Scaling And Redundancy - Snom 4S NAT Filter Admin Manual

a=rtpmap:0 pcmu/8000
a=rtpmap:8 pcma/8000
a=rtpmap:3 gsm/8000
a=rtpmap:18 g729/8000
a=rtpmap:2 g726-32/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=sendrecv
a=silenceSupp:off - - - -
The NAT Filter changes the private address to a globally routable
address and inserts the local port. It also inserts a hint that tells the other
user agent that it should not do silence suppression. This reduces the risk
that the connection is closed during a talk spurt of one of the parties.

2.4 Scaling and Redundancy

The NAT Filter product was designed to support distributed server
farms. That means that the servers act stateless in principle; user agents
may randomly pick a server in a server farm. This feature allows opera-
tors to set up very large and robust networks.
Table 1: NAT conbimations
To/From Public IP
Public IP Always
Full Cone NAT
Restricted
NAT
Symmetrical
NAT
18 • Architecture
[ 4 S N A T F
S N O M
Full Cone
NAT
When
STUN
support is
available
When
STUN is
available
]
I L T E R
Restricted Symmetrical
NAT NAT
When STUN When STUN
and ICE are and ICE are
available available
When STUN When STUN
and ICE are and ICE are
available available
When STUN When STUN
and ICE are and ICE are
available available
and no port
checking
Needs filter