Moxa Technologies EDS-518A Series - Manual (Page 41)

EDS-518A Series User’s Manual Featured Functions
3-26
The following figure shows an example of a network that contains VLANs 1 and 2. The VLANs
are connected using the 802.1Q-tagged link between Switch B and Switch C. By default, this link
has a port cost of 100 and is automatically blocked because the other Switch-to-Switch
connections have a port cost of 36 (18+18). This means that both VLANs are now
subdivided—VLAN 1 on Switch units A and B cannot communicate with VLAN 1 on Switch C,
and VLAN 2 on Switch units A and C cannot communicate with VLAN 2 on Switch B.
Block
Switch A
Switch B Switch C
VLAN1
VLAN2
802.1Q tagged,
10BaseTx
half-duplex Link
carries VLAN1, 2
(path cost = 100)
100BaseTX
full-duplex Link;
only carries VLAN2
(path cost = 18) 100BaseTX
full-duplex Link;
only carries VLAN1
(path cost = 18)
VLAN1
VLAN2 VLAN1
VLAN2
To avoid subdividing VLANs, all inter-switch connections should be made members of all
available 802.1Q VLANs. This will ensure connectivity at all times. For example, the connections
between Switches A and B, and between Switches A and C should be 802.1Q tagged and carrying
VLANs 1 and 2 to ensure connectivity.
See the “Configuring Virtual LANs” section for more information about VLAN Tagging.
Configuring STP/RSTP
The following figures indicate which Spanning Tree Protocol parameters can be configured. A
more detailed explanation of each parameter follows.
At the top of this page, the user can check the “Current Status” of this function. For RSTP, you
will see: