Enterasys C5G124-24

Configuring MSTP
Fixed Switch Configuration Guide 15-25
Example 1: Configuring MSTP for Traffic Segregation
This example illustrates the use of MSTP for traffic segregation by VLAN and SID. Bridges A, B, C
and D participate in VLAN 10. Bridges A, B, E and F participate in VLAN 20. Figure 15-11 shows
the problem that arises when using a single Spanning Tree configuration for traffic segregation
with redundancy.
Figure 15-11 Traffic Segregation in a Single STP Network Configuration
In a single Spanning Tree configuration a bridge can only have one port forwarding towards the
root for all traffic. Bridge A has the lowest priority and is the root. Bridge B forwards traffic
towards the root on port ge.1.2. All other ports are blocked. For this configuration, Bridge B will
not have any active links forwarding for VLAN 20.
Figure 15-12 on page 15-26 shows the solution using MSTP. By configuring separate Spanning
Tree instances to overlay the two VLAN topologies, Bridge B port ge.1.2 forwards on VLAN 10 for
SID 1 and port ge.1.3 forwards on VLAN 20 for SID 2.
Monitoring MSTP 15-29
For information about... Refer to page...
VLAN 10
VLAN 10
ge.1.1
ge.1.2
MAC Address:
00-00-00-00-00-03
Priority = 32768
VLAN 10
VLAN 10
ge.1.1
ge.1.2
MAC Address:
00-00-00-00-00-04
Priority = 32768
ge.1.1
ge.1.2
MAC Address:
00-00-00-00-00-01
Priority = 4096
ge.1.3
ge.1.4
ge.1.1
ge.1.2
MAC Address:
00-00-00-00-00-02
Priority = 8192
ge.1.3
g
e.1.4
VLAN 20
VLAN 20
ge.1.1
ge.1.2
MAC Address:
00-00-00-00-00-05
Priority = 32768
VLAN 20
VLAN 20
ge.1.1
ge.1.2
MAC Address:
00-00-00-00-00-06
Priority = 32768
KEY:
SID 0
Blocked Port
Bridge C
Bridge A Bridge B
Bridge D
Bridge E
Bridge F