snom technology AG • 3
Table of Contents
1
Overview ..........................................................5
1.1
Applications ...................................................................... 6
1.2
Features ........................................................................... 6
2
Architecture .....................................................9
2.1
The NAT Filter and SIP ........................................................ 9
2.2
NAT ............................................................................... 10
2.2.1
How does NAT work?
..............................................................................................................................................
11
2.2.2
Symmetrical RTP
............................................................................................................................................................
11
2.2.3
Signalling SIP
.......................................................................................................................................................................
11
2.2.4
Media RTP
...................................................................................................................................................................................
12
2.2.5
Classification of User Agents
....................................................................................................................
12
2.2.6
Probing Media Paths
.................................................................................................................................................
13
2.2.7
The Role of the NAT Filter
..............................................................................................................................
13
2.2.8
Optimizing the Media Path for Symmetrical NAT
..................................................
14
2.3
Filter Behaviour ............................................................... 15
2.3.1
Registering without UA Support
..........................................................................................................
15
2.3.2
Registering with UA Support
.....................................................................................................................
16
2.3.3
RTP Relay
....................................................................................................................................................................................
18
2.4
Scaling and Redundancy ................................................... 20
2.5
Detecting the right NAT Filter ............................................ 21
2.6
Requirements on User Agents ............................................ 21
2.6.1
Non NAT-Aware User Agents
.....................................................................................................................
21
2.6.2
STUN/ICE-Aware User Agents
................................................................................................................
22
2.7
Defining the Maximum Session Time .................................. 22
3
Installation .....................................................25
3.1
Windows ......................................................................... 25
3.2
Linux ............................................................................. 30
4
Configuration ..................................................33
4.1
Logging In ...................................................................... 33
4.2
Port Binding .................................................................... 33
4.3
System Settings .............................................................. 35
4.3.1
Logging
...........................................................................................................................................................................................
35
4.3.2
Preparing Recovery
...................................................................................................................................................
36
