von september ‘98 1 9/17/98 von standards update jonathan rosenberg bell laboratories september...

VoN September ‘9819/17/98

VoN Standards Update

Jonathan Rosenberg

Bell LaboratoriesSeptember 17, 1998


IETF - brief intro• Internet Engineering Task Force

• Large open international community concerned with the evolution of the Internet architecture and the smooth operation of the Internet– Vendors, researchers, service providers

– Completely open

– Organized into areas

– Many working groups in each area

– Working groups do the work; focused charter and milestones

• http://www.ietf.org


• Real Time Streaming Protocol (RTSP) [RFC2326]

• Session Description Protocol (SDP) [RFC2327]

• Session Announcement Protocol (SAP)

– pint: PSTN and Internet Internetworking

• PINT Protocol

• pre-PINT Implementation Experiences (last call)

– iptel: IP Telephony

VoN related Working Groups• Transport Area

– avt: Audio Video Transport• Real Time Transport Protocol

(RTP) [RFC1889]

• RTP Media Encapsulation [RFC1890]

• Many RTP Payload Formats

– mmusic: Multiparty Multimedia Session Control

• Session Initiation Protocol (SIP) - now in last call


iptel History• Group initially proposed to

look at SIP for IP telephony

• Based on discussions on lists, focus of group changed to develop new IP telephony services

• BoF Session first held at Washington IETF in December

• Group chartered for two activities– Call Processing Syntax

– Gateway Location Protocol


Call Processing Syntax• Specifies behavior of a

server or terminal in responding to incoming and outgoing calls

• Textual description of desired operation

• Independent of underlying signaling protocol

• Generated in many ways– Written by savvy users– Written and provided by

system administrators– Created by the user as a result

of some GUI application– Written and provided by third

party “call logic providers”• Call screening services• Automatic mobility

services


Example Services• Call forward

– Based on time of day, caller, number of current calls

• Call redirect• Automatic call reject

– Based on caller

– Spam protection

• Distinctive ringing– Also based on caller,

priority of call, etc.

• Outgoing call screening– Prevent calls to porn

lines

– Prevent calls to recruiters..


Automatic Call Forward

Joe

Jack’s PC

Jack’s Cell Phone

Gatekeeper orServer

Gateway

1

2

3

4

5

6

1. Jack uploads CPS toserver2. Joe calls Jack; call arrivesat server3. Server processes CPS; Jack has requested calls from Joe tobe proxied to cell phone.Serverlocates gateway andproxies call request there4. Gateway calls cell phone, Jackanswers5. Gateway accepts call6. Accept forwarded to Joe


What might it look like?• Textual

– Allows for cross platformusage, easy editing

• Simple commands

• A few variables representing call state

• Several approaches

– Tcl/Tk

– XML!!

if $caller = “joe” proxy “tel://555-1212”

proxy “[email protected]”if $result = no_answer proxy “tel://555-1212”

Automatic Call Forward

Call Forward No Answer


Key Issues• Safety

– Generation exposed to users

– Must be safe to execute!

• Extensibility– Vendor specific services

– Interoperability - language can provide powerful support

• Framework– How do multiple scripts interact?

– Who/what do they “represent”

• Security– CPS transferred from PC to server, possibly

from server to server

– Authentication a clear must

– Encryption may be needed

• Simplicity– Sky is the limit

– MUST KEEP IT SIMPLE - or it will never be done or be used


Whats to be generated?• Service Framework

Document– Overviews services

enabled

– Describes its usage

– Discusses transport

– Details security

• Call Processing Syntax– Syntax itself

– Functions available, semantics

– Variables available

– Extension mechanisms


Gateway Location Problem

• PC to PSTN Calling

• PSTN to IP to PSTN calling

• Must locate a remote IP-PSTN gateway

• Gateways can be within another administrative domain

• Need to “learn” about remote gateways Gateway

GatewayGateway

?

Gateway

MultimediaPC


Gateway Location Protocol• Distribution Protocol• Gateways distribute attributes

– Proxies possible

• Servers receive them– Gatekeepers

– SIP servers

– PC clients

– Gateways

• Has aspects of routing and directory services

Gateway Location Protocol

Server

Gateways

Proxy


Requirements• Multi-Criteria

Selection– Client preferences

• Billing methods Authentication methods

• Provider

• Codec and protocol support

– ISP preferences• Confederation membership

• Quality filters

– Set of available gateways

• Security– Non-repudiation,

authentication

• Rapid Operation• Automated• Quick Updates


Whats to be generated?• Standards track RFC

• Describes basic architecture

• Protocol

• Security issues


Conclusion• IETF has several working groups doing

VoN related activities

• Newest is IETF iptel

• Two main outputs– Call processing syntax– Gateway Location Protocol

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