Draft: draft-ietf-mmusic-mdns-ice-candidates

Commentary: Legacy parsers may not be able to parse non - IP - addresses . It might be worth mentioning this issue in that section . Also : Section 5.3 says : " When an endpoint that supports mDNS communicates with an endpoint that does not , the legacy endpoint will still provide its local IP addresses , and accordingly a direct connection can still be attempted , even though the legacy endpoint can not resolve the mDNS names provided by the new endpoint . " Please make it more clear that the legacy endpoint is the one that does not support mDNS . Something like : " When an endpoint that supports mDNS communicates with a legacy endpoint that does not , the ... " Taken from Christer review at 
 Seems reasonable , I think just inserting that one additional word is sufficient . 
 made one other comment : " We have seen one issue with a particular endpoint that did not implement ICE prflx candidates and could not follow the guidance in the text . This is already alluded to in S 4.3 , but we may want to explicitly use the phrase " peer - reflexive " to make clear what behavior is needed from the legacy ICE agent . "
Mailing list commentary: It seems like I some of the Q4 text to Q3 . Here is a corrected version of my question : Q1 : I think it needs to be more clear that mDNS domain names ( .local ) can only be resolved by remote peers within the same local network . Section 5.1 does talk about this , and it may be an implicit assumption , but I think it should be pointed out in the beginning of the document .
Paragraph (version A):
For the most part, backward compatibility does not present a
significant issue for the mDNS technique.  When an endpoint that
supports mDNS communicates with an endpoint that does not, the legacy
endpoint will still provide its local IP addresses, and accordingly a
direct connection can still be attempted, even though the legacy
endpoint cannot resolve the mDNS names provided by the new endpoint.
In the event the legacy endpoint attempts to resolve mDNS names using
Unicast DNS, this may cause ICE to take somewhat longer to fully
complete, but should not have any effect on connectivity or
connection setup time.
Paragraph (version A):
However, some legacy endpoints are not fully spec-compliant and can
behave unpredictably in the presence of ICE candidates that contain a
hostname, potentially leading to ICE failure.  Some endpoints may
also fail to handle a connectivity check from an address that they
have not received in signaling.  During the aforementioned
experimental testing, the connection rate when interacting with
endpoints that provided raw IP addresses (and therefore should be
unaffected) decreased by 3% (relative), presumably for these reasons.
Paragraph (version B):
For the most part, backward compatibility does not present a
significant issue for the mDNS technique.  When an endpoint that
supports mDNS communicates with a legacy endpoint that does not, the
legacy endpoint will still provide its local IP addresses, allowing
the new endpoint to attempt direct connections to those addresses.
Through the process of learning peer-reflexive candidates described
in RFC8445, the legacy endpoint will also learn the IP addresses of
the mDNS-aware endpoint, allowing ICE to succeed even though the
legacy endpoint cannot resolve the mDNS names.  In the event the
legacy endpoint attempts to resolve the mDNS names using Unicast DNS,
this may cause ICE to take somewhat longer to fully complete, but
should not have any effect on connectivity or connection setup time.
Paragraph (version B):
However, some legacy endpoints are not fully spec-compliant and can
behave unpredictably in the presence of ICE candidates that contain a
hostname, potentially leading to ICE failure.  Specifically, the SDP
parsers in these endpoints may raise a fatal error when receiving
such candidates, rather than simply ignoring them.
Paragraph (version B):
Some endpoints may also fail to handle a connectivity check from an
address that they have not received in signaling (i.e., they do not
support learning peer-reflexive candidates as described above),
leading to ICE failure.  During the aforementioned experimental
testing, the connection rate when interacting with endpoints that
provided raw IP addresses (and therefore should be unaffected)
decreased by 3% (relative), presumably for these reasons.