Configuring Subtend Configurations

This chapter describes how to set up subtend configurations and how to set child DSLAM subscriber PVCs. Using subtend configurations allows you to use one ATM backbone for multiple Cisco DSLAMs.

This chapter includes the following sections:

Overview of Subtend Configurations

Using subtend configurations is a DSLAM feature that reduces the cost per subscriber by amortizing the expense of the network interface module and the edge-switch interface connection over a large number of subscribers. Subtend configurations provide the following advantages:

Services and aggregates the data from one or more remotely located Cisco DSLAM into a host Cisco DSLAM. This configuration takes advantage of the data network interface on the host Cisco DSLAM.
Reduces the number of ATM edge-switch interfaces that are required to terminate the Cisco DSLAM.

CDM subtend configurations support the following topology configurations:

Tree
Daisy chain
Star

CDM subtend configurations supports the following DSLAM interconnections, where the host chassis is called the parent, and the subtended chassis is called the child:

NI-2 as parent with NI-2 as child
NI-2 as parent with NI-1 as child
NI-1 as parent with NI-1 as child

Figure 5-1 illustrates the connections of a subtend DSLAM configuration in a tree topology with six child systems. The example in this illustration uses Cisco 6100 DSLAMs but applies to all Cisco DSLAM chassis types.

Figure 5-1 Subtend Connections

Note The same WAN technology must be used between a parent DSLAM and its subtended chassis (for example OC-3 to OC-3 or DS3 to DS3, single mode to single mode, and multimode to multimode), and all chassis must be physically connected. In this illustration, the parent DSLAM is using DS3 technology, but you can also set up a subtend configuration using OC-3 technology. In that case, the parent DSLAM also uses OC-3 technology.

Figure 5-2 shows valid address ranges for each DSLAM. The example in this illustration uses Cisco 6100/6130 DSLAMs, but applies to all Cisco DSLAM chassis types.

Figure 5-2 Valid ATM Connection Space

Guidelines for Configuring a Subtend System

The following guidelines apply to setting up a subtend configuration:

Before you use CDM to manage a subtend system, you must set up the physical subtend configuration, and you must have a telnet session on a DSLAM to provide for IOS configurations.
You can subtend several Cisco DSLAMs to one parent host Cisco DSLAM that is connected to the ATM network backbone (which is illustrated in Figure 5-1). The number of DSLAMS that one host or parent DSLAM can subtend, based on the type of topology, is as follows:

Tree topology—6 subtended DSLAMs (children)
Daisy chain topology—13 subtended DSLAMS (children)
Star topology—8 subtended DSLAMS (children)

Figure 5-3 shows an example of a star topology using a Cisco 6015 DSLAM; the configuration of this topology applies to all DSLAM chassis types.

Figure 5-3 Subtended Network—Star Topology

Note The DS3 interface is designated as the trunk in a subtended network configuration. Ask your network architect or Cisco customer service representative for examples of other subtend topology configurations.

Use standard Cisco DSLAM network interface modules on the subtended DSLAM for interconnection to the host node.
Subtend as many as 8 chassis to support up to 2800 subscribers per network connection.
The Cisco DSLAM can support up to 9000 VCCs. The total number depends on the amount of system-controller and network-interface RAM that the resident software application requires.
Cisco recommends a maximum of 1500 VCCs within the valid address space. Software limits might not be built in because of the temporary nature of this ceiling.
You must conduct data path tests between your Cisco DSLAM and far-end equipment.
Use these guidelines for configuring VPIs and VCIs for NI-2:

 
modem port <--> trunk

 
modem port: VPI = 0-255; VCI = 0-255

 
trunk port: VPI = 0-255; VCI = 32-16383

 
trunk <--> subtend port

 
trunk port: VPI = 0-255; VCI = 32-16383

 
subtend port: VPI = 0-255; VCI = 32-16383

Use these guidelines for configuring VPIs and VCIs for NI-1:

 
Subscriber side:

 
VPI = 1; VCI = 0-3.

