Configuring Multiple Stgs - Lenovo Flex System Fabric CN4093 Application Manual

Configuring Multiple STGs

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Chassis
Switch A
18
STG 3
VLAN 3
2
8
Application
Switch C
The VLAN participation for each Spanning Tree Group in Figure 14 on page
as follows:
 VLAN 1 Participation
Assuming Switch B to be the root bridge, Switch B transmits the BPDU for
VLAN 1 on ports 1 and 2. Switch C receives the BPDU on port 2, and Switch D
receives the BPDU on port 1. Because there is a network loop between the
switches in VLAN 1, either Switch D will block port 8 or Switch C will block
port 1, depending on the information provided in the BPDU.
 VLAN 2 Participation
Switch B, the root bridge, generates a BPDU for STG 2 from port 8. Switch A
receives this BPDU on port 17, which is assigned to VLAN 2, STG 2. Because
switch B has no additional ports participating in STG 2, this BPDU is not
forwarded to any additional ports and Switch B remains the designated root.
VLAN 3 Participation

For VLAN 3, Switch A or Switch C may be the root bridge. If Switch A is the root
bridge for VLAN 3, STG 3, then Switch A transmits the BPDU from port 18.
Switch C receives this BPDU on port 8 and is identified as participating in
VLAN 3, STG 3. Since Switch C has no additional ports participating in STG 3,
this BPDU is not forwarded to any additional ports and Switch A remains the
designated root.
This configuration shows how to configure the three instances of STGs on the
switches A, B, C, and D illustrated in Figure 14 on page
Because VASA is enabled by default, each new VLAN is automatically assigned its
own STG. However, for this configuration example, some VLANs are explicitly
reassigned to other STGs.
Application
Switch B
STG 2
17 8
VLAN 2
2 1
STG 1
VLAN 1
1
1
8
Application
Switch D
154.
Chapter 11: Spanning Tree Protocols
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