From: Joseph Brunner (joe@affirmedsystems.com)
Date: Fri Dec 07 2007 - 04:33:53 ART
If it's a layer 2 switch it only goes by cam table entries and if need be,
will flood unknown unicast frames to the entire broadcast domain (VLAN)... a
vlan as far as we are concerned here is a segmentation of the cam table and
again if unknown, floodable broadcast domain. If host A in vlan 1 wants to
talk to host b in vlan 2, being in different vlans puts them in different
broadcast domains. The hosts will need to be speaking to an ip address off
their subnet to require they use their default gateway.
So the hosts decide when to route to their default gateway. The switch just
behaves as above.
The switch does not care about vlan #'s when receiving untagged frames on a
non-trunking port. It just uses the vlan assignments to scope the cam/frame
flood process.
Remember a switch...
1. Learns addresses
2. addresses forwarding & filtering
3. prevents bridge loops
If you divide a switch into vlans you really make multiple little layer 2
switches.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Donghai Zhang
Sent: Friday, December 07, 2007 2:18 AM
To: groupstudy
Subject: question about vlan transfer
Hi,guys,
I was just wondering a simple question,maybe stupid.Suppose a switch has
two ports belonging to vlan 1 and vlan 2 , seperately. When this
switch receives a frame from port 1, which belong to vlan 1, and destinate
to vlan 2, which is at port 2.How dose the swich know it cann't do this
directly(send to port 2) and must send it first to router and then come back
to port 2?
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