 
Subtend Port:

 
VPI = 0-6; VCI = 0-399 (0-1599 for VPI=1)

 
Network side:

 
VPI=0-27; VCI=0-399 (0-1599 for VPI=1)

For example, if using only NI-1 nodes, the following example applies (approximately)

 
Source: VPI = 1 VCI = 0 - 3

 
Destination: VPI = 0 - 6 VCI = 0 - 399

Suppose you have connections like this:

 
A <- B <- C

 
A is at top

 
B is subtended to A

 
C is subtended to B

When you provide VPI/VCI value pairs for example, S=src & D=Dst), then three PVCs are created in the three nodes, as follows:

 
1. S <-> D in C

 
2. D <-> D in B

 
3. D <-> D in A

Setting the DSLAM IOS Password

Before you configure a subtend system, you must set the IOS passwords so that CDM can create a PVC and discover the subtend topology. You only need to do this procedure if you use autodiscovery when you deploy the DSLAMs.

Complete the following steps to set the IOS passwords.

Step 1 From the left side of the Map Viewer window within the Physical view, right-click the chassis for which you want to set up a subtend configuration to access the object menu.

Step 2 Choose Cisco DSL Manager > Chassis > Administration > IOS Settings.

The Management Information window opens. (See Figure 5-4.)

Figure 5-4 Management Information Window—IOS/Command Line Security Tab

Step 3 In the IOS Host object list, select the DSLAM chassis that you want to configure as a parent host.

Step 4 Click the IOS/Command Line Security tab.

Step 5 In the Login Password field, enter the password that you will use to login to the DSLAM, for example, via Telnet.

Step 6 In the Confirm Login Password field, enter the login password again.

Step 7 In the Exec Password field, enter the password that you will use after the enable command.

Step 8 In the Confirm Exec Password field, enter the executive password again.

Step 9 Click Save Locally.

Preparing IOS Configurations

This section includes the following topics:

When you set up an ATM subtend configuration through CDM, you must first use the IOS CLI to prepare each subtended DSLAM chassis to be configured by CDM. Then use CDM to connect all the DSLAMs in the subtend configuration.

Before you can connect any of the DSLAMS, you need to determine which connections will be used as the trunk lines for both the parent DSLAM and each of its children. After you have defined these trunk lines for every DSLAM in the subtend topology, use the CDM Subtend Configuration window to connect the DSLAM. CDM can only connect the DSLAM; CDM does not designate which IMA groups will use the trunk in each DSLAM.

The following sections provide instructions to complete these tasks.

Note You must designate either an IMA link or IMA group as the trunk for each child in the topology. You use IOS to disable the DS3 line for each child; therefore you should not designate a DS3 or OC-3 connection as the trunk for a child DSLAM. The IMA links between DSLAMs serve as the connections. You can designate a DS3 or an OC-3 connection as a trunk only for a parent DSLAM.

The following sections provide instructions to complete these tasks.

Note You can also use the IOS CLI neighbor activate command to determine the IP address of DSLAMS that are in parent and children relationships. Refer to the Command Reference for Cisco DSLAMs with NI-2 guide for information on using the neighbor commands.

Creating a Child DSLAM Using Telnet

This section describes how to use a telnet session to create a child DSLAM.

Note Before you create any children, be sure that the hardware is physically connected according to the desired topology.

To create a child DSLAM chassis using a Telnet session from CDM, complete the following steps:

Step 1 From the left side of the Map Viewer window, right-click the chassis name that you want to configure as the child.

The icon that represents that DSLAM displays on the right side of the Map Viewer window.

Step 2 Right-click the chassis icon to access the object menu.

Step 3 Choose Technology Specific Tools > Initiate Telnet Session.

A Telnet window opens.

Step 4 Enter your password.

Step 5 Enter the exec password.

Step 6 At the prompt, enter en to gain access to the topology network.

