Configuring ICE messaging support
The
ICE support
option is a per-zone and per-subzone configuration setting that controls how the VCS
supports ICE messages to and from SIP devices within that zone or subzone.
The behavior depends upon the configuration of the
ICE support
setting on the incoming (ingress) and
outgoing (egress) zone or subzone. When there is a mismatch of settings i.e.
On
on one side and
Off
on the
other side, the VCS invokes its back-to-back user agent (B2BUA) to perform ICE negotiation with the
relevant host.
All zones and subzones have
ICE support
set to
Off
by default.
When the B2BUA performs ICE negotiation with a host, it can offer TURN relay candidate addresses. To do
this, the B2BUA must be configured with the addresses of the TURN servers to offer (via
Applications >
B2BUA > B2BUA TURN servers
).
The following matrix shows the VCS behavior for the different possible combinations of the
ICE support
setting when handling a call between, for example, zone A and zone B:
ICE
support
setting
Zone A
Off
On
Zone
B
Off
Standard VCS proxying behavior.
B2BUA is not normally invoked (however, see the
note below regarding media encryption policy).
B2BUA is invoked.
B2BUA includes ICE candidates in messages to
hosts in Zone A.
On
B2BUA is invoked.
B2BUA includes ICE candidates in messages to
hosts in Zone B.
Standard VCS proxying behavior.
B2BUA is not normally invoked (however, see the
note below regarding media encryption policy).
Effect of media encryption policy when combined with ICE support
The VCS also invokes the B2BUA if it has to apply a
media encryption policy
(any encryption setting other
than
Auto
). This table shows the effect on ICE negotiation behavior depending on the ICE support and media
encryption modes of the ingress and egress zones or subzones:
ICE support
Media encryption
mode
B2BUA
invoked
Effect on ICE negotiation
Both zones /
subzones =
Off
At least one zone /
subzone is
not
Auto
Yes
The B2BUA will not perform any ICE negotiation with
either host.
Both zones /
subzones =
On
At least one zone /
subzone is
not
Auto
Yes
The B2BUA will perform ICE negotiation with both hosts.
Both zones /
subzones =
On
Both zones / subzones
=
Auto
No
The VCS will not offer any TURN relay candidate
addresses to either of the ICE capable hosts. However,
note that each host device may have already been
provisioned with TURN relay candidate addresses.
Note that:
n
B2BUA routed calls are identified in the call history by a component type of
Encryption B2BUA
.
n
A traversal call license is consumed when a call goes via the encryption B2BUA.
n
There is a limit of 100 concurrent calls (500 calls on Large VM servers) that can be routed via the encryption
B2BUA.
Cisco VCS Administrator Guide (X8.1.1)
Page 137 of 507
Zones and neighbors
Configuring ICE messaging support