Cisco ONS 15454 Installation and Operations Guide, Release 3.1
Chapter 9, Ethernet Operation

Table Of Contents

Ethernet Operation

9.1 Ethernet Cards

9.1.1 E100T-12/E100T-G

9.1.2 E1000-2/E1000-2-G

9.1.3 Port Provisioning for Ethernet Cards

9.2 Multicard and Single-Card EtherSwitch

9.2.1 Multicard EtherSwitch

9.2.2 Single-Card EtherSwitch

9.2.3 ONS 15454 and ONS 15327 EtherSwitch Circuit Combinations

9.3 Ethernet Circuit Configurations

9.3.1  E-Series Circuit Protection

9.3.2 Point-to-Point Ethernet Circuits

9.3.3 Shared Packet Ring Ethernet Circuits

9.3.4 Hub and Spoke Ethernet Circuit Provisioning

9.3.5 Ethernet Manual Cross-Connects

9.4 VLAN Support

9.4.1 Q-Tagging (IEEE 802.1Q)

9.4.2 Priority Queuing (IEEE 802.1Q)

9.4.3 VLAN Membership

9.5 Spanning Tree (IEEE 802.1D)

9.5.1 Multi-Instance Spanning Tree and VLANs

9.5.2 Spanning Tree Parameters

9.5.3 Spanning Tree Configuration

9.5.4 Spanning Tree Map

9.6 Ethernet Performance and Maintenance Screens

9.6.1 Statistics Screen

9.6.2 Line Utilization Screen

9.6.3 History Screen

9.6.4 MAC Table Screen

9.6.5 Trunk Utilization Screen

9.7 Remote Monitoring Specification Alarm Thresholds


Ethernet Operation


The Cisco ONS 15454 integrates Ethernet into a SONET time-division multiplexing (TDM) platform. Unlike traditional transport products, which map Ethernet frames directly over dedicated TDM bandwidth, the ONS 15454 incorporates layer 2 switching to allow more efficient data transport over the existing SONET backbone.

This chapter describes the Ethernet capabilities of the ONS 15454, including:

Ethernet cards

Multicard and Single-card Etherswitch

Ethernet circuit combinations and configurations

VLAN and IEEE 802.1Q support

Spanning tree and IEEE 802.1D support

Ethernet performance and maintenance screens

Ethernet alarm thresholds (RMON)

9.1 Ethernet Cards

The ONS 15454 shelf assembly holds up to ten Ethernet cards in any multispeed slot. Ethernet cards include the E100T-12, E100T-G, E1000-2 and E1000-2-G. The E100T-12 is the functional equivalent of the E100T-G, and the E1000-2 is the functional equivalent of the E1000-2-G. An ONS 15454 using XC10G cards requires the G versions of the Ethernet cards.

Ethernet card faceplates have two card-level LEDs and a pair of port-level LEDs next to each port.

Table 9-1 Card-level LEDS

LED State
Description
Red FAIL LED

The red FAIL LED indicates that the card's processor is not ready or a catastrophic software failure occurred on the Ethernet card. As part of the boot sequence, the FAIL LED is turned on until the software deems the card operational.

Green ACT LED

A green ACT LED provides the operational status of the E100T-G. When the ACT LED is green it indicates that the Ethernet card is active and the software is operational.


Table 9-2 Port-level LEDs

LED State
Description
Amber

Transmitting and Receiving

Solid Green

Idle and Link Integrity

Green Light Off

Inactive Connection or Unidirectional Traffic


9.1.1 E100T-12/E100T-G

E100T-12/E100T-G cards provide twelve switched, IEEE 802.3-compliant 10/100 Base-T Ethernet ports. Ports detect the speed of an attached device by auto-negotiation and automatically connect at the appropriate speed and duplex mode, either half or full duplex, and determine whether to enable or disable flow control. An E100T-12/E100T-G card consumes 55 W, 1.46 AMPS, and 188 BTU/Hr.

9.1.2 E1000-2/E1000-2-G

E1000-2/E1000-2-G cards provides two switched, IEEE 802.3-compliant Gigabit Ethernet (1000 Mbps) ports that support full duplex operation. An E100T-12/E100T-G card consumes 60 W, 1.25 AMPS, and 205 BTU/Hr.

Gigabit interface converters (GBICs) are hot-swappable input/output devices that plug into a Gigabit Ethernet (E1000-2 or E1000-2-G) card to link the port with the fiber-optic network and determine the maximum distance that the Ethernet traffic will travel from the E1000-2/E1000-2-G card to the next network device.

E1000-2/E1000-2-G cards support two types of standard Cisco GBICs: the IEEE 1000Base-SX compliant 850 nm "short reach" and the IEEE 1000Base-LX compliant 1300 nm "long reach." The 850 nm SX optics are designed for multimode fiber and distances up to 220 meters on 62.5 micron fiber and up to 550 meters on 50 micron fiber. The 1300 nm LX optics are designed for single-mode fiber and distances up to 5 kilometers.

Figure 9-1 A gigabit interface converter

Table 9-3 shows the available GBICs.

Table 9-3 Available GBICs

GBIC
Product Number

Short wavelength (1000BaseSX)

15454-GBIC-SX

Long wavelength/long haul (1000BaseLX)

15454-GBIC-LX


For GBIC installation and cabling instructions, see the "Fiber-Optic Cable Installation" section on page 1-52.


Caution E1000-2/E1000-2-G cards lose traffic for approximately 30 seconds when an ONS 15454 database is restored. Traffic is lost during the period of spanning tree reconvergence. The CARLOSS alarm will appear and clear during this period.

For detailed specifications of the Ethernet cards, refer to the Cisco ONS 15454 Troubleshooting and Maintenance Guide.

9.1.3 Port Provisioning for Ethernet Cards

This section explains how to provision Ethernet ports on an Ethernet card. Most provisioning requires filling in two fields: Enabled and Mode. However, you can also map incoming traffic to a low priority or a high priority queue using the Priority column, and you can enable spanning tree with the Stp Enabled column. For more information about spanning tree, see the "Spanning Tree (IEEE 802.1D)" section. The Status column displays information about the port's current operating mode, and the Stp State column provides the current spanning tree status.

Procedure: Provision Ethernet Ports


Step 1 Display CTC and double-click the card graphic to open the Ethernet card.

Step 2 Choose the Provisioning > Port tabs.

