Cable Modem Troubleshooting Tips
Streaming media
This page applies to applications for playing streaming media, such as Real Player, Windows Media Player, QuickTime Player.
Performance issues
Players for streaming media, such as Real Player, Windows Media Player, QuickTime Player have options in their preferences settings for telling them the bandwidth of your network connection. By default, they usually assume a slow dial-up modem connection. You should set this preference option to the available value equal to (or next less than) your downstream bandwidth. For instance, if your nominal downstream bandwidth is 512 kbps, and the nearest options available are T1 (too high) and Dual-ISDN (too low), then select Dual-ISDN, as being the highest option less than 512 kbps. The exception is the Windows version of Microsoft Media Player 7, where you should check Detect my connection speed (not available in Mac version).
For instance, on a 512 kbps or better download broadband connection, configure RealOne Player as follows:
- In RealOne Player, pull down the Tools menu, and select Preferences...
- In the left-hand Category panel, click Connection.
- In the right-hand Connection panel:
- In the Normal pull-down, select DSL/Cable (400 Kbps and above).
- In the Maximum pull-down, select DSL/Cable (400 Kbps and above).
- Click OK to close Preferences.
Streaming protocols and Firewalls or NAT routers
Some streaming protocols do not work if you have a firewall, or if your PC is behind a NAT router (either a physical router or ICS). In the preferences for the above streaming players, you can usually specify which protocol options to allow or deny:
- Multicast is the most efficient, but is unlikely to work on a cable connection.
- UDP is the next most efficient, but:
- requires UDP ports to be opened in any firewall; and
- requires UDP port-forwarding through any NAT router.
- TCP is less efficient than UDP, but will work automatically through firewalls and NAT routers without any special configuration.
- HTTP is the least efficient, will always work, but is subject to web proxy cache degradation.
If you are behind a firewall or a NAT router, you might have to:
- either: configure your player to restrict UDP to specified port numbers; configure your firewall to open those ports, and/or configure your NAT router to port-forward those ports. See http://www.practicallynetworked.com/sharing/app_port_list.htm for lists of default ports that require to be forwarded for each steaming protocol. Some cheap firewalls might not have the ability to be configured to open specific port numbers.
- or: turn off UDP protocol options in your streaming player preferences;
For example, to prevent RealOne Player for Windows from attempting to use the UDP protocol:
- In RealOne Player (original or v2.0), pull down the Tools menu, and select Preferences...
- In the left-hand Category panel, click the [+] beside Connection.
- In the expanded list, click Network Transports.
- In the right-hand Network Transports panel, check the box Manually configure connections settings.
- Click PNA Settings.
- Click Reset to Recommended, then:
- Uncheck Attempt to use Multicast for live content.
- Uncheck Attempt to use UDP for all content.
- Click OK to exit PNA Transport Settings.
- Click RTSP Settings.
- Click Reset to Recommended, then:
- Uncheck Attempt to use Multicast for live content.
- Uncheck Attempt to use UDP for all content.
- Click OK to exit RTSP Transport Settings.
- Click OK to close Preferences.
- In the older RealPlayer 8, pull down the View menu, and select Preferences...
- Click tab Transport.
- Check Use specified transports:
- Click RTSP Settings...
- Uncheck Attempt to use Multicast for live content.
- Uncheck Attempt to use UDP (etc).
- Click OK to exit RTSP Transport Settings.
- Click PNA Settings...
- Uncheck Attempt to use Multicast for live content.
- Uncheck Attempt to use UDP (etc).
- Click OK to exit PNA Transport Settings.
- Click OK to close Preferences.
Now the player will attempt to use only TCP and HTTP protocols, which should work through firewalls and NAT routers without special configuration. These preferences will apply also to the Real Player plug-in for web browsers.
Real Player 8 for Macintosh is able to recover from non-working UDP and fall back to TCP without special configuration.
Streaming protocols and Inktomi Traffic Servers
Some ISPs use Inktomi Traffic Servers to cache streaming protocol data in a similar way to how they use them as a transparent web proxy cache. The interception of streaming protocol data is meant to be transparent, but for some reasons (not understood) Real Player does not work correctly for some sources (it appears to work for RTSP, but not for PNA protocols), and Windows Media Player does not work correctly for some sources (MMS protocol). Consult the following work-arounds for possible fixes:
Real Player on Windows - work-around
On Windows, the symptom of this problem is:
either an error dialogue from the RealPlayer web browser plug-in saying:
A General Error has occurred.
or an error dialogue from the RealOne Player application saying:
Connection to server has been lost. You may be experiencing network problems.
Configure Real Player for Windows to work around this Inktomi problem as follows:
- Discover the address of a local streaming media proxy: see Finding the Streaming Media Proxy below.
- Discover the version of Real Player you have by pulling down the Help menu and selecting About RealOne Player.
- Configure Real Player according to the version you have:
- In RealOne Player v2.0, pull down the Tools menu, and select Preferences...
- In the left-hand Category panel, click the [+] beside Connection.
- In the expanded list, click Proxy.
- In the right-hand Proxy panel, under Streaming Settings, click Change Settings....
- Under PNA and RTSP Proxies, check Use Proxies:
- In the row PNA:
- In the box Proxy address, enter the name of the streaming media proxy.
- In the box Port, enter 1090.
- [only if found to be necessary: In the row RTSP:
- In the box Proxy address, enter the name of the streaming media proxy.
- In the box Port, enter 9231.]
