draft-ietf-mmusic-ice-dualstack-fairness-00.txt   draft-ietf-mmusic-ice-dualstack-fairness-01.txt 
MMUSIC P. Martinsen MMUSIC P. Martinsen
Internet-Draft T. Reddy Internet-Draft T. Reddy
Intended status: Standards Track P. Patil Intended status: Standards Track P. Patil
Expires: November 14, 2015 Cisco Expires: December 24, 2015 Cisco
May 13, 2015 June 22, 2015
ICE Multihomed and IPv4/IPv6 Dual Stack Fairness ICE Multihomed and IPv4/IPv6 Dual Stack Fairness
draft-ietf-mmusic-ice-dualstack-fairness-00 draft-ietf-mmusic-ice-dualstack-fairness-01
Abstract Abstract
This document provides guidelines on how to make Interactive This document provides guidelines on how to make Interactive
Connectivity Establishment (ICE) conclude faster in multihomed and Connectivity Establishment (ICE) conclude faster in multihomed and
IPv4/IPv6 dual-stack scenarios where broken paths exist. The IPv4/IPv6 dual-stack scenarios where broken paths exist. The
provided guidelines are backwards compatible with the original ICE provided guidelines are backwards compatible with the original ICE
specification. specification.
Status of This Memo Status of This Memo
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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 November 14, 2015. This Internet-Draft will expire on December 24, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 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
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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
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
3. Improving ICE Multihomed Fairness . . . . . . . . . . . . . . 3 3. Improving ICE Multihomed Fairness . . . . . . . . . . . . . . 3
4. Improving ICE Dual Stack Fairness . . . . . . . . . . . . . . 3 4. Improving ICE Dual Stack Fairness . . . . . . . . . . . . . . 4
5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
Applications should take special care to deprioritize network Applications should take special care to deprioritize network
interfaces known to provide unreliable connectivity when operating in interfaces known to provide unreliable connectivity when operating in
a multihomed environment. For example certain tunnel services might a multihomed environment. For example certain tunnel services might
provide unreliable connectivity. The simple guidelines presented provide unreliable connectivity. Doing so will ensure a more fair
here describes how to deprioritize interfaces known by the distribution of the connectivity checks across available network
application to provide unreliable connectivity. This application interfaces on the device. The simple guidelines presented here
knowledge can be based on simple metrics like previous connection describes how to deprioritize interfaces known by the application to
success/failure rates or a more static model based on interface types provide unreliable connectivity.
like wired, wireless, cellular, virtual, tunnelled and so on.
There is a also need to introduce more fairness in the handling of There is a also a need to introduce more fairness when handling of
connectivity checks for different IP address families in dual-stack connectivity checks for different IP address families in dual-stack
IPv4/IPv6 ICE scenarios. Section 4.1.2.1 of ICE [RFC5245] points to IPv4/IPv6 ICE scenarios. Section 4.1.2.1 of ICE [RFC5245] points to
[RFC3484] for prioritizing among the different IP families. [RFC3484] for prioritizing among the different IP families.
[RFC3484] is obsoleted by [RFC6724] but following the recommendations [RFC3484] is obsoleted by [RFC6724] but following the recommendations
from the updated RFC will lead to prioritization of IPv6 over IPv4 from the updated RFC will lead to prioritization of IPv6 over IPv4
for the same candidate type. Due to this, connectivity checks for for the same candidate type. Due to this, connectivity checks for
candidates of the same type (host, reflexive or relay) are sent such candidates of the same type (host, reflexive or relay) are sent such
that an IP address family is completely depleted before checks from that an IP address family is completely depleted before checks from
the other address family are started. This results in user the other address family are started. This results in user
noticeable setup delays if the path for the prioritized address noticeable setup delays if the path for the prioritized address
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the other address family are started. This results in user the other address family are started. This results in user
noticeable setup delays if the path for the prioritized address noticeable setup delays if the path for the prioritized address
family is broken. family is broken.
To avoid such user noticeable delays when either IPv6 or IPv4 path is To avoid such user noticeable delays when either IPv6 or IPv4 path is
broken or excessive slow, this specification encourages intermingling broken or excessive slow, this specification encourages intermingling
the different address families when connectivity checks are the different address families when connectivity checks are
performed. Introducing IP address family fairness into ICE performed. Introducing IP address family fairness into ICE
connectivity checks will lead to more sustained dual-stack IPv4/IPv6 connectivity checks will lead to more sustained dual-stack IPv4/IPv6
deployment as users will no longer have an incentive to disable IPv6. deployment as users will no longer have an incentive to disable IPv6.
