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
An ILS network comprises the following components:
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.
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.
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.
Global Dial Plan 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 or +E.164 number catalog from a CSV file into
any hub cluster in the ILS network. ILS maintains the 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 or +E.164 numbers from any server in the ILS network.
The imported catalog appears as its own item in the ILS Clusters and Global Dial Plan Imported Catalogs view in the ILS Configuration
You can import a third party catalog into a hub cluster only. You cannot import a third party catalog into a spoke cluster.
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.
For detailed information on setting up an ILS network topology, see the Cisco Unified Communications System SRND.
ILS Network Capacities
ILS networking can scale up to 100 total clusters with at most 10 hubs and 10 spokes per hub. Hub and spoke combination topology
is used to avoid too many TCP connections created within each cluster.