Well, you have port-based VLANs and protocol-based
VLANs.
A switch/bridge builds a MAC address table (CAM) and
association MAC address's with a port. So, within the
switch arch. they extend these tables for VLAN
membership(s).
Lets say ports 1-5 are in VLAN 1 and 6-12 are in VLAN
2. So any MAC address in ports 1-5 are in VLAN 1 and
6-12 in VLAN 2. Similar thing for protocol-based but
they need to look at more information to determine
which MAC address is in which VLAN(s).
Within the switch, they have internal index #s / id #s
to tell difference between VLANs. Usually these
indexes are not configurable by the user - but on some
switches you can change the index #.
Thats it basically. Some switches have extended VLAN
features (mostly propiertary). If you want to know how
802.1q and ISL do it there are plenty of web sites
that explain it. Check the archives and search on
google.com.
--- Santosh Koshy <[EMAIL PROTECTED]> wrote:
> How are vlans uniquely identified then; if the
> switch itself supports only
> 1024 MAC addresses.
> Can u point me to some white paper or tutorial as to
> how this works...
>
> Thanx,
> Santosh
>
> ""Brant Stevens"" <[EMAIL PROTECTED]> wrote in
> message
>
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > I believe the limit is 4096 when using 802.1q...
> >
> > Brant I. Stevens
> > Internetwork Solutions Engineer
> > Thrupoint, Inc.
> > 545 Fifth Avenue, 14th Floor
> > New York, NY. 10017
> > 646-562-6540
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Z
> > Sent: Sunday, February 18, 2001 11:08 PM
> > To: Santosh Koshy; [EMAIL PROTECTED]
> > Subject: Re: How many VLAN's on a switch
> >
> >
> > You got it...1024 VLANs allowed...God forbid you
> ever have to handle a
> > network that has that many of them though. ;o)
> >
> >
>
********************************************************************
> > This has been an Eyez Only streaming e-mail
> broadcast...We are watching.
> >
> > ~ NetEyez ~ CCNP, CCDA
> >
> > ----- Original Message -----
> > From: Santosh Koshy <[EMAIL PROTECTED]>
> > Newsgroups: groupstudy.cisco
> > To: <[EMAIL PROTECTED]>
> > Sent: Sunday, February 18, 2001 10:31 PM
> > Subject: How many VLAN's on a switch
> >
> >
> > > VLAN 1 will be the first MAC address in the
> switch's supervisor module's
> > > range of 1024 MAC aaddressess. VLAN 2 will be
> the second MAC address.
> VLAN
> > 3
> > > will be the third MAC address and so on and so
> forth.
> > >
> > > From the above statement, am I correct in
> deducing that one can create
> > only
> > > 1024 VLANS on a switch....
> > >
> > > Thanx,
> > > Santosh Koshy
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