draft-ietf-mmusic-trickle-ice-00.txt   draft-ietf-mmusic-trickle-ice-01.txt 
Network Working Group E. Ivov Network Working Group E. Ivov
Internet-Draft Jitsi Internet-Draft Jitsi
Intended status: Standards Track E. Rescorla Intended status: Standards Track E. Rescorla
Expires: April 11, 2014 RTFM, Inc. Expires: August 11, 2014 RTFM, Inc.
J. Uberti J. Uberti
Google Google
October 08, 2013 February 7, 2014
Trickle ICE: Incremental Provisioning of Candidates for the Interactive Trickle ICE: Incremental Provisioning of Candidates for the Interactive
Connectivity Establishment (ICE) Protocol Connectivity Establishment (ICE) Protocol
draft-ietf-mmusic-trickle-ice-00 draft-ietf-mmusic-trickle-ice-01
Abstract Abstract
This document describes an extension to the Interactive Connectivity This document describes an extension to the Interactive Connectivity
Establishment (ICE) protocol that allows ICE agents to send and Establishment (ICE) protocol that allows ICE agents to send and
receive candidates incrementally rather than exchanging complete receive candidates incrementally rather than exchanging complete
lists. With such incremental provisioning, ICE agents can begin lists. With such incremental provisioning, ICE agents can begin
connectivity checks while they are still gathering candidates and connectivity checks while they are still gathering candidates and
considerably shorten the time necessary for ICE processing to considerably shorten the time necessary for ICE processing to
complete. complete.
skipping to change at page 1, line 42 skipping to change at page 1, line 42
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 11, 2014. This Internet-Draft will expire on August 11, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 35 skipping to change at page 2, line 35
6.1. Sending the Initial Answer . . . . . . . . . . . . . . . 10 6.1. Sending the Initial Answer . . . . . . . . . . . . . . . 10
6.2. Forming check lists and beginning connectivity 6.2. Forming check lists and beginning connectivity
checks . . . . . . . . . . . . . . . . . . . . . . . . . 10 checks . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.3. Encoding the SDP . . . . . . . . . . . . . . . . . . . . 11 6.3. Encoding the SDP . . . . . . . . . . . . . . . . . . . . 11
7. Receiving the Initial Answer . . . . . . . . . . . . . . . . 11 7. Receiving the Initial Answer . . . . . . . . . . . . . . . . 11
8. Performing Connectivity Checks . . . . . . . . . . . . . . . 11 8. Performing Connectivity Checks . . . . . . . . . . . . . . . 11
8.1. Check List and Timer State Updates . . . . . . . . . . . 11 8.1. Check List and Timer State Updates . . . . . . . . . . . 11
9. Discovering and Sending Additional Local Candidates . . . . . 12 9. Discovering and Sending Additional Local Candidates . . . . . 12
9.1. Pairing newly learned candidates and updating 9.1. Pairing newly learned candidates and updating
check lists . . . . . . . . . . . . . . . . . . . . . . . 14 check lists . . . . . . . . . . . . . . . . . . . . . . . 14
9.2. Encoding the SDP for Additional Candidates . . . . . . . 14 9.2. Encoding the SDP for Additional Candidates . . . . . . . 15
9.3. Announcing End of Candidates . . . . . . . . . . . . . . 15 9.3. Announcing End of Candidates . . . . . . . . . . . . . . 15
9.4. Receiving an End Of Candidates Notification . . . . . . . 17
10. Receiving Additional Remote Candidates . . . . . . . . . . . 17 10. Receiving Additional Remote Candidates . . . . . . . . . . . 17
11. Concluding ICE Processing . . . . . . . . . . . . . . . . . . 17 11. Receiving an End Of Candidates Notification . . . . . . . . . 17
12. Subsequent Offer/Answer Exchanges . . . . . . . . . . . . . . 18 12. Trickle ICE and Peer Reflexive Candidates . . . . . . . . . . 17
13. Interaction with ICE Lite . . . . . . . . . . . . . . . . . . 18 13. Concluding ICE Processing . . . . . . . . . . . . . . . . . . 18
14. Example Flow . . . . . . . . . . . . . . . . . . . . . . . . 19 14. Subsequent Offer/Answer Exchanges . . . . . . . . . . . . . . 18
15. Security Considerations . . . . . . . . . . . . . . . . . . . 20 15. Interaction with ICE Lite . . . . . . . . . . . . . . . . . . 18
