDonald, Ira" <[email-masked]>
Date: Tue, 28 Jun 2005 09:26:09 -0700

Hi Jerry,

I think we should change to 1023 octets for 'ppmPortIEEEDeviceID'
with normative 'intelligent truncation' rules (strip whole key/value
pairs) stated in the object and its OBJECT clause back in the
MODULE-COMPLIANCE macro.

Justification appears in the following note from the latest IETF
"Guidelines for Authors and Reviewers of MIB Documents", page 34:

  "Note 2.  DisplayString does not support internationalized text.
            It MUST NOT be used for objects that are required to
            hold internationalized text (which is always the case
            if the object is intended for use by humans [RFC2277]).
            Designers SHOULD consider using SnmpAdminString,
            Utf8String, or LongUtf8String for such objects."

SnmpAdminString (which we have been using per Bert Wijnen) is defined 
in the SNMP Framework MIB (RFC 3411), but is _limited_ to 255 octets.

LongUtf8String is defined in the System Application MIB (RFC2287)
and is limited to 1024 octets (but IPP/1.1 limits strings to 1023,
so for PWG Semantic Model coherence we should use 1023).

I don't like importing from RFC 2287.  I suggest make this one object 
plain ASN.1 'OCTET STRING' and constrain it in the DESCRIPTION clause 
to UTF-8 (with max length 1023 octets and an OBJECT clause allowing
support for only 255 octets).

Comments?

Cheers,
- Ira

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
[email-masked]
Sent: Tuesday, June 28, 2005 11:33 AM
To: [email-masked]
Subject: RE: PMP> PortMon Mib question

Ira, 

A 1284 ID length of 1023 octets would probably encompass the vast majority
of strings in use today,  and 
we(Lexmark) probably could live with 255 if that's what is decided, however
we (PWG)  would still need to explain the 
truncation rules regardless of the length we decide (simple truncation at
the final byte, or truncation at the last full key/value 
pair before reaching the limit etc....). 

JT 

        To:        "[email-masked]'" <[email-masked]>,
[email-masked] 
        cc:         
        Subject:        RE: PMP> PortMon Mib question

Hi Jerry,

Cheers,
- Ira

-----Original Message-----

Jerry Thrasher

---

From: "Ivan Pavicevic" <[email-masked]>
Date: Tue, 28 Jun 2005 11:34:40 -0700

Regarding truncation our requirement is that the device Id has to have
MANUFACTURER (or MFG) and MODEL (or MDL) fields in order to be able to
calculate PnPId.

I'm fine with Ira's suggestion about having a plain OCTET STRING with
constrains we define.

Thanks,
Ivan

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
McDonald, Ira
Sent: Tuesday, June 28, 2005 9:26 AM
To: [email-masked]'; [email-masked]
Subject: RE: PMP> PortMon Mib question

Hi Jerry,

Comments?

Cheers,
- Ira

-----Original Message-----

Ira, 

A 1284 ID length of 1023 octets would probably encompass the vast
majority
of strings in use today,  and 
we(Lexmark) probably could live with 255 if that's what is decided,
however
we (PWG)  would still need to explain the 
truncation rules regardless of the length we decide (simple truncation
at
the final byte, or truncation at the last full key/value 
pair before reaching the limit etc....). 

JT 

Hi Jerry,

Cheers,
- Ira

-----Original Message-----

Jerry Thrasher

---

From: "McDonald, Ira" <[email-masked]>
Date: Tue, 28 Jun 2005 11:41:14 -0700

Hi Ivan,

Yes - I just realized that we need to say that every implementation
of the MIB MUST include both MANUFACTURER (or MFG) and MODEL (or MDL) 
fields within the first 255 octets (the minimum legal string size
for conformance in our new OBJECT clause in MODULE-COMPLIANCE macro),
so that any intermediate gateway can't accidentally truncate these
principal fields.

Cheers,
- Ira

> From: Ivan Pavicevic [mailto:[email-masked]]
> Sent: Tuesday, June 28, 2005 2:35 PM
> To: McDonald, Ira; [email-masked]; [email-masked]