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In STP topology 3 (shown in the lower middle), if you have enabled the root guard feature on the STP port on Switch C that
connects to device D, and device D sends a superior BPDU that would trigger the election of device D as the new root bridge, the
BPDU is ignored and the port on Switch C transitions from a forwarding to a root-inconsistent state (shown by the green X icon). As
a result, Switch A becomes the root bridge.
Figure 131. STP Root Guard Prevents Bridging Loops
Configuring Root Guard
Enable STP root guard on a per-port or per-port-channel basis.
Dell Networking OS Behavior
: The following conditions apply to a port enabled with STP root guard:
•
Root guard is supported on any STP-enabled port or port-channel interface except when used as a stacking port.
•
Root guard is supported on a port in any Spanning Tree mode:
–
–
Rapid Spanning Tree Protocol (RSTP)
–
Multiple Spanning Tree Protocol (MSTP)
–
Per-VLAN Spanning Tree Plus (PVST+)
•
When enabled on a port, root guard applies to all VLANs configured on the port.
•
You cannot enable root guard and loop guard at the same time on an STP port. For example, if you configure root guard on a port
on which loop guard is already configured, the following error message displays:
• % Error: LoopGuard is
configured. Cannot configure RootGuard
.
•
When used in an MSTP network, if root guard blocks a boundary port in the CIST, the port is also blocked in all other MST
instances.
To enable the root guard on an STP-enabled port or port-channel interface in instance 0, use the following command.
•
Enable root guard on a port or port-channel interface.
INTERFACE mode or INTERFACE PORT-CHANNEL mode
Spanning Tree Protocol (STP)
853
Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...