16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 16. Example Flow . . . . . . . . . . . . . . . . . . . . . . . . 19
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 17. Security Considerations . . . . . . . . . . . . . . . . . . . 20
17.1. Normative References . . . . . . . . . . . . . . . . . . 20 18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
17.2. Informative References . . . . . . . . . . . . . . . . . 20 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
19.1. Normative References . . . . . . . . . . . . . . . . . . 20
19.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Open issues . . . . . . . . . . . . . . . . . . . . 22 Appendix A. Open issues . . . . . . . . . . . . . . . . . . . . 22
A.1. MID/Stream Indices in SDP . . . . . . . . . . . . . . . . 22 A.1. MID/Stream Indices in SDP . . . . . . . . . . . . . . . . 22
A.2. Starting checks . . . . . . . . . . . . . . . . . . . . . 22 A.2. Starting checks . . . . . . . . . . . . . . . . . . . . . 23
Appendix B. Changes From Earlier Versions . . . . . . . . . . . 22 Appendix B. Changes From Earlier Versions . . . . . . . . . . . 23
B.1. Changes From draft-ivov-00 . . . . . . . . . . . . . . . 22 B.1. Changes From draft-ivov-01 and draft-mmusic-00 . . . . . 23
B.2. Changes From draft-rescorla-01 . . . . . . . . . . . . . 23 B.2. Changes From draft-ivov-00 . . . . . . . . . . . . . . . 23
B.3. Changes From draft-rescorla-00 . . . . . . . . . . . . . 24 B.3. Changes From draft-rescorla-01 . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 B.4. Changes From draft-rescorla-00 . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
The Interactive Connectivity Establishment (ICE) protocol [RFC5245] The Interactive Connectivity Establishment (ICE) protocol [RFC5245]
describes mechanisms for gathering, candidates, prioritizing them, describes mechanisms for gathering, candidates, prioritizing them,
choosing default ones, exchanging them with the remote party, pairing choosing default ones, exchanging them with the remote party, pairing
them and ordering them into check lists. Once all of the above have them and ordering them into check lists. Once all of the above have
been completed, and only then, the participating agents can begin a been completed, and only then, the participating agents can begin a
phase of connectivity checks and eventually select the pair of phase of connectivity checks and eventually select the pair of
candidates that will be used in the following session. candidates that will be used in the following session.
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6.2. Forming check lists and beginning connectivity checks 6.2. Forming check lists and beginning connectivity checks
After exchanging offer and answer, and as soon as they have obtained After exchanging offer and answer, and as soon as they have obtained
local and remote candidates, agents will begin forming candidate local and remote candidates, agents will begin forming candidate
pairs, computing their priorities and creating check lists according pairs, computing their priorities and creating check lists according
to the vanilla ICE procedures described in [RFC5245]. Obviously in to the vanilla ICE procedures described in [RFC5245]. Obviously in
order for candidate pairing to be possible, it would be necessary order for candidate pairing to be possible, it would be necessary
that both the offer and the answer contained candidates. If this was that both the offer and the answer contained candidates. If this was
not the case agents will still create the check lists (so that their not the case agents will still create the check lists (so that their
Active/Frozen state could be monitored and updated) but they will Active/Frozen state could be monitored and updated) but they will
only populate them once they actually have the candidates. only populate them once they actually have the candidate pairs.
Initially, all check lists will have their Active/Frozen state set to Initially, all check lists will have their Active/Frozen state set to
Frozen. Frozen.