Figure 9-2 shows the Provisioning tab with the Port function subtab selected.

Figure 9-2 Provisioning Ethernet ports

Step 3 From the Port screen, choose the appropriate mode for each Ethernet port. Valid choices for the E100T-12/E100T-G card are Auto, 10 Half, 10 Full, 100 Half, or 100 Full. Valid choices for the E1000-2/E1000-2-G card are 1000 Full or Auto.

Both 1000 Full and Auto mode set the E1000-2 port to the 1000 Mbps and Full duplex operating mode; however, flow control is disabled when 1000 Full is selected. Choosing Auto mode enables the E1000-2 card to autonegotiate flow control. Flow control is a mechanism that prevents network congestion by ensuring that transmitting devices do not overwhelm receiving devices with data. The E1000-2 port handshakes with the connected network device to determine if that device supports flow control.

Step 4 Click the Enabled checkbox(s) to activate the corresponding Ethernet port(s).

Step 5 Click Apply.

Your Ethernet ports are now provisioned and ready to be configured for VLAN membership.

Step 6 Repeat this procedure for all other cards that will be in the VLAN.


9.2 Multicard and Single-Card EtherSwitch

The ONS 15454 enables multicard and single-card EtherSwitch modes. At the Ethernet card view in CTC, click the Provisioning > Card tabs to reveal the Card Mode option.

9.2.1 Multicard EtherSwitch

Multicard EtherSwitch provisions two or more Ethernet cards to act as a single layer 2 switch. It supports one STS-6c shared packet ring, two STS-3c shared packet rings, or six STS-1 shared packet rings. The bandwidth of the single switch formed by the Ethernet cards matches the bandwidth of the provisioned Ethernet circuit up to STS-6c worth of bandwidth.

Figure 9-3 A Multicard EtherSwitch configuration


Caution Whenever you drop two STS-3c multicard EtherSwitch circuits onto an Ethernet card and delete only the first circuit, you should not provision STS-1 circuits to the card without first deleting the remaining STS-3c circuit. If you attempt to create a STS-1 circuit after deleting the first STS-3c circuit, the STS-1 circuit will not work and no alarms will indicate this condition. To avoid this condition, delete the second STS-3c prior to creating the STS-1 circuit.

9.2.2 Single-Card EtherSwitch

Single-card EtherSwitch allows each Ethernet card to remain a single switching entity within the ONS 15454 shelf. This option allows a full STS-12c worth of bandwidth between two Ethernet circuit points. Figure 9-4 illustrates a single-card EtherSwitch configuration.

Figure 9-4 A Single-card EtherSwitch configuration

Seven scenarios exist for provisioning single-card EtherSwitch bandwidth:

1. STS 12c

2. STS 6c + STS 6c

3. STS 6c + STS 3c + STS 3c

4. STS 6c + 6 STS-1s

5. STS 3c + STS 3c +STS 3c +STS 3c

6. STS 3c +STS 3c + 6 STS-1s

7. 12 STS-1s


Note When configuring scenario 3, the STS 6c must be provisioned before either of the STS 3c circuits.


9.2.3 ONS 15454 and ONS 15327 EtherSwitch Circuit Combinations

The following table shows the Ethernet circuit combinations available in ONS 15454s and ONS 15327s

.

Table 9-4 ONS 15454 and ONS 15327 Ethernet Circuit Combinations

15327 Single-Card
15327 Multicard
15454 Single-Card
15454 Multicard

six STS-1s

three STS-1s

one STS 12c

six STS-1s

two STS 3cs

one STS 3c

two STS 6cs

two STS 3cs

one STS 6c

 

one STS 6c and two STS 3cs

one STS 6c

one STS 12c

 

one STS 6c and six STS-1s

 
   

four STS 3cs

 
   

two STS 3cs and six STS-1s

 
   

twelve STS-1s

 

9.3 Ethernet Circuit Configurations

Ethernet circuits can link ONS nodes through point-to-point, shared packet ring, or hub and spoke configurations. Two nodes usually connect with a point-to-point configuration. More than two nodes usually connect with a shared packet ring configuration or a hub and spoke configuration. This section includes procedures for creating these configurations and also explains how to create Ethernet manual cross-connects. Ethernet manual cross-connects allow you to cross connect individual Ethernet circuits to an STS channel on the ONS 15454 optical interface and also to bridge non-ONS SONET network segments.

9.3.1  E-Series Circuit Protection

Different combinations of E-Series circuit configurations and SONET network topologies offer different levels of E-Series circuit protection. Table 9-5 details the available protection.

Table 9-5 Protection for E-Series Circuit Configurations 

Configuration
UPSR
BLSR
1 + 1

Point-to-Point Multicard Etherswitch

None

SONET

SONET

Point-to-Point Single-Card Etherswitch

SONET

SONET

SONET

Point-to-Point Port-mapped Mode

SONET

SONET

SONET

Shared Packet Ring Multicard Etherswitch

STP

SONET

SONET

Common Control Card Switch

STP

STP

STP



Note Before making Ethernet connections, choose a circuit size from STS-1, STS-3c, STS-6c, or STS-12c.



Note When making an STS-12c Ethernet circuit, Ethernet cards must be configured as single-card EtherSwitch. Multi-card mode does not support STS-12c Ethernet circuits.


9.3.2 Point-to-Point Ethernet Circuits

The ONS 15454 can set up a point-to-point (straight) Ethernet circuit as Single-card or Multicard. Multicard EtherSwitch limits bandwidth to STS-6c of bandwidth between two Ethernet circuit points, but allows adding nodes and cards and making a shared packet ring. Single-card EtherSwitch allows a full STS-12c of bandwidth between two Ethernet circuit points.

Figure 9-5 A Multicard EtherSwitch point-to-point circuit

Figure 9-6 A Single-card Etherswitch point-to-point circuit

Procedure: Provision an EtherSwitch Point-to-Point Circuit (Multicard or Single-Card)


Step 1 Display CTC for one of the ONS 15454 Ethernet circuit endpoint nodes.

Step 2 Double-click one of the Ethernet cards that will carry the circuit.

Step 3 Click the Provisioning > Card tabs.

Step 4 If you are building a Multicard Etherswitch point-to-point circuit:

a. Under Card Mode, verify that Multi-card EtherSwitch Group is checked.

b. If Multi-card EtherSwitch Group is not checked, check it and click Apply.

c. Repeat Steps 2 - 4 for all other Ethernet cards in the ONS 15454 that will carry the circuit.

