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Conference 7.286::fddi

Title:	FDDI - The Next Generation

Moderator:	NETCAD::STEFANI

Created:	Thu Apr 27 1989
Last Modified:	Thu Jun 05 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	2259
Total number of notes:	8590

1910.0. "High interrupt stack activity" by SCASS1::BUENSUCESO () Tue Dec 19 1995 12:56

    Folks,
    
        I have a question and a problem.
    
    1.	Could someone enlighten me as to what the term "promiscuous mode"
    means and how it is turned off and on? 
    
    2. We have a VAX 7620 that's spending a lot of time on the interrupt stack 
    while others don't. We had to change the network option from a DEMFA to 
    a DEMNA to elliminate the problem. It started recently with nothing to
    coinside with it to point to the cause. We are running VAXVMS 5.5-2 in
    a cluster of 6 VAX 7620/30's. 
    
    regards,

T.R Title User Personal
Name Date Lines

1910.1 STAR::STOCKDALE Wed Dec 20 1995 08:55 23

T.R	Title	User	Personal Name	Date	Lines
1910.1		STAR::STOCKDALE		`Wed Dec 20 1995 08:55`	23
	1. Could someone enlighten me as to what the term "promiscuous mode" means and how it is turned off and on? An application can enable it to receive all packets on the wire. Stopping the application would turn it off. 2. We have a VAX 7620 that's spending a lot of time on the interrupt stack while others don't. We had to change the network option from a DEMFA to a DEMNA to elliminate the problem. It started recently with nothing to coinside with it to point to the cause. We are running VAXVMS 5.5-2 in a cluster of 6 VAX 7620/30's. So the system must be doing a fair amount of I/O? The DEMNA driver is more efficient than the DEMFA driver, but if the demands for I/O are about the same, I'm surprised that changing devices made a big difference. I'd look for tuning problems such as LRPSIZE being large enough so the DEMFA driver allocates pool from the lookaside lists rather than general pool, and if you are doing much cluster I/O with PEDRIVER, make sure that NISCS_MAX_PKTSIZE (or whatever it's called) is large enough so that PEDRIVER uses the DEMFA more efficiently. Also, while the DEMNA driver is more efficient per packet, the DEMFA is much more efficient @ 4500 bytes/packet than 3 times the DEMNA @ 1500 bytes/packet.

    1.	Could someone enlighten me as to what the term "promiscuous mode"
    means and how it is turned off and on? 

An application can enable it to receive all packets on the wire.  Stopping
the application would turn it off.
    
    2. We have a VAX 7620 that's spending a lot of time on the interrupt stack 
    while others don't. We had to change the network option from a DEMFA to 
    a DEMNA to elliminate the problem. It started recently with nothing to
    coinside with it to point to the cause. We are running VAXVMS 5.5-2 in
    a cluster of 6 VAX 7620/30's. 
    
So the system must be doing a fair amount of I/O?  The DEMNA driver is more
efficient than the DEMFA driver, but if the demands for I/O are about the
same, I'm surprised that changing devices made a big difference.  I'd look
for tuning problems such as LRPSIZE being large enough so the DEMFA driver
allocates pool from the lookaside lists rather than general pool, and if
you are doing much cluster I/O with PEDRIVER, make sure that NISCS_MAX_PKTSIZE
(or whatever it's called) is large enough so that PEDRIVER uses the DEMFA more
efficiently.

Also, while the DEMNA driver is more efficient per packet, the DEMFA is much
more efficient @ 4500 bytes/packet than 3 times the DEMNA @ 1500 bytes/packet.