Cisco 15327 - Manual (Page 402)

23-22
Ethernet Card Software Feature and Configuration Guide, R7.2
Chapter 23 E-Series and G-Series Ethernet Operation
E-Series Spanning Tree (IEEE 802.1D)
Figure 23-18 Spanning Tree Map on Circuit Window
Note Green represents forwarding spans and purple represents blocked (protect) spans. If you have a packet
ring configuration, at least one span should be purple.
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 xxxvii for information on how to
contact Cisco TAC.