Cisco Unified Communications Manager Features and Services Guide, Release 9.1(1)
Intercluster Lookup Service
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Intercluster Lookup Service

Intercluster Lookup Service

When the Intercluster Lookup Service (ILS) is configured on multiple clusters, ILS updates Cisco Unified Communications Manager with the current status of remote clusters in the ILS network.

The ILS cluster discovery service allows Cisco Unified Communications Manager to learn about remote clusters without the need for an administrator to manually configure connections between each cluster.

The ILS URI Replication feature enables ILS to exchange directory URI catalogs with the other clusters in an ILS network. URI Replication provides support for intercluster URI dialing.

ILS runs on a cluster-wide basis. When you configure ILS on one cluster node, ILS propagates that configuration to the other nodes in the cluster.

Set Up ILS Network

The following procedure describes the steps required to set up an ILS network.

Procedure
    Step 1   Study your network and design an ILS topology.
    Step 2   Assign unique cluster IDs for each cluster in your network.
    Step 3   If you want to use TLS authentication between clusters, and you are not using certificates that have been signed by a trusted certificate authority, you must exchange Tomcat certificates between each cluster in the ILS topology. From Cisco Unified Operating System Administration, use the Bulk Certificate Management feature to:
    1. From each cluster in your network, export certificates to a central location.
    2. From one server in your ILS network, consolidate exported certificates.
    3. From each cluster in your network, import certificates into the local cluster.
    Step 4   If you want to use password authentication between remote clusters, assign a password for all communications between clusters in your ILS network.
    Step 5   Activate ILS on the first hub cluster in your ILS network by doing the following:
    1. In Cisco Unified CM Administration, choose Advanced Features > ILS Configuration.
    2. Change the Role to Hub Cluster and click Save.
    3. In the ILS Configuration Registration popup window, leave the Registration Server text box empty and click OK.
    Step 6   Activate ILS on the remaining hub and spoke clusters in your ILS network. When prompted for a registration server, enter the IP address of any node that is located in an existing hub cluster in your ILS network and that has ILS activated on the local server.
    Step 7   Confirm that your ILS network is configured by viewing the network in the ILS Clusters and Directory URI Imported Catalogs view in the ILS Configuration window. When the full network appears, your ILS network is configured for cluster discovery.
    Note   

    The remaining steps are performed only if you want to configure ILS to support intercluster URI dialing.

    Step 8   If you want to use ILS to support intercluster URI dialing, check the Exchange Directory URI Catalogs with Remote Clusters check box in the Intercluster Directory URI Configuration window.
    Step 9   In the Intercluster Directory URI Configuration window, enter a route string for the local cluster.
    Step 10   Configure SIP route patterns that match the route strings for your remote clusters to an outbound trunk.
    Step 11   If you want to connect your ILS network to a call control system that is not running ILS, such as a Cisco VCS, import directory URI catalogs from the other system into Cisco Unified Communications Manager.

    ILS Network Components

    In Cisco Unified CM Administration, you can configure ILS on a pair of clusters and then join those clusters to form an ILS network. ILS allows you to join additional clusters to the network without having to configure the connections between each cluster.

    An ILS network comprises the following components:

    • Hub clusters
    • Spoke clusters
    • Directory URI imported catalogs

    You must configure each cluster in your ILS network as either a hub cluster or a spoke cluster. Each ILS network must have at least one hub cluster.

    You can view the current structure and status of the ILS network from the ILS Clusters and Directory URI Imported Catalogs view in the ILS Configuration window of Cisco Unified CM Administration.

    Hub Clusters

    Each ILS network must have at least one hub cluster. Hub clusters form the backbone of an ILS network. Hub clusters exchange ILS updates with the other hub clusters in the ILS network, and then relay that information to and from their spoke clusters.

    ILS uses automesh functionality to create a full mesh connection between all hub clusters within an ILS network. When a new hub cluster registers to another hub cluster in an existing ILS network, ILS automatically creates a full mesh connection between the new hub cluster and all the existing hub clusters in the ILS network.

    You can connect a hub cluster to multiple other hub clusters, or you might configure a hub cluster as the only hub cluster in the network. In addition, you can connect a hub cluster to multiple spoke clusters, or you might configure the hub cluster with no spokes clusters.

    Spoke Clusters

    A spoke cluster in an ILS network relies on the hub cluster that it is connected to in order to relay ILS updates to and from the rest of the ILS network. Although a hub cluster can have many spokes, a spoke cluster can have only one hub cluster. Spoke clusters contact only their local hub cluster and never directly contact other hub clusters or other spoke clusters.

