[Int-area] Regarding draft-ietf-intarea-tunnels-15

Tiger Xu <[email protected]> Tue, 22 Jul 2025 13:32:36 +0000
Newsgroups gmane.ietf.int,gmane.ietf.mpls
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<html>
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<div dir=3D"ltr">
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);">Hi
 all,</span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><br>
</span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);">I
 find this architectural draft quite valuable. Furthermore, since UDP has b=
een widely used as an effective tunneling
<span style=3D"text-decoration: none; display: inline !important; backgroun=
d-color: rgba(0, 0, 0, 0.04);">
technology,</span> such as MPLS-over-UDP (<a href=3D"https://datatracker.ie=
tf.org/doc/rfc7510/">https://datatracker.ietf.org/doc/rfc7510/</a>), it wou=
ld be
<span style=3D"text-decoration: none; display: inline !important; backgroun=
d-color: rgba(0, 0, 0, 0.04);">
very</span> helpful to include more guidance on how to design elegant UDP t=
unnels.&nbsp;</span></span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);"><br>
</span></span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);">Let
 me give a concrete example: GUE variation 1 is just the encapsulation of I=
P within UDP. But to distinguish between variation 1 and variation 0 (i.e.,=
 complete GUE header), which share the same UDP destination port, GUE has t=
o resort to the nibble (i.e., the
 first 4 bits) after the UDP <span style=3D"text-decoration: none; display:=
 inline !important; background-color: rgba(0, 0, 0, 0.04);">
header=A1Xan</span> <span style=3D"text-decoration: none; display: inline !=
important; background-color: rgba(0, 0, 0, 0.04);">
inelegant</span> method that MPLS has to use because its label stack lacks =
a protocol identifier field (<a href=3D"https://datatracker.ietf.org/doc/dr=
aft-xu-mpls-payload-protocol-identifier/">https://datatracker.ietf.org/doc/=
draft-xu-mpls-payload-protocol-identifier/</a>).&nbsp;</span></span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);"><br>
</span></span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);">The
 UDP destination port already plays <span style=3D"text-decoration: none; d=
isplay: inline !important; background-color: rgba(0, 0, 0, 0.04);">
the</span> role of a protocol <span style=3D"text-decoration: none; display=
: inline !important; background-color: rgba(0, 0, 0, 0.04);">
<span style=3D"text-decoration: none; display: inline !important; backgroun=
d-color: rgba(0, 0, 0, 0.04);">identifier,</span> and therefore</span> it s=
eems straightforward to allocate dedicated ports for IP-in-UDP encapsulatio=
ns, as described in
<a href=3D"https://datatracker.ietf.org/doc/draft-xu-intarea-ip-in-udp/">ht=
tps://datatracker.ietf.org/doc/draft-xu-intarea-ip-in-udp/</a>, rather than=
 using the inelegant approach as mentioned above.</span></span><br>
</div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);"><br>
</span></span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><span style=3D"text-decoration: none; white-space: pre-wrap; disp=
lay: inline !important; background-color: rgba(0, 0, 0, 0.04);">If
 the UDP destination port resource were so <span style=3D"text-decoration: =
none; display: inline !important; background-color: rgba(0, 0, 0, 0.04);">
scarce,</span> the UDP destination port reserved for <span style=3D"text-de=
coration: none; display: inline !important; background-color: rgba(0, 0, 0,=
 0.04);">
multicast</span> <span style=3D"text-decoration: none; display: inline !imp=
ortant; background-color: rgba(0, 0, 0, 0.04);">
applications</span>=A1]<a href=3D"https://datatracker.ietf.org/doc/draft-ie=
tf-intarea-multicast-application-port-00">https://datatracker.ietf.org/doc/=
draft-ietf-intarea-multicast-application-port-00</a>=A1^could be donated fo=
r IP-in-UDP encapsulation.
</span></span></div>
<div dir=3D"ltr"><span style=3D"text-decoration: none; font-family: Inter, =
-apple-system, system-ui, &quot;Segoe UI&quot;, &quot;SF Pro SC&quot;, &quo=
t;SF Pro Display&quot;, &quot;SF Pro Icons&quot;, &quot;PingFang SC&quot;, =
&quot;Hiragino Sans GB&quot;, &quot;Microsoft YaHei&quot;, &quot;Helvetica =
Neue&quot;, Helvetica, Arial, sans-serif; orphans: 2; widows: 2; display: i=
nline !important; color: rgba(0, 0, 0, 0.85); background-color: rgb(255, 25=
5, 255);"><br>
</span></div>
<div dir=3D"ltr" style=3D"font-family: Aptos, Arial, Helvetica, sans-serif;=
 font-size: 12pt;">
Best regards,</div>
<div dir=3D"ltr" style=3D"font-family: Aptos, Arial, Helvetica, sans-serif;=
 font-size: 12pt;">
Xiaohu</div>
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