Practical configuration of authentication policy
VCS Control
The table below contains practical guidelines for configuring authentication policy on a VCS Control.
Authentication point Guideline
Default Zone Use Check credentials.
Default Subzone Use Check credentials.
Specific local subzones For known local subnets, to avoid having to configure all local endpoints with
credentials, use Treat as authenticated.
Although this is a practical solution, we recommend that no Treat as
authenticated subzones are used, and that every endpoint is populated with
appropriate and unique credentials and that Check credentials is used.
Other subzones Use Check credentials.
Traversal zone Use Check credentials. Always check the credentials of requests coming from
the VCS Expressway.
Neighbor zone Use Do not check credentials and set SIP authentication trust mode to On.
VCS Expressway
Ideally, VCS Expressway authentication policy, should follow exactly the same guidelines as for the VCS
Control. However if AD Direct or H.350 access is required, many security policies will not allow a device in a
DMZ access to those resources. Practicality therefore recommends that authentication is left to the VCS
Control. For SIP devices you can use delegated credential checking; this allows SIP devices to register to
the VCS Expressway but be authenticated via a device authentication mechanism configured on the VCS
Control.
You can also use registration allow and deny lists to limit what can register to the VCS Expressway. If it is
required that outbound calls may only be made by authenticated users, ensure that all call requests are
routed to the VCS Control and it only forwards requests back that it can authenticate.
Infrastructure devices
You are recommended to configure your VCS so that infrastructure products, such as MCUs, register to a
dedicated subzone with an authentication policy set to Treat as authenticated.
Configuring VCS authentication methods
The VCS supports 3 different methods of verifying authentication credentials:
n against an on-box local database (which includes any Cisco TMS-supplied credentials)
n via an LDAP connection to an external H.350 directory service
n via direct access to an Active Directory server using a Kerberos connection (NTLM challenges only)
The VCS attempts to verify the credentials presented to it by first checking against its on-box local database
of usernames and passwords. The local database also includes checking against credentials supplied by
Cisco TMS if your system is using device provisioning. If the username is not found in the local database, the
VCS may then attempt to verify the credentials via a real-time LDAP connection to an external H.350
Cisco VCS Administrator Guide (X8.1.1) Page 116 of 507
Device authentication
About device authentication
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