Snom 4S manual RTP Relay

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2.

[ S N O M 4 S N A T F I L T E R ]

0637ced821ef40a3;ua=c9b140ab598290e5bb491e9c3aaca440 Via: SIP/2.0/UDP 203.145.183.113:12975;branch=z9hG4bK- abx3au3mxb01;rport=17401

From: <sip:denny@snomag.de>;tag=k9p6fmeg7h

To: <sip:denny@snomag.de>;tag=epuy85kzm5

Call-ID: 3c26701d7cb9-pady07b5783t@203-145-183-113

CSeq: 14 REGISTER

Contact: <sip:217.115.141.99:5082;ua=c9b140ab598290e5bb491e9c3aaca44 0>;expires=3600;gruu=”sip:denny@snomag.de;gruu=hobiv52b”

Date: Wed, 26 May 2004 16:03:33 GMT

Content-Length: 0

SIP/2.0 200 Ok

Via: SIP/2.0/UDP 203.145.183.113:12975;branch=z9hG4bK- abx3au3mxb01;rport=17401

From: “denny” <sip:denny@snomag.de>;tag=k9p6fmeg7h

To: “denny” <sip:denny@snomag.de>;tag=epuy85kzm5

Call-ID: 3c26701d7cb9-pady07b5783t@203-145-183-113

CSeq: 14 REGISTER

Contact: <sip:denny@203.145.183.113:12975;line=lhynyb3y>;expires=360 0;gruu=”sip:denny@snomag.de;gruu=hobiv52b”

Date: Wed, 26 May 2004 16:03:33 GMT

Content-Length: 0

The SBC will make the registration short enough to keep the con- nection alive. The UA will reregister shortly after. However, because the registration binding time in the registrar is longer, the SBC will not forward the request to the registrar and answer it locally.

2.3.3 RTP Relay

When initiating a call, user agents usually include a Session De- scription Protocol (SDP) attachment that describes where they expect media. If the user agent operates on a public Internet address, there is no need to interfere in this process. In this case the SBC will just forward the request.

Operators should encourage customers to use equipment that operates on a public Internet address or properly allocates a globally routable Internet address. Because media relay is an expensive opera- tion, it reduces the overall load on the network and at the same time in- creases the quality of the service.

However, when a user agent is behind NAT, it might not be able to receive media directly. In some cases this is because the user agent is

16 • Architecture

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Contents Snom 4S NAT Filter Admin Manual Snom 4S NAT Filter Version Table of Contents Snmp Overview Features ApplicationsSnom technology AG Overview Architecture NAT Filter and SIPNAT How does NAT work? Signalling SIPSymmetrical RTP Media RTP Classification of User AgentsProbing Media Paths Role of the NAT FilterOptimizing the Media Path for Symmetrical NATSBC Behaviour RegisteringRTP Relay Snom technology AG Scaling and Redundancy NATDetecting the right NAT Filter Non NAT-Aware User Agents Requirements on User AgentsSTUN/ICE-Aware User Agents Defining the Maximum Session Time Architecture Installation WindowsInstallation Snom technology AG Installation Snom technology AG Linux Rpm -ihv snomnatf-2.10.*.rpm Installation Logging Port BindingStandard Port Random Port System Settings LoggingPreparing Recovery General Outound ProxyMedia Ports Port BudgetsMedia Relay Controlling RoutingMultiple 2xx Handling Trusted Addresses ChallengingMaximum Packet Size Connection Oriented Media Silence SuppressionRemoving Headers Web Server Integration Codec ControlClir Addresses Timeout Settings Register TimeoutsCall Timeouts Security Settings Snom technology AG Outbound Proxy List System Information Server LogTrace Call History Current Ports Currently Handled UA Memory StatisticsConfiguration Web Server Integration Authentication Interface to the Web ServerSnom technology AG Web Server Integration Registration Call Initiation Snom technology AG Call Termination Snom technology AG Web Server Integration Setup of the SBC Setup of the ToolsAvailable OID OIDSnom technology AG Snmp Checklist for Installation Checklist for Installation Reader‘s Feedback Snom technology AG All rights reserved