Administrator’s Guide - SoundPoint IP / SoundStation® IP

Optimization

4.6.2.6 Network Address Translation <nat/>

These parameters define port and IP address changes used in NAT traversal. The port changes will change the port used by the phone, while the IP entry simply changes the IP advertised in the SIP signaling. This allows the use of simple NAT devices that can redirect traffic, but do not allow for port mapping. For example, port 5432 on the NAT device can be sent to port 5432 on an internal device, but not port 1234.

 

Permitted

 

 

Attribute

Values

Default

Interpretation

 

 

 

 

nat.ip

dotted-deci-

Null

IP address to advertise within SIP signaling -

 

mal IP

 

should match the external IP address used by the

 

address

 

NAT device.

 

 

 

 

nat.signalPort

1024 to

Null

If non-Null, this port will be used by the phone for

 

65535

 

SIP signaling, overriding the value set for voIp-

 

 

 

Prot.local.signalPort in sip.cfg.

 

 

 

 

nat.mediaPortStart

1024 to

Null

If non-Null, this attribute will be used to set the

 

65535

 

initially allocated RTP port, overriding the value

 

 

 

set for tcpIpApp.port.rtp.mediaPortRangeStart in

 

 

 

sip.cfg. Refer to 4.6.1.10.3.1 RTP <RTP/> on

 

 

 

page 124.

 

 

 

 

nat.keepalive.inter-

0 to 3600

Null

If non-Null (or 0), the keepalive interval in sec-

val

 

 

onds. This parameter is used to set the interval at

 

 

 

which phones will send a keep-alive packet to the

 

 

 

gateway/NAT device to keep the communication

 

 

 

port open so that NAT can continue to function as

 

 

 

setup initially.

 

 

 

The Microsoft® Office Live Communications

 

 

 

Server 2005 keepalive feature will override this

 

 

 

interval. If you want to deploy phones behind a

 

 

 

NAT and connect them to Live Communications

 

 

 

Server, the keepalive interval received from the

 

 

 

Live Communications Server must be short

 

 

 

enough to keep the NAT port open. Once the TCP

 

 

 

connection is closed, the phones stop sending

 

 

 

keep-alive packets.

 

 

 

 

160

Copyright © 2006 Polycom, Inc.

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Polycom 1725-11530-200 Rev A1 manual Network Address Translation nat