Remote Ua Behind Nat; First Incoming Packet Mechanism - AudioCodes MediaPack MP-118 User Manual

User's Manual
IP address for media of all outgoing SIP messages sent on any of its network interfaces to
this public IP address.
Note:

To configure a single static NAT IP address for all interfaces:
1. Open the SIP General Parameters page (Configuration tab > VoIP menu > SIP
Definitions submenu > General Parameters).
Figure 11-11: Configuring Static NAT IP Address in SIP General Parameters Page
2. In the 'NAT IP Address' field, enter the NAT IP address in dotted-decimal notation.
3. Click Submit.
4. Save the setting to the device's flash memory with a device reset (see 'Saving
Configuration' on page 324).

11.8.2 Remote UA behind NAT

If the remote User Agent with which the device needs to communicate with is located
behind NAT, the device can resolve the problem of activating the RTP/RTCP/T.38 streams
to an invalid IP address / UDP port.
To resolve this NAT traversal issue, the device offers the following features:

First Incoming Packet Mechanism - see 'First Incoming Packet Mechanism' on page
127

RTP No-Op packets according to the avt-rtp-noop draft - see 'No-Op Packets' on page
128
The figure below illustrates a typical network architecture where the remote UA is located
behind NAT:

11.8.2.1 First Incoming Packet Mechanism

If the remote device resides behind a NAT device, it's possible that the device can activate
the RTP/RTCP/T.38 streams to an invalid IP address / UDP port. To avoid such cases, the
device automatically compares the source address of the first received incoming
RTP/RTCP/T.38 stream with the IP address and UDP port of the remote device when the
Version 6.6
The NAT IP address can also be configured using the ini file parameter,
StaticNATIP.
Figure 11-12: Remote UA behind NAT
127
11. Network
MP-11x & MP-124