[babel] Mirja Kühlewind's Discuss on draft-ietf-babel-dtls-07: (with DISCUSS and COMMENT)

[Mirja Kühlewind via Datatracker <[e-mail]>]

Mirja Kühlewind has entered the following ballot position for
draft-ietf-babel-dtls-07: Discuss

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DISCUSS:
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Unfortunately I need to discuss the port request again.

First of all I would like to comment on the shepherd write-up which says:
"The document requires only the allocation of a port number for Babel
over DTLS. Having such a second port for the secured version of a
protocol is a fairly common practice. This is shown in the IANA
Considerations section."
This is not correct. Having a second port for the secured version of a protocol
WAS common practice. However RFC6335 say now "The use of separate
   service name or port number assignments for secure and insecure
   variants of the same service is to be avoided in order to discourage
   the deployment of insecure services."

Anyway, in this case I understand that a different port is desired because
unencrypted HELLO messages are still received over the default babel port.
However, it is not clear to me why a fixed/default port is needed. The
neighbour needs to be discovered in some why, no matter what, before a DTLS
connection can be established and this discovery procedure could indicate a
dynamic port number that the peer is listening on for babel over DTLS. E.g. the
multicast HELLO could have a new TLV with this port information. Please clarify
why this option is not suitable! Thanks!


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COMMENT:
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This specification seems to only support babel over DTLS for IPv6. This should
be stated clearly in the introduction.