About The Vcs's Directory Service; About Hop Counts; Configuring Hop Counts; About Transforms And Search Rules - Cisco TelePresence Video Communication Server Administrator's Manual

About the VCS's directory service

The VCS's directory service is an on-box repository of dial plan information. It contains call routing
information and can provide registration and call policy services.
The directory service has no user configurable options on the VCS. The dial plan and policy
information is managed on a separate dial plan server and its contents are pushed out to all of its client
VCSs. It is suited to large-scale deployments where a centrally-managed system can provide a
comprehensive directory of aliases and their corresponding routing information.
You can configure the VCS to use the directory service in the following areas:
Registration restriction
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Call Policy configuration: where it can be applied in addition to locally-defined Call Policy
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About hop counts

Each search request is assigned a hop count value by the system that initiates the search. Every time
the request is forwarded to another neighbor gatekeeper or proxy, the hop count value is decreased by
a value of 1. When the hop count reaches 0, the request will not be forwarded on any further and the
search will fail.
For search requests initiated by the local VCS, the hop count assigned to the request is configurable
on a zone-by-zone basis. The zone's hop count applies to all search requests originating from the local
VCS that are sent to that zone.
Search requests received from another zone will already have a hop count assigned. When the
request is subsequently forwarded on to a neighbor zone, the lower of the two values (the original hop
count or the hop count configured for that zone) is used.
For H.323, the hop count only applies to search requests. For SIP, the hop count applies to all
requests sent to a zone (affecting the Max-Forwards field in the request).
The hop count value can be between 1 and 255. The default is 15.
Note: if your hop counts are set higher than necessary, you may risk introducing loops into your
network. In these situations a search request will be sent around the network until the hop count
reaches 0, consuming resources unnecessarily. This can be prevented by setting the
detection mode to On.
When dialing by URI or ENUM, the hop count used is that for the associated DNS or ENUM zone via
which the destination endpoint (or intermediary SIP proxy or gatekeeper) was found.

Configuring hop counts

Hop counts are configured on a zone basis. To configure the hop count for a zone:
1. Go to the Zones page
2. Click on the name of the zone you want to configure. You are taken to the Edit zone page.
3. In the Configuration section, in the Hop count field, enter the hop count value you want to use for
this zone.
For full details on other zone options, see the

About transforms and search rules

The VCS can be configured to use transforms and search rules as a part of its call routing process.
Cisco VCS Administrator Guide (X6.1)
policies: as an alternative to using Allow and Deny Lists
(VCS configuration > Zones).
Zone configuration
Dial plan and call processing
Call loop
section.
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