Trickle ICE agents will then inspect the first check list and attempt Trickle ICE agents will then inspect the first check list and attempt
to unfreeze all candidates belonging to the first component on the to unfreeze all candidates belonging to the first component on the
first media stream (i.e. the first media stream that was reported to first media stream (i.e. the first media stream that was reported to
the ICE implementation from the using application). If this the ICE implementation from the using application). If this
checklist is still empty however, agents will hold off further checklist is still empty however, agents will hold off further
processing until this is no longer the case. processing until this is no longer the case.
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o if at least one of the components of the media stream has no pairs o if at least one of the components of the media stream has no pairs
in its valid list. in its valid list.
With trickle ICE, the above situation would often occur when With trickle ICE, the above situation would often occur when
candidate harvesting and trickling are still in progress and it is candidate harvesting and trickling are still in progress and it is
perfectly possible that future checks will succeed. For this reason perfectly possible that future checks will succeed. For this reason
trickle ICE agents add the following conditions to the above list: trickle ICE agents add the following conditions to the above list:
o all candidate harvesters have completed and the agent is not o all candidate harvesters have completed and the agent is not
expecting to learn any new candidates; expecting to discover any new local candidates;
o the remote agent has sent an end-of-candidates indication for that o the remote agent has sent an end-of-candidates indication for that
check list as described in Section 9.3. check list as described in Section 9.3.
Vanilla ICE requires that agents then update all other check lists, Vanilla ICE requires that agents then update all other check lists,
placing one pair in each of them into the Waiting state, effectively placing one pair in each of them into the Waiting state, effectively
unfreezing the check list. Given that with trickle ICE, other check unfreezing all remaining check lists. Given that with trickle ICE,
lists may still be empty at that point, a trickle ICE agent SHOULD other check lists may still be empty at that point, a trickle ICE
also maintain an explicit Active/Frozen state for every check list, agent SHOULD also maintain an explicit Active/Frozen state for every
rather than deducing it from the state of the pairs it contains. check list, rather than deducing it from the state of the pairs it
This state should be set to Active when unfreezing the first pair in contains. This state should be set to Active when unfreezing the
a list or when that couldn't happen because a list was empty. first pair in a list or when that couldn't happen because a list was
empty.
9. Discovering and Sending Additional Local Candidates 9. Discovering and Sending Additional Local Candidates
After an offer or an answer have been sent, agents will most likely After an offer or an answer have been sent, agents will most likely
continue discovering new local candidates as STUN, TURN and other continue discovering new local candidates as STUN, TURN and other
non-host candidate harvesting mechanisms begin to yield results. non-host candidate harvesting mechanisms begin to yield results.
Whenever an agent discovers such a new candidate it will compute its Whenever an agent discovers such a new candidate it will compute its
priority, type, foundation and component id according to normal priority, type, foundation and component id according to normal
vanilla ICE procedures. vanilla ICE procedures.
The new candidate is then checked for redundancy against the existing The new candidate is then checked for redundancy against the existing
list of local candidates. If its transport address and base match list of local candidates. If its transport address and base match
those of an existing candidate, it will be considered redundant and those of an existing candidate, it will be considered redundant and
will be ignored. This would often happen for server reflexive will be ignored. This would often happen for server reflexive
candidates that match the host addresses they were obtained from candidates that match the host addresses they were obtained from
(e.g. when the latter are public IPv4 addresses). Contrary to (e.g. when the latter are public IPv4 addresses). Contrary to
vanilla ICE, trickle ICE agents will consider the new candidate vanilla ICE, trickle ICE agents will consider the new candidate
redundant regardless of its priority. [TODO: is this OK? if not we redundant regardless of its priority.
need to check if the existing candidate was already used in conn
checks, cancel them, and then restart them with the new candidate ...
and in this specific case there's probably no point to do that].
Next the client sends (i.e. trickles) the newly learnt candidate(s) Next the client sends (i.e. trickles) the newly learnt candidate(s)
to the remote agent. to the remote agent. The actual delivery of the new candidates will
be specified by using protocols such as SIP. Trickle ICE imposes no
restrictions on the way this is done or whether it is done at all.
For example, some applications may choose not to send trickle updates
for server reflexive candidates and rely on the discovery of peer
reflexive ones instead.