If you are building a Single-card Etherswitch circuit:

d. Under Card Mode, verify that Single-card EtherSwitch is checked.

e. If Single-card EtherSwitch is not checked, check it and click Apply.

Step 5 Navigate to the other ONS 15454 Ethernet circuit endpoint.

Step 6 Repeat Steps 2 - 5.

Step 7 Click the Circuits tab and click Create.

The Circuit Creation (Circuit Attributes) dialog box opens ( Figure 9-7).

Figure 9-7 Provisioning an Ethernet circuit

Step 8 In the Name field, type a name for the circuit.

Step 9 From the Type pull-down menu, choose STS.

Step 10 The VT and VT Tunnel types do not apply to Ethernet circuits.

Step 11 Choose the size of the circuit from the Size pull-down menu.

The valid circuit sizes for an Ethernet Multicard circuit are STS-1, STS-3c and STS6c.

The valid circuit sizes for an Ethernet Single-card circuit are STS-1, STS-3c, STS6c and STS12c.

Step 12 Verify that the Bidirectional checkbox is checked and click Next.

The Circuit Creation (Circuit Source) dialog box opens ( Figure 9-8).

Figure 9-8 Choosing a circuit source

Step 13 Choose the circuit source from the Node menu. Either end node can be the circuit source.

Step 14 If you are building a Multicard EtherSwitch circuit, choose Ethergroup from the Slot menu and click Next.

Step 15 If you are building a Single-card EtherSwitch circuit, from the Slot menu choose the Ethernet card where you enabled the single-card Etherswitch and click Next.

The Circuit Creation (Destination) dialog box opens.

Step 16 Choose the circuit destination from the Node menu, in this example Node 2. Choose the node that is not the source.

Step 17 If you are building a Multicard EtherSwitch circuit choose Ethergroup from the Slot menu and click Next.

Step 18 If you are building a Single-card EtherSwitch circuit, from the Slot menu choose the Ethernet card for which you enabled the Single-card Etherswitch and click Next.

The Circuit Creation (Circuit VLAN Selection) dialog box opens.

Step 19 Create the VLAN:

a. Click the New VLAN tab.

b. Assign an easily-identifiable name to your VLAN.

c. Assign a VLAN ID.

d. 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.

e. Click OK.

f. Highlight the VLAN name and click the arrow >> tab to move the available VLAN(s) to the Circuit VLANs column.

Step 20 Click Next.

The Circuit Creation (Circuit Routing Preferences) dialog box opens.

Step 21 Confirm that the following information about the point-to-point circuit is correct:

Circuit name

Circuit type

Circuit size

VLANs on the circuit

ONS 15454 nodes included in the circuit

Step 22 Click Finish.

Step 23 You now need to provision the Ethernet ports and assign ports to VLANs. For port provisioning instructions, see the "Provision Ethernet Ports" procedure. For assigning ports to VLANs, see the "Provision Ethernet Ports for VLAN Membership" procedure. For information about manually provisioning circuits, see the "Ethernet Manual Cross-Connects" procedure.


9.3.3 Shared Packet Ring Ethernet Circuits

This section provides steps for creating a shared packet ring ( Figure 9-9). Your network architecture may differ from the example.

Figure 9-9 A shared packet ring Ethernet circuit

Procedure: Provision a Shared Packet Ring


Step 1 Display CTC for one of the ONS 15454 Ethernet circuit endpoints.

Step 2 Double-click one of the Ethernet cards that will carry the circuit.

Step 3 Click the Provisioning > Card tabs.

Step 4 Under Card Mode, verify that Multi-card EtherSwitch Group is checked.

Step 5 If Multi-card EtherSwitch Group is not checked, check it and click Apply.

Step 6 Display the node view.

Step 7 Repeat Steps 2 - 6 for all other Ethernet cards in the ONS 15454 that will carry the shared packet ring.

Step 8 Navigate to the other ONS 15454 endpoint.

Step 9 Repeat Steps 2 - 7.

Step 10 Click the Circuits tab and click Create.

The Circuit Creation (Circuit Attributes) dialog box opens.

Step 11 In the Name field, type a name for the circuit.

Step 12 From the Type pull-down menu, choose STS. The VT and VT Tunnel types do not apply to Ethernet circuits.

Step 13 From the Size pull-down menu, choose the size of the circuit.

For shared packet ring Ethernet, valid circuit sizes are STS-1, STS-3C and STS-6c.

Step 14 Verify that the Bidirectional checkbox is checked.


Note You must manually provision the circuits if you are building a shared packet ring configuration.


Step 15 Click Next.

The Circuit Creation (Circuit Source) dialog box opens.

Step 16 From the Node menu, choose the circuit source.

Any shared packet ring node can serve as the circuit source.

Step 17 Choose Ethergroup from the Slot menu and click Next.

The Circuit Creation (Circuit Destination) dialog box opens.

Step 18 Choose the circuit destination from the Node menu.

Step 19 Except for the source node, any shared packet ring node can serve as the circuit destination.

Step 20 Choose Ethergroup from the Slot menu and click Next.

The Circuit Creation (Circuit VLAN Selection) dialog box opens.

Step 21 Create the VLAN:

a. Click the New VLAN tab.

The Circuit Creation (Define New VLAN) dialog box opens ( Figure 9-10).

Figure 9-10 Choosing a VLAN name and ID

b. Assign an easily-identifiable name to your VLAN.

c. Assign a VLAN ID.

This VLAN ID number must be unique. It is usually the next available number not already assigned to an existing VLAN (between 2 and 4093). Each ONS 15454 network supports a maximum of 509 user-provisionable VLANs.

d. Click OK.

Figure 9-11 Selecting VLANs

e. Highlight the VLAN name and click the >> tab to move the VLAN(s) from the Available VLANs column to the Circuit VLANs column ( Figure 9-11).

By moving the VLAN from the Available VLANs column to the Circuit VLANs column, all the VLAN traffic is forced to use the shared packet ring circuit you created.

Step 22 Click Next.

Step 23 Uncheck the Route Automatically checkbox and click Next.

Figure 9-12 Adding a span

Step 24 Click either span (green arrow) leading from the source node ( Figure 9-12).

The span turns white.

Step 25 Click Add Span.

