User Manual

24-Port and 48-Port Gigabit Ethernet PoE+ Smart Switches with 4 SFP Ports
Configuration Examples User Manual531
Since the edge ports are not at risk for network loops, ports with Fast Link enabled
transition directly to the forwarding state.
8. Click the Apply button.
You can use the CST Port Status page to view spanning tree information about each
port.
9. On the MST Configuration page, create a MST instances with the following settings:
• MST ID. 1
• Priority. Use the default (32768)
• VLAN ID. 300
For more information, see
View the Rapid STP information on page 202.
10. Click the Add button.
11. Create a second MST instance with the following settings
• MST ID. 2
• Priority. 49152
• VLAN ID. 500
12. Click the Add button.
In this example, assume that Switch 1 became the root bridge for the MST instance 1, and
Switch 2 became the root bridge for MST instance 2. Switch 3 supports hosts in the sales
department (ports 1/0/1, 1/0/2, and 1/0/3) and in the HR department (ports 1/0/4 and 1/0/5).
Switches 1 and 2 also include hosts in the sales and HR departments.
The hosts connected
from Switch 2 use VLAN 500, MST instance 2 to communicate with the hosts on Switch 3
directly
. Likewise, hosts of Switch 1 use VLAN 300, MST instance 1 to communicate with the
hosts on Switch 3 directly.
The hosts use different instances of MSTP to effectively use the links across the switch. The
same concept can be extended to other switches and more instances of MSTP
.
VLAN routing interfaces
VLANs divide broadcast domains in a LAN environment. When hosts in one VLAN must
communicate with hosts in another VLAN, the traffic must be routed between them. This is
known as inter-VLAN routing. On the switch, it is accomplished by creating Layer 3 interfaces
(switch virtual interfaces [SVI]).
When a port is enabled for bridging (the default) rather than routing, all normal bridge
processing is performed for an inbound packet, which is then associated with a VLAN. Its
MAC destination address (MAC DA) and VLAN ID are used to search the MAC address
table. If routing is enabled for the VLAN, and the MAC DA of an inbound unicast packet is
that of the internal bridge-router interface, the packet is routed.
An inbound multicast packet
is forwarded to all ports in the VLAN, plus the internal bridge-router interface, if it was
received on a routed VLAN.