Subject: [Adslmib] BITS vs OCTET STRING

From: [email-masked]
Date: Sun, 10 Jul 2005 15:45:49 +0300

Hello Randy,

As you may know the ADSLMIB WG is currently working on the draft:
draft-ietf-adslmib-adsl2-00.txt.
I would like to request your advice regarding one of the issues raised:

Currently the draft has defined a Textual Conventions - Adsl2ScMaskDs
which  uses the SYNTAX  BITS to
define 512 bits;  bit0 (0)   .... bit511(511). This bit map indicates
whether the corresponding bin is in use or not. The value
zero indicating that the bin is in use and the value one indicating that
the bin is not in use. This textual convention is used by
the adsl2LConfProfScMaskDs parameter which is part of the ADSL2 line
configuration profile. The
adsl2LConfProfScMaskDs field is not expected to be changed dynamically.

There is also a similar parameter for the upstream direction.

An alternative has been proposed in which an OCTET STRING be used instead
of BITS.

The argument put forward for this change is: Using an OCTET STRING instead
of a very large BITS type, provides a better economy of description.

Questions:
1. The BITS data type was added only in SNMPv2 and it is stored as an OCTET
STRING. Is the current situation (sequence of 1-bit flags) an example for
which the BITS data type was defined?
2. Are there any particular issues that we should be aware of, in the use
of either of the data types?
3. What would you advise as the better approach?

Thank you kindly for your assistance.

Best Regards,

Menachem Dodge
ECI Telecom Ltd.
Broadband Access Division

Tel:      +972-3-9268421
Mobile: +972-54-5788421
Fax:      +972-3-9287342

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From: "Randy Presuhn" <[email-masked]>
Date: Sun, 10 Jul 2005 21:07:17 -0700

Hi -

Apologies for the massive CC list - is there anyone who is not on the adslmib list?

----- Original Message ----- 
> From: <[email-masked]>
> To: <[email-masked]>
> Cc: <[email-masked]>; "Robert Ray" <[email-masked]>; <[email-masked]>; <[email-masked]>;
<[email-masked]>; <[email-masked]>
> Sent: Sunday, July 10, 2005 5:45 AM
> Subject: BITS vs OCTET STRING
...
> There is also a similar parameter for the upstream direction.

It's probably  time for a TC, no matter which SYNTAX you use.

> which the BITS data type was defined?

It sounds like it's really an array, rather than a sequence, since the bits
are many instances of the same semantic respectively reporting on many
instances of the same resource type.

Although one *could* use BITS for this, this scenario is not what motivated
the development of the BITS construct.

> of either of the data types?

One advantage of using BITS for this is that extending a MIB module to add
more bits is permitted.  A possible (RFC 2578 section 10.2 (1))  A possible
disadvantage is how generic user interface tools might like to display
the information.

> 3. What would you advise as the better approach?
...

I have a *very* slight preference for OCTET STRING, but could live with
either one.  If you think this thing might grow in future versions of the MIB
module, then BITS  becomes preferable.  You might also consider how well
the tools used for managing these devices handle display of the two types,
in light of the semantics of these objects.

Randy