I you haven't read the FAQ recently, you haven't read the FAQ.  The version
with 3.0 is a pretty extensive update/rewrite, although some stuff has
changed since I did that in December...

See inline.

-----Burton

> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of
> Michael Handiboe
> Sent: Tuesday, March 16, 2004 9:08 AM
> To: [EMAIL PROTECTED]
> Subject: Re: [Ntop] plea for information
>
>
> Having read the FAQ (but a while ago), I thought Burton would either
> barrage me or The Boss.  :-)
>
> Thanks to all for the many responses.  I will do two things:
>
> 1-continue reading up on our 3Com 3300TM (3C16986A)
> But from what I've seen, it looks like I can only 'connect' one
> port to one port for purposes of traffic "mirroring".

Yes, but think creatively and you'll be amazed at what you can do if you can
'waste' a pair of ports.

Say you configure 24 to monitor 23.  What's on 23??? It can be every VLAN in
the box.  With or without 802.1q tagging.

So for example, I have four vlans - RED (unfiltered ethernet - from my ISP),
GREEN and YELLOW/ORANGE (two DMZs).  For sanity sake, I don't want to mix
the RED lan with anything else, so I use two wires to uplink to my 3c16981
(one RED, no tagging, one GREEN+YELLOW+ORANGE, 802.1q tagged).

But for ntop, I can put all four VLANs, untagged on port 23.  Then monitor
it on port 24, so that there's no chance of injecting traffic into the mixed
port.

Dump that into a hub and you can easily have two ntop hosts monitor the same
flows.


Now, a Cisco span port can do a lot more - I've got a client who uses FOUR
spans.  They do something like NAT on some of the traffic, but they want
ntop to see the un-NATed traffic, so they combine NAT-in + NAT-out +
notNAT-in + notNAT-out from different points in their switching fabric,
netFlow that and have a full picture of the traffic.

But I paid $36 on eBay for the 3c16985XM, vs. $600 used or $2000 new for the
Cisco...






> 2-(re)look over the stuff Burton talked about and I'll post my
> command line here.
>
> Yeah, my Boss is a self-made (and self-proclaimed) networking guru.
> I'm in a bit of a pinch -- ya'll can see that I'm hardly a
> networking ninja.
>
> Anyway, three cheers to the Open Source community!
>

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