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Cisco ONS 15454 Procedure Guide, R5.0
August 2005
Chapter 6 Create Circuits and VT Tunnels
NTP-A191 Create an E-Series EtherSwitch Circuit (Multicard or Single-Card Mode)
Step 16 Click Next.
Step 17 In the Circuit VLAN Selection area, click New VLAN. If the desired VLAN already exists, continue
with Step 20.
Tip You can also add VLANs in network view by choosing Tools > Manage VLANs. In the All
VLANs dialog box, click the Create button to open the Define New VLAN dialog box.
Step 18 In the Define New VLAN dialog box, complete the following:
• VLAN Name—Assign an easily identifiable name to your VLAN.
• VLAN ID—Assign a VLAN ID. The VLAN ID should be the next available number between 2 and
4093 that is not already assigned to an existing VLAN. Each ONS 15454 network supports a
maximum of 509 user-provisionable VLANs.
• Topology Host—Choose the topology host ID from the drop-down list.
Step 19 Click OK.
Step 20 In the Circuit VLAN Selection area, highlight the VLAN name and click the arrow button (>>) to move
the available VLANs to the Circuit VLANs column.
Step 21 If you are building a single-card EtherSwitch circuit and want to disable spanning tree protection on this
circuit, uncheck the Enable Spanning Tree check box and click OK in the Disabling Spanning Tree
dialog box. The Enable Spanning Tree box remains checked or unchecked for the creation of the next
single-card, point-to-point Ethernet circuit.
Caution Disabling spanning-tree protection increases the likelihood of logic loops on an Ethernet network.
Caution Turning off spanning tree on a circuit-by-circuit basis means that the ONS 15454 is no longer protecting
the Ethernet circuit and that the circuit must be protected by another mechanism in the Ethernet network.
Caution Multiple circuits with spanning tree protection enabled incur blocking if the circuits traverse the same
E-Series card and use the same VLAN.
Note Spanning-tree rules prevent users from creating new circuits or modifying existing circuits if the circuits
do not meet certain VLAN assignment constraints. If the VLAN set of the new circuit overlaps existing
circuits, the same spanning-tree instance is used for all circuits. If the VLAN set of the new circuit
overlaps with VLAN sets of existing circuits with different spanning-tree instances, the VLAN
assignment fails. Cisco recommends that you plan VLAN assignments so that circuits with larger VLAN
sets and a higher chance of overlap are added first. This means that if a circuit with an overlapping
VLAN set is added, it collapses into the same spanning tree. To view circuits mapped to a spanning tree
and their VLAN assignments, see the “DLP-A430 View Spanning Tree Information” task on page 21-9.
Note You can disable or enable spanning tree protection on a circuit-by-circuit basis only for single-card,
point-to-point Ethernet circuits. Other E-Series Ethernet configurations disable or enable spanning tree
on a port-by-port basis.
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