Table Of Contents

Configuring the ACNS Network for Content Distribution

Preparing for Channel Distribution of Content

Creating and Modifying Locations

Configuring Channel Elements

Creating and Modifying Content Providers

Deleting Content Providers

Creating and Modifying Websites

Deleting Websites

Configuring Channels for Channel Distribution

Creating and Modifying Channels

Creating a Channel

Modifying a Channel

Designating the Root Content Engine

Adding and Removing Content Engines from Channels

Adding and Removing Device Groups from Channels

Deleting Channels

Viewing Channels

Distributing Content Through Unicast Replication

Configuring Location Leader Preference and Forwarder Selection Probability

Configuring the Forwarder Lookup Level

Configuring the Content Metadata Poll Interval Multiplier

Configuring Unicast Content Distribution Through a NAT Firewall

Commands Related to Distribution Settings

Distributing Content Through Multicast Replication

About IP Multicasting

About Multicast Clouds

About Configuring Carousel Passes

About Multicast Logging Enhancements

About the NACK Interval Multiplier

About the File Resend or Stop Feature

About Configuring Multicast Forward Error Correction

About Configuring the Multicast Sender Delay Interval

Configuring PGM and File Transmission Parameters Using Multicast Expert Mode

About Configuring Channel Options for Content Replication

Enabling Content Engines for Multicasting

Configuring Multicast Cloud Properties

Modifying a Multicast Cloud

Deleting Multicast Clouds

Viewing Multicast Clouds

Assigning Content Engines to a Multicast Cloud

Assigning and Removing Multicast Clouds from Channels

Verifying the Multicast Configuration

Commands Related to Multicasting

Troubleshooting the Distribution Hierarchy

Where to Go Next

Configuring the ACNS Network for Content Distribution

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Once the hardware devices that make up your ACNS network are properly installed and configured, you are ready to use the information contained in this chapter to organize those devices into an ACNS network that is capable of serving pre-positioned content or live media to end users.

In the ACNS network, content is replicated through a channel distribution architecture. Content in channels can be transmitted by unicast pull or, if multicasting is enabled, by multicast push. This chapter provides information about configuring the network elements for channel distribution and multicasting. It contains the following sections:

•Preparing for Channel Distribution of Content

•Configuring Channel Elements

•Configuring Channels for Channel Distribution

•Distributing Content Through Unicast Replication

•Distributing Content Through Multicast Replication

•Troubleshooting the Distribution Hierarchy

•Where to Go Next

Figure 5-1 shows the task flow for configuring channels for unicast and multicast content distribution.

Figure 5-1 Distributing Content in the ACNS Network

Preparing for Channel Distribution of Content

Channel distribution describes the manner in which content is distributed from the origin web server to all the Content Engines that are subscribed to the content or, more specifically, assigned to the channel that represents that group of content objects. (For an overview of the channel distribution architecture, see the "Content Acquisition and Distribution Architecture" section on page 1-10.)

In preparing for channel distribution of content, you should configure the following network elements in this order:

1. Locations—Creating and Modifying Locations

2. Content providers—Creating and Modifying Content Providers

3. Websites—Creating and Modifying Websites

4. Channels—Creating and Modifying Channels

Creating and Modifying Locations

Locations are set up in the Content Distribution Manager GUI, and they organize and group Content Engines into virtual networks for distribution of content through channels.

Locations need to be configured before you can activate Content Engines and Content Routers and bring them online in the ACNS network. A default location is created automatically when you use the Content Distribution Manager Quick Start tool to activate your devices. If you wish to create a new location or modify the default location, use the procedure in this section.

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Note For more information on working with locations, see the "Working with Device Locations" section on page 13-5.

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To create a new location, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Devices > Locations. The Locations window appears. (See Figure 5-2.)

Figure 5-2 Locations Window

Step 2 Click the Create New Location icon in the taskbar. The Creating New Location window appears. (See Figure 5-3.)

Figure 5-3 Creating New Location Window

Step 3 Enter a location name in the Name field.

Step 4 Choose a parent location (or choose None) from the Parent Location drop-down list.

A location with no parent location assigned is a level 1 location. A location with a level 1 parent becomes a level 2 location, and so forth. The location level is displayed after you choose a parent location (or choose None) and click Submit to save the configuration.

Step 5 If you wish, enter comments about the location in the Comments field.

Step 6 Click Submit.

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To modify an existing location, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Devices > Locations. The Locations window appears. (See Figure 5-2.)

Step 2 Click the Edit icon next to the name of the location you want to modify.

Step 3 Change the location name, parent location, or description as needed.

Step 4 To save the changes, click Submit.

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Configuring Channel Elements

This section describes how to create and modify content providers and websites. If you wish to associate a company name with its website, you must create a content provider directory listing. Websites must be set up in your ACNS network before you can create channels.

Creating and Modifying Content Providers

When you are creating a channel, you must choose the name of a content provider from the Content Provider drop-down list, or you can choose None. To populate this list, you must create a directory listing with the name, address, and contact information of a content provider. Content provider listings are created in the Content Distribution Manager GUI.