    Directory URI Imported Catalogs

    You cannot connect a third party call control system into an ILS network. However, in order to provide URI dialing compatibility with third party systems, you can manually import a third party directory URI catalog from a CSV file into any hub cluster in the ILS network. ILS maintains the directory URI imported catalog and replicates that catalog out to the other clusters in the network so that you can dial one of the third party directory URIs from any server in the ILS network. The directory URI imported catalog appears as its own item in the ILS Clusters and Directory URI Imported Catalogs view in the ILS Configuration window.

    You can import a third party directory URI catalog into a hub cluster only. You cannot import a third party directory URI catalog into a spoke cluster.

    Synchronization Updates

    For cluster synchronization updates, ILS uses a pull-based model in which an ILS cluster sends out an update request to a remote cluster and the remote cluster responds with the requested information. The time interval between update requests depends on the synchronization interval that is configured in the ILS Configuration window in Cisco Unified CM Administration.

    In addition, within an individual ILS cluster, synchronization intervals determine how long it takes for the various cluster nodes to synchronize their ILS settings.

    For detailed information on setting up an ILS network topology, see the Cisco Unified Communications System SRND.

    ILS Cluster Discovery

    Cluster discovery is the base service that ILS provides. ILS cluster discovery allows Cisco Unified Communications Manager clusters to learn dynamically about remote clusters without the need for an administrator to manually configure connections between those clusters.

    For example, if you have an existing ILS network of four Cisco Unified Communications Manager clusters and you want to add an additional cluster, you can configure ILS on the new cluster and then register that cluster to any hub cluster in the existing ILS network. ILS automatically informs the new cluster of all clusters in the existing network.

    Each cluster in an ILS network exchanges update messages, called peer info vectors, that are designed to inform remote clusters of the status of each cluster in the network. The update messages contain information about the known clusters in the network, including:

    • Cluster IDs
    • Cluster descriptions and versions
    • Fully qualified domain name of the host
    • IP addresses and hostnames for the cluster nodes that have ILS activated

    The ILS cluster discovery feature automatically populates the list of remote clusters that can be viewed in Cisco Unified CM Administration by choosing Advanced Features > Cluster View. From this window, you can configure services such as Extension Mobility Cross Cluster, TFTP, and RSVP Agent for remote clusters.

    If URI Replication is also enabled in the network, ILS sends separate messages containing the list of directory URIs.

    Directory URI Replication with ILS

    Cisco Unified Communications Manager uses the Intercluster Lookup Service (ILS) to support intercluster URI dialing. Using ILS, you can create large networks of remote Cisco Unified Communications Manager clusters. ILS also contains an optional directory URI replication feature that allows the clusters in an ILS network to replicate their directory URIs to the other clusters in the ILS network.

    Directory URI Replication is configured individually for each cluster. Be aware that if you leave the feature disabled on a single cluster, it can affect other clusters in the network. For example, if directory URI replication is configured across the ILS network but is left disabled on a single hub cluster, the spoke clusters that are connected to that hub cannot exchange directory URIs with the rest of the ILS network.

    To enable URI Replication in a cluster, check the Exchange Directory URIs with Remote Clusters check box that appears in Intercluster Directory URI Configuration. When this check box is checked, each cluster sends the following to the other clusters in the ILS network:

    • All directory URIs known by the local cluster.
    • The local route string for each set of directory URIs.

    Directory URI Catalog Types

    Within an individual cluster, directory URIs can be categorized as follows:

    • Local directory URIs—Directory URIs that are configured on the local system and which are saved in the local Unified CM database.
    • Remote directory URIs—Directory URIs that were configured in another cluster and then replicated to this cluster.
    • Imported Directory URI catalogs—Third party directory URIs that were manually imported into this cluster.
    • Remote Imported Directory URI catalogs—Third party directory URIs that were manually imported into another cluster in the ILS network and then replicated to this cluster with ILS.

    Local directory URIs are saved in the local Unified CM database. All other directory URIs are saved in CSV files that are maintained by ILS. When directory URI replication is enabled, ILS exchanges all types of directory URIs to the other clusters in the ILS network.

    Route Strings

    In order to implement intercluster URI dialing, each cluster in the ILS network must be configured with a route string and SIP route patterns that match the route strings to an outbound trunk.

    In many cases, the host portion of the directory URI is not granular enough for Unified CM to locate the cluster with the phone that is associated to that directory URI. Route strings provide additional information that Unified CM can use to route a call. When URI Replication is enabled, Unified CM exchanges directory URIs and the route string for the local cluster where that directory URI is saved.

