WARNOCK@clemson.CSNET.UUCP (11/22/86)
What is the best place to find out about the promiscuious mode on ETHERNET ? In particular, what's required to implement this from an application program (ie: a network monitor ...) Are their publications that deal with this type of application ? Thanks in advance.
LEICHTER-JERRY@YALE.ARPA (11/24/86)
What is the best place to find out about the promiscuious mode on ETHERNET ?
In particular, what's required to implement this from an application
program (ie: a network monitor ...) Are their publications that deal with
this type of application ?
To get at promiscuous mode, you need to use the QIO interface to the DExNA
(hmm, now {DExNA,DELUA}) driver. This is all documented in the I/O User's
Reference Manual, Part II.
The beast probably has the most complex interface of any VMS driver, and
unfortunately the documentation is not the clearest around. There were some
improvements with the VMS V4.4 doc set upgrade, so I would definitely start
there, rather than with a V4.2 set. Expect to read through the things several
times.
I have a document called "Using the DEUNA/DEQNA Ethernet Interface Under VMS",
by Ned Freed, Kevin Carosso and Dan Newman of the MATHLIB Project at Harvey
Mudd College. (Kevin, at least, is no longer there; he writes to this list
frequently from Hughes Aircraft.) The document appeared in a DECUS publica-
tion within the last couple of years; sorry, I don't have the exact date.
It's an excellent introduction. Unfortunately, it's too long (over 100
blocks) to mail.
WARNING: Be aware of one restriction, which may not be obvious when you first
read the documentation: An Ethernet interface in promiscuous mode cannot be
shared. In particular, you will not be able to run DECnet through the device
while you are using it in this mode.
-- Jerry
-------rick@NGP.UTEXAS.EDU (Rick Watson) (11/25/86)
>WARNING: Be aware of one restriction, which may not be obvious when you first >read the documentation: An Ethernet interface in promiscuous mode cannot be >shared. In particular, you will not be able to run DECnet through the device >while you are using it in this mode. I believe that this is incorrect. There may be a limitation that there can only be one promiscuous user. However, DECnet must be the first process to start the device so it can change the default hardware address (or the first user must set the correct address for DECnet -- there is a special function to do this). Rick Watson University of Texas Computation Center arpa: rick@ngp.UTEXAS.EDU rick@ngp.ARPA uucp: ...seismo!ut-sally!ut-ngp!rick rick@ut-ngp.UUCP bitnet: ccaw001@utadnx phone: 512/471-3241
LEICHTER-JERRY@YALE.ARPA (11/26/86)
Thanks to Rick Watson and Gerard K. Newman for pointing out the error in my warning about not being able to enable promiscuous mode when there were any other users on a DExNA. Since Mr. Newman has a running program that does this, it's kind of hard to argue that it's impossible! Take this as another warning that the DExNA documentation is tough going. The actual text reads: "Only one unit on a DEUNA may be active with promiscuous mode enabled". This can be parsed in two ways.... One thing remains unclear to me, and was the reason I made the interpretation I did: I don't believe that the driver will duplicate a received packet, so anything that comes in will be delivered to at most one receiving process. (It may get dropped on the floor if there are NO eligible receivers.) So, what does a promiscuous receiver on a shared DExNA receive: Just those packets no one else is interested in, or does the driver in fact duplicate packets? -- Jerry -------
cetron%utah-ced@UTAH-CS.ARPA (Ed Cetron) (11/26/86)
If I can still read the doc set (and no guarantee that IT is right) in 4.4 and down, you CAN have a promiscuious/shared channel.... HOWEVER, the doc for the 4.5 update mentions that this will go away shortly... -ed cetron Center for Engineering Design