From: "David P. Reed" <[EMAIL PROTECTED]> Subject: Network Address Translation harmful to RTP FYI, and a request for help from anyone who has conquered the following: Having struggled with poor performance, stuttering, dropped connections, unexplained errors, etc. when accessing high quality RealVideo and Quicktime 4 over my otherwise wonderful cable modem on MediaOne, I noticed that UDP was not being used (even when RealPlayer and QuickTime are configured to try to use it). As we know, the UDP flows under RTP are essential for smooth playback of high bitrate video and audio. After much research and digging, I discovered that the Network Address Translation (NAT) gateway I was using to allow multiple computers to connect to the cable modem does not support mapping of RTP's UDP ports. Thus, Real G2 was falling back to TCP service, and QT4 was tending to fail utterly (it doesn't automatically fall back). I've been using Microsoft's Internet Connection Sharing (which they acquired from Nevod, and bundle with Win98 2nd edition). But reading the websites for Sygate and Wingate, it looks like they don't fix this either. Both Apple and Real seem to indicate that (unlike firewalls and proxies) NAT servers don't work. This may turn out to be a real issue for sites that want to serve broadband content to early adopters - since many of those folks have installed home networks and are using NAT boxes since RoadRunner and other services don't offer multiple IP addresses for home LANs at this point in time. Perhaps content providers and Real can apply strong pressure to NAT vendors, such as Microsoft, Sygate, Wingate, etc. to add RTP mapping ASAP, and simultaneously apply pressure to MediaOne/RoadRunner to get its act together and support multiple addresses for home LANS (so NAT is not needed). - David -------------------------------------------- WWW Page: http://www.reed.com/dpr.html ******************************************************* The RealForum is an email discussion group focused on using RealNetworks products. The RealForum is a place to post messages about the best methods for creating content using RealNetworks technologies and the planning and implementation of streaming-media web sites. If you ever want to remove yourself from this mailing list, you can send mail to <[EMAIL PROTECTED]> with the following command in the body of your email message: unsubscribe realforum or from another account, besides the address you subscribed with: unsubscribe realforum <[EMAIL PROTECTED]>
