Re: Two-octet bandwidth values

["Frank Hujber" <fhujber@hotmail.com>]

It occurs to me that the smallest increment of reservable bandwidth, from a
practical perspective, is a DS1 (1.544 Mbps). If this is so, why do we need
to be able to represent values to +/- 10bps?

The builders of OXCs and PXCs can see down the road to OC-3072 even though
there's not much being spent on it in the lab just yet, and some of aren't
even looking much further back than OC-48. "Bonds" sound linke a proprietary
implementation which no one will want to be beholden to.

This ought to be considered further, even if it has to be put in a separate
sub-TLV for backward compatibility reasons.

Frank Hujber
fhujber@hotmail.com
----- Original Message -----
From: John Drake <jdrake@calient.net>
To: 'Bora Akyol' <akyol@pluris.com>; Kireeti Kompella <kireeti@juniper.net>
Cc: <ccamp@ops.ietf.org>; <OSPF@DISCUSS.MICROSOFT.COM>
Sent: Monday, March 26, 2001 8:36 PM
Subject: RE: Two-octet bandwidth values


> ditto
>
> -----Original Message-----
> From: Bora Akyol [mailto:akyol@pluris.com]
> Sent: Monday, March 26, 2001 5:16 PM
> To: Kireeti Kompella
> Cc: ccamp@ops.ietf.org; OSPF@DISCUSS.MICROSOFT.COM
> Subject: Re: Two-octet bandwidth values
>
>
>
> On Sunday, March 25, 2001, at 08:05 PM, Kireeti Kompella wrote:
>
> > Let's get the ball rolling.  Please send questions and comments to the
> > list.  Here are mine:
> >
> > Questions to vendors:
> > 1) Is floating point arithmetic a burdensome requirement?  Is having
> >    a new library of functions for the two-octet "floating point"
> >    representation a burdensome requirement?
> >
>
> I don't see what exactly is wrong with the present approach, we have no
> problem working with the present TE TLVs and no problems with floating
> point.
>
> > 2) Is halving the size of the bandwidth TLVs a big win (keep in mind
> >    that more bandwidth TLVs are being proposed)?
> >    (a) for ISIS?
> >    (b) for OSPF?
> >    (c) if the answers for ISIS and OSPF differ, is it acceptable to
> >        have different formats for the two protocols?
> >
>
> I think it is unacceptable to have OSPF and ISIS TE TLVs differ. I think
> halving the size of the bandwidth TLVs is not very useful. It causes yet
> another "transition" problem just as people are getting used to the
> present scheme.
>
>
> > Questions to vendors & carriers:
> > 1) Is 10 bits of dynamic range (0.1% accuracy) good enough?
> >
> This depends a lot on the bandwidth, on an OC768c this will translate to
> a whopping 400 Mbps, which to me is inadequate.  Our routers also
> support bundled links which we call "Bonds" that can achieve bandwidths
> much larger than 40 Gbps. So my answer to 10 bits of dynamic range is NO.
>
> > 2) Are you in favor of this draft, or against?
> >
>
> Seems like we have more important stuff to focus on then this particular
> topic.
>
> Bora
>
>