Step 7 Enter the IOS security password.

Step 8 Disable the DS3 connection (atm 0/1) for the child chassis by entering the following commands:

config t
int atm 0/0
shut

Step 9 Deactivate the T1 (atm 0/2 to 0/9) connection that you want to designate as the trunk for this child by entering the following commands:

config t
int atm 0/x

Where x is the interface number of the T1 line (0/2 to 0/9). See Figure 5-5 for a diagram of Cisco 6015 T1 line interface addresses.

shut
end

Figure 5-5 interface Addresses for Cisco 6015 Chassis T1 Lines

Step 10 Designate the selected T1 connection as the trunk for the child by entering the following commands:

configure terminal
atm ni2-switch trunk ATM0/x

Where x is the interface number of the T1 line (0/2 to 0/9).

end

Step 11 Reactivate the T1 connection by entering the following commands:

config t
int atm 0/x

Where x is the interface number of the T1 line (0/2 to 0/9).

no shut

Step 12 Write the configuration to NVRAM.

Step 13 Repeat Step 8 through Step 12 for each child chassis.

Step 14 To end the telnet session, enter the following command:

exit

When you have created all children chassis, continue with the "Connecting the Children DSLAMs" section. Also, see the "Using Inverse Multiplexing over ATM on Cisco 6015, 6160, and 6260 DSLAMs" section for information about setting up the IMA links.

Connecting the Children DSLAMs

After you have established the trunk lines for each child, use CDM to connect each child to the parent DSLAM. As you connect each child to the parent, an icon that represents that child displays in the Map Viewer window.

To connect a child to the parent DSLAM, complete the following steps:

Step 1 From the left side of the Map Viewer window within the Subtend view, right-click the parent DSLAM to which you want to connect a child.

Step 2 Choose Cisco DSL Manager > Subtend > Subtend Configuration from the object menu.

The Subtend Configuration window opens. (See Figure 5-6.)

Figure 5-6 Subtend Configuration Window

The DSLAM chassis that you have chosen to be the parent displays in the top list box on the left side of the window. After CDM discovers the subtend interfaces that you set up in the "Creating a Child DSLAM Using Telnet" section (when you click Discover in Step 3 below), the interfaces display in the lower list box on the left.

Note Do not manually enter an IP address in the neighborIPAddress fields. CDM provides the IP address of each child as it discovers and connects each child.

Step 3 Click Discover.

CDM discovers all the children (the subtend interfaces that you set up in the "Creating a Child DSLAM Using Telnet" section) and displays them in the lower list box on the left side of the window.

Step 4 Click the interface of the child DSLAM in the lower list box that you want CDM to connect to the parent DSLAM.

Step 5 Click Discover; or, for NI-1 configurations, click Connect.

The IP address of the child chassis displays in the neighborIPAddress field.

Step 6 Repeat Step 4 and Step 5 for each child chassis that you want to connect to the parent chassis.

Deploying a Parent DSLAM

You deploy a parent Cisco DSLAM by using the same basic procedure that you use to deploy any other chassis. You also set up profiles and preprovision the line cards as you would in any DSLAM. This section summarizes the steps for deploying a parent DSLAM, as follows:

Step 1 From the left side of the Map Viewer window, under the Physical Site view, right-click to access the object menu.

Step 2 Choose Deployment > Deploy Cisco DSLAM.

The Deployment Wizard window opens.

Step 3 Follow the instructions in the series of Deployment Wizard windows to deploy the parent DSLAM.

Note See the "Manually Deploying a Cisco DSLAM Chassis" section for instructions to deploy a DSLAM.

The newly deployed parent chassis displays under the site to which you deployed it as CiscoDSLAMUnit-[Name of TopShelf DSLAM Chassis]. Next you must commission the newly deployed parent chassis, as follows:

Step 4 Right-click CiscoDSLAMUnit-[Name of TopShelf DSLAM Chassis] to access the object menu.

