GROBJ Problem Statement – GROBJ BoF – IETF76 1

GROBJ BoF:Problem Statement

Dan Wing, dwing@cisco.com

v0.3, revised: 2-Nov-2009

GROBJ Problem Statement – GROBJ BoF – IETF76 2

Application Connection Problem

• Things are getting more complicated1. IPv6/IPv4

2. Transport protocol

3. Path selection

4. Optimal path selection

5. NATs

GROBJ Problem Statement – GROBJ BoF – IETF76 3

Three Party Case

• “Alice”, “Bob”, “Carol”• Slightly more complex• GRO’s model ◄• Solving this case

solves the 2 party case

XMPP XMPP

alice bob

XMPP

GRO

carol

1 2

3

GRO

GROBJ Problem Statement – GROBJ BoF – IETF76 4

Two Party Case

• “Alice, Bob”• Simple to understand• demonstrates we

have a problem

Discussed in this presentation

XMPP XMPP

alice bob

voice, gaming

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Setup: Alice and Bob

XMPP XMPP

alice

• Alice and Bob want to communicate directly

– Interactive video

– File sharing

– Gaming

• They are using a rendezvous service (XMPP)

bob

voice, gaming

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Problem 1: IP Family

XMPP XMPP

alice

• Alice’s network supports IPv6

• Bob’s network supports IPv4

• That’s a problem!

bob

IPv4? IPv6?

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Problem 2: transport protocol

XMPP XMPP

alice

• Alice’s wants to use fancy new transport (e.g., MP-TCP, SCTP)

• Bob’s network only handles TCP

• That’s a problem!bob

MP-TCP? SCTP?

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Problem 3: path selection

XMPP XMPP

alice

• Alice and Bob are on several networks

• Which paths work?

• That’s a problem!

bob

?

?

GROBJ Problem Statement – GROBJ BoF – IETF76 9

Problem 4: optimal path selection

XMPP XMPP

alice

• Alice and Bob are on several networks

• Which paths work best?

– cost

– performance

• That’s a problem!bob

?

?

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Problem 5: NATs

XMPP XMPP

alice

• Alice is behind a NAT

– NAT64 or NAT44

• Alice doesn’t have global IPv4 address scope.

• That’s a problem!bob

?

XMPP

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Problem Summary

• Solving the problems is hard.

• Most applications don’t bother– “My users aren’t multihomed” – but WiFi,

wired Ethernet, and 3G/4G changes that– “My application will use UPnP IGD”– IPv6 transition: native IPv6, NAT64, NAT44

(DS-Lite)

• All applications should make the same decisions– Games, SIP, XMPP

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Proposed Solution

• Applications send a Generic Referral Object (GRO)– Contains everything

necessary to communicate directly

XMPP XMPP

alice bob

XMPP

GRO

carol

GRO

1 2

3

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GRO and ICE

• ICE also allows choosing UDP/TCP/IPv6/IPv4• But, ICE is specific to SDP and SIP’s

Offer/Answer model• ICE has been used by other protocols:

– RTSPv2, XMPP

• GROBJ is more general– remove the intertwining of an application– So that GROBJ can be useful to other applications

ICE: draft-ietf-mmusic-iceRTSPv2 with ICE: draft-ietf-mmusic-rtsp-nat

XMPP with ICE: http://xmpp.org/extensions/xep-0176.html

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GROBJ Purpose • Provide guidance to applications to better

use host network connectivity

Today

• share one IPv4 address, and maybe a port

Tomorrow with GRO

• Share all available IPv4 & IPv6 addresses and ports, and transport protocols

• Indicate preferences

Applications