The cost is a small penalty to the address type that otherwise would The cost is a small penalty to the address type that otherwise would
have been prioritized. have been prioritized.
This document describes how to fairly order the candidates in
multihomed and dual-stack environments, thus affecting the sending
order of the connectivity checks. Ultimately it is up to the agent
to decide what candidate pair is best suited for transporting media.
The guidelines outlined in this specification are backward compatible The guidelines outlined in this specification are backward compatible
with a standard ICE implementation. This specification only alters with a standard ICE implementation. This specification only alters
the values used to create the resulting checklists in such a way that the values used to create the resulting checklists in such a way that
the core mechanisms from ICE [RFC5245] are still in effect. The the core mechanisms from ICE [RFC5245] are still in effect. The
introduced fairness might be better, but not worse than what exists introduced fairness might be better, but not worse than what exists
today. today.
2. Notational Conventions 2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
This document uses terminology defined in [RFC5245]. This document uses terminology defined in [RFC5245].
3. Improving ICE Multihomed Fairness 3. Improving ICE Multihomed Fairness
A multihomed ICE agent can potentially send and receive connectivity A multihomed ICE agent can potentially send and receive connectivity
checks on all available interfaces. To avoid unnecessary delay when checks on all available interfaces and IP addresses. It is possible
performing connectivity checks it would be beneficial to prioritize for an interface to have several IP addresses associated with it. To
interfaces known by the agent to provide connectivity. avoid unnecessary delay when performing connectivity checks it would
be beneficial to prioritize interfaces and IP addresses known by the
agent to provide stable connectivity. If the agent have access to
information about the physical network it is connected to (Like SSID
in a WiFi Network) this can be used as information regarding how that
network interface should be prioritized at this point in time.
The application knowledge regarding the reliability of an interface
can also be based on simple metrics like previous connection success/
failure rates or a more static model based on interface types like
wired, wireless, cellular, virtual, tunneled and so on.
Candidates from a interface known to the application to provide Candidates from a interface known to the application to provide
unreliable connectivity SHOULD get a low candidate priority. This unreliable connectivity SHOULD get a low candidate priority. This
ensures they appear near the end of the candidate list, and would be ensures they appear near the end of the candidate list, and would be
the last to be tested during the connectivity check phase. This the last to be tested during the connectivity check phase. This
allows candidate pairs more likely to succeed to be tested first. allows candidate pairs more likely to succeed to be tested first.
If the application is unable to get any interface information If the application is unable to get any interface information
regarding type or unable to store any relevant metrics, it SHOULD regarding type or unable to store any relevant metrics, it SHOULD
treat all interfaces as if they have reliable connectivity. This treat all interfaces as if they have reliable connectivity. This
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IPv4 and IPv6 address families. However, modifying the check list IPv4 and IPv6 address families. However, modifying the check list
directly can lead to uncoordinated local and remote check lists that directly can lead to uncoordinated local and remote check lists that
result in ICE taking longer to complete or in the worst case scenario result in ICE taking longer to complete or in the worst case scenario
fail. The best approach is to modify the formula for calculating the fail. The best approach is to modify the formula for calculating the
candidate priority value described in ICE [RFC5245] section 4.1.2.1. candidate priority value described in ICE [RFC5245] section 4.1.2.1.
Implementations SHOULD prioritize IPv6 candidates by putting some of Implementations SHOULD prioritize IPv6 candidates by putting some of
them first in the the intermingled checklist. This increases the them first in the the intermingled checklist. This increases the
chance of a IPv6 connectivity checks to complete first and be ready chance of a IPv6 connectivity checks to complete first and be ready
for nomination or usage. This enables implementations to follow the for nomination or usage. This enables implementations to follow the
intent of [RFC6555]Happy Eyeballs: Success with Dual-Stack Hosts. intent of [RFC6555] "Happy Eyeballs: Success with Dual-Stack Hosts".
It is worth noting that the timing recommendations in [RFC6555] are
to excessive for ICE usage.