Step 5 Choose Cisco DSL Manager > Chassis > Configuration.

The Chassis Configuration window opens.

Step 6 If more than one chassis is listed in the list box on the left of this window, highlight the name of the chassis you want to commission by clicking it.

Step 7 Click Commission at the bottom of the window to commission the newly deployed parent chassis.

Step 8 After CDM successfully commissions the parent DSLAM chassis, you can close this window.

You can see the populated parent DSLAM on the right side of the Map Viewer window. Next you must update the parent DSLAM so that it recognizes the children DSLAM chassis.

Using CDM to Configure a Subtend System

CDM supports the following subtend management capabilities:

You can connect two DSLAMs into a subtend configuration.
You can disconnect two DSLAMs from a subtend configuration.
CDM discovers the topology. For a given DSLAM, CDM discovers the entire topology of all DSLAMs that are connected in a subtend relationship. (See the "Connecting the Children DSLAMs" section.)
You can create a subtend PVC.
You can delete a subtend PVC.

Discovering the System Topology of a Subtend Configuration

This section includes instructions for updating and discovering subtend topology and applies only to a configuration in which an NI-1 subtends an NI-2.

Note The parent DSLAM and any children DSLAMS, must be physically connected before you update the topology.

Complete the following steps to update the topology for a selected subtend DSLAM configuration.

Step 1 From the left side of the Map Viewer window, within the Component Managed view, right-click the CiscoDSLAMUnit [name of parent chassis] that you have deployed to access the object menu.

Step 2 Choose Cisco DSL Subtend Manager > Subtend > Subtend Configuration.

The Subtend Configuration window opens. (See Figure 5-7.)

Figure 5-7 Subtend Configuration Window

Step 3 From the list box of chassis on the left side of the window, click the chassis whose topology you want to update.

Step 4 Click Discover to initiate discovery of all DSLAMS that are connected to the DSLAM that you selected from the list box.

Step 5 From the list box on the left of network interfaces, click the trunk interface.

In the Subtend Configuration area, the Interface Type field displays "trunk." The neighborIPAddress field displays the IP address of the subtend interface on the parent DSLAM.

Step 6 From the list box on the left, click the parent chassis (this is the trunk).

Step 7 From the left side of the Map Viewer window, within the Subtend hierarchy view, right-click the name of the network interface for the child chassis.

This DSLAM appears as a child of the parent DSLAM subtend interface.

Setting Up a Subtend Configuration Using an NI-2 DSLAM as Parent and NI-1 DSLAMs as Children

CDM supports a subtend configuration in which an NI-2 DSLAM is the parent of DSLAMs that have NI-1 cards. To set up this type of subtend configuration, complete the following steps. In this type of configuration, the subtend interface of the NI-2 card is connected to the trunk interface of the NI-1 card.

Step 1 From the left side of the Map Viewer window, right-click the CiscoDSLAMUnit [name of parent chassis] that you have deployed to access the object menu.

Step 2 Choose Cisco DSL Subtend Manager > Subtend > Subtend Configuration.

The Subtend Configuration window opens. (See Figure 5-8.)

Figure 5-8 Subtend Configuration Window

Step 3 From the top list box, highlight the name of the parent DSLAM.

The Interface Type field in the Subtend Configuration area displays "trunk" for the parent chassis interface and displays "subtend" for the child chassis interface.

Step 4 From the lower list box that displays network interfaces, click the interface of this DSLAM chassis.

Step 5 In the Subtend Configuration area neighbor IP Address field, enter the IP address of the child NI-1 DSLAM chassis that you want the parent DSLAM to subtend.

Note When configuring an NI-2 parent DSLAM with NI-2 child DSLAMS, you do not need to use the Subtend Configuration area in this window.

Step 6 Click Connect.

CDM connects the child NI-1 DSLAM to the parent NI-2 DSLAM.

