intercluster lookup service

Intercluster Lookup Service

When the Intercluster Lookup Service (ILS) is configured on multiple clusters, ILS updates Cisco UnifiedCommunications 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 remoteclusters 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 inan 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 thatconfiguration to the other nodes in the cluster.

• Set Up ILS Network, page 1

• ILS Network Components, page 2

• ILS Cluster Discovery, page 3

• Directory URI Replication with ILS, page 4

• ILS Configuration Window , page 5

• ILS Troubleshooting Tips, page 8

Set Up ILS NetworkThe 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 theILS topology. From Cisco Unified Operating System Administration, use the Bulk Certificate Managementfeature to:a) From each cluster in your network, export certificates to a central location.

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b) From one server in your ILS network, consolidate exported certificates.c) 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 communicationsbetween clusters in your ILS network.

Step 5 Activate ILS on the first hub cluster in your ILS network by doing the following:a) In Cisco Unified CM Administration, choose Advanced Features > ILS Configuration.b) Change the Role to Hub Cluster and click Save.c) 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 registrationserver, enter the IP address of any node that is located in an existing hub cluster in your ILS network and thathas 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 URIImported Catalogs view in the ILS Configuration window. When the full network appears, your ILS networkis configured for cluster discovery.

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

Note

Step 8 If you want to use ILS to support intercluster URI dialing, check the Exchange Directory URI Catalogswith 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 ComponentsIn Cisco Unified CM Administration, you can configure ILS on a pair of clusters and then join those clustersto form an ILS network. ILS allows you to join additional clusters to the network without having to configurethe 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 ILSnetwork 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 URIImported Catalogs view in the ILS Configuration window of Cisco Unified CM Administration.

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Intercluster Lookup ServiceILS Network Components

Hub Clusters

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

ILS uses automesh functionality to create a full mesh connection between all hub clusters within an ILSnetwork.When a new hub cluster registers to another hub cluster in an existing ILS network, ILS automaticallycreates 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 onlyhub cluster in the network. In addition, you can connect a hub cluster to multiple spoke clusters, or you mightconfigure 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 updatesto and from the rest of the ILS network. Although a hub cluster can have many spokes, a spoke cluster canhave only one hub cluster. Spoke clusters contact only their local hub cluster and never directly contact otherhub 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 URIdialing compatibility with third party systems, you can manually import a third party directory URI catalogfrom a CSV file into any hub cluster in the ILS network. ILS maintains the directory URI imported catalogand replicates that catalog out to the other clusters in the network so that you can dial one of the third partydirectory URIs from any server in the ILS network. The directory URI imported catalog appears as its ownitem 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 partydirectory 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 updaterequest to a remote cluster and the remote cluster responds with the requested information. The time intervalbetween update requests depends on the synchronization interval that is configured in the ILS Configurationwindow in Cisco Unified CM Administration.

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

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

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

For example, if you have an existing ILS network of four Cisco Unified Communications Manager clustersand you want to add an additional cluster, you can configure ILS on the new cluster and then register that


Intercluster Lookup ServiceILS Cluster Discovery

cluster to any hub cluster in the existing ILS network. ILS automatically informs the new cluster of all clustersin the existing network.

Each cluster in an ILS network exchanges update messages, called peer info vectors, that are designed toinform remote clusters of the status of each cluster in the network. The update messages contain informationabout 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 inCisco Unified CM Administration by choosing Advanced Features > Cluster View. From this window, youcan 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 directoryURIs.

Directory URI Replication with ILSCisco Unified Communications Manager uses the Intercluster Lookup Service (ILS) to support interclusterURI dialing. Using ILS, you can create large networks of remote Cisco Unified Communications Managerclusters. ILS also contains an optional directory URI replication feature that allows the clusters in an ILSnetwork 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 featuredisabled on a single cluster, it can affect other clusters in the network. For example, if directory URI replicationis configured across the ILS network but is left disabled on a single hub cluster, the spoke clusters that areconnected 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 boxthat appears in Intercluster Directory URI Configuration. When this check box is checked, each cluster sendsthe 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 inthe local Unified CM database.

• Remote directory URIs—Directory URIs that were configured in another cluster and then replicated tothis cluster.

• Imported Directory URI catalogs—Third party directory URIs that were manually imported into thiscluster.

• Remote Imported Directory URI catalogs—Third party directory URIs that were manually importedinto another cluster in the ILS network and then replicated to this cluster with ILS.


Intercluster Lookup ServiceDirectory URI Replication with ILS

Local directory URIs are saved in the local Unified CM database. All other directory URIs are saved in CSVfiles that are maintained by ILS. When directory URI replication is enabled, ILS exchanges all types ofdirectory 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 aroute 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 thecluster with the phone that is associated to that directory URI. Route strings provide additional informationthat Unified CM can use to route a call. When URI Replication is enabled, Unified CM exchanges directoryURIs 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 theroute strings for the next hop clusters in your ILS network. For example, in the San Jose cluster, you couldconfigure a SIP route pattern that routes calls with a route string of Paris.France.Europe to an outbound SIPtrunk.

