One document matched: draft-reddy-mmusic-ice-happy-eyeballs-00.xml
<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="3"?>
<?rfc tocindent="yes"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
<?rfc comments="yes"?>
<?rfc inline="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<rfc category="std" docName="draft-reddy-mmusic-ice-happy-eyeballs-00"
ipr="trust200902">
<front>
<title abbrev="Happy Eyeballs for ICE ">Happy Eyeballs Extension for
ICE</title>
<author fullname="Tirumaleswar Reddy" initials="T." surname="Reddy">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<postal>
<street>Cessna Business Park, Varthur Hobli</street>
<street>Sarjapur Marathalli Outer Ring Road</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560103</code>
<country>India</country>
</postal>
<email>tireddy@cisco.com</email>
</address>
</author>
<author fullname="Prashanth Patil" initials="P." surname="Patil">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<postal>
<street>Cessna Business Park, Varthur Hobli</street>
<street>Sarjapur Marthalli Outer Ring Road</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560103</code>
<country>India</country>
</postal>
<email>praspati@cisco.com</email>
</address>
</author>
<author fullname="Dan Wing" initials="D." surname="Wing">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<postal>
<street>170 West Tasman Drive</street>
<city>San Jose</city>
<region>California</region>
<code>95134</code>
<country>USA</country>
</postal>
<email>dwing@cisco.com</email>
</address>
</author>
<date />
<workgroup>MMUSIC</workgroup>
<abstract>
<t>This document specifies requirements for algorithms that make ICE
connectivity checks more aggressive to reduce delays in dual stack host
connectivity checks when there is a path failure for the address family
preferred by the application or by the operating system. As IPv6 is
usually preferred, the procedures in this document helps avoid
user-noticable delays wheen the IPv6 path is broken or excessively
slow.</t>
</abstract>
</front>
<middle>
<section anchor="introduction" title="Introduction">
<t>In situations where there are many IPv6 addresses, <xref
target="RFC5245">ICE</xref> will prefer IPv6 <xref
target="RFC6724"></xref> and will attempt connectivity checks on all the
IPv6 candidates before trying an IPv4 candidate. If the IPv6 path is
broken, this fallback to IPv4 can consume a lot of time, harming user
satisfaction of dual stack devices.</t>
<t>This document describes an algorithm that makes ICE connectivity
checks more responsive to failures of an address family by performing
connectivity checks with both IPv6 and IPv4 candidates in parallel if
IPv6 connectivity checks have not yet succeeded. This document specifies
requirements for any such algorithm, with the goals that the ICE agent
need not be inordinately harmed with a simple parallelisation of IPv6
and IPv4 connectivity checks and ensuring that the priority of
precedence defined in <xref target="RFC6724"></xref> be honored.</t>
<t>For either of the address families, there is also a very realistic
chance that connectivity checks for relayed candidates will always work.
There are scenarios where firewalls block connectivity checks for
Host/Server Reflexive candidates or for IPv4 or for IPv6. This document
also proposes an optimization where connectivity checks with relayed
checks are performed earlier than usual if connectivity checks using
other candidates do not succeed.</t>
</section>
<section anchor="notation" title="Notational Conventions">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119"></xref>.</t>
<t>This note uses terminology defined in <xref
target="RFC5245"></xref>.</t>
</section>
<section anchor="problem_stmt" title="Candidates Priority">
<t>A prioritization formula is used by ICE <xref
target="RFC5245"></xref> so that most preferred address pairs are tested
first, and if a sufficiently good pair is discovered, the tests can be
stopped. With IPv6, addresses obtained from local network interfaces,
called host candidates, are recommended as high-priority ones to be
tested first since if they work, they provide usually the best path
