HP VCX Software manual Remote SIP Connectivity, Base retransmission timeout for SIP requests

Chapter 10. SIP Services

Base retransmission timeout for SIP requests

When the Telecommuting Module sends out a SIP request, it will expect a reply within a certain time. If no reply has been received within the Base retransmission timeout, the Telecommuting Module will start resending the request.

Maximum number of retransmissions for INVITE requests

When the Telecommuting Module sends out an INVITE request, it will wait for a reply until the Base retransmission timeout and then start to retransmit the request. The time intervals between retransmissions will double for each new retransmission.

Example: If the Base retransmission timeout is 0.5 seconds and the Maximum number of retransmissions is 6, the INVITE requests will be sent with intervals of 0.5 s, 1 s, 2 s, 4 s, 8 s, and 16 s.

Maximum number of retransmissions for non-INVITE requests

When the Telecommuting Module sends out a request which is not an INVITE request, it will wait for a reply until the Base retransmission timeout and then start to retransmit the request. The time intervals between retransmissions will double for each new retransmission until the interval reaches 4 seconds. After that, retransmissions will be made with a 4-second interval.

Example: If the Base retransmission timeout is 0.5 seconds and the Maximum number of retransmissions is 7, the requests will be sent with intervals of 0.5 s, 1 s, 2 s, 4 s, 4 s, 4 s, and 4 s.

Maximum SIP packet size

This setting allows you to set a limit to the size of SIP packets. A high value will increase performance, but use more memory. A low value will decrease performance, but use less memory.

Save

Saves the Sessions and Media configuration to the preliminary configuration.

Cancel

Reverts all of the above fields to their previous configuration.

Remote SIP Connectivity

If you are at a hotel or somewhere else where you find yourself behind a NAT-ing device that does not understand SIP, you will have use of the SIP Remote Connectivity of 3Com VCX IP Telecommuting Module. This will help your client to traverse the NAT, even if the device doing the NAT does not understand SIP. The SIP Remote Connectivity is only available if you have installed the Remote Connectivity module.

If you have a STUN-capable SIP client, you need just turn on the STUN server of the Telecommuting Module to make the client work behind NAT. If you have a SIP client that

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