Jonathan,
I'm confused by your paragraph below. I'm not sure what you mean by
this. The prot_type field disappearing in subsequent packets has no
bearing on extensibility as I understand it. For example, if you were
to in the future decide to carry, say, RNP ("random network protocol")
over the current lowpan encapsulation, you'd have a prot_type value
assigned for RNP. This would allow you to send RNP over lowpan even if
you had a mesh configuration underneath (the mesh delivery header being
a general lowpan layer service), or if your RNP packets were large
(by using the fragmentation service, again a general lowpan layer
service). If a receiving station were to receive, say, a fragment
for an packet, it might not be able to know that it is RNP until
more fragments arrive. But it wouldn't be able to do anything until
the entire RNP packet arrives anyways. Just like in IPv4 or v6 fragmentation.
Or did you have something else in mind?
tnx,
-gabriel
----- Original Message ----
In the current 6lowpan proposal, the prot_type field disappears in
packets that are subsequent fragments. Thus, the prot_type field in the
current proposal only allows extensibility in upper layer protocols and
possibly in packets that do not require fragmentation. In the current
6lowpan proposal it wasn't clear to us how a new mesh protocol that
wanted to add a field to the header would do so in a clean way. Also,
what we were trying to convey with the "piggybacking" capability with
the stacked headers was that it was possible, not that we should promote
it.
In the current 6lowpan proposal, the prot_type field disappears in
packets that are subsequent fragments. Thus, the prot_type field in the
current proposal only allows extensibility in upper layer protocols and
possibly in packets that do not require fragmentation. In the current
6lowpan proposal it wasn't clear to us how a new mesh protocol that
wanted to add a field to the header would do so in a clean way. Also,
what we were trying to convey with the "piggybacking" capability with
the stacked headers was that it was possible, not that we should promote
it.
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