D-STAR Data Performance

As mentioned earlier in this website, we were most interested in the data performance (or perhaps networking capability) of the D-STAR system. Most of our transmissions used the IP protocol, but the D-STAR will support other protocols such as SMB (Windows) and NCP (Novell), and Appletalk (Macintosh). Our tests centered around IP, where all types of computers could interact with the network.

Shown below are screenshots of packet traces showing the activity on the network. The pictures are graphics intensive, but are worthy of discussion.

The above picture shows the DHCP initialization sequence for the Linux laptop, the remote computer for these tests. As shown, the D-STAR network handled all the protocols just fine.

The above picture shows a DNS and Ping test. The Linux Laptop, using the IP 192.168.1.223, makes contact with the DNS server 192.168.1.1 looking for the record of www.apple.com. That IP address comes back to the linux computer, and then the ping process begins.

Next, as this was a fresh RedHat 9.0 Linux install on the laptop, I wanted to test FTP and HTTPS protocols on the computer. This required me to download, via FTP a file called update*.rpm. The window above shows the successful initiation of the request, along with the beginning of the download. Note also that the FTP protocol really consumes the available bandwidth of the network. The D-Star radio was able to handle near the ethernet standard MTU of 1550 bytes/packet, by centering on an value of 1448 bytes/packet. We clocked out an effective speed of 90 Kbs, which is less than the 128 Kbs predicted maximum, but certainly understandable considering protocol overheads. At this rate, the D-STAR is about 1.5 times faster as the fastest dialup connections available in the US.

Our last screen shot shows a simple telnet session in the middle of the RedHat updates. The screen shot shows the text we saw in our terminal window.