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DecNET over IP perfomance


DecNET over IP perfomance

Has anybody knows DecNET over IP perfomance in compare with pure DecNET IV phase. How much DecNET over IP slover in average.

We have network master program on Alpha originaly wroted to use DecNET. This program transmit data from server to client's PC. When this program been rewroted to use IP perfomance of data transmition reduces 2 times slover at least (depends of useful data size in 1,5K packet of IP).
Honored Contributor

Re: DecNET over IP perfomance

Hello Enemy,
I have not direct information about compare performance between DecNet IV and DecNet V but I think problem is not over DecNet over IP.
You could explain more detail about your application; I can't understand how write data from server to client; may be on client run a FAL.EXE (and you are running pathwork32 on PC) or you recall a DecNet Remote Procedure Call.
Now how you modify application? Use transfer again using FAL on client? DO you upgrade a client software? Server software is changed, also OS and TCP/IP?
There no way to make an accuractly response without furthermore details.

Antonio Maria Vigliotti

Re: DecNET over IP perfomance

Master program on AXP and PC-client uses DecNET sockets to compunicate each other. I don't really known details of comunication algorithm so far - where are using third party software.
John Eerenberg
Valued Contributor

Re: DecNET over IP perfomance


We run DECnet over IP and Phase V. When speed is an issue, we use, for example, ftp instead of $ Copy (i.e., Copy/FTP does IP only as well).

Sounds like your application has been rewritten to use IP instead of DECnet which means the DECnet stack on the PC plays an important part in performance. Another factor in performance is how the PC's IP stack hands off the packet to DECnet. So both have an impact on performance.
Now that you have bypassed DECnet, it makes sense that you run faster using just IP. It also makes sense that your rewritten app now using just IP is 2x faster (if I misunderstood this, let me know) since most performance gains are from recoding an app.

That said . . . in my environment, we don't see enough difference to worry about DECnet-over-IP vs. IP performance on a daily basis. File copies that take an hour plus or minus a few minutes are okay. But it is always VMS talking to VMS; no PC's are involved. Though memory serves that PC DECnet are noticably slow, but that was 10 years ago.
Since the DECnet packet is encapsulated within an IP packet, you have CPU overhead to handle all this, but for our environment we can't measure the CPU impact; I know their is CPU overhead, but frankly, it is too small for us to dig into any deeper (remember this is on the VMS systems, not the PC -- the DECnet stack on a PC may or may not have a lot of overhead).
For an actual copy that takes 1 hour we see some small improvements when using ftp but nothing to write home about.

Let me know if I can clarify anything about our experience in this area.

It is better to STQ then LDQ