The span turns blue and adds the span to the Included Spans field.

Step 26 Click the node at the end of the blue span.

Step 27 Click the green span leading to the next node.

The span turns white.

Step 28 Click Add Span.

The span turns blue.

Step 29 Repeat Steps 24 - 27 for every node remaining in the ring. Figure 9-13 shows the Circuit Path Selection dialog box with all the spans selected.

Figure 9-13 Viewing a span

Step 30 Verify that the new circuit is correctly configured.


Note If the circuit information is not correct, click the Back button and repeat the procedure with the correct information. You can also click Finish, delete the completed circuit, and begin the procedure again.


Step 31 Click Finish.

Step 32 You now need to provision the Ethernet ports and assign ports to VLANs. For port provisioning instructions, see the "Provision Ethernet Ports" procedure. For assigning ports to VLANs, see the "Provision Ethernet Ports for VLAN Membership" procedure.


9.3.4 Hub and Spoke Ethernet Circuit Provisioning

This section provides steps for creating a hub and spoke Ethernet circuit configuration. The hub and spoke configuration connects point-to-point circuits (the spokes) to an aggregation point (the hub). In many cases, the hub links to a high-speed connection and the spokes are Ethernet cards. Figure 9-14 illustrates a sample hub and spoke ring. Your network architecture may differ from the example.

Figure 9-14 A Hub and Spoke Ethernet circuit

Procedure: Provision a Hub and Spoke Ethernet Circuit


Step 1 Display CTC for one of the ONS 15454 Ethernet circuit endpoints.

Step 2 Double-click the Ethernet card that will create the circuit.

Step 3 Click the Provisioning > Card tabs.

Step 4 Under Card Mode, check the Single-card EtherSwitch checkbox.

If Single-card EtherSwitch is not checked, check it and click Apply.

Step 5 Navigate to the other ONS 15454 endpoint and repeat Steps 2 - 4.

Step 6 Display the node view or network view.

Step 7 Click the Circuits tab and click Create.

The Circuit Creation (Circuit Attributes) dialog box opens ( Figure 9-7).

Step 8 In the Name field, type a name for the circuit.

Step 9 From the Type pull-down menu, choose STS.


Note The types VT and VT Tunnel do not apply to Ethernet circuits.


Step 10 Choose the size of the circuit from the Size pull-down menu.

Step 11 Verify that the Bidirectional checkbox is checked and click Next.

The Circuit Creation (Circuit Source) dialog box opens.

Step 12 From the Node menu, choose the circuit source.

Either end node can be the circuit source.

Step 13 From the Slot menu, choose the Ethernet card where you enabled the single-card EtherSwitch and click Next.

The Circuit Creation (Circuit Destination) dialog box opens.

Step 14 Choose the circuit destination from the Node menu.

Choose the node that is not the source.

Step 15 From the Slot menu, choose the Ethernet card where you enabled the single-card EtherSwitch and click Next.

The Circuit Creation (Circuit VLAN Selection) dialog box opens ( Figure 9-8).

Step 16 Create the VLAN:

a. Click the New VLAN tab.

The Circuit Creation (Define New VLAN) dialog box opens ( Figure 9-10).

b. Assign an easily-identifiable name to your VLAN.

c. Assign a VLAN ID.

This should be the next available number (between 2 and 4093) not already assigned to an existing VLAN. Each ONS 15454 network supports a maximum of 509 user-provisionable VLANs.

d. Click OK.

e. Highlight the VLAN name and click the >> tab to move the VLAN(s) from the Available VLANs column to the Circuit VLANs column ( Figure 9-11).

Step 17 Click Next.

The Circuit Creation (Circuit Routing Preferences) dialog box opens.

Step 18 Confirm that the following information about the point-to-point circuit is correct:

Circuit name

Circuit type

Circuit size

VLANs that will be transported across this circuit

ONS 15454 nodes included in this circuit


Note If the circuit information is not correct, click the Back button and repeat the procedure with the correct information. You can also click Finish, delete the completed circuit, and start the procedure from the beginning.


Step 19 Click Finish.You must now provision the second circuit and attach it to the already-created VLAN.

Step 20 Log into the ONS 15454 Ethernet circuit endpoint for the second circuit.

Step 21 Double-click the Ethernet card that will create the circuit. The CTC card view displays.

Step 22 Click the Provisioning > Card tabs.

Step 23 Under Card Mode, check Single-card EtherSwitch.

If the Single-card EtherSwitch checkbox is not checked, check it and click Apply.

Step 24 Log into the other ONS 15454 endpoint for the second circuit and repeat Steps 21 - 23.

Step 25 Display the CTC node view.

Step 26 Click the Circuits tab and click Create.

Step 27 Choose STS from the Type pull-down menu.


Note The types VT and VT Tunnel do not apply to Ethernet circuits.


Step 28 Choose the size of the circuit from the Size pull-down menu.

Step 29 Verify that the Bidirectional checkbox is checked and click Next.

Step 30 Choose the circuit source from the Node menu and click Next.

Either end node can be the circuit source.

Step 31 Choose the circuit destination from the Node menu.

Choose the node that is not the source.

Step 32 From the Slot menu, choose the Ethernet card where you enabled the single-card EtherSwitch and click Next.

The Circuit Creation (Circuit VLAN Selection) dialog box is displayed.

Step 33 Highlight the VLAN that you created for the first circuit and click the >> tab to move the VLAN(s) from the Available VLANs column to the Selected VLANs column.

Step 34 Click Next and click Finish.

Step 35 You now need to provision the Ethernet ports and assign ports to VLANs. For port provisioning instructions, see the "Provision Ethernet Ports" procedure. For assigning ports to VLANs, see the "Provision Ethernet Ports for VLAN Membership" procedure.


9.3.5 Ethernet Manual Cross-Connects

ONS 15454s require end-to-end CTC visibility between nodes for normal provisioning of Ethernet circuits. When other vendors' equipment sits between ONS 15454s, OSI/TARP- based equipment does not allow tunneling of the ONS 15454 TCP/IP-based DCC. To circumvent this lack of continuous DCC, the Ethernet circuit must be manually cross connected to an STS channel riding through the non-ONS network. This allows an Ethernet circuit to run from ONS node to ONS node utilizing the non-ONS network.


Note Provisioning manual cross-connects for Multicard Etherswitch circuits is a separate procedure from provisioning manual cross-connects for Single-card Etherswitch circuits. Both procedures are listed below.