To create a content provider listing, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Content Provider.

Step 2 Click the Create New Content Provider icon in the taskbar. The Creating New Content Provider window appears.

Step 3 Enter the company name. You also have the option to enter the address and contact information.

Step 4 Click Submit.

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To modify a content provider listing, follow these steps:

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Step 1 Choose Services > Web > Content Provider, and click the Edit icon next to the content provider that you want to modify. The Modifying Content Provider window appears. (See Figure 5-4.)

Figure 5-4 Modifying Content Provider Window

Step 2 Enter any changes you want to make to the company name and address, the primary contact information, or the optional secondary contact information.

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Note Clicking Cancel returns you to the Modifying Channel window.

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Step 3 Click Submit.

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Deleting Content Providers

You can delete content providers as needed.

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Note When you delete a content provider, all websites and channels that have been added for the content provider are also deleted.

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To delete a content provider, follow these steps:

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Step 1 Choose Services > Web > Content Provider, and click the Edit icon next to the content provider that you want to delete. The Modifying Content Provider window appears. (See Figure 5-4.)

Step 2 Click the Trash icon. You are prompted to confirm your decision.

Step 3 Click OK to execute your request.

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Creating and Modifying Websites

Websites must be defined in your ACNS network before you can create channels. Channels then map the website content to the Content Engines in your ACNS network. The Content Distribution Manager GUI allows you to define websites in your ACNS network. A website listing must provide the URL for the origin web server that stores the website content.

To create a website, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Websites.

Step 2 Click the Create New Web Site icon in the task bar. The Creating New Web Site window appears. (See Figure 5-5.)

Figure 5-5 Creating New Web Site Window

Step 3 Enter the name, content provider (or choose None), and origin server for the website. (See Table 5-1 for a description of website properties.)

Table 5-1 Website Properties 

Property	Description
Name*1	Unique name for the website.
Content Provider*	Name of the company that is providing the content. The default is None. Note The content provider must be predefined in the Creating New Content Provider window. (See the "Creating and Modifying Content Providers" section.)
Origin Server*	Fully qualified domain name of the origin server where the content resides.
Request Routed FQDN	Fully qualified domain name to route requests when using a Content Router.
WMT Authentication Type	Basic authentication or NTLM authentication. Note This setting must match the setting on the origin server for the stream to play correctly.
Pure DNS Routing	When checked, uses only the DNS server specified in the incoming packets for DNS requests. This causes the DNS caching name service to determine the original destination IP address. When unchecked (the default), allows the DNS caching name service to use the servers configured on the Content Engine and allows WCCP interception of DNS requests.
Ignore case of URLs during playback	When checked, allows case-insensitive URL matching during the playback of pre-positioned content.

1 * = required field. All other fields are optional.

Step 4 If you wish, choose a WMT authentication type from the WMT Authentication Type drop-down list.

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Note This setting must match the setting on the origin server for the stream to play correctly.

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Step 5 Check the Pure DNS Routing check box if you want to use only the DNS server specified in the incoming packets for DNS requests. This causes the DNS caching name service to determine the original destination IP address.

Step 6 Check the Ignore case of URLs during playback check box if you want to allow case-insensitive URL matches between the acquisition URL and the publishing URL.

Step 7 To save the configuration, click Submit.

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To modify a website, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Websites.

Step 2 Click the Edit icon of the website that you want to modify. The Modifying Web Site window appears.

Step 3 Enter changes to the website data as needed.

Step 4 To save the changes, click Submit.

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Deleting Websites

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Note When you delete a website, all channels that have been added for the website are also deleted.

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To delete a website, follow these steps:

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Step 1 To delete a website, go to the Modifying Web Site window.

Step 2 Click the Trash icon. You are prompted to confirm your decision.

Step 3 To execute your request, click OK.

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Configuring Channels for Channel Distribution

Channel distribution describes the manner in which content is distributed from the origin web server to all the Content Engines that are subscribed to the content, or more specifically, assigned to the channel that represents that group of content objects. (For an overview of the channel distribution architecture, see the "Content Acquisition and Distribution Architecture" section on page 1-10.)

Creating and Modifying Channels

Channels map the content from a website to the devices in your ACNS network. When you create a channel, you first create a directory of your content providers and then provide URLs to their websites. (See the "Creating and Modifying Content Providers" section and the "Creating and Modifying Websites" section.)

Using the Content Distribution Manager, you can create, modify, or remove channels from the ACNS network. Keep in mind that modifying channels can affect the availability of content on the ACNS network.

You create a channel by defining the following items:

•Name

•Content provider

•Website

•Channel quota

•Channel properties (channel priority, multicasting)

Creating a Channel

To create a channel, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels. The Channels window appears, listing all the channels in your ACNS network.

Step 2 Click the Create New Channel icon in the taskbar. The Creating New Channel window appears. (See Figure 5-6.)

Figure 5-6 Creating New Channel—Channel Properties

Step 3 Use the fields provided under the Channel Information heading to configure the channel name and website with which the channel is associated.

