SIP in wireless SIP in wireless applicationsapplications

Henning SchulzrinneDept. of Computer Science

Columbia University

OverviewOverview New developments

presence and IM location-based services

identity management Standardization status Issues

complexity integration spam

Resources

New developments: New developments: presence, location-based presence, location-based services, IMservices, IM Old ring-and-hope (or ring-and-annoy) model is obsolete Presence and event notification model:

human availability environmental events (alarms) business events (e.g., machine malfunction)

Mobile devices as prime sources of presence information:

recent device use: outbound calls answered calls unanswered calls

location information (from Phase II 911) including motion (driving)

longer term: activity information

GEOPRIV and SIMPLE GEOPRIV and SIMPLE architecturesarchitectures

targetlocationserver

locationrecipient

rulemaker

presentity

caller

presenceagent

watcher

callee

GEOPRIV

SIPpresence

SIPcall

PUBLISHNOTIFY

SUBSCRIBE

INVITE

publicationinterface

notificationinterface

XCAP(rules)

INVITE

DHCP

The role of presence for call The role of presence for call routingrouting Two modes:

watcher uses presence information to select suitable contacts

advisory – caller may not adhere to suggestions and still call when you’re in a meeting

user call routing policy informed by presence

likely less flexible – machine intelligence

“if activities indicate meeting, route to tuple indicating assistant”

“try most-recently-active contact first” (seq. forking)

LESS

translateRPID

CPL

PA

PUBLISH

NOTIFY

INVITE

RPID: rich presenceRPID: rich presence<person>

<tuple>

<device>

<activities>

<class>

<mood>

<place-is>

<place-type>

<privacy>

<relationship>

<service-class>

<sphere>

<status-icon>

<time-offset>

<user-input>

New developments: location-New developments: location-based servicesbased services

My lab working on language for end-system services (LESS), including location-based services

User (or administrator) creates services

Designed to be portable across devices

Java APIs alternatives with different trade-offs

SIP is PBX/Centrex readySIP is PBX/Centrex readycall waiting/multiple calls

RFC 3261

hold RFC 3264

transfer RFC 3515/Replaces

conference RFC 3261/callee caps

message waiting message summary package

call forward RFC 3261

call park RFC 3515/Replaces

call pickup Replaces

do not disturb RFC 3261

call coverage RFC 3261

from Rohan Mahy’s VON Fall 2003 talk

simultaneous ringing

RFC 3261

basic shared lines

dialog/reg. package

barge-in Join

“Take” Replaces

Shared-line “privacy”

dialog package

divert to admin RFC 3261

intercom URI convention

auto attendant RFC 3261/2833

attendant console

dialog package

night service RFC 3261

centr

ex-s

tyle

featu

res

boss/admin features

attendant features

A constellation of SIP RFCsA constellation of SIP RFCs

Resource mgt. (3312)Reliable prov. (3262)INFO (2976)UPDATE (3311)Reason (3326)SIP (3261)

DNS for SIP (3263)Events (3265)REFER (3515)

DHCP (3361)DHCPv6 (3319)

Digest AKA (3310)Privacy (3323)P-Asserted (3325)Agreement (3329)Media auth. (3313)AES (3853)

Non-adjacent (3327)Symmetric resp. (3581)Service route (3608)User agent caps (3840)Caller prefs (3841)

ISUP (3204)sipfrag (3240)

Security & privacy

Configuration

Core

Mostly PSTN

Content types

Request routing

An eco system, not just a An eco system, not just a protocolprotocol

SIP

XCAP(config)

RTSP

SIMPLEpolicyRPID

….

SDP

XCON(conferencing)

STUNTURN

RTP

configures

initiates carries

carriescontrols provide addresses

SIP, SIPPING & SIMPLE –00 draftsSIP, SIPPING & SIMPLE –00 drafts

0

10

20

30

40

50

60

70

1999 2000 2001 2002 2003 2004

SIPSIPPINGSIMPLE

includes draft-ietf-*-00 and draft-personal-*-00

RFC publicationRFC publication

0

2

4

6

8

10

12

14

2001 2002 2003 2004

SIP

SIPPING

SIMPLE

When are we going to get When are we going to get there?there?

Currently, 14 SIP + 33 SIPPING + 17 SIMPLE WG Internet Drafts = 64 total does not count individual drafts likely to be

“promoted” to WG status The .com consultant linear extrapolation

technique®

pessimist 4 more years if no new work is added to the queue and we can keep up productivity

optimist 3 more years (lots of drafts are in almost-done stage)

SIP – a bi-cultural protocolSIP – a bi-cultural protocol

• overlap dialing• DTMF carriage• key systems• notion of lines• per-minute billing• early media• ISUP & BICC interoperation• trusted service providers

• multimedia• IM and presence• location-based service• user-created services• decentralized operation• everyone equally suspect

Does it have to be that Does it have to be that complicated?complicated?

• highly technical parameters, with differing names• inconsistent conventions for user and realm• made worse by limited end systems (configure by multi-tap)• usually fails with some cryptic error message and no indication which parameter• out-of-box experience not good

Issues for SIP in Issues for SIP in 3GPP/3GPP23GPP/3GPP2 Complexity

14+ messages PSTN-based worldview somewhat peculiar notions of scaling may be able to combine multiple logical elements

Cross-carrier roaming Integration with non-3G systems

e.g., seamless integration with enterprise SIP systems or landline service providers

separation of bearer and identity possibly share same mobile device

Service creation by non-carriers e.g., vertical applications

3G Architecture 3G Architecture (Registration)(Registration)

visited IM domain

home IM domain

servingCSCF

interrogating

proxy

interrogating

mobility managementsignaling

registration signaling (SIP)_

SIP network architectureSIP network architectureScalability requirement depends on roleScalability requirement depends on role

GW

GW

MG

MG

MG

IP network

PSTN

SIP/PSTNSIP/MGC

SIP/MGC

Carrier network

ISP

ISP

Cybercafe

IP

PSTNGW

PBX

IP phones

PSTN phones T1 PRI/BRI

Reliability and scalabilityReliability and scalabilityAnalysis, simulation and measurement Analysis, simulation and measurement proposalproposal

When is stateless proxy stage needed What are the optimal values for S,B,P

for required scalability (1-10 million BHCA) and reliability (99.999%) using commodity hardware

Master

Slave

Master

Slave

s1

s2

s3

a1

a2

b1

b2

S=3

B=2

P=1+1

ex

= R + P

REGISTER+INVITE, etc

r, p s

/B

Rs Ms

Rp Mp

Scaling exampleScaling example

Scaling and reliabilityScaling and reliability No single point of failure Geographical redundancy Can use commodity servers to build

6-nines system: Each cluster with 3 servers with 99%

uptime (3 days/year outage) 99.9999% availability

Scalable to roughly 10 million BHCA 5ESS: 4 m BHCA

Software ResourcesSoftware Resources Lots of commercial and open-source

components, e.g., proxies

iptel.org (OSS), sipd, … application servers

Ubiquity, Broadsoft SIP stacks

reSIProcate (OSS), Hughes, RADvision, various Java stacks

SIP test tools sipsak, SIP Forum test suite (SFTF)

http://www.cs.columbia.edu/sip/implementations.html

Why is Skype successful?Why is Skype successful? All the advantages of a proprietary protocol Peer-to-peer coincidental Good out-of-box experience

Software vendor = service provider Didn’t know that you couldn’t do voice quality

beyond PSTN others too focused on PSTN interoperability – why do

better voice than PSTN? Simpler solutions for NAT traversal

use TCP if necessary use port 80

Did encryption from the very beginning Kazaa marketing vehicle