Hi, Russ,
Addng The Usual Suspects for our conversation...
Was your comment about "outermost IP" resolved?
At least "sort of". My biggest concern with 05 was that this qualifier was
introduced suddenly, at the end of section 4, with no explanation. That
usage has gone away in 07, but there's a NEW usage that was added in 07, in
section 6, which now says
(second paragraph)
On its own, this baseline encoding cannot support both ECN marking
end to end and PCN marking within a PCN-domain. It is possible to do
this by carrying e2e ECN across a PCN domain within the inner header
of an IP in IP tunnel, or by using a richer encoding such as the
proposed experimental scheme in [I-D.ietf-pcn-3-state-encoding].
(third paragraph)
In any PCN deployment, traffic can only enter the PCN-Domain through
PCN-ingress-nodes and leave through PCN-egress-nodes. PCN-ingress-
nodes ensure that any packets entering the PCN- domain have the ECN-
-> field in their outermost IP header set to the appropriate PCN
codepoint. PCN-egress-nodes then guarantee that the ECN-field of any
packet leaving the PCN-domain has the correct ECN semantics. This
prevents leakage of ECN marks into or out of the PCN-domain and thus
reduces backward compatibility issues.
If the third paragraph is about tunneled packets, I'd prefer it to say "any
tunnelled packets entering the PCN-domain". If the third paragraph is about
all packets (whether tunneled or not), I'd prefer s/outermost//.
You guys are the ones who get to say whether this preference matters, of
course :-)
Since most of this text is new, I should also ask - 05 called out both
IP-in-IP and IPsec tunnels, while 07 calls out only IP-in-IP (plus the
experimental encoding that was added). Was that change intentional? I'm just
asking about the difference, I don't have a preference ...
Spencer
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