Re: [Spud] Putting Network-Layer Information in the Network Layer

[Joe Touch <[e-mail]>]

Hi, Tom,

On 7/10/2015 9:19 AM, Tom Herbert wrote:
> This "new network layer" breaks down at fragmentation. Only the first
> fragment carries port numbers and the embedded network layer
> information in the payload. Other fragments will carry neither, but
> still can carry IP options, DSCP, TTL, ECN marking, flow labels in
> IPv6.

Right. Which goes to the point that port numbers are NOT part of the
network layer.

Those who want to filter on port numbers are operating network devices
that act on behalf of endpoints - which is fine, but also means they
really ought to be reassembling the network-layer fragments.

I.e., the benefit of port filtering needs to come with the work of
reassembly. Or, "with great (filtering) power, comes great (don't break
the Internet) responsibility".

> An alternate possibility would be to embed IP options within UDP.

That would be a tunnel, and you might look at GUE.

However, you'd have the problem of the relationship of the inner and
outer options and how to maintain them as consistent if they're related.

Joe