Network Address Translation Support; Device Located Behind Nat - AudioCodes Mediant 3000 User Manual

User's Manual
Parameter
[NFSServers_NfsVersion
]
Authentication Type
[NFSServers_AuthType]
User ID
[NFSServers_UID]
Group ID
[NFSServers_GID]
VLAN Type
[NFSServers_VlanType]
11.9

Network Address Translation Support

Network Address Translation (NAT) is a mechanism that maps internal IP addresses (and
ports) used within a private network to global IP addresses and vice versa, providing
transparent routing to end hosts. The primary advantages of NAT include (1) reduction in
the number of global IP addresses required in a private network (global IP addresses are
only used to connect to the Internet) and (2) better network security by hiding the internal
architecture.
The design of SIP creates a problem for VoIP traffic to pass through NAT. SIP uses IP
addresses and port numbers in its message body. However, the NAT server is unable to
modify the SIP messages and thus, can't change local addresses to global addresses.
This section discusses the device's solutions for overcoming NAT traversal issues.

11.9.1 Device Located behind NAT

Two different streams traverse through NAT - signaling and media. A device located
behind a NAT, that initiates a signaling path has problems receiving incoming signaling
responses as they are blocked by the NAT server. Therefore, the initiating device must
inform the receiving device where to send the media. To resolve this NAT problem, the
following solutions are provided by the device, listed in priority of the selected method used
by the device:
a. If configured, uses an external STUN server to assign a NAT address to all interfaces
- see .Configuring STUN on page 138.
b. If configured, uses the single Static NAT IP address for all interfaces - see 'Configuring
a Static NAT IP Address for All Interfaces' on page 139.
c. If configured, uses the NAT Translation table which configures NAT per interface - see
Configuring NAT Translation per IP Interface on page 140.
If NAT is not configured by any of the above-mentioned methods, the device sends the
packet according to its IP address configured in the Multiple Interface table.
Version 6.6

[2] NFS Version 2

[3] NFS Version 3 (default)
Authentication method used for accessing the remote file system.

[0] Null

[1] Unix (default)
User ID used in authentication when using Unix.
The valid range is 0 to 65537. The default is 0.
Group ID used in authentication when using Unix.
The valid range is 0 to 65537. The default is 1.
The VLAN type for accessing the remote file system.

[0] OAM

[1] MEDIA (default)
Note: This parameter applies only if VLANs are enabled or if Multiple
IPs is configured (see 'Configuring IP Network Interfaces' on page
116).
137
Description
11. Network
Mediant 3000