7/21/2019 Sbmain Elab DNS

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3G IMS Illustrated(2nd Level)

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Marketing Aspects

References/Qui

3G !kt "#$ain Basics

%#ntents

&r#$ %kt/!kt '# IMS

3G IMS Arcitecture

Intr#ducti#n

Better Communication

3G IMS perati#n

'ake*a*+reakA++rev,IMS

"-S

"-Sstands for "#$ain -a$e Serviceor "#$ain -a$e Server. It is typically use

return an IP address for a given host name (A record(Astands forAddress)). It can balso to return addressing information of mail echange servers as !ell as "IP servers (#$and %AP&'"'records respectively).

&his addressing information may include transport protocols* port numbers and host namaddresses to be used for contacting the appropriate servers.

A relatively ne! and interesting type of +%" service is +%" ,%-#. &his is used for tran,./0 phone numbers to "IP -'1s* hence enabling P"&% users to calllocate "IP users* uold fashion !ay of addressing (i.e. ,./0 phone number). 2hen a P"&% user dials the n

(digits) of a "IP phone user* the call !ill be routed via the P"&% net!or3 to a "IP4P"&% 5&he "IP4P"&% gate!ay !ill loo3up the "IP -'I of the net hop using +%" ,%-# loo3up

#ore specifically* the "IP4P"&% gate!ay !ill input the dialed ,./0 encoded telephone n

into an initial +%" %AP&' type of search. &he appropriate %AP&' record !ill return thof the called "IP phone. &he resulted "IP -'I can then serve as an input to a final %AP&+%" search.

%ote6 throughout the call flo!s in this e1earning course* +%" servers return the re7ueste

information straight a!ay... 8o!ever* in reality* it may be a bit more complicated* sinceInternet4!ide domain name system is hierarchical. 9or instance* the host name :sip.ieee

identifies a specific host in the sub domain :ieee: of the top domain :org:.

http://sbsceninv_elab_dns_srv_naptr.ppt/http://www.ietf.org/rfc/rfc2916.txthttp://sbmain_help.ppt/http://www.ietf.org/rfc/rfc2916.txthttp://sbsceninv_elab_dns_srv_naptr.ppt/

7/21/2019 Sbmain Elab DNS

2/2

3G IMS Illustrated(2nd Level)

Back

Marketing Aspects

References/Qui

3G !kt "#$ain Basics

%#ntents

&r#$ %kt/!kt '# IMS

3G IMS Arcitecture

Intr#ducti#n

Better Communication

3G IMS perati#n

'ake*a*+reakA++rev,IMS

"-S

In that case* the +%" server* !hich represent the top domain :org: is consulted first. It tfor!ards the re7uest (assuming it !or3s in a recursive mode) to the +%" server* !hich rthe sub domain :ieee:* !hich returns the definitive ans!er* i.e.* the addressing informatcomputer :sip:. In many cases efficient caching done by intermediate +%" servers cansignificantly simplify this tedious process.

http://sbmain_help.ppt/