SIP in wireless applications Henning Schulzrinne Dept. of Computer Science Columbia University.
-
Upload
sarah-rogers -
Category
Documents
-
view
218 -
download
2
Transcript of SIP in wireless applications Henning Schulzrinne Dept. of Computer Science Columbia University.
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presence, location-based presence, location-based services, IMservices, IM Old ring-and-hope (or ring-and-annoy) model is obsolete Presence and event notification model: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
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 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