By ThinGuy on Sep 26, 2007
CLAIM: The optional UDP protocol requires a DHCP server to be accessible to the Sun Rays, and also uses custom DHCP tags to locate the Sun Ray Server. This enables Sun Rays to be installed without requiring any local configuration or setup of the client itself.
Optional UDP Protocol requires DHCP? Someone needs to do a little reading up on TCP/IP, not to mention basic networking. It's true that the display protocol is UDP driven, but it is not optional. If by installing you mean opening a card board box and setting on a desk and never having to touch the device again, then we see eye to eye on that point.
Regarding "custom" DHCP tags, this is more FUD. The Sun Ray used to required DHCP vendor tags to discover the server. You still can do that since we care about backward compatibility for existing deployments. MS uses vendor tags too, have customers check their MS DHCP Server. Other options for a Sun Ray locating the server are using DNS entries and broadcast. We also offer multiple ways of using DHCP and DNS in case the option (49, 66) may be already in use at the customer. Also with the newest rev of Sun Ray Firmware, you can choose to store this information in the unit so DHCP becomes optional. This however adds more state to the device (we'll cover the "me too" stateless claims tomorrow).
The competition loves to bring up UDP, and they love to point out that the U stands for unreliable (when it really stands for user). The benefit of using UDP is in avoiding the overhead of checking whether every packet actually arrived. This is like watering a plant, you don't need to watch every molecule of water hit the plant, you know another one will come along shortly to do the job.
This makes UDP faster and more efficient, at least for applications that do not need guaranteed delivery. Since most users are updating their screens somewhat regularly it's our opinion that UDP makes for an excellent choice when drawing the screen.
Customers may be interested in these other UDP powered technologies such as DNS, IPTV, VoIP, tftp, video teleconferencing, and many others. Why do these technologies choose to use UDP instead of TCP? Quite simply because they have real-time delivery requirements that TCP cannot reliably satisfy. Hence, the Sun Ray protocol is generally more responsive in real-time, especially in unreliable networks, where TCP may experience retransmission back-off.
This can be demonstrated nicely by disconnecting the network cable from a Sun Ray and from another device whose protocol uses TCP, and then plug the cables back in. The Sun Ray will start back up immediately; the other device will not. The TCP based protocol device will wait for the backed-off TCP retransmission timeout.
Furthermore, what the competition fails to understand is that Sun Ray stack is not purely UDP based, though they often misquote that it is. The authentication protocol is TCP based and it handles session identification and server location. The remote device protocol is TCP based and it handles things like printer, smart cards, USB Mass Storage, serial, parallel, and libUSB devices. The grouping manager is UDP based which handles simple fail over and session location.