[OT] Layer 3 switching and vlans

Bob Chiodini rchiodin at bellsouth.net
Mon Jan 31 17:27:19 UTC 2005

On Mon, 2005-01-31 at 10:38 -0600, Richard Humphrey wrote:
> Forgive the OT of this post but I am stumped and not sure where to
> turn. I have a 3Com NBX 100 phone system (VOIP) and a  3Com Superstack
> 3226 connected to our LAN in building A. We have Building B that is
> joined to the LAN via a Tsunami Quickbridge Wireless link.
> I am trying to seperate the NBX traffic into it's own vlan to control
> the broadcasting on our LAN. I successfully did this on Saturday
> during some testing but I ultimately blocked the phone traffic from
> reaching building B.
> My question is, do I need another 3226 in building B to route packets
> between the 2 networks for this to work. This is new technology to me
> (Layer 3 switching) and so I am not sure how to proceed to seperate
> phone traffic in both buildings.
> Thanks in advance for any input.
> -- 
> Richard Humphrey

You would need switches in building B that could support VLAN trunking
to building A.  The Quickbridge product looks like a layer 2 device and
would probably pass the VLAN trunks (call them and ask).  What kind of
switches are you using in building B.  Do they already support VLAN

VLANs are not really layer 3, tags are added (based on physical port) to
the layer 2 packets at ingress into the switch and are read and stripped
at the egress of the destination switch.

Configuring all of the switch ports connected to phones to one VLAN and
configuring all of the ports connected to computers to another VLAN will
separate the broadcast traffic from the separate VLANS, however the
broadcast traffic will still consume bandwidth in the trunk between
switches (buildings).


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