>From news
(I map the mac to the machine with wmi)

> I understand that these switches interface with snmp.  We have
> a Bay Networks Centillion 100, actually 3, that I would like
> to query for a mac address to port listing.
ftp://angus.ind.wpi.edu/pub/cra-contrib/nortel-tools/nortel-perl-tools-0.2.0.tar.gz

I wrote one, cnfdb.pl inside this archive:


--- Faron Hopper <[EMAIL PROTECTED]> wrote:
> Steven,
>    What are you trying to do by having the users "know" what switch they
> are on?
> 
> Faron
> 
> ------------------------------------------------------------
> Contact Information
> ------------------------------------------------------------
> Faron Hopper
> Cap Gemini Ernst & Young
> Kansas City Service Center
> Network Services
> 816-459-5139 Voice
> 816-459-6767 Fax
> 816-757-5236 Pager
> [EMAIL PROTECTED]
> 
> 
> >>> "Patrick J. LoPresti" <[EMAIL PROTECTED]> 12/12/03 08:29 AM
> >>>
> "Steven Satelle (Service Desk)" <[EMAIL PROTECTED]> writes:
> 
> > What I would like to do is have each pc on boot, check which switch
> > it is connected to. If it changes prompt the user for his new
> > location. I've been looking into using snmp for this but all the
> > stuff I've found needs to know hostname or ip address of the switch
> > (I think, I dont really know much about Cisco). What I want is for
> > the host to detect the switch change automatically, not have to
> > manually tell it what switch it is on. Does anyone know if this is
> > possible?          
> 
> As far as I know, this is not trivial.  The whole point of a switch is
> to be transparent to network traffic.
> 
> What you can do is use SNMP to query the "forwarding database" (FDB)
> of each switch.  The FDB on the switch maps Ethernet (MAC) addresses
> to port numbers.  If you know which ports on each switch connect to
> other switches, you can eventually locate the port which corresponds
> to a particular MAC address.
> 
> The process would go like this:
> 
>   1) Determine your MAC address.
> 
>   2) Ping each "core" switch (i.e., those at the root of your
>      topology) to guarantee your MAC address is in the FDB of each
>      switch between yourself and the core.
> 
>   3) Use SNMP to query each "core" switch's FDB to learn where (i.e.,
>      out which port) it forwards packets with your MAC address.  The
>      table you want is the dot1dTpFdbTable; see
>      http://www.faqs.org/rfcs/rfc1493.html and/or do a Google search.
> 
>   4) If that port goes to another switch, query that switch's FDB.
>      Repeat until you find the leaf switch and port to where your
>      packets are forwarded.
> 
> If you are interested in working by IP address instead of MAC address,
> you need to use the ipNetToMediaTable (the ARP table, essentially);
> see http://www.faqs.org/rfcs/rfc1213.html and/or do a Google search.
> 
> I wrote a Perl script to do all this a while ago, but it was very
> messy and only ran on Linux, so it is not worth sharing.
> 
> Good luck!
> 
>  - Pat
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