Step 4 Use the fields provided under the Acquisition and Distribution Properties heading to configure channel priority, enable multicasting, or disable encryption. (See Table 5-2 for a description of the channel properties fields. Required fields are indicated by an asterisk in the GUI and in Table 5-2.)

Table 5-2 Channel Properties 

Property	Description
Channel information
Name*1	Unique name for the channel.
Request Routed FQDN	Fully qualified domain name to route requests. Read only. This field is configured from the Creating New Web Site window (see the "Creating and Modifying Websites" section) and is used if you have a Content Router in your network.
Origin Server	Fully qualified domain name of the origin server. Read only. This field is configured from the Creating New Web Site window. (See the "Creating and Modifying Websites" section.)
Content Provider*	Name of the content provider associated with this channel. The default is None. To add a new content provider to this drop-down list, see the "Creating and Modifying Content Providers" section.
WebSite*	Name of the website belonging to the content provider that is associated with this channel. Note The website must be predefined in the Creating New Web Site window.
Live Channel	When checked, creates a live channel to distribute live or scheduled programs to the Content Engines associated with this channel. This channel does not have a related manifest file and cannot be used to distribute file-based content as regular channels do. The live channel learns about a live program through a program file that describes the attributes of the program. Checking this check box disables the Channel Quota field and fields in the Acquisition and Distribution Properties section.
Channel Quota*	Maximum content storage size in megabytes for pre-positioning content for this channel. See the "Channel Quota" section on page 6-26.
Acquisition and Distribution Properties
Distribution Priority*	Content distribution priority setting. Options are High, Normal, and Low. The default is Normal. See the "Distribution Priority" section on page 6-25
Multicast only, Multicast/Unicast, or Unicast only*	Enables multicast-only, multicast transmission with failover to unicast, or unicast-only transmission. See the "About IP Multicasting" section.
Use null cipher for Distribution	When checked, disables encryption for distribution.
Root CE failover/fallback grace period*	Number of minutes before a root Content Engine failover or a temporary root Content Engine fallback occurs. The range is 20 to120 minutes. (See the "About the Root Content Engine Failover and Fallback Grace Period Setting" section.)
Never	When checked, Content Engine failover or fallback will never occur.
Use system-wide settings for QoS for unicast data	When checked, applies the system-wide QoS settings for unicast data to the channel. (See the "Configuring System-Wide Distribution QoS Settings Based on Channel Priority" section on page 20-16.) To override the system-wide QoS settings with channel-specific QoS values, leave this check box unchecked, and configure the channel-specific QoS values in the QoS value for unicast data field.
QoS value for unicast data*	Configures a Differentiated Services Code Point (DSCP) value for the QoS. (See Table 5-3.) If you choose Other, enter a decimal value in the corresponding field. Note Cisco ACNS software allows you to set QoS settings on a per-channel basis and a system-wide global configuration basis. Channel settings take precedence over global settings.

1 * = required field. All other fields are optional.

Step 5 If you wish to add comments regarding the channel for the benefit of other Content Distribution Manager users, enter them in the Comments field provided.

Step 6 To save the channel configuration, click Submit.

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Table 5-3 lists and describes the DSCP values for unicast QoS.

Table 5-3 DSCP Values

DSCP value	Description
af11	Sets packets with AF11 dscp (001010)
af12	Sets packets with AF12 dscp (001100)
af13	Sets packets with AF13 dscp (001110)
af21	Sets packets with AF21 dscp (010010)
af22	Sets packets with AF22 dscp (010100)
af23	Sets packets with AF23 dscp (010110)
af31	Sets packets with AF31 dscp (011010)
af32	Sets packets with AF32 dscp (011100)
af33	Sets packets with AF33 dscp (011110)
af41	Sets packets with AF41 dscp (100010)
af42	Sets packets with AF42 dscp (100100)
af43	Sets packets with AF43 dscp (100110)
cs1	Sets packets with CS1(precedence 1) dscp (001000)
cs2	Sets packets with CS2(precedence 2) dscp (010000)
cs3	Sets packets with CS3(precedence 3) dscp (011000)
cs4	Sets packets with CS4(precedence 4) dscp (100000)
cs5	Sets packets with CS5(precedence 5) dscp (101000)
cs6	Sets packets with CS6(precedence 6) dscp (110000)
cs7	Sets packets with CS7(precedence 7) dscp (111000)
default	Sets packets with default dscp (000000)
ef	Sets packets with EF dscp (101110)

About the Root Content Engine Failover and Fallback Grace Period Setting

Cisco ACNS software supports failover of the root Content Engine to another Content Engine in your network when the root Content Engine is down or not functioning.

The secondary Content Engine polls the root Content Engine at preset intervals to make sure that the root Content Engine is functioning properly. If the polling of the root Content Engine does not return a positive response, the secondary Content Engine waits for the grace period and then takes over as the root Content Engine until the end of the grace period. The time interval before a Content Engine takes over as the root Content Engine is set by using the Root CE failover/fallback grace period option in the Create a New Channel window. You can choose a time interval between 20 and 120 minutes using increments of 10.