Figure 9-15 Ethernet manual cross-connects

Procedure: Provision a Single-card EtherSwitch Manual Cross-Connect


Step 1 Display CTC for one of the ONS 15454 Ethernet circuit endpoints.

Step 2 Double-click one of the Ethernet cards that will carry the circuit.

Step 3 Click the Provisioning > Card tabs.

Step 4 Under Card Mode, verify that Single-card EtherSwitch is checked.

If the Single-card EtherSwitch is not checked, check it and click Apply.

Step 5 Display the node view.

Step 6 Click the Circuits tab and click Create.

The Circuit Creation (Circuit Attributes) dialog box opens ( Figure 9-16).

Figure 9-16 Creating an Ethernet circuit

Step 7 In the Name field, type a name for the circuit.

Step 8 From the Type pull-down menu, choose STS.


Note The types VT and VT Tunnel do not apply to Ethernet circuits.


Step 9 Choose the size of the circuit from the Size pull-down menu.

The valid circuit sizes for an Ethernet Multicard circuit are STS-1, STS-3c and STS-6c.

Step 10 Verify that the Bidirectional checkbox is checked and click Next.

The Circuit Creation (Circuit Source) dialog box opens.

Step 11 From the Node menu, choose the current node as the circuit source.

Step 12 From the Slot menu, choose the Ethernet card that will carry the circuit and click Next.

The Circuit Creation (Circuit Destination) dialog box opens.

Step 13 From the Node menu, choose the current node as the circuit destination.

Step 14 From the Slot menu, choose the optical card that will carry the circuit.

Step 15 Choose the STS that will carry the circuit from the STS menu and click Next.


Note For Ethernet manual cross-connects, the same node serves as both source and destination.


The Circuit Creation (Circuit VLAN Selection) dialog box opens ( Figure 9-11).

Step 16 Create the VLAN:

a. Click the New VLAN tab.

The Circuit Creation (Define New VLAN) dialog box opens ( Figure 9-10).

b. Assign an easily-identifiable name to your VLAN.

c. 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.

d. Click OK.

Figure 9-17 Selecting VLANs

e. Highlight the VLAN name and click the arrow >> tab to move the VLAN(s) from the Available VLANs column to the Circuit VLANs column ( Figure 9-17).

Step 17 Click Next.

The Circuit Creation (Circuit Routing Preferences) dialog box opens.

Step 18 Confirm that the following information is correct:

Circuit name

Circuit type

Circuit size

VLANs on this circuit

ONS 15454 nodes included in this circuit


Note If the circuit information is not correct use the Back button, then redo the procedure with the correct information. Alternately, you can click Finish, then delete the completed circuit and start the procedure from the beginning.


Step 19 Click Finish.

Step 20 You now need to provision the Ethernet ports and assign ports to VLANs. For port provisioning instructions, see the "Provision Ethernet Ports" procedure. For assigning ports to VLANs, see the "Provision Ethernet Ports for VLAN Membership" procedure.

Step 21 After assigning the ports to the VLANs, repeat Steps 1 - 19 at the second ONS 15454 Ethernet manual cross-connect endpoint.


Note The appropriate STS circuit must exist in the non-ONS 15454 equipment to connect the two STSs from the ONS 15454 Ethernet manual cross-connect endpoints.



Procedure: Provision a Multicard EtherSwitch Manual Cross-Connect


Step 1 Display CTC for one of the ONS 15454 Ethernet circuit endpoints.

Step 2 Double-click one of the Ethernet cards that will carry the circuit.

Step 3 Click the Provisioning > Card tabs.

Step 4 Under Card Mode, verify that Multi-card EtherSwitch Group is checked.

If the Multicard-card EtherSwitch Group is not checked, check it and click Apply.

Step 5 Display the node view.

Step 6 Repeat Steps 2 - 5 for any other Ethernet cards in the ONS 15454 that will carry the circuit.

Step 7 Click the Circuits tab and click Create.

The Circuit Creation (Circuit Attributes) dialog box opens ( Figure 9-18).

Figure 9-18 Creating an Ethernet circuit

Step 8 In the Name field, type a name for the circuit.

Step 9 From the Type pull-down menu, choose STS.


Note The types VT and VT Tunnel do not apply to Ethernet circuits.


Step 10 Choose the size of the circuit from the Size pull-down menu.

The valid circuit sizes for an Ethernet Multicard circuit are STS-1, STS-3c and STS-6c.

Step 11 Verify that the Bidirectional checkbox is checked and click Next.

The Circuit Creation (Circuit Source) dialog box opens.

Step 12 From the Node menu, choose the current node as the circuit source.

Step 13 Choose Ethergroup from the Slot menu and click Next.

The Circuit Creation (Circuit Destination) dialog box opens.

Step 14 From the Node menu, choose the current node as the circuit destination.

Step 15 Choose Ethergroup from the Slot menu and click Next.


Note For the Ethernet manual cross-connect, the destination and source should be the same node.


The Circuit Creation (Circuit VLAN Selection) dialog box opens ( Figure 9-11).

Step 16 Create the VLAN:

a. Click the New VLAN tab.

The Circuit Creation (Define New VLAN) dialog box opens ( Figure 9-10).

b. Assign an easily-identifiable name to your VLAN.

c. 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.

d. Click OK.

Figure 9-19 Selecting VLANs

e. Highlight the VLAN name and click the arrow >> tab to move the VLAN(s) from the Available VLANs column to the Circuit VLANs column ( Figure 9-19).

Step 17 Click Next.

The Circuit Creation (Circuit Routing Preferences) dialog box opens.

Step 18 Confirm that the following information is correct:

Circuit name

Circuit type

Circuit size

VLANs on this circuit

ONS 15454 nodes included in this circuit


Note If the circuit information is not correct use the Back button, then redo the procedure with the correct information. Alternately, you can click Finish, then delete the completed circuit and start the procedure from the beginning.


Step 19 Click Finish.

You now need to provision the Ethernet ports and assign ports to VLANs. For port provisioning instructions, see the "Provision Ethernet Ports" procedure. For assigning ports to VLANs, see the "Provision Ethernet Ports for VLAN Membership" procedure. Return to the following step after assigning the ports to VLANs.

Step 20 Highlight the circuit and click Edit.

The Edit Circuit dialog box opens.