    You can create whatever route strings you want. For example, if you are joining clusters in San Jose and Paris, you could assign SanJose.USA.NorthAmerica and Paris.France.Europe as route strings for the two clusters.

    After you assign route strings for the various clusters, you must configure SIP route patterns that match the route strings for the next hop clusters in your ILS network. For example, in the San Jose cluster, you could configure a SIP route pattern that routes calls with a route string of Paris.France.Europe to an outbound SIP trunk.

    If the San Jose cluster receives a call that is addressed to a directory URI from the Paris cluster, Unified CM checks the list of directory URIs maintained by ILS and pulls the directory URI and its local route string of Paris.France.Europe. If a SIP route pattern is configured that routes calls for Paris.France.Europe, Unified CM sends the call to the outbound trunk for that route pattern.

    For more detail on configuring route strings, refer to the Cisco Unified Communications System SRND

    ILS Configuration Window

    In Cisco Unified Communications Manager Administration, use the Advanced Features > ILS Configuration menu path to configure the Intercluster Lookup Service (ILS) on Cisco Unified Communications Manager clusters.

    Although ILS is activated and runs on individual cluster nodes, the configuration settings are applied on a cluster-wide basis. After ILS is configured on a cluster node, those settings are propagated out to the other cluster nodes. The length of time that it takes for ILS settings to be propagated to other cluster nodes depends on the synchronization value that you enter.

    The following table describes the ILS Configuration field settings.

    Table 1 ILS Configuration Settings
    Field Description

    Role

    From the drop-down list box, choose the ILS role for this cluster from the following options:

    • Stand Alone Cluster—Stand alone clusters cannot join an ILS network. This is the default option.
    • Hub Cluster—Hub clusters act as hubs within the ILS network. Hub clusters may connect to multiple hub and spoke clusters. Hub clusters exchange ILS updates with other hub clusters and then communicate that information to their spoke clusters. If the cluster that you are configuring is a hub cluster, and you want to connect this hub cluster to a remote hub cluster, you can enter a registration server for the remote hub cluster in the ILS Cluster Registration popup window that appears after you click Save. If you want to connect this hub cluster to another hub cluster, click the Register to another hub button and enter the IP address or hostname of a server in the hub cluster to which you want to connect. This button does not appear if the local cluster is enabled as a stand alone cluster or as a spoke cluster.
    • Spoke Cluster—Spoke clusters register to a single hub cluster. Spoke clusters rely on the hub in order to communicate with remote clusters. If you choose a spoke cluster, you must enter a registration server in the text box that appears after you click the Save button

    Synchronize Clusters Every

    Enter the delay, in minutes, between when the local cluster checks with remote clusters for ILS updates. The default value is 10 minutes.

    ILS Authentication

    Use TLS Certificates

    Click this radio button to configure ILS to use TLS to encrypt communications between remote clusters. If you check this radio button, and you are using certificates that are not signed by a trusted certificate authority, you must exchange Tomcat certificates between the clusters in your network.

    Use Password

    Click this radio button to configure ILS to use TCP authentication for communications between remote clusters. If you check this radio button, you must enter a password. You must configure all clusters in your network with the same password.

    Confirm Password

    If you checked Use Password, confirm your password here.

    Server Activation

    Click the (+) symbol to open the Server Activation section. From this section, you can activate and deactivate ILS on individual servers within the cluster. Click the arrows to move servers between the Activated and Deactivated list boxes. After making your changes, click Save to activate or deactivate ILS on the server.

    • Activated—This list box displays all of the servers within the local cluster where the ILS service is currently activated.
    • Deactivated—This list box displays all of the servers within the local cluster where the ILS service is not activated.
    Note   

    After you move a server to the Activated list box, the ILS service will not activate on the server until you click Save. After you activate ILS on a server, it may take several minutes for the ILS service to activate on that server

    Registration Server

    The Registration Server text box appears in the ILS Cluster Registration popup window that displays after you change the Role to Spoke Cluster or Hub Cluster and click Save.

    To enter a registration server, enter the IP address or fully qualified domain name of any server in the hub cluster to which you want to connect. You must enter a registration server in the following circumstances:

    • If you are configuring a spoke cluster, you must enter a registration server for the hub cluster to which you want to connect.
    • If you are configuring a hub cluster, you only have to enter a registration server if you want to connect this hub cluster to another hub cluster in the ILS network. Otherwise, you can leave the field blank.

