1© 2002, Cisco Systems, Inc. All rights reserved.

SIP 标准进展

222© 2002, Cisco Systems, Inc. All rights reserved.

SIP标准化进展

• Enterprise “PBX Features”

• NAT/FW traversal

• Security

• Caller ID Services and Privacy

• DTMF

• QoS

• Configuration/Management

• Gateways to Other Protocols/TDM

333© 2002, Cisco Systems, Inc. All rights reserved.

Enterprise User-Based “PBX Features” (1)

• Centrex Style Features

Call Waiting / Multiple Calls RFC 3261

Hold RFC 3264

Transfer RFC 3515 / Replaces

Conference RFC 3261 / RFC 3840

Message Waiting RFC 3842

Call Forward RFC 3261

Park RFC 3515 / Replaces

Pickup Replaces

Do Not Disturb RFC 3261

• Call Coverage RFC 3261

444© 2002, Cisco Systems, Inc. All rights reserved.

Enterprise User-Based “PBX Features” (2)

• Boss/Admin Features

Simultaneous Ringing RFC 3261

Basic Shared Lines Dialog pkg (stable) / RFC 3680

Barge-In Join (ready)

“Take” Replaces (ready)

Shared-Line “Privacy” Dialog pkg

Divert to Admin RFC 3261

Intercom URI convention

• Attendant Services

Auto-attendant RFC 3261 / RFC 2833

Attendant Console Dialog pkg

Night Service RFC 3261

555© 2002, Cisco Systems, Inc. All rights reserved.

Perhaps we need Business “Feature Packs” for SIP Phones

• Feature Pack “A”

Basic Call

Attended Transfer w/ REFER and Replaces

Caller ID and Privacy

Message Waiting

Basic Dial Plan

Basic Conferences

• Feature Pack “X”Integrated Presence (as NOTIFIER)

IM Receiver

• Feature Pack “B”

Join

Dialog Package

Phone configuration

Shared Line support

click to dial using REFER

TLS

Autodial and autoanswer URIs

• Feature Pack “C”

ENUM

Remote dialog manipulation with REFER

End-to-end encryption

Conference Roster

666© 2002, Cisco Systems, Inc. All rights reserved.

NAT/FW Traversal

• SIPSymmetric Response—RFC 3581Connection Reuse—SIP WG IDSession Policy—Requirements doneGlobally Routable URIs—IESG Review

• MediaSTUN—RFC 3489TURN—Individual IDProtocol-specific RelaysICE—to become an MMUSIC WG IDB2BUAs with Media

• Putting it all togetherNAT scenarios—SIPPING WG ID

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Security: Works really well

• Authentication

Digest Authentication—RFC 2617 / RFC 3261

Digest AKA for GSM SIM auth—RFC 3310

• Signaling protection

TLS (hop-by-hop)—In core spec

S/MIME (end-to-end)—In core spec

S/MIME AES—Minor update to core spec - RFC ed

Authenticated ID Body—AIB draft

End-to-Middle, Middle-to-end—Requirements

• Media protection

SRTP—RFC 3711

888© 2002, Cisco Systems, Inc. All rights reserved.

Caller ID Services and Privacy

• Identity

End-to-End—RFC 3261

Transitive Trust Model—RFC 3325

Asserted by Third Party—“Identity” Draft (Solid)

• Privacy

Privacy Header—RFC 3323

New privacy tokens for transitive trust

• Role-based Authorization

999© 2002, Cisco Systems, Inc. All rights reserved.

DTMF / Digits

• Time synchronized with media: it works

In-band (tones blended in with the speech codec)

RFC2833 “AVT Tones”

• In “signaling”: it sucks

Many Proprietary Approaches

various payloads in INFO, SUB/NOT

All have some bad side effects

Double-Digits

Poor timing characteristics

• Using Markup: it will work (Stable)

KPML

App Interaction Framework

101010© 2002, Cisco Systems, Inc. All rights reserved.

QoS

• Diffserv-style

Just set it (diffserv markings)

• Intserv-style, post-ring

Just do it (send RSVP requests post-ring)

• Intserv-style, pre-ring

QoS Preconditions—RFC 3313

• Alternate routing on QoS failure?

Just works. You get it for free.

111111© 2002, Cisco Systems, Inc. All rights reserved.

Configuration and Management

• Phone configuration

event package—Solid

config format—Mud

• SIP MIB—Fairly Solid

• TRIP and TGREP

TRIP is an RFC

TGREP is in AD review

121212© 2002, Cisco Systems, Inc. All rights reserved.

PSTN Interworking Issues #1

• Early Media—No new extensions, BCP in works (Stable)

Basic Early Media works fine

Early Media + forking does not

If it hurts, don’t do that!

• Overlap Dialing—RFC 3578

It works. Providers can use three variations on the approach when receiving numbers in their network

• Telephony-Specific Addressing—WG IDs in IPTEL

Calling Party Category / Nature of Party

Trunk Group and Carrier Codes

Number Portability indicator

131313© 2002, Cisco Systems, Inc. All rights reserved.

PSTN Interworking Issues #2

• Redirection Information: 3 approachesPut the info in the URI: works, requires no extensions, but most folks do not understand the idea. requires coordinated configuration between gateway and proxies

cc-diversion: proprietary. functional but with swiss cheese security

Request-History: Moist Clay

• Emergency Services and Prioritized Call completion

911/112 Calls: Works for fixed locations, Working on mobile locations. (PSTN 911 has the same problem)

MLPP and IEPS: Request-History—Stable

• Tunnelling Telephony Signaling—DoneRFC 3398 / 3204 / 3372

141414© 2002, Cisco Systems, Inc. All rights reserved.

Gateway Services

• PSTN Gateways

ISUP, ISDN, E&M, FXO, FXS gateways have been working for years now. Millions of minutes each day.

• QSIG Gateways

Basic calls and Caller ID works just fine

Mapping complex features is work in progress

• H.323 Gateways

Works just as well as PSTN

Commercial deployments doing millions of basic calls per month