The acting root Content Engine keeps polling the original root Content Engine to see if the root Content Engine is back online. When the acting root Content Engine obtains a positive response from the original root Content Engine, the acting root Content Engine waits for the fallback grace period and then goes back to its original mode if the positive responses are consistent. When the acting root Content Engine goes back to its original mode, the original root Content Engine takes over the duties of the root Content Engine. Both failover and fallback grace period values are configured in the same field, and use the same value.

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Note To configure manifest file and manifest proxy information for a channel, see the "Configure Manifest File and Proxy Information for the Channel" section on page 6-27.

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Modifying a Channel

To modify a channel, follow these steps:

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Step 1 Choose Services > Web > Channels to get to the Channels window.

Step 2 Click the Edit icon next to the name of the channel that you want to change. The Modifying Channel window appears. (See Figure 5-7.)

Figure 5-7 Modifying Channel Window

Step 3 Make changes to the channel configuration as needed.

To modify the Content Provider or WebSite fields, click the Edit Content Provider or Edit Website button. (See the "Configuring Channel Elements" section.)

Step 4 To effect any changes you have made to the channel configuration, click Submit. The Content Distribution Manager updates the channel information.

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After you create a new channel, you need to designate a root Content Engine for the channel and then assign Content Engines or device groups to the channel. Although designating a root Content Engine and assigning devices to the channel can be done from the same GUI window, the following sections break out these steps into separate procedures.

Designating the Root Content Engine

The root Content Engine is the one Content Engine that is authorized to go directly to the origin web server for content. The root Content Engine then publishes the content to other Content Engines in the channel. You must designate a root Content Engine for content distribution to take place.

To designate one Content Engine to be the root Content Engine for a channel, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

Step 2 Click the Edit icon next to the name of the channel to which you want to assign a root Content Engine. The Modifying Channel window appears. (See Figure 5-7.)

Step 3 You can designate a root Content Engine when assigning device groups to the channel or when assigning Content Engines to the channel.

•In the Contents pane, click Assign Content Engines. The Content Engine assignment to Channel window appears. Click the Assign button next to the name of the Content Engine, or click the Assign All Content Engines icon in the task bar and proceed to Step 4.

•Alternatively, click Assign device groups. The Device Group assignments for Channel window appears. Click the Assign button next to the name of the Content Engine, or click the Assign All Device Groups icon in the task bar and proceed to Step 4.

Step 4 Choose a Content Engine from the Root CE drop-down list. This list contains all of the Content Engines currently assigned to the channel in which you are working.

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Note If there are no Content Engines or device groups assigned to the channel, no choices appear in the Root CE drop-down list. To add Content Engines to a channel, see the next two sections, "Adding and Removing Content Engines from Channels," and "Adding and Removing Device Groups from Channels."

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Step 5 Click Submit.

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Adding and Removing Content Engines from Channels

To add or remove Content Engines from a channel, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

Step 2 Click the Edit icon next to the name of the channel that you want to change. The Modifying Channel window appears. (See Figure 5-7.)

Step 3 In the Contents pane, choose Assign Content Engines. The Content Engine assignments for Channel window appears.

This window displays a list of the Content Engines in all locations to which they have been assigned, as well as the unreserved and total disk space in the cdnfs partition for each Content Engine. Content Engines can be added to the channel from more than one location.

Step 4 Click the Assign icon (blue cross mark) next to the name of the Content Engine that you wish to associate with the channel. Alternatively, you can click the Assign all Content Engines icon in the taskbar to perform a bulk addition of all Content Engines in various locations to the channel.

Step 5 To add the Content Engines to the channel, click Submit. Upon submission, a green tick mark appears next to the assigned Content Engine.

Step 6 To remove Content Engines, click the Unassign icon (green tick mark) next to the name of the Content Engine that you want to remove from the channel. Alternatively, you can click the Unassign all Content Engines icon in the taskbar to perform a bulk removal of all Content Engines from the selected channel.

Step 7 To remove the Content Engines from the channel, click Submit. The list of Content Engines in the channel shows a blue cross mark next to the name of the removed Content Engine.

If the Content Engine that you removed was the root Content Engine, and if there is at least one Content Engine still assigned to the channel, you must designate a new root Content Engine. (See the "Designating the Root Content Engine" section.)

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Adding and Removing Device Groups from Channels

Device groups are assigned to channels through the Content Distribution Manager GUI. Whenever a channel is created and additional device groups are added, or when a channel assignment to the device group changes, devices in the group are notified of their assignment to the associated channel.

The relationship between device groups and channels is many-to-many. A channel can have multiple device groups and device groups, in turn, can belong to multiple channels.

To add a device group from a channel, follow these steps.

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

Step 2 Click the Edit icon next to the name of the channel to which you want to assign a device group or from which you want to remove a device group. The Modifying Channel window appears. (See Figure 5-7.)

