Manual

Introduction
Why add an “OCS Gateway” Cisco VCS Control?
The “OCS gateway” Cisco VCS is an interface between an existing working video network and the
Microsoft OCS system. There are a number of settings that need to be configured on the “OCS
gateway” that are different from the recommended configurations for standard video routing Cisco
VCSs. For instance the “OCS gateway” Cisco VCS requires that Call routed mode be set to “Always”,
as the Cisco VCS has to modify the OCS SIP signaling to make it suitable for standard video
endpoints, MCUs etc. The knock-on effect of this is that call licenses are always used on this “OCS
gateway” Cisco VCS. It also requires interworking to be “On” rather than “RegisteredOnly” which can
cause calls to be interworked when they need not.
Having the separate “OCS gateway” Cisco VCS and making it the video network presence server also
allows this Cisco VCS or cluster of Cisco VCS peers to handle the subscriptions and presence
requests from OCS for video network users. Handling them in the “OCS gateway” prevents the OCS
presence requests being “spammed” into the existing video network and adversely affecting the run
time operation of the previously working system.
OCS Relay requires dedicated CPL. If CPL is required anywhere else in the network (for example, to
limit which calls are allowed to be routed to ISDN gateways or other resources) it is hard to merge
different CPL scripts.
For FindMe™ to re-write the caller ID, calls must be routed through the Cisco VCS holding the
relevant FindMe™; having an “OCS gateway” helps funnel all calls through the correct place.
OCS can only send calls to
 Cisco VCSs that have “same domain” OCS Relay FindMe™ users registered to the OCS, and
 a single FQDN (though this may have a round robin DNS address to support a cluster of Cisco
VCSs for resilience) for calls to endpoints accessible via a static domain route defined in OCS
If OCS supports multiple domains, all domains can be handled by a single “OCS gateway” Cisco VCS
/ cluster, or one “OCS gateway” Cisco VCS / cluster can be used for each domain.
 If different OCS domains are handled by different “OCS gateway” Cisco VCSs or Cisco VCS
clusters, take care to ensure that each “OCS gateway” Cisco VCS or Cisco VCS cluster is
authoritative for the presence information that is required for the OCS Relay FindMe™ users and
all endpoints that are referenced by those FindMe™ entries.
 If one “OCS gateway” Cisco VCS or Cisco VCS cluster is used, note that only one domain can be
handled by OCS Relay.
Having a dedicated “OCS gateway” Cisco VCS or Cisco VCS cluster also limits the number of trusted
devices that need to be configured in OCS.
Although in the example, nothing is shown registered to the “OCS gateway” Cisco VCS, it is often a
good place to register an MCU if significant numbers of MOC callers are going to be sharing
conferences with standard video endpoint users.
Small test and demo networks?
For small test
and demo networks, video endpoints may be registered to the “OCS gateway” Cisco
VCS Control, the small Video Network being controlled by the same Cisco VCS that is the interface to
OCS.
Scaling up from a small test and demo network
As extra ca
pacity, regional management and reduced license usage is required it is possible to scale
away from the ‘small test and demo network’ system to the “OCS gateway” Cisco VCS connected to
video network approach. This is achieved by adding video network Cisco VCSs and neighboring them
(directly, or indirectly through other Cisco VCSs) to the “OCS gateway” Cisco VCS. Endpoints can be
added to the video network Cisco VCSs and endpoints and other devices then gradually migrated off
the “OCS gateway” Cisco VCS onto the video network Cisco VCSs.
Cisco VCS Deployment Guide: Microsoft OCS 2007 R1 and R2 and Cisco VCS X5.2 Page 8 of 92