When trickle updates are sent however, each candidate MUST be
delivered to the receiving Trickle ICE implementation not more than
once and in the same order that they were sent. In other words, if
there are any candidate retransmissions, they must be hidden from the
ICE implementation.
Also, candidate trickling needs to be correlated to a specific ICE
negotiation session, so that if there is an ICE restart, any delayed
updates for a previous session can be recognized as such and ignored
by the receiving party.
One important aspect of Vanilla ICE is that connectivity checks for a One important aspect of Vanilla ICE is that connectivity checks for a
specific foundation and component be attempted simultaneously by both specific foundation and component be attempted simultaneously by both
agents, so that any firewalls or NATs fronting the agents would agents, so that any firewalls or NATs fronting the agents would
whitelist the both endpoints and allow all except for the first whitelist both endpoints and allow all except for the first (suicide)
packets to go through. This is also crucial to unfreezing candidates packets to go through. This is also crucial to unfreezing candidates
in the right time. in the right time.
In order to preserve this feature with trickle ICE, agents MUST In order to preserve this feature here, when trickling candidates
respect the order of the components in the Offer or Answer. A agents MUST respect the order of the components as they appear
candidate for a specific component MUST NOT be sent prior to (implicitly or explicitly) in the Offer/Answer descriptions.
candidates for other components within the same foundation. Therefore a candidate for a specific component MUST NOT be sent prior
to candidates for other components within the same foundation.
For example, the following session description contains two For example, the following session description contains two
components (RTP and RTCP), and two foundations (host and the server components (RTP and RTCP), and two foundations (host and the server
reflexive): reflexive):
v=0 v=0
o=jdoe 2890844526 2890842807 IN IP4 10.0.1.1 o=jdoe 2890844526 2890842807 IN IP4 10.0.1.1
s= s=
c=IN IP4 10.0.1.1 c=IN IP4 10.0.1.1
t=0 0 t=0 0
skipping to change at page 13, line 40 skipping to change at page 13, line 46
raddr 10.0.1.1 rport 8998 raddr 10.0.1.1 rport 8998
For this description the RTCP host candidate MUST NOT be sent prior For this description the RTCP host candidate MUST NOT be sent prior
to the RTP host candidate. Similarly the RTP server reflexive to the RTP host candidate. Similarly the RTP server reflexive
candidate MUST be sent together with or prior to the RTCP server candidate MUST be sent together with or prior to the RTCP server
reflexive candidate. reflexive candidate.
Note that the order restriction only applies among candidates that Note that the order restriction only applies among candidates that
belong to the same foundation. belong to the same foundation.
Then, after the candidates have been sent, the agent checks if any It is also equally important to preserve this order across media
remote candidates are currently known for this same stream. If this streams and this is covered by the requirement to always start
is not the case the new candidate will simply be added to the list of unfreezing candidates starting from the first media stream
local candidates. Section 6.2.
Once the candidate has been sent to the remote party, the agent
checks if any remote candidates are currently known for this same
stream. If this is not the case the new candidate will simply be
added to the list of local candidates.
Otherwise, if the agent has already learned of one or more remote Otherwise, if the agent has already learned of one or more remote
candidates for this stream and component, it will begin pairing the candidates for this stream and component, it will begin pairing the
new local candidates with them and adding the pairs to the existing new local candidates with them and adding the pairs to the existing
check lists according to their priority. check lists according to their priority.
9.1. Pairing newly learned candidates and updating check lists 9.1. Pairing newly learned candidates and updating check lists
Forming candidate pairs will work the way it is described by the Forming candidate pairs will work the way it is described by the
vanilla ICE specification. Actually adding the new pair to a check vanilla ICE specification. Actually adding the new pair to a check
list however, will happen according to the rules described below. list however, will happen according to the rules described below.
If the check list where the pair is to be added already contains the
maximum number of candidate pairs (100 by default as per [RFC5245]),
the new pair is discarded.