Step 3 In the Contents pane, choose Assign Device Groups. The Device Group assignments for Channel window appears, displaying the minimum unreserved disk space in the cdnfs partition. An asterisk (*) under the Note column denotes that there is no free space available to be assigned to this channel. A double asterisk (**) under the Note column denotes that Content Engines associated with this device group have been already assigned to this channel.

Step 4 Click the Assign icon (blue cross mark) next to the name of the device group that you wish to associate with the channel. A green tick mark appears next to the assigned device group after you click Submit. Alternatively, you can click the Assign all Device Groups icon in the taskbar to perform a bulk addition of all device groups in various locations to the channel.

Step 5 To add the device groups to the channel, click Submit.

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Note When a device group is removed from a channel, the Content Engines that were part of the device group are also removed from the channel. When a device is removed from a device group containing the original channel assignment, this device is also unassigned from channels. Similarly, when a channel is removed from a device group, the associated devices are also unassigned.

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To remove a device group from a channel, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

Step 2 Click the Edit icon next to the name of the channel to which you want to assign a device group or from which you want to remove a device group. The Modifying Channel window appears. (See Figure 5-7.)

Step 3 In the Contents pane, choose Assign Device Groups. The Device Group assignments for Channel window appears, displaying the minimum unreserved disk space in the cdnfs partition. An asterisk (*) under the Note column denotes that there is no free space available to be assigned to this channel. A double asterisk (**) under the Note column denotes that Content Engines associated with this device group have been already assigned to this channel.

Step 4 Click the Unassign icon (green tick mark) next to the name of the device group that you want to remove from the channel. Alternatively, you can click the Unassign all Device Groups icon in the taskbar to perform a bulk removal of all device groups from the selected channel.

Step 5 To remove the device groups from the channel, click Submit. The browser window refreshes, listing the updated channels with a blue cross mark next to the unassigned device groups.

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Deleting Channels

To delete a channel, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

Step 2 Click the Edit icon next to the name of the channel that you want to delete. The Modifying Channel window appears. (See Figure 5-7.)

Step 3 Click the Trash icon. You are prompted to confirm your decision to delete the channel.

Step 4 Click OK to confirm your decision. The channel is removed from the ACNS network.

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Viewing Channels

To view all channels across your ACNS network, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

The Channels window appears, listing all the channels in your ACNS network.

The channel type and the website that is associated with each channel are displayed in the row for each channel.

Step 2 To sort the channels by type, website, status, or state, click the respective column heading.

Step 3 To print the channel display table, click the Printer icon.

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Viewing All Content Engines Assigned to a Channel

In the Content Distribution Manager GUI, a distinction is made between devices that are assigned directly to a channel or devices that are assigned through a device group. The assignments are tracked separately. For tracking purposes, the View all Content Engines assigned to Channel window displays all Content Engines assigned to a channel, regardless of whether they are assigned directly or through device groups.

To view the list of all Content Engines assigned to a channel, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Services > Web > Channels.

Step 2 Click the Edit icon next to the name of the channel that you want to view. The Modifying Channel window appears.

Step 3 In the Contents pane, choose List all assigned Content Engines. The View all Content Engines assigned to Channel window appears and lists all Content Engines assigned to the specified channel. Table 5-4 describes the information that is displayed in this window.

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Table 5-4 Content Engine Channel Assignment Information

Column Heading	Description
Content Engine	Name of the Content Engine assigned to the channel.
Directly Assigned	Indicates whether the Content Engine was assigned directly to the channel (Yes or No).
Assigned through device group	Indicates whether or not the Content Engine was assigned through a device group. If yes, then this column displays the name of the device group. If no, then this column displays the value Not Applicable (N/A).

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Distributing Content Through Unicast Replication

Once content is acquired from the origin server by the root Content Engine of a channel, it can be replicated through the channel either by unicast or multicast transmission. The basic channel distribution architecture provides for unicast content replication using a hop-by-hop, store-and-forward methodology with the forwarder Content Engines systematically selected on the basis of the manually configured location hierarchy.

To distribute content through unicast, the ACNS network automatically creates a unidirectional distribution tree for each channel. The root node of the tree is the root Content Engine of the channel, and each Content Engine subscribed to the channel is a node on the tree.

For each node, its parent node is also called its forwarder Content Engine. The algorithm for automatically designating the forwarder Content Engine is called the channel routing algorithm.

Three general rules in the current channel routing algorithm are as follows:

1. In each location for each channel, only one Content Engine fetches content from another location for that channel. We call this Content Engine the location leader of the channel. All other Content Engines in this location use the location leader as the forwarder for this channel. There can be only one location leader per channel per location. Note that within one location, different channels may have different location leaders.

The location leader is computed automatically by the channel routing algorithm. ACNS 5.4 software enables you to influence which Content Engines are chosen as location leaders by setting a priority level for individual Content Engines in the location. Content Engines are all set to the lowest priority by default. The Content Engine with the highest priority is more likely to be chosen as the location leader. (See the next section, "Configuring Location Leader Preference and Forwarder Selection Probability".)

