Reasons for one way mediastreaming (kb2545)
The information in this article applies to:
- SwyxIt! from version 3
- SwyxWare all versions
I can hear the remote party, but the remote party cannot here me or vice versa. Why ?
There are 3 typical reasons for one way mediastreaming:
- Quality of Service (QoS) is configured differently on some machines
- The SwyxServer is installed on a machine with more than 1 IP address
- The RTP mediastream is blocked through a firewall (or virusscanner)
SwyxWare does use the Quality of Service services of the Microsoft Windows OS to prioritise the voice packets higher than the data packets. This assures, that the voice packets will always arrive in a timely manner compared to the rest of the network traffic.
To ensure, that QoS works correctly it is a must to configure QoS for all machines in use the same way! Please doublecheck this requirement, because otherwise you will recognize the one way mediastreaming. Keep in mind, that Microsoft Windows XP/Windows Server 2003 and Windows 2000 (Server) uses different default configurations after installation (Windows XP and Windows Server 2003 do install the "QoS Packet Scheduler" on default, but Windows 2000 (Server) does not).
Additionaly you should check, that the 802.1p configuration at the network board configuration is set to the same value on all machines!
Details about the QoS mechanisms and the configuration/installation can be found in the Knowledgebase articles:
- Support QoS (Quality of Service) (kb2340)
- How do I install QoS (Quality of Service) on Windows 2000 machines ? (kb2051)
On SwywWare installation on servers using more than 2 IP addresses you should tell the SwyxServer and SwyxGate services via registry (topic LocalIpAddress) which IP address to use for telephony. More than 1 IP address is a typical scenario on using a VPN server on the SwyxWare server. Please take a look for the details to Knowledgebase article
If there is a hard- or software firewall between the enddevices and/or the SwyxWare services it may block the RTP mediastream in one direction because of its configuration.
Please do not forget that beside classical firewalls also some virusscanners may contain a firewall/ip-filter.
Please read also the following knowledgebase articles:
- Which Ports are used by SwyxWare (<= v6.01) (kb2308)
- Which Ports are used by SwyxWare (v6.02 - 7.0) (kb3593)
- Connecting a SwyxIt! to a SwyxServer through a firewall (kb2623)
- SwyxIt! and Desktop Firewall Software (kb2751)
- SwyxIt! and Windows XP Service Pack 2 - Firewall settings (kb2891)