between the two hosts. The ICE specification recommends to use the rules
defined in <xref target="RFC6724"> </xref> as part of the prioritization
formula for IPv6 host candidates and <xref
target="I-D.keranen-mmusic-ice-address-selection"></xref> updates the
ICE rules on how IPv6 host candidates are selected.</t>
<t>For dual stack hosts the preference for IPv6 host candidates is
higher than IPv4 host candidates based on precedence value of IP
addresses described in <xref target="RFC6724"></xref>. IPv6 server
reflexive candidates have higher precedence than IPv4 server reflexive
candidate since NPTv6 is stateless and transport-agnostic.</t>
<t><figure anchor="Figure1"
title="Candidate Preferences in decreasing order">
<artwork align="center"><![CDATA[ (highest) IPv6 Host Candidate
IPv4 Host Candidate
IPv6 Server Reflexive Candidate
IPv4 Server Reflexive Candidate
IPv6 Relayed Transport Candidate
(lowest) IPv4 Relayed Transport Candidate ]]></artwork>
</figure></t>
<t>By using the technique in <xref target="alg_overview"></xref> IPv6
candidate pairs will be tested first as usual, but if connectivity
checks are not successful after a certain period of time, the algorithm
will become more aggressive and connectivity checks using IPv6/IPv4
host/server-reflexive candidates will be performed simultaneously. If
connectivity checks with IPv6 candidate pairs do not yield any
successful result then ICE endpoints can immediately start sending media
using IPv4 host/server-reflexive candidates.</t>
<t>Note: <xref target="RFC6724"> </xref> permits administrator to change
the policy table to prefer IPv4 addresses over IPv6 addresses in which
case the algorithm described in the next section is reversed.</t>
</section>
<section anchor="alg_overview" title="Algorithm overview">
<t>The Happy Eyeballs Extension for ICE is governed by a timer (Te) that
is started just before carrying out the ICE connectivity checks for each
check list under the following conditions:</t>
<t><list style="numbers">
<t>when the candidates pairs include IPv6 and IPv4 addresses</t>
<t>list of IPv6 candidate pairs is higher than a configured
threshold (MAX_PAIRS_HAPPYEYE_STAGE_I). <xref
target="RFC5245"></xref> recommends a limit of 100 for the candidate
pairs.</t>
</list></t>
<t>When the timer (Te) fires, if the connectivity check using IPv6
candidate pairs are not yet successful and if the number of IPv6
candidate pairs with remote candidates of type host in the check list
that are in Waiting and Frozen state are non-zero, the ICE agent
performs the following Happy Eyeball steps in parallel with the regular
ICE Ordinary checks: <list style="symbols">
<t>Find the highest priority pair in the checklist that is in the
Waiting state with candidate address family being IPv4 and remote
candidate of type host. If there are no remote IPv6 candidates of
type server-reflexive then IPv4 remote candidates of type
server-reflexive will be added to the search. <list style="numbers">
<t>If there is such a pair then perform ICE connectivity check
on this pair and set the state of the candidate pair to
In-Progress.</t>
<t>If there is no such pair find the highest priority pair in
the checklist that is in the Frozen state with candidate address
family being IPv4 and remote candidate of type host candidate.
If there are no remote IPv6 candidates of type server-reflexive
then IPv4 remote candidates of type server-reflexive will be
added to the search. If there is such pair in Frozen state then
unfreeze the pair, perform connectivity check on this pair and
set the state of the candidate pair to In-Progress.</t>
</list></t>
<t>The above mentioned steps will be followed every Ta milliseconds
and stopped when any of the below conditions are met:<list
style="numbers">
<t>All IPv6 candidate pairs with remote candidates of type host
in the check list are in any of the following states Succeeded,
In-Progress or Failed states. The parallel activity is not
required beyond this point because the regular ICE algorithm
will itself pick up IPv4 candidate pairs not yet tested.</t>
<t>All IPv4 candidate pairs with remote candidates of type
host/server reflexive are in any of the following states