Step 21 Click Drops and click Create.

The Define New Drop dialog box opens.

Step 22 From the Slot menu, choose the optical card that links the ONS 15454 to the non-ONS 15454 equipment.

Step 23 From the Port menu, choose the appropriate port.

Step 24 From the STS menu, choose the STS that matches the STS of the connecting non-ONS 15454 equipment.

Step 25 Click OK.

The Edit Circuit dialog box opens.

Step 26 Confirm the circuit information that displays in the Circuit Information dialog box and click Close.

Step 27 Repeat Steps 1 - 26 at the second ONS 15454 Ethernet manual cross-connect endpoint.


Note The appropriate STS circuit must exist in the non-ONS 15454 equipment to connect the two ONS 15454 Ethernet manual cross-connect endpoints.



9.4 VLAN Support

Users can provision up to 509 VLANs with the CTC software. Specific sets of ports define the broadcast domain for the ONS 15454. The definition of VLAN ports includes all Ethernet and packet-switched SONET port types. All VLAN IP address discovery, flooding, and forwarding is limited to these ports.

The ONS 15454 802.1Q-based VLAN mechanism provides logical isolation of subscriber LAN traffic over a common SONET transport infrastructure. Each subscriber has an Ethernet port at each site, and each subscriber is assigned to a VLAN. Although the subscriber's VLAN data flows over shared circuits, the service appears to the subscriber as a private data transport.

9.4.1 Q-Tagging (IEEE 802.1Q)

IEEE 802.1Q allows the same physical port to host multiple 802.1Q VLANs. Each 802.1Q VLAN represents a different logical network.

The ONS 15454 works with Ethernet devices that support IEEE 802.1Q and those that do not support IEEE 802.1Q. If a device attached to an ONS 15454 Ethernet port does not support IEEE 802.1Q, the ONS 15454 only uses Q-tags internally. The ONS 15454 associates these Q-tags with specific ports.

With Ethernet devices that do not support IEEE 802.1Q, the ONS 15454 takes non-tagged Ethernet frames that enter the ONS network and uses a Q-tag to assign the packet to the VLAN associated with the ONS network's ingress port. The receiving ONS node removes the Q-tag when the frame leaves the ONS network (to prevent older Ethernet equipment from incorrectly identifying the 8021.Q packet as an illegal frame). The ingress and egress ports on the ONS network must be set to Untag for the process to occur. Untag is the default setting for ONS ports. Example #1 in Figure 9-20 illustrates Q-tag use only within an ONS network.

With Ethernet devices that support IEEE 802.1Q, the ONS 15454 uses the Q-tag attached by the external Ethernet devices. Packets enter the ONS network with an existing Q-tag; the ONS 15454 uses this same Q-tag to forward the packet within the ONS network and leaves the Q-tag attached when the packet leaves the ONS network. Set both entry and egress ports on the ONS network to Tagged for this process to occur. Example #2 in Figure 9-20 illustrates the handling of packets that both enter and exit the ONS network with a Q-tag.

For more information about setting ports to Tagged and Untag, see the "Provision Ethernet Ports for VLAN Membership" procedure.

Figure 9-20 A Q-tag moving through a VLAN

9.4.2 Priority Queuing (IEEE 802.1Q)


Note IEEE 802.1Q was formerly IEEE 802.1P.


Networks without priority queuing handle all packets on a first-in-first-out basis. Priority queuing reduces the impact of network congestion by mapping Ethernet traffic to different priority levels. The ONS 15454 supports priority queuing. The ONS 15454 takes the eight priorities specified in IEEE 802.1Q and maps them to two queues ( Table 9-6). Q-tags carry priority queuing information through the network.

The ONS 15454 uses a "leaky bucket" algorithm to establish a weighted priority (not a strict priority). A weighted priority gives high-priority packets greater access to bandwidth, but does not totally preempt low-priority packets. During periods of network congestion, roughly 70% of bandwidth goes to the high-priority queue and the remaining 30% goes to the low-priority queue. A network that is too congested will drop packets.

Table 9-6 Priority Queuing

User Priority
Queue
Allocated Bandwidth

0,1,2,3

Low

30%

4,5,6,7

High

70%


Figure 9-21 The priority queuing process

9.4.3 VLAN Membership

This section explains how to provision Ethernet ports for VLAN membership. For initial port provisioning (prior to provisioning VLAN membership) see the "Port Provisioning for Ethernet Cards" section.

Procedure: Provision Ethernet Ports for VLAN Membership

The ONS 15454 allows you to configure the VLAN membership and Q-tag handling of individual Ethernet ports.


Step 1 Display the CTC card view for the Ethernet card.

Step 2 Click the Provisioning > VLAN tabs ( Figure 9-22).

Figure 9-22 Configuring VLAN membership for individual Ethernet ports

Step 3 To put a port in a VLAN, click the port and choose either Tagged or Untag. Figure 9-22 shows Port 1 in the red VLAN and Port 2 through Port 12 in the default VLAN. Table 9-7 shows valid port settings.

If a port is a member of only one VLAN, go to that VLAN's row and choose Untag from the Port column. Choose -- for all the other VLAN rows in that Port column. The VLAN with Untag selected can connect to the port, but other VLANs cannot access that port.

If a port is a trunk port, it connects multiple VLANs to an external device, such as a switch, which also supports trunking. A trunk port must have tagging (802.1Q) enabled for all the VLANs that connect to that external device. Choose Tagged at all VLAN rows that need to be trunked. Choose Untag at one or more VLAN rows in the trunk port's column that do not need to be trunked, for example, the default VLAN. Each Ethernet port must attached to at least one untagged VLAN.

Step 4 After each port is in the appropriate VLAN, click Apply.

Table 9-7 Port Settings

Setting
Description

--

A port marked with this symbol does not belong to the VLAN.

Untag

The ONS 15454 will tag ingress frames and strip tags from egress frames.

Tagged

The ONS 15454 will handle ingress frames according to VLAN ID; egress frames will not have their tags removed.



Note If Tagged is chosen, the attached external devices must recognize IEEE 802.1Q VLANs.



Note Both ports on individual E1000-2/E1000-2-G cards cannot be members of the same VLAN.