If the new pair's local candidate is server reflexive, the server If the new pair's local candidate is server reflexive, the server
reflexive candidate MUST be replaced by its base before adding the reflexive candidate MUST be replaced by its base before adding the
pair to the list. Once this is done, the agent examines the check pair to the list. Once this is done, the agent examines the check
list looking for another pair that would be redundant with the new list looking for another pair that would be redundant with the new
one. If such a pair exists, the newly formed pair is ignored. one. If such a pair exists, the newly formed pair is ignored.
For all other pairs, including those with a server reflexive local For all other pairs, including those with a server reflexive local
candidate that were not found to be redundant: candidate that were not found to be redundant:
o if all check lists are empty and in the Frozen state, or in other
words, if this is the first pair the agent is adding to any check
list, both the pair and its containing check list will be placed
in an Active state.
o if this check list is Frozen then the new pair will also be o if this check list is Frozen then the new pair will also be
assigned a Frozen state. assigned a Frozen state.
o else if the check list is Active and it is either empty or o else if the check list is Active and it is either empty or
contains only candidates in the Succeeded and Failed states, then contains only candidates in the Succeeded and Failed states, then
the new pair's state is set to Waiting. the new pair's state is set to Waiting.
o else if the check list is non-empty and Active, then the new pair o else if the check list is non-empty and Active, then the new pair
state will be set to state will be set to
Frozen: if there is at least one pair in the list whose Frozen: if there is at least one pair in the list whose
foundation matches the one in the new pair and whose state foundation matches the one in the new pair and whose state is
is neither Succeeded nor Failed (eventually the new pair neither Succeeded nor Failed (eventually the new pair will get
will get unfrozen after the the on-going check for the unfrozen after the the on-going check for the existing pair
existing pair concludes); concludes);
Waiting: if the list contains no pairs with the same foundation Waiting: if the list contains no pairs with the same foundation
as the new one, or, in case such pairs exist but they are as the new one, or, in case such pairs exist but they are all
all in either the Succeeded or Failed states. in either the Succeeded or Failed states.
9.2. Encoding the SDP for Additional Candidates 9.2. Encoding the SDP for Additional Candidates
To facilitate interoperability an ICE agent will encode additional To facilitate interoperability an ICE agent will encode additional
candidates using the vanilla ICE SDP syntax. For example: candidates using the vanilla ICE SDP syntax. For example:
a=candidate:2 1 UDP 1658497328 198.51.100.33 5000 typ host a=candidate:2 1 UDP 1658497328 198.51.100.33 5000 typ host
Given that such lines do not provide a relationship between the Given that such lines do not provide a relationship between the
candidate and the m line that it relates to, signalling protocols candidate and the m line that it relates to, signalling protocols
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only possible through an ICE restart. only possible through an ICE restart.
It is important to note that This specification does not override It is important to note that This specification does not override
vanilla ICE semantics for concluding ICE processing. This means that vanilla ICE semantics for concluding ICE processing. This means that
even if end-of-candidates indications are sent agents will still have even if end-of-candidates indications are sent agents will still have
to go through pair nomination. Also, if pairs have been nominated to go through pair nomination. Also, if pairs have been nominated
for components and media streams, ICE processing will still conclude for components and media streams, ICE processing will still conclude
even if end-of-candidate indications have not been received for all even if end-of-candidate indications have not been received for all
streams. streams.
9.4. Receiving an End Of Candidates Notification
When an agent receives an end-of-candidates notification for a
specific check list, they will update its state as per Section 8.1.
In case the list is still in the Active state after the update, the
agent will persist the the fact that an end-of-candidates
notification has been received for and take it into account in future
list updates.
[TODO would we like to say anything about nomination? in general this
would be up to implementers but is there a need for some basic
guidelines?]
10. Receiving Additional Remote Candidates 10. Receiving Additional Remote Candidates
At any point of ICE processing, a trickle ICE agent may receive new At any point of ICE processing, a trickle ICE agent may receive new
candidates from the remote agent. When this happens and no local candidates from the remote agent. When this happens and no local
candidates are currently known for this same stream, the new remote candidates are currently known for this same stream, the new remote
candidates are simply added to the list of remote candidates. candidates are simply added to the list of remote candidates.