Succeeded, In-Progress or Failed states.</t>
</list></t>
</list></t>
<section anchor="result" title="Processing the Results">
<t>If ICE connectivity checks using an IPv4 candidate is successful
then ICE Agent will performs as usual "Discovering Peer Reflexive
Candidates" (Section 7.1.3.2.1 of <xref target="RFC5245"></xref>),
"Constructing a Valid Pair" (Section 7.1.3.2.2 of <xref
target="RFC5245"></xref>), "Updating Pair States" (Section 7.1.3.2.3
of <xref target="RFC5245"></xref>), "Updating the Nominated Flag"
(Section 7.1.3.2.4 of <xref target="RFC5245"></xref>).</t>
<t>If ICE connectivity checks using an IPv4 candidate is successful
for each component of the media stream and connectivity checks using
IPv6 candidates is not yet successful, the ICE endpoint will declare
victory, conclude ICE for the media stream and start sending media
using IPv4. However, it is also possible that ICE endpoint continues
to perform ICE connectivity checks with IPv6 candidate pairs and if
checks using higher-priority IPv6 candidate pair is successful then
media stream can be moved to the IPv6 candidate pair. Continuing to
perform connectivity checks can be useful for subsequent connections,
to optimize which connectivity checks are tried first. Such
optimization is out of scope of this document.</t>
<t>The following diagram shows the behaviour during the connectivity
check when Alice calls Bob and Agent Alice is the controlling agent
and uses the aggressive nomination algorithm. "USE-CAND" implies the
presence of the USE-CANDIDATE attribute.</t>
<figure anchor="Figure2" title="Happy Eyeballs Extension for ICE">
<artwork align="left"><![CDATA[ Alice Bob
| |
| Bind Req USE-CAND Bind Req |
| using IPv6 using IPv6 |
|------------------>X X<-----------------------|
| Bind Req USE-CAND Bind Req |
| using IPv6 after Ta using IPv6 |
|------------------>X X<-----------------------|
| Bind Req USE-CAND |
| using IPv6 after Ta Bind Req |
|------------------>X using IPv6 |
| X<-----------------------|
| |
[Timer Te fires, try IPv4 in parallel] |
| |
| Bind Req USE-CAND |
| using IPv4 |
|------------------------------------------------------------>|
| Bind Req USE-CAND |
| using IPv6 after Ta |
|------------------> X |
| Bind Resp |
| using IPv4 |
|<----------------------------------------------------------- |
| RTP |
|============================================================>|
| Bind Req |
| using IPv4 |
|<------------------------------------------------------------|
| Bind Response |
| using IPv4 |
|------------------------------------------------------------>|
| RTP |
|<===========================================================>|
]]></artwork>
</figure>
</section>
</section>
<!--
<section anchor="nptv6" title="NPTv6">
<t>The Timer (Te) is started again just before carrying further ICE
connectivity checks for each check list under the following conditions:
<list style="numbers">
<t>when the candidates pairs yet to be tested in the check list
include remote IPv6/IPv4 server-reflexive candidates</t>
<t>If there are no successful connectivity checks till that
time.</t>
<t>If the number of remaining IPv6 candidate pairs yet to be tested
is higher than a configured threshold
(MAX_PAIRS_HAPPYEYE_STAGE_II).</t>
</list></t>
<t>When the timer (Te) fires and if connectivity check using IPv6 candidate
pairs are not yet successful and if the number of IPv6 candidate pairs with
remote candidates of type server reflexive in the check list that in
Waiting and Frozen state are non-zero, the ICE agent performs the following Happy Eyeball steps
in parallel with the regular ICE Ordinary checks :</t>
<t>o Find the highest priority pair in the checklist that is in the
Waiting state with candidate address family being IPv4 and remote
candidate of type server-reflexive.</t>
<t><list style="numbers">
<t>If there is such a pair then perform ICE connectivity check on
this pair and set the state of the candidate pair to
In-Progress.</t>
<t>If there is no such pair find the highest priority pair in the
checklist that is in the Frozen state with candidate address family
being IPv4 and remote candidate of type server-reflexive candidate.