Use the show distribution channel EXEC command to see which Content Engine is the current forwarder for a channel. The reason/status field in the command output shows why a Content Engine is unable find a forwarder. Use the show distribution forwarder-list EXEC command to see the forwarder selection order of a Content Engine for a channel.

2. The location leader finds a subscribed Content Engine from the closest location on the path toward the root Content Engine as its forwarder. If all the potential forwarders in a parent location are down (or unreachable) the location leader skips to the next location level in the hierarchy (towards the root Content Engine location) to find a forwarder.

ACNS 5.4 software allows you to set the number of levels that a location leader can search to find a forwarder. (See the "Configuring the Forwarder Lookup Level" section.)

You can also influence the selection of a forwarder by configuring the Content Engine with a distribution weight, by setting it to be used only as a last resort, or by taking it out of the forwarder list completely. The Content Engine configured with the heaviest weight has the highest probability of becoming the forwarder. (See the next section, "Configuring Location Leader Preference and Forwarder Selection Probability".)

3. If the location leader Content Engine fails for some time, another Content Engine in the location takes over as the location leader. If the root Content Engine fails, another Content Engine in the location takes over as the temporary root Content Engine.

When multicast transmission is desirable, channels and Content Engines can be enabled for multicasting.

(See also the "Configuring Weighted Load Balancing for Live Stream Splitting" section on page 9-35.)

Configuring Location Leader Preference and Forwarder Selection Probability

To configure the location leader preference and forwarder probability settings, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Devices > Devices.

Step 2 Click the Edit icon next to the name of the Content Engine that you want to configure.

Step 3 In the Contents pane, choose Prepositioning > Location Leader and Forwarder. The Location Leader and Forwarder Settings for Content Engine window appears.

Step 4 To configure the location leader settings, click and slide the control button on the scale to the priority level (1-20) that you want. The lower the number, the lower the priority. The Content Engine with the highest priority is most likely to be chosen as the location leader.

Step 5 To configure the forwarder settings, choose an option (Weighted, Last Resort, Never Use) by clicking one of the Forwarder Probability radio buttons.

If you choose Weighted, click and slide the control button on the scale to the weight (1-20) that you want. The Content Engine with the greatest weight is most likely to be chosen as the forwarder.

Step 6 To save the settings, click Submit.

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Configuring the Forwarder Lookup Level

To configure the forwarder lookup level, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Devices > Devices.

Step 2 Click the Edit icon next to the name of the Content Engine that you want to configure.

Step 3 In the Contents pane, choose Prepositioning > Distribution. The Distribution Settings for Content Engine window appears. (See Figure 5-8.)

Figure 5-8 Distribution Settings

Step 4 Click one of the Forwarder Lookup radio button options; chose Unlimited or chose Maximum, and enter a number to limit how many location levels the location leader can search to find a forwarder.

Step 5 To save the settings, click Submit.

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Configuring the Content Metadata Poll Interval Multiplier

Sender and receiver Content Engines exchange information before they transmit the actual content. This information is called metadata. Included in the metadata is the wait time between content updates (or the metadata polling interval), which the sender Content Engine sends to the receiver. The sender calculates this wait time based on a number of factors, such as the number of devices in the ACNS network or the number of receivers in the forwarder's queue. You can lengthen or shorten the wait time by configuring the content metadata poll interval multiplier on receiver Content Engines. This multiplier enables you to control how often receiver Content Engines notice changes in content. The polling interval that is calculated by the sender Content Engine will be either shorter or longer by a factor of the content metadata poll interval multiplier that you configure.

When the receiver Content Engine obtains the wait time from the sender, it multiplies the wait time by the value you specify in the multiplier. You can scale the unicast receiver Content Engine's next metadata poll interval down to 10 percent of normal or up to 10 times normal. For example, if you set the multiplier to 10 percent of normal, and the wait time between update polls is 120 seconds, the effective polling interval is shortened to 12 seconds (10 percent of normal or 0.1 x 120 is 12 seconds).

The higher the multiplier, the longer it takes for the receiver to be notified of changes in content and the less the network traffic that results from polling. On the other hand, the lower the multiplier, the less time it takes for the receiver to be notified of content changes, and the greater the network traffic that results from polling.

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Note The content metadata poll interval multiplier applies only to a unicast receiver Content Engine, which regularly polls for new content metadata from its forwarder.

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To configure the content metadata poll interval, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Devices > Devices.

Step 2 Click the Edit icon next to the name of the Content Engine that you want to configure.

Step 3 In the Contents pane, choose Prepositioning > Distribution. The Distribution Settings for Content Engine window appears. (See Figure 5-8.)

Step 4 Under the Distribution Settings heading, slide the Content Metadata Poll Interval Multiplier control either down or up to scale the unicast receiver Content Engine's next metadata poll interval.

Step 5 To save the settings, click Submit.

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Configuring Unicast Content Distribution Through a NAT Firewall

ACNS 5.4 software supports communication between two Content Engines that are located behind different NAT devices. Content Engines can be configured for unicast content distribution with a NAT address and port, as well as with a primary IP address and port.