9.5 Spanning Tree (IEEE 802.1D)

The Cisco ONS 15454 operates spanning tree protocol (STP) according to IEEE 802.1D when an Ethernet card is installed. STP operates over all packet-switched ports including Ethernet and SONET ports. On Ethernet ports, STP is disabled by default but may be enabled with a check box under the Provisioning > Port tabs at the card-level view. On SONET interface ports, STP activates by default and cannot be disabled.

The Ethernet card can enable STP on the Ethernet ports to allow redundant paths to the attached Ethernet equipment. STP spans cards so that both equipment and facilities are protected against failure.

STP detects and eliminates network loops. When STP detects multiple paths between any two network hosts, STP blocks ports until only one path exists between any two network hosts ( Figure 9-23). The single path eliminates possible bridge loops. This is crucial for shared packet rings, which naturally include a loop.

Figure 9-23 An STP blocked path

To remove loops, STP defines a tree that spans all the switches in an extended network. STP forces certain redundant data paths into a standby (blocked) state. If one network segment in the STP becomes unreachable, the spanning-tree algorithm reconfigures the spanning-tree topology and reactivates the blocked path to reestablish the link. STP operation is transparent to end stations, which do not discriminate between connections to a single LAN segment or to a switched LAN with multiple segments. The ONS 15454 supports one STP instance per circuit and a maximum of eight STP instances per ONS 15454.

9.5.1 Multi-Instance Spanning Tree and VLANs

The ONS 15454 can operate multiple instances of STP to support VLANs in a looped topology. You can dedicate separate circuits across the SONET ring for different VLAN groups (i.e., one for private TLS services and one for Internet access). Each circuit runs its own STP to maintain VLAN connectivity in a multi-ring environment.

Procedure: Enable Spanning Tree on Ethernet Ports


Step 1 Display the CTC card view.

Step 2 Click the Provisioning > Port tabs.

Step 3 In the left-hand column, find the applicable port number and check the Stp Enabled checkbox to enable STP for that port.

Step 4 Click Apply.


9.5.2 Spanning Tree Parameters

Default spanning tree parameters are appropriate for most situations. Contact the Cisco Technical Assistance Center (TAC) at 1-877-323-7368 before you change the default STP parameters.

At the node view, click the Maintenance > Etherbridge > Spanning Trees tabs to view spanning tree parameters.

Table 9-8 Spanning Tree Parameters

BridgeID

ONS 15454 unique identifier that transmits the configuration bridge protocol data unit (BPDU); the bridge ID is a combination of the bridge priority and the ONS 15454 MAC address

TopoAge

Amount of time in seconds since the last topology change

TopoChanges

Number of times the spanning tree topology has been changed since the node booted up

DesignatedRoot

Identifies the spanning tree's designated root for a particular spanning tree 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


9.5.3 Spanning Tree Configuration

To view the spanning tree configuration, at the node view click the Provisioning tab and Etherbridge subtab.

Table 9-9 Spanning Tree Configuration

Column
Default Value
Value Range

Priority

32768

0 - 65535

Bridge max age

20 seconds

6 - 40 seconds

Bridge Hello Time

2 seconds

1 - 10 seconds

Bridge Forward Delay

15 seconds

4 - 30 seconds


9.5.4 Spanning Tree Map

The Circuit screen shows forwarding spans and blocked spans on the spanning tree map.

Procedure: View the Spanning Tree Map


Step 1 On the circuit screen ( Figure 9-24), double-click an Ethernet circuit.

Figure 9-24 The spanning tree map on the circuit screen


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.



9.6 Ethernet Performance and Maintenance Screens

CTC provides Ethernet performance information, including line-level parameters, the amount of port bandwidth used, and historical Ethernet statistics. CTC also includes spanning tree information, MAC address information, and the amount of circuit bandwidth used. To view spanning tree information, see the "Spanning Tree Parameters" section.

9.6.1 Statistics Screen

The Ethernet statistics screen lists Ethernet parameters at the line level. Table 9-10 defines the parameters. Display the CTC card view for the Ethernet card and click the Performance > Statistics tabs to display the screen.

Table 9-10 Ethernet Parameters

Parameter
Meaning

Link Status

Indicates whether link integrity is present; up means present, and down means not present

RX Packets

Number of packets received since the last counter reset

RX Bytes

Number of bytes received since the last counter reset

TX Packets

Number of packets transmitted since the last counter reset

TX Bytes

Number of bytes transmitted since the last counter reset

RX Total Errors

Total number of receive errors

RX FCS

Number of packets with a Frame Check Sequence (FCS) error. FCS errors indicate Frame corruption during transmission

RX Alignment

Number of packets with alignment errors; alignment errors are received incomplete frames

RX Runts

Number of packets received that are less than 64 bytes in length

RX Giants

Number of packets received that are greater than 1518 bytes in length for untagged interfaces and 1522 bytes for tagged interfaces

TX Collisions

Number of transmit packets that are collisions; the port and the attached device transmitting at the same time caused collisions

TX Excessive

Number of consecutive collisions

TX Deferred

Number of packets deferred


9.6.2 Line Utilization Screen

The Line Utilization screen shows the percentage of line, or port, bandwidth used and the percentage used in the past. Display the CTC card view and click the Performance and Utilization tabs to display the screen. From the Interval menu, choose a time segment interval. Valid intervals are 1 minute, 15 minutes, 1 hour, and 1 day. Press Refresh to update the data.


Note Line utilization numbers express the average of ingress and egress traffic as a percentage of capacity.


9.6.3 History Screen

The Ethernet History screen lists past Ethernet statistics. At the CTC card view, click the Performance tab and History subtab to view the screen. Choose the appropriate port from the Line menu and the appropriate interval from the Interval menu. Press Refresh to update the data. Table 9-10 defines the listed parameters.

9.6.4 MAC Table Screen

A MAC address is a hardware address that physically identifies a network device. The ONS 15454 MAC table, also known as the MAC forwarding table, will allow you to see all the MAC addresses attached to the enabled ports of an Ethernet card or an Ethernet Group. This includes the MAC address of the network device attached directly to the port and any MAC addresses on the network linked to the port. The MAC addresses table lists the MAC addresses stored by the ONS 15454 and the VLAN, Slot/Port/STS, and circuit that links the ONS 15454 to each MAC address ( Figure 9-25).

Figure 9-25 MAC addresses recorded in the MAC table

Procedure: Retrieve the MAC Table Information


Step 1 Click the Maintenance > EtherBridge > MAC Table tabs.