If there is such pair in Frozen state then unfreeze the pair,
perform connectivity check on this pair and set the state of the
candidate pair to In-Progress.</t>
</list></t>
<t>The above mentioned steps will be followed every Ta milliseconds and
stopped when any of the below conditions are met:</t>
<t><list style="numbers">
<t>All IPv6 candidate pairs with remote candidates of type
server-reflexive are in are in any of the following states
Succeeded, In-Progress or Failed states. The parallel activity is
not required beyond this point because the regular ICE algorithm
will itself pick up IPv4 candidate pairs not yet tested.</t>
<t>All IPv4 candidate pairs with remote candidates of type server
reflexive are in are in any of the following states Succeeded,
In-Progress or Failed states.</t>
</list></t>
<t>The ICE agent will perform the steps in <xref
target="result"></xref>.</t>
</section>
-->
<section anchor="relayed" title="Relayed Candidates">
<t>The optimization proposes doing connectivity checks with relayed
candidates in parallel with other candidates. The algorithm does not
make a distinction between IPv6/IPv4 relayed candidates and will choose
the existing order among relayed candidate pair defined by ICE. If ICE
connectivity check is successful using a relayed candidate from either
of the IP address families, the ICE agent can stop connectivity checks
for other relayed candidates.</t>
<t>This part of the Happy Eyeballs Extension for ICE is governed by a
timer (Tr) that is started just before carrying out the ICE connectivity
checks for each check list under the following conditions:</t>
<t><list style="numbers">
<t>when the candidates pairs include IPv6 and IPv4 relayed
addresses</t>
<t>list of candidate pairs is higher than a configured threshold
(MAX_PAIRS_HAPPYEYE_STAGE_I).</t>
</list></t>
<t>When the timer (Tr) fires, If no ICE connectivity checks are
successful as yet and if ICE Connectivity checks using IPv6 and IPv4
local relayed candidates have not yet been attempted then the following
steps will be started by the ICE agent in parallel with other
connectivity checks:</t>
<t>o Find the highest priority pair in the checklist that is in the
Waiting state with local candidate of type relayed.</t>
<t><list style="numbers">
<t>If there is such a pair then perform ICE connectivity check on
this pair and set the state of the candidate pair to
In-Progress.</t>
<t>If there is no such pair find the highest priority pair in the
checklist that is in the Frozen state with local candidate of type
relayed. If there is such pair in Frozen state then unfreeze the
pair, perform connectivity check on this pair and set the state of
the candidate pair to In-Progress.</t>
</list></t>
<t>If ICE connectivity checks using relayed candidate is successful then
ICE Agent will performs as usual "Constructing a Valid Pair" (Section
7.1.3.2.2 of <xref target="RFC5245"></xref>), "Updating Pair States"
(Section 7.1.3.2.3 of <xref target="RFC5245"></xref>), "Updating the
Nominated Flag" (Section 7.1.3.2.4 of <xref target="RFC5245"></xref>).
If ICE connectivity checks using local relayed candidates is successful
for each component of the media stream and connectivity checks using
higher priority candidate pairs has not yet succeeded then conclude ICE
for the media stream and proceed to send media using local relayed
candidate.</t>
<t>However ICE connectivity checks MUST be continued and if the check
succeeds for a pair whose priority is higher than the previously
selected candidate pair then media session will be moved to this pair.
Hence media will only be sent briefly on TURN relays. Additional TURN
server load is created due to this recommendations, especially when
connectivity check using IPv6/IPv4 host/server-reflexive candidates are
not completing quickly and the side affect could be that RTP receivers
will receive packets out of order during switchover.</t>
</section>
<section anchor="values"
title="Setting Te, Tr and MAX_PAIRS_HAPPYEYE_STAGE">
<t>The value of Ta, Tr, MAX_PAIRS_HAPPYEYE_STAGE_I,
MAX_PAIRS_HAPPYEYE_STAGE_II and SHOULD be configurable, and SHOULD have
a default of:</t>
<figure anchor="Figure3" title="Default Values">
<artwork align="center"><![CDATA[
Te : 150ms
Tr : 500ms
MAX_PAIRS_HAPPYEYE_STAGE_I : 12
MAX_PAIRS_HAPPYEYE_STAGE_II : 6 ]]></artwork>
</figure>
</section>
<section title="IANA Considerations">
<t>None.</t>
</section>
<section anchor="security" title="Security Considerations">
<t>STUN connectivity check using MAC computed during key exchanged in
the signaling channel provides message integrity and data origin
authentication as described in section 2.5 of <xref
target="RFC5245"></xref> apply to this use.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include="reference.RFC.5245"?>
<?rfc include="reference.RFC.4566"?>
<?rfc include='reference.I-D.keranen-mmusic-ice-address-selection'?>
<?rfc include="reference.RFC.6724"?>
</references>
<references title="Informative References">
<?rfc include='reference.RFC.2663'?>
<!---->
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 13:07:00 |