Otherwise, the new candidates are used for forming candidate pairs Otherwise, the new candidates are used for forming candidate pairs
with the pool of local candidates and they are added to the local with the pool of local candidates and they are added to the local
check lists as described in Section 9.1. check lists as described in Section 9.1.
Once the remote agent has completed candidate harvesting, it will Once the remote agent has completed candidate harvesting, it will
send an end-of-candidates event. Upon receiving such an event, the send an end-of-candidates event. Upon receiving such an event, the
local agent MUST update check list states as per Section 8.1. This local agent MUST update check list states as per Section 8.1. This
may lead to some check lists being marked as Failed. may lead to some check lists being marked as Failed.
11. Concluding ICE Processing 11. Receiving an End Of Candidates Notification
When an agent receives an end-of-candidates notification for a
specific check list, they will update its state as per Section 8.1.
In case the list is still in the Active state after the update, the
agent will persist the the fact that an end-of-candidates
notification has been received for and take it into account in future
list updates.
12. Trickle ICE and Peer Reflexive Candidates
Even though Trickle ICE does not explicitly modify the procedures for
handling peer reflexive candidates, their processing could be
impacted in implementations. With Trickle ICE, it is possible that
server reflexive candidates be discovered as peer reflexive in cases
where incoming connectivity checks are received from these candidates
before the trickle updates that carry them.
While this would certainly increase the number of cases where ICE
processing nominates and selects candidates discovered as peer-
reflexive it does not require any change in processing.
It is also likely that, some applications would prefer not to trickle
server reflexive candidates to entities that are known to be publicly
accessible and where sending a direct STUN binding request is likely
to reach the destination faster than the trickle update that travels
through the signalling path.
13. Concluding ICE Processing
This specification does not directly modify the procedures ending ICE This specification does not directly modify the procedures ending ICE
processing described in Section 8 of [RFC5245], and trickle ICE processing described in Section 8 of [RFC5245], and trickle ICE
implementations will follow the same rules. implementations will follow the same rules.
12. Subsequent Offer/Answer Exchanges 14. Subsequent Offer/Answer Exchanges
Either agent MAY generate a subsequent offer at any time allowed by Either agent MAY generate a subsequent offer at any time allowed by
[RFC3264]. When this happens agents will use [RFC5245] semantics to [RFC3264]. When this happens agents will use [RFC5245] semantics to
determine whether or not the new offer requires an ICE restart. If determine whether or not the new offer requires an ICE restart. If
this is the case then agents would perform trickle ICE as they would this is the case then agents would perform trickle ICE as they would
in an initial offer/answer exchange. in an initial offer/answer exchange.
The only differences between an ICE restart and a brand new media The only differences between an ICE restart and a brand new media
session are that: session are that:
o during the restart, media can continue to be sent to the o during the restart, media can continue to be sent to the
previously validated pair. previously validated pair.
o both agents are already aware whether or not their peer supports o both agents are already aware whether or not their peer supports
trickle ICE, and there is no longer need for performing half trickle ICE, and there is no longer need for performing half
trickle or confirming support with other mechanisms. trickle or confirming support with other mechanisms.
13. Interaction with ICE Lite 15. Interaction with ICE Lite
Behaviour of Trickle ICE capable ICE lite agents does not require any Behaviour of Trickle ICE capable ICE lite agents does not require any
particular rules other than those already defined in this particular rules other than those already defined in this
specification and [RFC5245]. This section is hence added with an specification and [RFC5245]. This section is hence added with an
informational purpose only. informational purpose only.