For example, if a forwarder Content Engine is behind a NAT device, you can set its NAT address on the Content Distribution Manager GUI, and the Content Distribution Manager will propagate the forwarder Content Engine NAT address to all the devices in the ACNS network so that the receiver Content Engine can set up a connection with the forwarder using the NAT address.

NAT address configuration also supports the following types of communications between Content Engines and other devices in a centrally managed network:

•Receiver Content Engine polling for content metadata from a sender

•Unicast receiver polling for data files from a unicast sender

•Multicast receiver sending a negative acknowledgment (NACK) to a multicast sender

•Content Distribution Manager polling for configuration updates from Content Engines and Content Routers

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Note ACNS 5.4 software does not support communication between a primary multicast sender and a backup multicast sender through a NAT firewall.

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NAT configuration logic works in the following manner: A receiver Content Engine first attempts to contact a forwarder Content Engine using the Content Engine primary IP address. If the receiver cannot contact the forwarder Content Engine by using the primary IP address, the receiver attempts to contact the forwarder Content Engine using the Content Engine NAT IP address, if a NAT IP address has been configured. If the receiver successfully initiates communication with the forwarder using the NAT IP address, the receiver will retry the primary IP address periodically and fall back to using the primary IP address, if it becomes operational.

To configure a NAT IP address for a Content Engine, follow these steps:

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Step 1 From the Content Distribution Manager GUI, choose Devices > Devices.

Step 2 Click the Edit icon next to the name of the Content Engine for which you want to configure a NAT IP address. The Device Home window appears.

In the Contents pane, chose Device Activation. The Device Activation window appears with fields for editing the properties of the selected Content Engine.

Step 3 Under the NAT Configuration heading, configure the NAT settings.

•To use the IP address configured on the primary interface of the Content Engine as the management IP address, check the Use CE's primary IP Address check box.

•To allow the Content Distribution Manager to communicate with devices in the ACNS network that are behind the NAT firewall using an explicitly configured IP address, enter the NAT address of the Content Engine in the NAT Address field.

•In the Port field, enter the port number for the NAT address.

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Note If the Content Distribution Manager cannot contact a device using the primary IP address, it will attempt to communicate using NAT IP address.

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Step 4 To save the configuration, click Submit.

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Commands Related to Distribution Settings

Table 5-5 lists and describes CLI commands that are related to distribution settings. For complete descriptions of these commands, including usage guidelines and examples, refer to the Cisco ACNS Software Command Reference, Release 5.4 publication.

Table 5-5 Distribution-Related Commands 

Command	Syntax	Description
show distribution	show distribution location-leader-preference channel-id channel-id	Shows the configured location-leader-priority of the Content Engines that are subscribed to the channel.
show distribution	show distribution forwarder-load-weight channel-id channel-id	Shows the configured forwarder-load-weight of the Content Engines that are subscribed to the channel.
show distribution	show distribution channel	Shows which Content Engine is the current forwarder for a channel.
show distribution	show distribution forwarder-list	Shows the forwarder selection order of a Content Engine for a channel.

Distributing Content Through Multicast Replication

Multicasting allows efficient distribution of content to multiple Content Engines and is useful when many end users are interested in the same content. ACNS software supports Pragmatic General Multicast (PGM)-based multicast replication using either satellite or multicast-enabled terrestrial infrastructures.

To prepare for multicast transmission of content, you should perform these tasks in the order presented in this section:

1. Enabling Content Engines for Multicasting

2. Configuring Multicast Cloud Properties

3. Assigning Content Engines to a Multicast Cloud

4. Assigning and Removing Multicast Clouds from Channels

About IP Multicasting

Multicast delivery enables the distribution of streaming media by allowing different receiving devices on the IP multicast to receive a single stream of media content from the Content Engine simultaneously. This type of delivery can save significant network bandwidth consumption because a single stream is sent to many devices, rather than sending a single stream to a single device every time that this stream is requested.

This multicast delivery feature is enabled by setting up a multicast address on the Content Engine to which different devices, configured to receive content from the same channel, can subscribe. The delivering device sends content to the multicast address set up at the Content Engine, from which it becomes available to all subscribed receiving devices.

To take advantage of multicasting, all devices, including Content Engines and routers, as well as clients, must be multicast-enabled. For this reason, multicasting is mostly used in local networks where routers can be configured for multicasting. Multicast delivery over the Internet can only be accomplished when all devices that participate in the multicast have been enabled for multicasting.

About Multicast Clouds

For multicast content replication, Content Engines are grouped into multicast clouds. A multicast cloud consists of one sender Content Engine, an optional backup sender Content Engine, and at least one receiver Content Engine in a hub and spoke topology. All Content Engines in one multicast cloud share a unique advertisement address that allows them to communicate multicast session information. The multicast cloud is then associated with one or more multicast-enabled channels.

