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Re: maximum active vlans in a crisco 6509

  • From: Bora Akyol
  • Date: Tue Jun 20 23:59:21 2000

If you put all of the users on seperate switch ports, then would they be
able to snoop each other's traffic? At least the switches that I have seen
prevent this behavior unless you put a particular switch port in "monitor"

As long as all rooms in this hotel are on seperate switch ports, you would
basically be OK even without using VLANs.

Yes, multicast sessions, ARP requests etc can still be snooped.


----- Original Message -----
From: "Bennett Todd" <[email protected]>
To: "Roeland Meyer (E-mail)" <[email protected]>
Cc: "'Bob Biver'" <[email protected]>; <[email protected]>
Sent: Tuesday, June 20, 2000 8:45 PM
Subject: Re: maximum active vlans in a crisco 6509

> Hash: SHA1
> 2000-06-20-23:01:45 Roeland Meyer (E-mail):
> > > Bob Biver: Tuesday, June 20, 2000 7:28 PM
> > > the docs say max 250, is this informational or a limit of
> > > spanning tree?
> >
> > If I recall correctly, that's also real close to the maximum
> > number of physical connections to the chasis, with all modules
> > installed. Personally, I've never run anywhere near that number.
> > I don't think it is useful to have less than 2 members in a vlan.
> > You would also be surpassing the bandwidth limitations of that
> > chasis, even if all the connections were 100baseTX.
> For many uses, I think you certainly have a clear and reasonable
> point. But while I don't know what the original poster had in mind,
> I can fantasize a use for thousands of vlans, even on a switch that
> doesn't have thousands of distinct ports. And without necessarily
> exceeding available bandwidth.
> Lessee, suppose I were designing something like an
> internet-access-for-hotel-rooms, or thereabouts. Or suppose
> otherwise I had thousands of users who didn't trust each other, at
> all, who I didn't want to have sniffing each other's traffic, who
> were just wanting to share access to an internet connection, itself
> less than 100BaseT, maybe even much less.
> One way I could fantasize doing it would be to assign a separate
> VLAN to each port of as many different switches, interconnected with
> 802.1Q or ISL, as it took to provide ports to every room. Run one
> 802.1Q line into the one router in this picture, say a Linux box
> using iproute2 for traffic shaping.
> Ok, so maybe 6509s would be way overkill for this application, no
> way you need that kind of backplane bandwidth. But as circumstances
> emerge where you want to have a fully-routed network (next step up
> the protocol ladder from a fully-switched network --- each host gets
> its own dedicated router port) I can anticipate settings where VLANs
> might get abused in a most remarkable way.
> - -Bennett
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