    If ILS is running on both the local and remote clusters, ILS uses the registration server to form a relationship with the remote cluster. Once ILS forms a connection, the registration server is no longer used.

    Activate the intercluster lookup service on all nodes in the cluster

    This check box appears in the ILS Cluster Registration popup window that displays after you change the Role to Spoke Cluster or Hub Cluster and click Save. Check this check box if you want to automatically activate ILS on all nodes in the cluster.

    ILS Clusters and Imported Directory URI Catalogs

    ILS Clusters and Imported Directory URI Catalogs

    This section displays a snapshot of the current ILS network, including all hub clusters, spoke clusters, and imported directory URI catalogs. Spoke clusters are displayed under their associated hub cluster. The cluster that you are currently logged into is identified as the local cluster

    For large networks, you can use the Find button to filter the display to just those clusters that meet specific search criteria.

    The table contains the following columns:

    • Cluster ID/Name—This column displays the cluster ID for the remote cluster. If the other cluster is from a non-ILS system that was manually imported into Cisco Unified CM, the field displays the imported catalog name and the Role column lists the catalog as a Directory URI Imported Catalog.
    • Last Contact Time—This column displays the last time the local cluster had direct contact with this cluster.
      Note   

      Spoke clusters only make direct contact with their local hub cluster. Spoke clusters never contact remote hub clusters, or other spokes.

    • Role—This column displays whether the remote cluster is a hub cluster, spoke cluster, or an imported directory URI catalog. The cluster that you are currently logged into is identified as the local cluster.
    • Cluster URI Route String—This column displays the SIP route string for the remote cluster or imported directory URI catalog.
    • Last URI Data Received—This column displays the last time the local cluster received an updated URI catalog from this cluster or imported catalog.
    • URI Data Synchronization Status—This column displays the URI replication status of the cluster or imported directory URI catalog.
    • Action—Click Disconnect if you want to remove this cluster from the ILS network.
    Note   

    Be aware that if you disconnect a hub cluster from the network, Cisco Unified Communications Manager also disconnects that hub cluster’s spoke clusters.

    ILS Troubleshooting Tips

    Local Cluster Cannot Connect to the ILS Network

    To troubleshoot connection issues within the local cluster, use the utils ils find xnode CLI command to determine which server within the cluster is the xnode, the node responsible for communicating ILS updates with remote clusters. After you determine which cluster node is the xnode, you can open RTMT and run alarms and diagnostic traces on that cluster node.

    In addition, connection issues may arise if authentication is improperly configured between clusters. Check authentication in the following manner:

    • If you are using TLS, make sure that all clusters in the network are using TLS and that Tomcat certificates have been exchanged for all the servers that need to communicate.

      Note


      Certificates exchanged using bulk certificate export, merge, and import can cause an untrusted ILS hub due to TLS errors.
    • If you are using TCP password authentication, make sure that all ILS clusters are using TCP password authentication and that the same TCP password is assigned across the network.

    Directory URIs Are Not Being Replicated Across the ILS Network

    This error can occur for a variety of reasons. Check the following:

    • Verify that all clusters in the network are configured to exchange directory URI catalogs. If a hub cluster is not configured to exchange directory URI catalogs, none of that hub’s spoke clusters will be able to exchange directory URI catalogs.
    • Allow enough time for end-to-end replication based on synchronization intervals (set on the ILS Configuration page) that are configured for all the clusters involved in the path. All clusters in an ILS network are a maximum of three hops from every other cluster in the network.
    • Use the utils ils showpeerinfo CLI command to monitor replication progress by looking at the USN values for the remote clusters.
    • Increase speed of replication by changing the ILS Sync Throttle Service Parameter. Note that a low setting can affect system performance.
    • Verify that all clusters in the ILS network have unique cluster IDs and that none of the clusters are configured with Stand Alone Cluster as its cluster ID. You can check Cluster IDs in Cisco Unified CM Administration under System > Enterprise Parameters.

    Directory URI Replication Is Configured, but Unified CM Still Cannot Place a Call to A Directory URI in a Remote ILS Cluster

    This condition can occur if ILS and URI replication are enabled on all clusters in the network, but SIP route patterns that route to the route strings for the remote clusters have not been configured. Do the following:

    • In the ILS Clusters and Directory URI Catalogs view in the ILS Configuration window, check the route string for the remote cluster.
    • In the SIP Route Pattern configuration window, make sure that you have route patterns that map to the route strings for your remote clusters.
    • Use the utils ils findroutestring CLI command to check for duplicate route strings.