Step 2 Select the appropriate Ethernet card or Ethergroup from the Layer 2 Domain pull-down menu.

Step 3 Click Retrieve for the ONS 15454 to retrieve and display the current MAC IDs.



Note Click Clear to clear the highlighted rows and click Clear All to clear all displayed rows.


9.6.5 Trunk Utilization Screen

The Trunk Utilization screen is similar to the Line Utilization screen, but Trunk Utilization shows the percentage of circuit bandwidth used rather than the percentage of line bandwidth used. Click the Maintenance > Ether Bridge > Trunk Utilization tabs to view the screen. Choose a time segment interval from the Interval menu.


Note The percentage shown is the average of ingress and egress traffic.


9.7 Remote Monitoring Specification Alarm Thresholds

The ONS 15454 features Remote Monitoring (RMON) that allows network operators to monitor the health of the network with a Network Management System (NMS). For a detailed description of the ONS SNMP implementation, see Chapter 11, "SNMP."

One of the ONS 15454's RMON MIBs is the Alarm group. The alarm group consists of the alarmTable. An NMS uses the alarmTable to find the alarm-causing thresholds for network performance. The thresholds apply to the current 15-minute interval and the current 24-hour interval. RMON monitors several variables, such as Ethernet collisions, and triggers an event when the variable crosses a threshold during that time interval. For example, if a threshold is set at 1000 collisions and 1001 collisions occur during the 15-minute interval, an event triggers. CTC allows you to provision these thresholds for Ethernet statistics.


Note You can find performance monitoring specifications for all other cards in the Cisco ONS 15454 Troubleshooting and Maintenance Guide.



Note The following tables define the variables you can provision in CTC. For example, to set the collision threshold, choose etherStatsCollisions from the Variable menu.


Table 9-11 Ethernet Threshold Variables (MIBs) 

Variable
Definition

iflnOctets

Total number of octets received on the interface, including framing octets

iflnUcastPkts

Total number of unicast packets delivered to an appropriate protocol

iflnErrors

Number of inbound packets discarded because they contain errors

ifOutOctets

Total number of transmitted octets, including framing packets

ifOutUcastPkts

Total number of unicast packets requested to transmit to a single address

dot3statsAlignmentErrors

Number of frames with an alignment error, i.e., the length is not an integral number of octets and the frame cannot pass the Frame Check Sequence (FCS) test

dot3StatsFCSErrors

Number of frames with framecheck errors, i.e., there is an integral number of octets, but an incorrect Frame Check Sequence (FCS)

dot3StatsSingleCollisionFrames

Number of successfully transmitted frames that had exactly one collision

dot3StatsMutlipleCollisionFrame

Number of successfully transmitted frames that had multiple collisions

dot3StatsDeferredTransmissions

Number of times the first transmission was delayed because the medium was busy

dot3StatsLateCollision

Number of times that a collision was detected later than 64 octets into the transmission (also added into collision count)

dot3StatsExcessiveCollision

Number of frames where transmissions failed because of excessive collisions

etherStatsJabbers

Total number of Octets of data (including bad packets) received on the network

etherStatsUndersizePkts

Number of packets received with a length less than 64 octets

etherStatsFragments

Total number of packets that are not an integral number of octets or have a bad FCS, and that are less than 64 octets long

etherStatsPkts64Octets

Total number of packets received (including error packets) that were 64 octets in length

etherStatsPkts65to127Octets

Total number of packets received (including error packets) that were 65 - 172 octets in length

etherStatsPkts128to255Octets

Total number of packets received (including error packets) that were 128 - 255 octets in length

etherStatsPkts256to511Octets

Total number of packets received (including error packets) that were 256 - 511 octets in length

etherStatsPkts512to1023Octets

Total number of packets received (including error packets) that were 512 - 1023 octets in length

etherStatsPkts1024to1518Octets

Total number of packets received (including error packets) that were 1024 - 1518 octets in length

etherStatsJabbers

Total number of packets longer than 1518 octets that were not an integral number of octets or had a bad FCS

etherStatsCollisions

Best estimate of the total number of collisions on this segment

etherStatsCollisionFrames

Best estimate of the total number of frame collisions on this segment

etherStatsCRCAlignErrors

Total number of packets with a length between 64 and 1518 octets, inclusive, that had a bad FCS or were not an integral number of octets in length


Procedure: Creating Ethernet RMON Alarm Thresholds


Step 1 Display the CTC node view.

Step 2 Click the Provisioning > Etherbridge > Thresholds tabs.

Step 3 Click Create.

The Create Ether Threshold dialog box opens.

Figure 9-26 Creating RMON thresholds

Step 4 From the Slot menu, choose the appropriate Ethernet card.

Step 5 From the Port menu, choose the Port on the Ethernet card.

Step 6 From the Variable menu, choose the variable. Table 9-11 lists and defines the Ethernet Threshold Variables available in this field.

Step 7 From Alarm Type, indicate whether the event will be triggered by the rising threshold, falling threshold, or both the rising and falling thresholds.

Step 8 From the Sample Type pull-down menu, choose either Relative or Absolute. Relative restricts the threshold to use the number of occurrences in the user-set sample period. Absolute sets the threshold to use the total number of occurrences, regardless of any time period.

Step 9 Type in an appropriate number of seconds for the Sample Period.

Step 10 Type in the appropriate number of occurrences for the Rising Threshold.


Note For a rising type of alarm to fire, the measured value must shoot from below the falling threshold to above the rising threshold. For example, if a network is running below a falling threshold of 400 collisions every 15 seconds and a problem causes 1001 collisions in 15 seconds, these occurrences fire an alarm.


Step 11 Type in the appropriate number of occurrences for the Falling Threshold. In most cases a falling threshold is set lower than the rising threshold.

A falling threshold is the counterpart to a rising threshold. When the number of occurrences is above the rising threshold and then drops below a falling threshold, it resets the rising threshold. For example, when the network problem that caused 1001 collisions in 15 minutes subsides and creates only 799 collisions in 15 minutes, occurrences fall below a falling threshold of 800 collisions. This resets the rising threshold so that if network collisions again spike over a 1000 per 15 minute period, an event again triggers when the rising threshold is crossed. An event is triggered only the first time a rising threshold is exceeded (otherwise a single network problem might cause a rising threshold to be exceeded multiple times and cause a flood of events).

Step 12 Click the OK button to complete the procedure.