Draft: draft-ietf-ice-rfc5245bis

Commentary: Looks good to me . 
 LGTM ( even though it 's already merged :)
One criterion for selection of the type and local preference values
is the use of a media intermediary, such as a TURN server, a tunnel
service such as VPN server, or NAT.  With a media intermediary, if
media is sent to that candidate, it will first transit the media
intermediary before being received.  Relayed candidates are one type
of candidate that involves a media intermediary.  Another are host
candidates obtained from a VPN interface.  When media is transited
through a media intermediary, it can have an positive or negative
effect on the latency between transmission and reception.  It may or
may not increase the packet losses, because of the additional router
hops that may be taken.  It may increase the cost of providing
service, since media will be routed in and right back out of a media
intermediary run by a provider.  If these concerns are important, the
type preference for relayed candidates must be carefully chosen.  The
RECOMMENDED values are 126 for host candidates, 100 for server
reflexive candidates, 110 for peer reflexive candidates, and 0 for
relayed candidates.
One criterion for selection of the type and local preference values
is the use of a media intermediary, such as a TURN server, a tunnel
service such as VPN server, or NAT.  With a media intermediary, if
media is sent to that candidate, it will first transit the media
intermediary before being received.  Relayed candidates are one type
of candidate that involves a media intermediary.  Another are host
candidates obtained from a VPN interface.  When media is transited
through a media intermediary, it can have a positive or negative
effect on the latency between transmission and reception.  It may or
may not increase the packet losses, because of the additional router
hops that may be taken.  It may increase the cost of providing
service, since media will be routed in and right back out of a media
intermediary run by a provider.  If these concerns are important, the
type preference for relayed candidates must be carefully chosen.  The
RECOMMENDED values are 126 for host candidates, 100 for server
reflexive candidates, 110 for peer reflexive candidates, and 0 for
relayed candidates.
Furthermore, if an agent is multihomed and has multiple IP addresses,
the recommendation in I-D.ietf-ice-dualstack-fairness should be
followed.  If multiple TURN servers are used, local priorities for
the candidates obtained from the TURN servers are chosen in a similar
fashion as for multihomed local candidates: the local preference
value is used to indicate preference among different servers but the
preference MUST be unique for each one.
Another criterion for selection of preferences is IP address family.
ICE works with both IPv4 and IPv6.  It therefore provides a
transition mechanism that allows dual-stack hosts to prefer
connectivity over IPv6, but to fall back to IPv4 in case the v6
networks are disconnected.  Implementation should follow the
guidelines from I-D.ietf-ice-dualstack-fairness to avoid excessive
delays in the connectivity check phase if broken paths exists.
Furthermore, if an agent is multihomed and has multiple IP addresses,
the recommendation in I-D.ietf-ice-dualstack-fairness should be
followed.  If multiple TURN servers are used, local priorities for
the candidates obtained from the TURN servers are chosen in a similar
fashion as for multihomed local candidates: the local preference
value is used to indicate a preference among different servers but
the preference MUST be unique for each one.
Another criterion for selection of preferences is IP address family.
ICE works with both IPv4 and IPv6.  It provides a transition
mechanism that allows dual-stack hosts to prefer connectivity over
IPv6, but to fall back to IPv4 in case the v6 networks are
disconnected.  Implementation should follow the guidelines from I-
D.ietf-ice-dualstack-fairness to avoid excessively delays in the
connectivity check phase if broken paths exist.
Another criterion for selecting preferences is topological awareness.
This is most useful for candidates that make use of intermediaries.
In those cases, if an agent has preconfigured or dynamically
discovered knowledge of the topological proximity of the
intermediaries to itself, it can use that to assign higher local
preferences to candidates obtained from closer intermediaries.