On Tue, Feb 01, 2022 at 08:14:08PM +0000, Templin (US), Fred L wrote:
> > Section 5 of draft-templin-intarea-parcels-06 reads as if there is a
> > mandatory
> > dependency against draft-templin-6man-omni.
> > Q1: Is that true ? If not, then i must be overlooking a description how
> > parcels would work
> > in the absence of OMNI.
>
> IP parcels are packets that both set a non-zero IP {Total, Payload} Length
> value and
> also include a Jumbo Payload option. By RFC2675, this constitutes an illegal
> jumbo
> and so it is highly unlikely that any native links (let alone native paths)
> would pass
> the Parcel unless it was first encapsulated. So, encapsulation is required in
> any case,
> and OMNI encapsulation is the prime example given. But, it is possible that
> some
> other form of encapsulation besides OMNI might pick up on the concept.
Thanks. I would strongly suggest to improve the text so that it does not look as
if parcels depend solely on an individual submission draft - but instead
describe
the dependencies against the underlying layer.
For once, its not clear to me if/why those parcles could not simply be passed
over any
link-layer that can support frames large enough for a parcel. Likewise, if the
parcel
needs to be hop-by-hop segmented to fit smaller link layer size, a discussion
about
the benefits and downsides of that adaption would certainly be useful for the
document.
> > Q2: If there is this dependency, how do you think the parcel draft could go
> > to
> > standard given how OMNI is individual submission.
>
> I haven't really thought about that much yet but I don't think OMNI needs to
> be
> a normative dependency; some other form of encapsulation might decide to
> pick up on the parcel concept in the future.
See above.
> > Q3: Is it possible for parcel support to only exist on an initial sequence
> > of
> > subnets, and as soon as a parcel packet has to be sent out to an
> > interface
> > that does not support parcels, the parcel is fragmented into
> > normal/non-parcel
> > IP packets ?
>
> The parcel can only travel as far as the extent of the encapsulation, and
> once the
> encapsulation header is removed the only choices are: 1) deliver the parcel to
> upper layers in the case of local delivery, 2) insert a new encapsulation
> header
> (i.e., re-encapsulate) and forward the parcel further, or 3) unpack the
> parcel and
> forward each segment separately as an independent IP packet toward the final
> destination.
I think your 3) is what i was asking, and i don't see this explicitly written up
in the document.
> I had not really thought about case 3), and I will have to drop back and
> consider
> whether that is something we would want to support. And, I think this only
> applies
> for the final leg of the path from the decapsulator to the final destination
> and the
> same logic cannot be applied for the initial leg of the path from an original
> source
> to a first encapsulating node.
>
> What do you think?
If a path from a parcel capable source to a non-parcel capable destination could
consist of a sequence of one or more subnets thart can carry parcels, ending in
a
router that performs 3), aka: extracting the segments and passing them on as
normal
IP packets over one or more subnets up to the final destination.
That sounds like the most obvious incremental deployment option.
Btw: this where just questions i stumbled across. I still haven't gotten to the
point
of understanding what would be the benefit of parcels to existing network hops
except if there was a clear understanding that packets >> 64kb would create some
form of benefit for routers/network paths. But as far as i understood the
document and
discussion on the mailing list, you where primarily looking for performance
benefits
on the sending host though, not the network path.
Cheers
Toerless
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