A Trickle ICE capable ICE Lite agent would generate offers or answers A Trickle ICE capable ICE Lite agent would generate offers or answers
as per [RFC5245]. Both will indicate support for trickle ICE as per [RFC5245]. Both will indicate support for trickle ICE
(Section 5.1) and given that they will contain a complete set of (Section 5.1) and given that they will contain a complete set of
candidates (the agent's host candidates) these offers and answers candidates (the agent's host candidates) these offers and answers
skipping to change at page 19, line 19 skipping to change at page 19, line 27
cand disco| | cand disco| |
| | | |
|<=============== MEDIA FLOWS =================>| |<=============== MEDIA FLOWS =================>|
Figure 1: Example Figure 1: Example
In addition to reducing signaling traffic this approach also removes In addition to reducing signaling traffic this approach also removes
the need to discover STUN bindings, or to make TURN or UPnP the need to discover STUN bindings, or to make TURN or UPnP
allocations which may considerably lighten ICE processing. allocations which may considerably lighten ICE processing.
14. Example Flow 16. Example Flow
A typical successful trickle ICE exchange with an Offer/Answer A typical successful trickle ICE exchange with an Offer/Answer
protocol would look this way: protocol would look this way:
Alice Bob Alice Bob
| Offer | | Offer |
|---------------------------------------------->| |---------------------------------------------->|
| Additional Candidates | | Additional Candidates |
|---------------------------------------------->| |---------------------------------------------->|
| | | |
skipping to change at page 20, line 5 skipping to change at page 20, line 23
| Additional Candidates | | Additional Candidates |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
| Additional Candidates and Connectivity Checks | | Additional Candidates and Connectivity Checks |
|<--------------------------------------------->| |<--------------------------------------------->|
| | | |
|<=============== MEDIA FLOWS =================>| |<=============== MEDIA FLOWS =================>|
Figure 2: Example Figure 2: Example
15. Security Considerations 17. Security Considerations
[TODO] This specification inherits most of its semantics from [RFC5245] and
as a result all security considerations described there remain the
same.
16. Acknowledgements 18. Acknowledgements
The authors would like to thank Bernard Adoba, Christer Holmberg, The authors would like to thank Bernard Adoba, Christer Holmberg,
Enrico Marocco, Flemming Andreasen, Jonathan Lennox and Martin Dale R. Worley, Enrico Marocco, Flemming Andreasen, Jonathan Lennox
Thomson for their reviews and suggestions on improving this document. and Martin Thomson for their reviews and suggestions on improving
this document.
17. References 19. References
17.1. Normative References 19.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, June with Session Description Protocol (SDP)", RFC 3264, June
2002. 2002.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT) (ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245, April Traversal for Offer/Answer Protocols", RFC 5245, April
2010. 2010.
17.2. Informative References 19.2. Informative References
[I-D.ivov-mmusic-trickle-ice-sip] [I-D.ivov-mmusic-trickle-ice-sip]
Ivov, E., Marocco, E., and C. Holmberg, "A Session Ivov, E., Marocco, E., and C. Holmberg, "A Session
Initiation Protocol (SIP) usage for Trickle ICE", draft- Initiation Protocol (SIP) usage for Trickle ICE", draft-
ivov-mmusic-trickle-ice-sip-00 (work in progress), January ivov-mmusic-trickle-ice-sip-01 (work in progress), October
2013. 2013.
[I-D.keranen-mmusic-ice-address-selection] [I-D.keranen-mmusic-ice-address-selection]
Keraenen, A. and J. Arkko, "Update on Candidate Address Keraenen, A. and J. Arkko, "Update on Candidate Address
Selection for Interactive Connectivity Establishment Selection for Interactive Connectivity Establishment
(ICE)", draft-keranen-mmusic-ice-address-selection-01 (ICE)", draft-keranen-mmusic-ice-address-selection-01
(work in progress), July 2012. (work in progress), July 2012.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP E. Lear, "Address Allocation for Private Internets", BCP
skipping to change at page 22, line 40 skipping to change at page 23, line 20
suboptimal since, candidates can arrive randomly and we would be suboptimal since, candidates can arrive randomly and we would be
wasting time waiting for a checklist to fill (almost as if we were wasting time waiting for a checklist to fill (almost as if we were
doing vanilla ICE). We need to decide if unfreezing everything doing vanilla ICE). We need to decide if unfreezing everything
solely based on foundation is good enough. solely based on foundation is good enough.
