- Alcatel Switch/Router User Manual

AutoTracker VLANs
Page 22-13
So How Do I Get Devices Assigned to VLANs Over a Backbone?
The way to get devices assigned to
VLANs over a backbone is to define logical VLAN policies
that so assign them. An example is shown on the facing page utilizing IP and IPX protocol
policies. The network on the facing page uses port policies (and current port policy function-
ality) to assign the backbone port to VLANs on each switch so that traffic can flow out onto
the backbone from these VLANs.
The problem of remote
VLAN assignments is solved by the IP and IPX protocol policies. When
a frame is received from a backbone port, the frame is examined to determine if it matches
any VLAN membership rules. Let’s say Device D on switch 2 transmits an IP frame. The frame
travels the FDDI backbone and enters switch 1 on port 3-1. AutoTracker learns the frame and
assigns it to VLAN 3, since VLAN 3 has an IP protocol policy and the frame is IP.
Notice that with this approach:
• VLAN membership is consistent between the two switches.
• In a multi-switch environment, no frames are lost in switches along the traffic path because
of the inconsistent VLAN membership of a frame’s source and destination devices.
• Devices can be moved from switch to switch and they will be assigned to the same VLAN
– without reconfiguring AutoTracker or the device.
• As was the original intent, it is possible to create two
VLANs in this sample network, one
for Devices A and B and one for Devices C and D. As is apparent, this was impossible
using port policies.