Dell MX5108n OS10 Enterprise Edition User Guide for PowerEdge MX IO Modules Re - Page 232

Loop guard, Global parameters

Page 232 highlights

Executing IEEE compatible Spanning Tree Protocol Root ID Priority 24577, Address 90b1.1cf4.a523 Root Bridge hello time 2, max age 20, forward delay 15 Bridge ID Priority 24577, Address 90b1.1cf4.a523 We are the root of VLAN 1 Configured hello time 2, max age 20, forward delay 15 Interface Designated Name PortID Prio Cost Sts Cost Bridge ID PortID ethernet1/1/5 128.276 128 500 FWD 0 24577 90b1.1cf4.a523 128.276 ethernet1/1/6 128.280 128 500 LRN 0 24577 90b1.1cf4.a523 128.280 Interface Name Role PortID Prio Cost Sts Cost Link-type Edge ethernet1/1/5 Desg 128.276 128 500 FWD 0 AUTO No ethernet1/1/6 Desg 128.280 128 500 LRN 0 AUTO No Loop guard This information explains how to configure loop guard on an interface. • Enable loop guard on a per-port or port-channel interface in INTERFACE mode. spanning-tree guard {loop | root | none} - loop - Enables loop guard on an interface. - root - Enables root on an interface. - none - Enables the guard mode to none. • Disable loop guard on a port or port-channel interface in INTERFACE mode. no spanning-tree guard loop Port enabled with loop guard conditions • Loop guard is supported on any STP-enabled port or port-channel interface in RPVST+ mode. • You cannot enable root guard and loop guard at the same time on an STP port - the loop guard configuration overwrites an existing root guard configuration and vice versa. • Enabling BPDU guard and loop guard at the same time on a port results in a port that remains in a Blocking state and prevents traffic from flowing through it. For example, when you configure both Portfast BPDU guard and loop guard: - If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and no traffic forwards on the port. - If no BPDU is received from a remote device which was sending BPDUs, loop guard places the port in a Loop-Inconsistent Blocking state and no traffic forwards on the port. • When used in a PVST+ network, STP loop guard performs per-port or per port-channel at a VLAN level. If no BPDUs are received on a port-channel interface, the port or port-channel transitions to a Loop-Inconsistent (Blocking) state only for this VLAN. Global parameters All non-root bridges accept the timer values on the root bridge. Forward-time Hello-time Max-age Amount of time required for an interface to transition from the Discarding to the Learning state or from the Learning to the Forwarding state. Time interval within which the bridge sends BPDUs. Length of time the bridge maintains configuration information before it refreshes information by recomputing the RPVST+ topology. • Modify the forward-time (in seconds) in CONFIGURATION mode (4 to 30, default 15). spanning-tree vlan vlan-id forward-time seconds 232 Layer 2

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Executing IEEE compatible Spanning Tree Protocol
Root ID
Priority 24577, Address 90b1.1cf4.a523
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID
Priority 24577, Address 90b1.1cf4.a523
We are the root of VLAN 1
Configured hello time 2, max age 20, forward delay 15
Interface
Designated
Name
PortID
Prio
Cost Sts
Cost Bridge ID
PortID
----------------------------------------------------------------------
ethernet1/1/5
128.276
128
500
FWD
0
24577
90b1.1cf4.a523
128.276
ethernet1/1/6
128.280
128
500
LRN
0
24577
90b1.1cf4.a523
128.280
Interface
Name
Role PortID
Prio Cost Sts
Cost Link-type Edge
-------------------------------------------------------------
ethernet1/1/5
Desg 128.276 128
500
FWD
0
AUTO
No
ethernet1/1/6
Desg 128.280 128
500
LRN
0
AUTO
No
Loop guard
This information explains how to
configure
loop guard on an interface.
Enable loop guard on a per-port or port-channel interface in INTERFACE mode.
spanning-tree guard {loop | root | none}
loop
— Enables loop guard on an interface.
root
— Enables root on an interface.
none
— Enables the guard mode to none.
Disable loop guard on a port or port-channel interface in INTERFACE mode.
no spanning-tree guard loop
Port enabled with loop guard conditions
Loop guard is supported on any STP-enabled port or port-channel interface in RPVST+ mode.
You cannot enable root guard and loop guard at the same time on an STP port — the loop guard
configuration
overwrites an existing
root guard
configuration
and vice versa.
Enabling BPDU guard and loop guard at the same time on a port results in a port that remains in a Blocking state and prevents
traffic
from
flowing
through it. For example, when you
configure
both Portfast BPDU guard and loop guard:
If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and no
traffic
forwards
on the port.
If no BPDU is received from a remote device which was sending BPDUs, loop guard places the port in a Loop-Inconsistent Blocking
state and no
traffic
forwards on the port.
When used in a PVST+ network, STP loop guard performs per-port or per port-channel at a VLAN level. If no BPDUs are received on a
port-channel interface, the port or port-channel transitions to a Loop-Inconsistent (Blocking) state only for this VLAN.
Global parameters
All non-root bridges accept the timer values on the root bridge.
Forward-time
Amount of time required for an interface to transition from the Discarding to the Learning state or from the
Learning to the Forwarding state.
Hello-time
Time interval within which the bridge sends BPDUs.
Max-age
Length of time the bridge maintains
configuration
information before it refreshes information by recomputing the
RPVST+ topology.
Modify the forward-time (in seconds) in CONFIGURATION mode (4 to 30, default 15).
spanning-tree vlan
vlan-id
forward-time
seconds
232
Layer 2