5. Compatibility 5. Compatibility
ICE [RFC5245] section 4.1.2 states that the formula in section ICE [RFC5245] section 4.1.2 states that the formula in section
4.1.2.1 SHOULD be used to calculate the candidate priority. The 4.1.2.1 SHOULD be used to calculate the candidate priority. The
formula is as follows: formula is as follows:
priority = (2^24)*(type preference) + priority = (2^24)*(type preference) +
(2^8)*(local preference) + (2^8)*(local preference) +
(2^0)*(256 - component ID) (2^0)*(256 - component ID)
ICE [RFC5245] section 4.1.2.2 has guidelines for how the type ICE [RFC5245] section 4.1.2.2 has guidelines for how the type
preference and local preference value should be chosen. Instead of preference and local preference value should be chosen. Instead of
having a static local preference value for IPv4 and IPv6 addresses, having a static local preference value for IPv4 and IPv6 addresses,
it is possible to choose this value dynamically in such a way that it is possible to choose this value dynamically in such a way that
IPv4 and IPv6 address candidate priorities ends up intermingled IPv4 and IPv6 address candidate priorities ends up intermingled
within the same candidate type. within the same candidate type. It is also possible to assign lower
priorities to IP addresses derived from unreliable interfaces using
the local preference value.
It is also possible to dynamically change the type preference in such It is worth mentioning that [RFC5245] section 4.1.2 say that; "if
a way that IPv4 and IPv6 address candidates end up intermingled there are multiple candidates for a particular component for a
regardless of candidate type. This is useful if there are a lot of particular media stream that have the same type, the local preference
IPv6 host candidates effectively blocking connectivity checks for MUST be unique for each one".
IPv4 server reflexive candidates.
The local type preference can be dynamically changed in such a way
that IPv4 and IPv6 address candidates end up intermingled regardless
of candidate type. This is useful if there are a lot of IPv6 host
candidates effectively blocking connectivity checks for IPv4 server
reflexive candidates.
Candidates with IP addresses from a unreliable interface SHOULD be
ordered at the end of the checklist. Not intermingled as the dual-
stack candidates.
The list below shows a sorted local candidate list where the priority The list below shows a sorted local candidate list where the priority
is calculated in such a way that the IPv4 and IPv6 candidates are is calculated in such a way that the IPv4 and IPv6 candidates are
intermingled. To allow for earlier connectivity checks for the IPv4 intermingled (No multihomed candidates). To allow for earlier
server reflexive candidates, some of the IPv6 host candidates are connectivity checks for the IPv4 server reflexive candidates, some of
demoted. This is just an example of how a candidate priorities can the IPv6 host candidates are demoted. This is just an example of how
be calculated to provide better fairness between IPv4 and IPv6 a candidate priorities can be calculated to provide better fairness
candidates without breaking any of the ICE connectivity checks. between IPv4 and IPv6 candidates without breaking any of the ICE
connectivity checks.
Candidate Address Component Candidate Address Component
Type Type ID Priority Type Type ID Priority
------------------------------------------- -------------------------------------------
(1) HOST IPv6 (1) 2129289471 (1) HOST IPv6 (1) 2129289471
(2) HOST IPv6 (2) 2129289470 (2) HOST IPv6 (2) 2129289470
(3) HOST IPv4 (1) 2129033471 (3) HOST IPv4 (1) 2129033471
(4) HOST IPv4 (2) 2129033470 (4) HOST IPv4 (2) 2129033470
(5) HOST IPv6 (1) 2128777471 (5) HOST IPv6 (1) 2128777471
(6) HOST IPv6 (2) 2128777470 (6) HOST IPv6 (2) 2128777470
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7. Security Considerations 7. Security Considerations
STUN connectivity check using MAC computed during key exchanged in STUN connectivity check using MAC computed during key exchanged in
the signaling channel provides message integrity and data origin the signaling channel provides message integrity and data origin
authentication as described in section 2.5 of [RFC5245] apply to this authentication as described in section 2.5 of [RFC5245] apply to this
use. use.
8. Acknowledgements 8. Acknowledgements
Authors would like to thank Dan Wing, Ari Keranen, Bernard Aboba, Authors would like to thank Dan Wing, Ari Keranen, Bernard Aboba,
Martin Thomson, Jonathan Lennox, Balint Menyhart and Simon Perreault Martin Thomson, Jonathan Lennox, Balint Menyhart, Ole Troan and Simon
for their comments and review. Perreault for their comments and review.
9. References 9. References
9.1. Normative References 9.1. 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.
[RFC3484] Draves, R., "Default Address Selection for Internet [RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003. Protocol version 6 (IPv6)", RFC 3484, February 2003.
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