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©Stephen Kingham SIP Peering SIP Workshop APAN Taipei Taiwan 23rd Aug 2005 By Stephen Kingham mailto:[email protected] sip:[email protected]

©Stephen Kingham SIP Peering SIP Workshop APAN Taipei Taiwan 23rd Aug 2005 By Stephen Kingham mailto:[email protected] sip:[email protected]

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©Stephen Kingham

SIP Peering

SIP Workshop

APAN Taipei Taiwan 23rd Aug 2005

By Stephen Kingham

mailto:[email protected]

sip:[email protected]

©Stephen Kingham

This work is the intellectual property of the author. Permission is granted for this material to be shared for non-commercial, educational purposes, provided that this copyright statement appears on the reproduced materials and notice is given that the copying is by permission of the author. To disseminate otherwise or to republish requires written permission from the author.

Copyright Stephen Kingham 2004

©Stephen Kingham

Review Call Setup

SIP UA SIP UA

SIP Location Server

2. L

ook fo

r SRV re

cord

for f

linder

s.ed

u.au Call Control

Call Control andAudio and Video

SIP Redirect Server

DNS

3. INVITE

russ.nagel@flin

ders.edu.au

3. [email protected]

1. Register

Flinders University

Audio and VideoRTP UDP

©Stephen Kingham

• DNS is integral to SIP routing.• DNS is used to find a priority list of SIP servers for a

domain.• It does this by putting in SIP specific SRV records into

the DNS.• Just like MX records in DNS for mail.

• So it turns out it is easy to have backup servers in SIP.

• Good description found on the MIT Internet2 sip.edu project cookbook: http://mit.edu/sip/sip.edu/dns.shtml

SIP and DNS

©Stephen Kingham

• Specific SRV records added to your DNS for SIP,eg

IN A 192.94.63.28

;If we place the SRV record above the next line it fails to load

$ORIGIN aarnet.edu.au.

_sip._udp SRV 0 1 5060 ser.yarralumla.aarnet.edu.au._sip._udp SRV 1 1 5060 ser.nsw.aarnet.edu.au.

ser.yarrulumla.aarnet..edu.au. IN A 192.94.63.28ser.nsw.aarnet..edu.au. IN A 138.44.16.90

SIP and DNS

©Stephen Kingham

• On a unix host use the dig command:dig -t SRV _sip._udp.aarnet.edu.au

• You should get a response that has this in it:

;; QUESTION SECTION:;_sip._udp.aarnet.edu.au. IN SRV

;; ANSWER SECTION:_sip._udp.aarnet.edu.au. 333 IN SRV 1 1 5060 ser.yarralumla.aarnet.edu.au.

SIP and DNS TEST

©Stephen Kingham

• ENUM (rfc 2916) uses the DNS to find the full SIP address using a telephone number. ACA might have ENUM Tier 1 into Australia soon http://www.aca.gov.au/telcomm/telephone_numbering/enum_nsg2/.

SIP and ENUM

©Stephen Kingham

2. Today, many addresses

sip:[email protected]

tel:+61-399636844

mailto:[email protected]

tel:+46-706051234tel:+61-399636844

Source: Patrik Fältström, Area Director Applications Area IETF, from ITU Tutorial Workshop on ENUM 8 Feb 2002 Geneva

©Stephen Kingham

2. With ENUM, only one

tel:+61-399636844

mailto:[email protected]

tel:+46-706051234

sip:[email protected]

tel:+61-399636844

Give this number to friends:+61-399636844

ENUM

Source: Patrik Fältström, Area Director Applications Area IETF, from ITU Tutorial Workshop on ENUM 8 Feb 2002 Geneva

©Stephen Kingham

VoIP via PSTN to PSTN

DNS-Server

“ENUM”

SIP-Server

SIP-Server

Gateway

Gateway

Source: Patrik Fältström, Area Director Applications Area IETF, from ITU Tutorial Workshop on ENUM 8 Feb 2002 Geneva

©Stephen Kingham

ENUM in a nutshell

• take phone number +46-8-6859131

• turn into domain name 1.3.1.9.5.8.6.8.6.4.e164.arpa.

• return list of URI’ssip:[email protected]

• ask the DNS

mailto:[email protected]

Source: Patrik Fältström, Area Director Applications Area IETF, from ITU Tutorial Workshop on ENUM 8 Feb 2002 Geneva

©Stephen Kingham

• TRIP (rfc 3219) does for telephone numbers that BGP does for the entire Internet. Dynamic routing by advertisement!

• Presenter to review – BGP version 3– Traditional Telephone routing using static configurations– TRIP

SIP and TRIP (Telephone Routing over IP)

©Stephen Kingham

IETF voippeer BoF

©Stephen Kingham

“SIP.edu by numbers”

©Stephen Kingham

Peering in APAN - STATIC

• Project 1 of the APAN SIP Working Group

• Static entries in a central SIP Server at APAN.• Could be called “SIP Global Dialling Scheme (SGDS)”

– based on H.323 GDS– Central APAN SIP Server “relays” calls to the APAN

Member.– APAN Member must tell APAN the numbers they

support.

©Stephen Kingham

Peering in APAN – Private ENUM

• (not proposed yet).• APAN use a Private ENUM tree where APAN members

populate their E.164 numbers with NAPTR records that point to their SIP Servers.

• This would be used in conjunction with the “golden” ENUM DNS Tree.

• SIP Servers today can look up multiple ENUM trees!, see talk at APAN Taipei 2005 on Thursday.