Cisco ONS 15454 SDH - E-Series Multi-Instance Spanning Tree and Vlans; E-Series Spanning Tree Parameters; Spanning Tree on a Circuit-By-Circuit Basis

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Cisco ONS 15454 and Cisco ONS 15454 SDH Ethernet Card Software Feature and Configuration Guide, R8.0
Chapter 23 E-Series and G-Series Ethernet Operation
E-Series Spanning Tree (IEEE 802.1D)
Caution Multiple circuits with STP protection enabled will incur blocking if the circuits traverse a common card
and use the same VLAN.
Note E-Series port-mapped mode does not support STP (IEEE 802.1D).
E-Series Multi-Instance Spanning Tree and VLANs
The ONS node can operate multiple instances of STP to support VLANs in a looped topology. You can
dedicate separate circuits across the SONET/SDH ring for different VLAN groups. Each circuit runs its
own STP to maintain VLAN connectivity in a multi-ring environment.
Spanning Tree on a Circuit-by-Circuit Basis
You can also disable or enable STP on a circuit-by-circuit basis on single-card EtherSwitch E-Series
cards in a point-to-point configuration. This feature allows customers to mix spanning tree protected
circuits with unprotected circuits on the same card. It also allows two single-card EtherSwitch E-Series
cards on the same node to form an intranode circuit.
E-Series Spanning Tree Parameters
Default STP parameters are appropriate for most situations (Table 23-4). Contact the Cisco Technical
Assistance Center (Cisco TAC) before you change the default STP parameters. See the “Obtaining
Documentation and Submitting a Service Request” section on page xxxviii for information on how to
contact Cisco TAC.
Table 23-4 Spanning Tree Parameters
Parameter Description
BridgeID ONS node unique identifier that transmits the configuration bridge protocol data
unit (BPDU); the bridge ID is a combination of the bridge priority and the ONS
node MAC address.
TopoAge Amount of time in seconds since the last topology change.
TopoChanges Number of times the STP topology has been changed since the node booted up.
DesignatedRoot Identifies the STP’s designated root for a particular STP instance.
RootCost Identifies the total path cost to the designated root.
RootPort Port used to reach the root.
MaxAge Maximum time that received-protocol information is retained before it is discarded.
HelloTime Time interval, in seconds, between the transmission of configuration BPDUs by a
bridge that is the spanning tree root or is attempting to become the spanning tree
root.
HoldTime Minimum time period, in seconds, that elapses during the transmission of
configuration information on a given port.
ForwardDelay Time spent by a port in the listening state and the learning state.