Allied Telesis AT-S26 - Manual (Page 101)

AT-S26 Version 2.0.1 User’s Guide
101
The Engineering VLAN on the bottom AT-9006SX/SC switch has two
untagged ports and one tagged port, Port 2, which functions as the
uplink port to the top switch.
The Manufacturing VLAN also consists of two untagged ports. One port
is connected to an AT-8224XL switch and the other port is connected to
a legacy server, meaning that it is not capable of handing tagged frames
and, consequently, cannot be shared by multiple VLANs. This VLAN also
contains one tagged port, Port 2, which functions as the uplink.
The above configuration allows the traffic to remain restricted to a
particular VLAN where necessary, but also allows for resource sharing. It
also allows nodes to be a part of the same VLAN even though they are
connected to different Gigabit Switches.
The interconnection between the two Gigabit Switches is provided by
Port 5 on the top switch and port 2 on the bottom switch. These tagged
uplink ports are output enabled for every configured VLAN on the
switch. That is, they are a tagged member of each VLAN. Consequently,
when a broadcast packet is received on any port (representing a packet
on any VLAN), it is transmitted through the uplink port.
Note
The PVIDs on the uplink ports between two switches must match.
For example, they both must have PVIDs of 4.
An example of a VLAN spanning multiple Gigabit Switches is illustrated
by the Manufacturing VLAN. Even though it spans two Gigabit Switches,
both VLANs have the same VID, making them a part of the same VLAN.
Consequently, a node that is part of the Manufacturing VLAN in the top
AT-9006 Switch can access the legacy server in the Manufacturing VLAN
on the bottom switch. On the other hand, an end node from either the
Accounting VLAN or the Engineering VLAN cannot access the legacy
server because they belong to different VLANs.
An example of resource sharing across VLANs is provided by the IEEE
802.3Q compliant server connected to port 2 on the top Gigabit Switch.
This port has been designated as a tagged port in all VLANs, allowing all
VLANs access to the resource.