Configuring Turn Services - Cisco TelePresence Video Communication Server Administrator's Manual

its publicly-accessible address on the NAT device
n
a relay address on the TURN server
n
The endpoints then decide, by performing connectivity checks through ICE, how they are going to
communicate. Depending upon how the NAT devices are configured, the endpoints may be able to
communicate between their public-facing addresses on the NAT devices or they may have to relay the
media via the TURN server. If both endpoints are behind the same NAT device they can send media
directly between themselves using their internal host addresses.
After the media route has been selected the TURN relay allocations are released if the chosen
connection paths do not involve routing via the TURN server. Note that the signaling always goes via
the VCS, regardless of the final media communication path chosen by the endpoints.
Capabilities and limitations
The VCS supports up to 1800 relay allocations. This is typically enough to support 100 calls but
n
does depend on the network topology and the number of media stream components used for the call
(for example, some calls may use Duo Video, or other calls might be audio only).
Clustered VCSs: if the requested TURN server's relays are fully allocated the server will respond to
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the requesting client with the details of an alternative server in the cluster (the TURN server
currently with the most available resources).
The VCS's TURN services are supported over single and dual network interfaces. For dual network
n
interfaces, relays are allocated on the VCS's externally facing LAN interface.
ICE calls can only be made between devices registered to the VCS's Local Zone.
n
Microsoft ICE (which is not standards-based) is not supported.
n
The TURN server does not support bandwidth requests. (Note that traversal zone bandwidth limits
n
do not apply.)

Configuring TURN services

TURN relay services are only available on a VCS Expressway. To use
the TURN Relay option key (this controls the number of TURN relays that can be simultaneously
allocated by the VCS).
The TURN page (VCS configuration > Expressway >
Expressway's TURN settings.
The configurable options are:
Field Description
TURN Determines whether the
services VCS offers TURN
services to traversal
clients.
Port The listening port for
TURN requests. The
default is 3478.
Authentication The realm sent by the
realm server in its authentication
challenges.
Media port The lower and upper port
range start / in the range used for the
end allocation of TURN
relays.
Cisco VCS Administrator Guide (X6.1)
TURN services
TURN) is used to configure the VCS
Usage tips
If TURN services are already enabled, any change to
the port number will not come into effect until the
TURN services are stopped and restarted again.
Ensure the client's credentials are stored in the
authentication database.
Firewall traversal
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