In pull-based unicast content distribution, a unicast receiver pulls file data out of the proper forwarder (or root Content Engine) when a client requests the content. By contrast, in multicast content distribution, the sender Content Engine in a multicast cloud proactively pushes content into the cloud according to a preconfigured schedule.

The receiver Content Engines listen on the advertisement IP address for information on content to be replicated from the sender, and then the receiver Content Engines decide whether or not to accept an advertisement and receive the corresponding content.

Content metadata (machine-readable information that describes the characteristics of the content) must be distributed to a receiver first before the content itself can be replicated. Content metadata helps to define what content to retrieve, how content will be retrieved, how recently content has been updated, how content is to be pre-positioned (for example, expiration time), and so forth. Metadata is always distributed using unicast. Content, however, can be replicated using either multicast or unicast. A multicast receiver rejects the multicast sender's advertisement of a file if the proper content metadata has not yet arrived.

The Content Distribution Manager GUI allows you to configure multicast cloud parameters in the Creating New Multicast Cloud window. These parameters are discussed in the following sections.

Figure 5-9 shows the task flow for configuring a multicast cloud.

Figure 5-9 Multicast Cloud Configuration Task Flow

About Configuring Carousel Passes

The carousel pass setting defines the maximum number of times that the sender Content Engine can retransmit the multicast for missing files. The primary sender sends the first carousel pass automatically. After the first round, multicast receiver Content Engines request missing content by sending a negative acknowledgment (NACK) to the sender that identifies the missing content. The multicast sender sends out the requested content when it receives the NACK from the receiver. After all receiver Content Engines have received all the multicast content or the sender has reached the maximum number of carousel passes, whichever comes first, the sender stops transmitting content.

If the primary sender fails and the backup sender becomes active, the backup sender takes charge of NACK processing. The backup sender's carousel passes are always triggered by a NACK. When the maximum number of carousel passes is reached for a file on the current active sender, you can configure file distribution to fall back to unicast, if this is desired. (See the "About Configuring Channel Options for Content Replication" section for more information.)

To adjust the pacing of the multicast transmission, you can specify how much time must elapse before missing files are resent (the Delay between passes field) in the Content Distribution Manager GUI Modifying Multicast Cloud window (Devices > Multicast Clouds > Modifying Multicast Cloud).

About Multicast Logging Enhancements

The ACNS 5.3.5 software release includes enhanced multicast logging to identify the receiver Content Engine that is sending the retransmission requests (NACKs) and to identify why a file is scheduled for multicasting. These logging enhancements provide the following details:

•Any NACKs that are received by the multicast sender Content Engine are logged at the trace level in the dist-meta-sender error log on the multicast sender Content Engine.

•Any NACKs that are related to preparing a file for scheduling are logged in the transaction log.

•Any file that is scheduled for multicasting has the details about why it was scheduled for multicasting. You can obtain the details from the time-based queue or the priority-based queue.

About the NACK Interval Multiplier

To identify missing content and trigger a resend of a file, receiver Content Engines send a negative acknowledgement (NACK) message to the sender Content Engine. NACK messages generated by many receiver Content Engines could generate more traffic than the sender can handle. ACNS 5.x software allows you to adjust the average interval between NACKs by configuring a NACK interval multiplier for an individual receiver Content Engine. This value (an integer between 0.1 and 10) adjusts the default average NACK interval (the default is 20 minutes) by the value configured as the interval multiplier. For example, if you set the NACK interval multiplier to 3, the interval between NACKs becomes 20 minutes x 3, or 60 minutes.

This adjustment can be made as needed by choosing Devices > Devices > Prepositioning > Distribution in the Content Distribution Manager GUI.

To send an immediate NACK request rather than wait for the scheduled interval, you can issue the distribution multicast send-nack-now EXEC command on a multicast receiver Content Engine.

To configure the NACK interval multiplier, follow these steps:

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Step 1 In the Content Distribution Manager GUI, choose Devices > Devices.

Step 2 Click the Edit icon next to the name of the Content Engine that you want to configure.

Step 3 In the Contents pane, choose Prepositioning > Distribution. The Distribution Settings for Content Engine window appears. (See Figure 5-8.)

Step 4 Click and drag the Content NACK Interval Multiplier slider control across the calibrated ruler to adjust the interval between NACK messages. The scale ranges from 10 percent of normal to 10 times normal. The center of the scale corresponding to "normal" denotes the default value of 20 minutes. The value corresponding to the position of the slider is displayed in the field next to it.

Step 5 To save the settings, click Submit.

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About the File Resend or Stop Feature

To trigger resending of a particular file, or the content in a particular channel or all channels, you can issue the distribution multicast resend EXEC CLI command on a multicast sender. This command internally resets the number of carousel passes completed to zero for the desired target. Because the first resend of content always happens automatically without being triggered by a NACK, setting the carousel pass count to zero triggers a resend of the content. However, if the on-demand-only option is additionally specified, the first carousel pass made after the command has been issued can only be triggered by a NACK for the content involved.

To stop sending a particular file, a particular channel, or all channels, you can issue the distribution multicast stop