Note DSLAMs that are configured with NI-2 cards support the interim link management interface (ILMI) ATM specification. When two NI-2 DSLAMS are connected in a subtend relationship, CDM automatically discovers the neighbor IP address. You do not need to explicitly set up the connection when configuring an NI-2 subtended DSLAM as you do with an NI-1 subtended system. One consequence of ILMI support is that you are unable to disconnect a subtend connection. As long as the DSLAMs are physically connected, the connection is always present.

Disconnecting Two DSLAMs from a Subtend Configuration

To disconnect an NI-1 child DSLAM from an NI-1 or NI-2 parent DSLAM, complete the following steps:

Step 1 From the left side of the Map Viewer window, right-click the CiscoDSLAMUnit [name of parent chassis] that you have deployed to access the object menu.

Step 2 Choose Cisco DSL Subtend Manager > Subtend > Subtend Configuration.

The Subtend Configuration window opens. (See Figure 5-9.)

Figure 5-9 Subtend Configuration Window

Step 3 From the top list box, highlight the name of the parent chassis from which you want to disconnect a child chassis.

The Interface Type field in the Subtend Configuration area displays "trunk" for the parent chassis interface and displays "subtend" for the child chassis interface.

Step 4 From the list box of network interfaces on the left, click the interface of the child chassis.

Step 5 In the Subtend Configuration area neighborIPAddress field, enter the IP address of the child NI-1 DSLAM chassis that you want to disconnect.

Step 6 Click Disconnect.

CDM disconnects the child NI-1 DSLAM from the parent NI-2 DSLAM.

Note DSLAMs that are configured with NI-2 cards support the interim link management interface (ILMI) ATM specification. When two NI-2 DSLAMS are connected in a subtend relationship, CDM automatically discovers the neighbor IP address. You do not need to explicitly set up the connection when configuring an NI-2 subtended DSLAM as you do with an NI-1 subtended system.

One consequence of ILMI support is that you are unable to disconnect a subtend connection. As long as the DSLAMs are physically connected, the connection is always present. When you disconnect an NI-2 parent DSLAM that has NI-2 children DSLAMS, you do not use the Subtend Configuration area in the Subtend Configuration window. You only need to click Discover for CDM to discover whether the connection is present or absent.

Setting Up Subtended Subscribers

This section includes the following topics:

To set up subscribers in a subtend Cisco DSLAM, you create settings for the child DSLAM subscribers in the same manner as you would any subscribers, by creating and applying profiles. The parent and child chassis and line cards should be present on your system. The parent chassis displays on the left side of the Map Viewer window.

Setting Subscriber PVCs on a Subtend System

Complete the following steps to set PVCs for subscribers on a subtend system. See the "Guidelines for Configuring ATM Virtual Channels" section for more information on setting PVCs.

Step 1 Right-click the chassis on which you are going to set subtend subscribers and choose Cisco DSL Manager > Chassis > Administration > IOS Settings from the object menu.

Step 2 Click the IOS/Command Line Security tab and verify that both the IOS login and exec passwords are set, then close this window.

Step 3 From the left side of the Map Viewer window, under the Subtend view, click on the chassis object for which you want to set a subtend subscriber PVC.

Step 4 Right-click this interface name, for example DMT-4-1, to access the object menu.

Step 5 Choose Cisco DSL Manager > Subtend > Add Subtend PVC.

The Add Subtend PVC window opens. (See Figure 5-10).

Figure 5-10 Add Subtend PVC Window

Step 6 If you click the chassis to open this window, the names of many line cards display in the list box on the left. In that case, highlight the line card for which you want to create a subtend PVC.

Note For an NI-1 node, the DSL interface should have a subscriber already assigned to it before you can add the subtend PVC.

Step 7 Enter a unique ID in the Subscriber Subtend PVC ID field.

Note See the "Guidelines for Configuring a Subtend System" section for more information on setting PVCs.

