Re: [L2tpext] [RTG-DIR] rtg dir review of draft-ietf-l2tpext-sbfd-discriminator

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Sun, 03 January 2016 13:37 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: "Carlos Pignataro (cpignata)" <cpignata@cisco.com>, Loa Andersson <loa@pi.nu>
Thread-Topic: [RTG-DIR] rtg dir review of draft-ietf-l2tpext-sbfd-discriminator
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Date: Sun, 03 Jan 2016 13:37:42 +0000
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Subject: Re: [L2tpext] [RTG-DIR] rtg dir review of draft-ietf-l2tpext-sbfd-discriminator
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> 
> > Excuse me if I don't understand this figure
> >
> >                                                     No. of octets
> >                 +-----------------------------+
> >                 | Discriminator Value(s)      |     4/Discriminator
> >                 :                             :
> >                 +-----------------------------+
> >
> > First I think you say that a Discriminator is 4 octets Second there
> > can be a variable number of discriminators per attribute value field
> > The box in your figure seems to 29 bits wide, this is unorthodox.
> >
> 
> It’s the same as in draft-ietf-isis-sbfd-discriminator. The figure is clear. It does
> not show numbers of bits.
> 
[Les:] Since the IS-IS S-BFD draft has been cited...

In cases where the bits in a particular field are partitioned in some way it makes sense to do what Loa has suggested. However, when a field is simply a "32 bit value" (as in this case) I do not see the need to include a space for every bit. The size of the value field is clearly indicated by the "number of octets". To me, there is no problem with the representation in V1 of the L2TPEXT draft. 

   Les