Cisco Cisco Expressway Maintenance Manual
Structuring your Dial Plan
As you start deploying more than one Expressway, it is useful to neighbor the systems together so that they can query
each other about their registered endpoints. Before you start, you should consider how you will structure your dial
plan. This will determine the aliases assigned to the endpoints, and the way in which the Expressways are neighbored
together. The solution you choose will depend on the complexity of your system. Some possible options are described
in the following sections.
each other about their registered endpoints. Before you start, you should consider how you will structure your dial
plan. This will determine the aliases assigned to the endpoints, and the way in which the Expressways are neighbored
together. The solution you choose will depend on the complexity of your system. Some possible options are described
in the following sections.
Flat Dial Plan
The simplest approach is to assign each endpoint a unique alias and divide the endpoint registrations between the
Expressways. Each Expressway is then configured with all the other Expressway as neighbor zones. When one
Expressway receives a call for an endpoint which is not registered with it, it will send out a Location Request to all the
other neighbor Expressways.
Expressways. Each Expressway is then configured with all the other Expressway as neighbor zones. When one
Expressway receives a call for an endpoint which is not registered with it, it will send out a Location Request to all the
other neighbor Expressways.
While conceptually simple, this sort of flat dial plan does not scale very well. Adding or moving an Expressway
requires changing the configuration of every Expressway, and one call attempt can result in a large number of
location requests. This option is therefore most suitable for a deployment with just one or two Expressways plus its
peers.
requires changing the configuration of every Expressway, and one call attempt can result in a large number of
location requests. This option is therefore most suitable for a deployment with just one or two Expressways plus its
peers.
Structured Dial Plan
An alternative deployment would use a structured dial plan where endpoints are assigned an alias based on the
system they are registering with.
system they are registering with.
If you are using E.164 aliases, each Expressway would be assigned an area code. When the Expressways are
neighbored together, each neighbor zone would have an associated search rule configured with its corresponding
area code as a prefix (a Mode of Alias pattern match and a Pattern type of Prefix). That neighbor would then only be
queried for calls to numbers which begin with its prefix.
neighbored together, each neighbor zone would have an associated search rule configured with its corresponding
area code as a prefix (a Mode of Alias pattern match and a Pattern type of Prefix). That neighbor would then only be
queried for calls to numbers which begin with its prefix.
In a URI based dial plan, similar behavior may be obtained by configuring search rules for each neighbor with a suffix
to match the desired domain name.
to match the desired domain name.
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Cisco Expressway Administrator Guide
Zones and Neighbors