Re: Propagating IP/ECN field when L2TP sits between IP as both L2 payload and PSN
Bob Briscoe <[email protected]> Wed, 14 Jun 2017 12:20:30 +0100
| Newsgroups | gmane.ietf.l2tpext |
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Ignacio,
On 31/05/17 02:51, Ignacio Goyret wrote:
> Note that things are a bit more complicated in v2 because
> it transports PPP packets, which may include IP packets (or portions
> of PPP packets if using Multilink). I have no issue punting on L2TPv2
> details.
While going back over all the emails in this thread (I am writing up the
next rev of the draft), the above point raised a couple of questions in
my mind:
Q1. When you say "portions" of IP packets, does L2TPv2 fragmented these
as per IP fragmentation so that each 'portion' has an IP header, or are
they carved up in a PPP-specific way without IP headers on each?
Q2. Does L2TPv3 support PPP in the same way?
Q3. Are there other L2 protocols currently supported by L2TPv3 that can
carve up IP packets so that there will not be an IP header at the start
of each payload?
If framing boundaries might be different, I will need to refer to
section 5.6 of draft-ietf-tsvwg-ecn-encap-guidelines
<https://tools.ietf.org/html/draft-ietf-tsvwg-ecn-encap-guidelines-08#section-5.6>
"Reframing and Congestion Markings", but I don't want to add complexity
if it is not necessary.
Cheers
Bob
--
________________________________________________________________
Bob Briscoe http://bobbriscoe.net/
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Ignacio,<br>
<br>
<div class="moz-cite-prefix">On 31/05/17 02:51, Ignacio Goyret
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:[email protected]">
<pre wrap="">Note that things are a bit more complicated in v2 because
it transports PPP packets, which may include IP packets (or portions
of PPP packets if using Multilink). I have no issue punting on L2TPv2
details.</pre>
</blockquote>
While going back over all the emails in this thread (I am writing up
the next rev of the draft), the above point raised a couple of
questions in my mind:<br>
<br>
Q1. When you say "portions" of IP packets, does L2TPv2 fragmented
these as per IP fragmentation so that each 'portion' has an IP
header, or are they carved up in a PPP-specific way without IP
headers on each?<br>
<br>
Q2. Does L2TPv3 support PPP in the same way?<br>
<br>
Q3. Are there other L2 protocols currently supported by L2TPv3 that
can carve up IP packets so that there will not be an IP header at
the start of each payload?<br>
<br>
If framing boundaries might be different, I will need to refer to <a
moz-do-not-send="true"
href="https://tools.ietf.org/html/draft-ietf-tsvwg-ecn-encap-guidelines-08#section-5.6">section
5.6 of draft-ietf-tsvwg-ecn-encap-guidelines</a> "Reframing and
Congestion Markings", but I don't want to add complexity if it is
not necessary.<br>
<br>
Cheers<br>
<br>
<br>
Bob<br>
<br>
<pre class="moz-signature" cols="72">--
________________________________________________________________
Bob Briscoe <a class="moz-txt-link-freetext" href="http://bobbriscoe.net/">http://bobbriscoe.net/</a></pre>
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