Step 8 Enter appropriate settings in the Source area as follows:

a. In the VPI and VCI fields, enter the values to specify ingress for the subtend network.

b. Alternatively, you can use the down arrow in the Auto Allocate field to select Yes.

Note Setting Auto Allocate to Yes is valid only for NI-2 subtend DSLAMS and allows CDM to automatically allocate this pair of values for the subtend network ingress.

Step 9 Enter appropriate settings for the Destination VPIs and VCIs, as follows:

a. In the VPI and VCI fields, enter the values to specify egress for the subtend network.

b. Alternatively, you can use the down arrow in the Auto Allocate field to select Yes.

Note Setting Auto Allocate to Yes is only valid for NI-2 subtend DSLAMS, and allows CDM to automatically allocate this pair of values for the subtend network egress.

Step 10 For NI-2 subtend DSLAMs, in the NI2 Specific area ATM Profile field, enter the QoS profile that you want CDM to use for the NI-2 PVC.

Use the tooltips for guidance.

Note If you fail to enter a QoS profile in this field, CDM uses the default profile.

Step 11 For NI-1 subtend DSLAMs, set the following values in the NI1 Specific area of the Add Subtend PVC window (see Figure 5-10):

Note You must set these values for an NI-1 subtend chassis; CDM does not assign default values to these parameters.

a. Use the down arrow in the Queue Priority field to select one of the following:

Voice
Voice Signalling
Data, which is the recommended setting

b. Use the down arrow in the Path Latency field to select Fast or Interleaved.

Step 12 Click Add.

An Action Report window opens to inform you whether this procedure is successful. When CDM has successfully added the PVC, the left side of the Map Viewer window hierarchy view displays the Subtend PVC view. Below this, CDM displays the following information for that specific PVC:

CiscoSubtendPVC_<count of the node in the subtend path from the leaf node>_<Subtend PVC ID>

The leaf node is the lowest level DSLAM in the subtend network, and the root node (root of the subtend network) is the highest level DSLAM in the subtend network. You set the Subtend PVC ID in the Create Subtend PVC window. For example, create a subtend PVC with ID of Bubba on 172.21.177.15 in the following subtend network:

172.21.177.35 (root node) CiscoSubtendPVC_3_Bubba

172.21.177.45 CiscoSubtendPVC_2_Bubba

172.21.177.15 (leaf node) CiscoSubtendPVC_1_Bubba

For NI-2 node PVC objects, you can also see this hierarchy view below the Component Managed View.

Note The NI-1 controller does not add Cisco EMF objects for the PVCs that CDM creates for a particular parent DSLAM. You must verify that individual PVC components are indeed in the node by using a MIB browser or the command line interface (CLI).

The PVC connections that you add display in the map view hierarchy below the interface name. For example:

DMT-1-4
   CiscoSubtendPVC_1_(2)
      CiscoSubtendPVC_1_HighVCL
      CiscoSubtendPVC_1_LowVCL

The High VCL refers to the network side, and the Low VCL refers to the subscriber side.

Deleting Subtend PVCs

To delete a subtend PVC, complete the following steps:

Step 1 From the left side of the Map Viewer window, within the Subtend PVC view, right-click the subtend PVC chassis from which you want to delete a subtended PVC.

Step 2 Choose Cisco DSL Manager > Delete Subtend PVC from the object menu.

The Delete Subtend PVC window opens. (See Figure 5-11.)

Figure 5-11 Delete Subtend PVC Window

Step 3 In the list box on the left, click the subtend PVC that you want to delete.

Step 4 Click Delete.

An Action Report window opens and displays the details of the deletion process. To verify that CDM has deleted the PVCs, check the Subtend PVC hierarchy view on the left side of the Map Viewer window. All the children from the Subtend PVC that you deleted should no longer display. Any NI-2 PVC objects also should no longer display from the Component Managed view. Verify that CDM has deleted all Subtend PVCs from the node by using an SNMP browser or the CLI.

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