Appendix B. Changes From Earlier Versions Appendix B. Changes From Earlier Versions
Note to the RFC-Editor: please remove this section prior to Note to the RFC-Editor: please remove this section prior to
publication as an RFC. publication as an RFC.
B.1. Changes From draft-ivov-00 B.1. Changes From draft-ivov-01 and draft-mmusic-00
o Added a requirement to trickle candidates by order of components
to avoid deadlocks in the unfreezing algorithm.
o Added an informative note on peer-reflexive candidates explaining
that nothing changes for them semantically but they do become a
more likely occurrence for Trickle ICE.
o Limit the number of pairs to 100 to comply with 5245.
o Added clarifications on the non-importance of how newly discovered
candidates are trickled/sent to the remote party or if this is
done at all.
o Added transport expectations for trickled candidates as per Dale
Worley's recommendation.
B.2. Changes From draft-ivov-00
o Specified that end-of-candidates is a media level attribute which o Specified that end-of-candidates is a media level attribute which
can of course appear as session level, which is equivalent to can of course appear as session level, which is equivalent to
having it appear in all m-lines. Also made end-of-candidates having it appear in all m-lines. Also made end-of-candidates
optional for cases such as aggressive nomination for controlled optional for cases such as aggressive nomination for controlled
agents. agents.
o Added an example for ICE lite and trickle ICE to illustrate how, o Added an example for ICE lite and trickle ICE to illustrate how,
when talking to an ICE lite agent doesn't need to send or even when talking to an ICE lite agent doesn't need to send or even
discover any candidates. discover any candidates.
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o Closed the Open Issue about use about what to do with cands o Closed the Open Issue about use about what to do with cands
received after end-of-cands. Solution: ignore, do an ice restart received after end-of-cands. Solution: ignore, do an ice restart
if you want to add something. if you want to add something.
o Added more terminology, including trickling, trickled candidates, o Added more terminology, including trickling, trickled candidates,
half trickle, full trickle, half trickle, full trickle,
o Added a reference to the SIP usage for trickle ICE as requested at o Added a reference to the SIP usage for trickle ICE as requested at
the Boston interim. the Boston interim.
B.2. Changes From draft-rescorla-01 B.3. Changes From draft-rescorla-01
o Brought back explicit use of Offer/Answer. There are no more o Brought back explicit use of Offer/Answer. There are no more
attempts to try to do this in an O/A independent way. Also attempts to try to do this in an O/A independent way. Also
removed the use of ICE Descriptions. removed the use of ICE Descriptions.
o Added SDP specification for trickled candidates, the trickle o Added SDP specification for trickled candidates, the trickle
option and 0.0.0.0 addresses in m-lines, and end-of-candidates. option and 0.0.0.0 addresses in m-lines, and end-of-candidates.
o Support and Discovery. Changed that section to be less abstract. o Support and Discovery. Changed that section to be less abstract.
As discussed in IETF85, the draft now says implementations and As discussed in IETF85, the draft now says implementations and
skipping to change at page 24, line 19 skipping to change at page 25, line 10
can pre-gather part or all of your candidates before the user can pre-gather part or all of your candidates before the user
actually presses the call button. actually presses the call button.
o Added a short section about subsequent offer/answer exchanges. o Added a short section about subsequent offer/answer exchanges.
o Added a short section about interactions with ICE Lite o Added a short section about interactions with ICE Lite
implementations. implementations.
o Added two new entries to the open issues section. o Added two new entries to the open issues section.
B.3. Changes From draft-rescorla-00 B.4. Changes From draft-rescorla-00
o Relaxed requirements about verifying support following a o Relaxed requirements about verifying support following a
discussion on MMUSIC. discussion on MMUSIC.
o Introduced ICE descriptions in order to remove ambiguous use of o Introduced ICE descriptions in order to remove ambiguous use of
3264 language and inappropriate references to offers and answers. 3264 language and inappropriate references to offers and answers.
o Removed inappropriate assumption of adoption by RTCWEB pointed out o Removed inappropriate assumption of adoption by RTCWEB pointed out
by Martin Thomson. by Martin Thomson.
 End of changes. 37 change blocks. 
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