If the San Jose cluster receives a call that is addressed to a directory URI from the Paris cluster, Unified CMchecks the list of directory URIs maintained by ILS and pulls the directory URI and its local route string ofParis.France.Europe. If a SIP route pattern is configured that routes calls for Paris.France.Europe, UnifiedCM 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 WindowIn Cisco Unified CommunicationsManager Administration, use theAdvanced Features > ILSConfigurationmenu path to configure the Intercluster Lookup Service (ILS) on Cisco Unified Communications Managerclusters.

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

The following table describes the ILS Configuration field settings.


Intercluster Lookup ServiceILS Configuration Window

Table 1: ILS Configuration Settings

DescriptionField

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

• Stand Alone Cluster—Stand alone clusters cannot join an ILS network. Thisis the default option.

• Hub Cluster—Hub clusters act as hubs within the ILS network. Hub clustersmay connect to multiple hub and spoke clusters. Hub clusters exchange ILSupdates with other hub clusters and then communicate that information to theirspoke clusters.

If the cluster that you are configuring is a hub cluster, and you want to connectthis hub cluster to a remote hub cluster, you can enter a registration server forthe remote hub cluster in the ILS Cluster Registration popup window thatappears after you click Save.

If you want to connect this hub cluster to another hub cluster, click theRegisterto another hub button and enter the IP address or hostname of a server in thehub cluster to which you want to connect. This button does not appear if thelocal cluster is enabled as a stand alone cluster or as a spoke cluster.

• Spoke Cluster—Spoke clusters register to a single hub cluster. Spoke clustersrely on the hub in order to communicate with remote clusters. If you choose aspoke cluster, you must enter a registration server in the text box that appearsafter you click the Save button

Role

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

Synchronize ClustersEvery

ILS Authentication

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

Use TLS Certificates

Click this radio button to configure ILS to use TCP authentication for communicationsbetween 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.

Use Password

If you checked Use Password, confirm your password here.Confirm Password



DescriptionField

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

• Activated—This list box displays all of the servers within the local clusterwhere the ILS service is currently activated.

• Deactivated—This list box displays all of the servers within the local clusterwhere the ILS service is not activated.

After you move a server to the Activated list box, the ILS service will notactivate on the server until you click Save. After you activate ILS on aserver, it may take several minutes for the ILS service to activate on thatserver

Note

Server Activation

The Registration Server text box appears in the ILS Cluster Registration popupwindow that displays after you change the Role to Spoke Cluster or Hub Cluster andclick Save.

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

• If you are configuring a spoke cluster, you must enter a registration server forthe hub cluster to which you want to connect.

• If you are configuring a hub cluster, you only have to enter a registration serverif 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 registrationserver to form a relationship with the remote cluster. Once ILS forms a connection,the registration server is no longer used.

Registration Server

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

Activate theintercluster lookupservice on all nodesin the cluster

ILS Clusters and Imported Directory URI Catalogs



DescriptionField

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

For large networks, you can use the Find button to filter the display to just thoseclusters 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 intoCisco Unified CM, the field displays the imported catalog name and the Rolecolumn lists the catalog as a Directory URI Imported Catalog.

• Last Contact Time—This column displays the last time the local cluster haddirect contact with this cluster.

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

Note

• Role—This column displays whether the remote cluster is a hub cluster, spokecluster, or an imported directory URI catalog. The cluster that you are currentlylogged into is identified as the local cluster.

• Cluster URI Route String—This column displays the SIP route string for theremote cluster or imported directory URI catalog.

• Last URI Data Received—This column displays the last time the local clusterreceived an updated URI catalog from this cluster or imported catalog.

• URI Data Synchronization Status—This column displays the URI replicationstatus of the cluster or imported directory URI catalog.

• Action—Click Disconnect if you want to remove this cluster from the ILSnetwork.

Be aware that if you disconnect a hub cluster from the network, CiscoUnified CommunicationsManager also disconnects that hub cluster’s spokeclusters.

Note

ILS Clusters andImported DirectoryURI Catalogs

ILS Troubleshooting TipsLocal Cluster Cannot Connect to the ILS Network

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

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


Intercluster Lookup ServiceILS Troubleshooting Tips

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

Certificates exchanged using bulk certificate export, merge, and import can cause anuntrusted ILS hub due to TLS errors.

Note

• If you are using TCP password authentication, make sure that all ILS clusters are using TCP passwordauthentication 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 clusteris not configured to exchange directory URI catalogs, none of that hub’s spoke clusters will be able toexchange directory URI catalogs.

• Allow enough time for end-to-end replication based on synchronization intervals (set on the ILSConfiguration page) that are configured for all the clusters involved in the path. All clusters in an ILSnetwork 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 USNvalues for the remote clusters.

• Increase speed of replication by changing the ILS Sync Throttle Service Parameter. Note that a lowsetting can affect system performance.

• Verify that all clusters in the ILS network have unique cluster IDs and that none of the clusters areconfigured with Stand Alone Cluster as its cluster ID. You can check Cluster IDs in Cisco Unified CMAdministration under System > Enterprise Parameters.

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

This condition can occur if ILS and URI replication are enabled on all clusters in the network, but SIP routepatterns 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 routestring for the remote cluster.

• In the SIP Route Pattern configuration window, make sure that you have route patterns that map to theroute strings for your remote clusters.

• Use the utils ils findroutestring CLI command to check for duplicate route strings.



intercluster lookup service

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