- [only if found to be necessary: Under HTTP Proxy, click Use Proxy:
- In the box Proxy address, enter the name of the streaming media proxy or any other web proxy.
- In the box Port, enter 8080.]
- In the box Do not use proxy for:, enter 192.168.*
- Click OK to exit Streaming Proxy Settings.
- Click OK to close Preferences.
- In RealOne Player (original), pull down the Tools menu, and select Preferences...
- In the left-hand Category panel, click the [+] beside Connection.
- In the expanded list, click Proxy.
- In the right hand Proxy panel, check the box PNA proxy.
- In the box Proxy address, enter the name of the streaming media proxy.
- In the box Port, enter 1090.
- [only if found to be necessary: check the box RTSP proxy.
- In the box Proxy address, enter the name of the streaming media proxy.
- In the box Port, enter 9231.]
- [only if found to be necessary: Under HTTP Proxy, click the radio button Use proxy.
- In the box Proxy address, enter the name of the streaming media proxy or any other web proxy.
- In the box Port, enter 8080.]
- In the box Do not use proxy for, enter 192.168.*
- Click OK to close Preferences.
- In the older RealPlayer 8, pull down the View menu, and select Preferences...
- Click tab Proxy.
- Check the box Use PNA proxy:
- In the box, enter the name of the streaming media proxy.
- In the box Port, enter 1090.
- [only if found to be necessary: Check the box Use RTSP proxy:
- In the box, enter the name of the streaming media proxy.
- In the box Port, enter 9231.]
- [only if found to be necessary: Under HTTP Options, check the radio button Manually configure HTTP proxy.
- In the box Proxy Server, enter the name of the streaming media proxy.
- In the bix Port, enter 8080.]
- In the box Do not use proxy for, enter 192.168.*
- Click OK to close Preferences.
Now the player will explicitly send all requests via the selected Traffic Server. These preferences will apply also to the RealPlayer plug-in for web browsers.
If your PC is firewalled or behind a NAT router then you might also have to disable the UDP protocol under PNA Transport Settings as described in the previous section.
If after making this configuration, you receive an error dialogue from the RealOne Player saying:
Requested file not found. The link you followed may be outdated or inaccurate.
then the chosen Traffic Server does not support PNA proxy, or it is temporarily broken. You should try the above configuration again, specifying a different Traffic Server within your ISP's network, preferably one at your regional centre, otherwise one at a different regional centre.
[Technical note: the use of port 1090 for PNA proxy replaces the normal Real Player usage of port 7070 for PNA].
For more information about Real Player and firewalls, see http://service.real.com/firewall/.
Real Player on Macintosh - work-around
On Macintosh, the symptom of this problem is:
either an error dialogue from the RealPlayerG2 web browser plug-in saying:
Unable to connect to server. Check network transport settings or run auto-configure.
or an error dialogue from the RealPlayer application saying:
Connection to server could not be established. You may be experiencing network problems.
Configure Real Player 8 for Macintosh to work around this Inktomi problem as follows:
- First discover the address of a local streaming media proxy: see Finding the Streaming Media Proxy below.
- In Real Player, pull down the View menu, and select Preferences...
- In Preferences, click the right-arrow until the tab Proxy appears.
- Click the tab Proxy.
- Check the box Use PNA proxy:.
- In the next box, enter the name of your streaming media proxy.
- In the box Port:, enter 1090.
- Click the radio button Manually configure HTTP proxy.
- In the box Proxy server:, enter the name of your streaming media proxy.
- In the box Port:, enter 8080.
- In the box Do not use proxy for, enter 192.168.*
- Click OK to close Preferences.
These preferences will apply also to the RealPlayerG2 plug-in for web browsers.
Windows Media Player - work-around
Configure Windows Media Player as follows to work around a failure to play media over the MMS protocol via Inktomi traffic servers:
- In Windows Media Player, pull down the Tools menu and select Options...
- Click the tab Network.
- Under Streaming proxy settings, select MMS, then click Configure.
- Select Use the following proxy server:.
- In the box Address: enter the address of a streaming media proxy.
- Leave Port: set to 1755.
- Leave other boxes unchecked/blank.
- Click OK.
- Click OK.
Windows Media Player for Macintosh - no work-around
There is no method of setting an MMS proxy in Windows Media Player for Macintosh 7.1.
Finding the Streaming Media Proxy
The default streaming media proxy might not be the same server as the transparent web proxy cache (see Which is my web cache?). Nevertheless, sometimes the transparent web proxy can act also as a streaming media proxy. In cases where it can, use it. But sometimes it cannot, and you need to discover an alternative local streaming media proxy.
To discover the default streaming media proxy under Windows, launch a web browser, launch RealOne Player, and launch a command window. In the web browser, navigate to a site which contains links to Real Player clips that use the RTSP protocol (for instance, at the site http://news.bbc.co.uk/, the links to BBC News 24 and BBC One TV news use RTSP). While the RTSP clip is playing in RealOne Player, enter the command netstat -a in the command window, and look for an ESTABLISHED TCP connection to a host using a remote port other than 80 or 554: a port often seen used is 9231. This host will be the default streaming media proxy.
If the above procedure does not yield a working streaming media proxy, NTL users can experiment to find one as follows. First find the default transparent web proxy (see Which is my web cache?). It will have a name of the form
inktomiN-XXX.server.ntl.com
where N is a number, and XXX is a code for the local data centre. Try various values for N until you find one that works as a streaming media proxy.
Return to Index.