Cisco Cisco TelePresence Video Communication Server Expressway 관리 매뉴얼
Firewall traversal
Field
Description
TCP probe
keep alive
interval
keep alive
interval
The interval (in seconds) with which locally registered endpoints send a TCP probe to
the Cisco VCS Expressway after a call is established, in order to keep the firewall’s
NAT bindings open.
the Cisco VCS Expressway after a call is established, in order to keep the firewall’s
NAT bindings open.
Configuring traversal server ports
The Cisco VCS Expressway has specific listening ports used for firewall traversal. Rules must be set
on your firewall to allow connections to these ports. In most cases the default ports should be used.
However, you have the option to change these ports if necessary by going to the Ports page (
on your firewall to allow connections to these ports. In most cases the default ports should be used.
However, you have the option to change these ports if necessary by going to the Ports page (
VCS
configuration > Expressway > Ports
).
The options are:
Field
Description
Media demultiplexing RTP port
Port used for demultiplexing RTP media.
Default is 2776.
Default is 2776.
Media demultiplexing RTCP port
Port used for demultiplexing RTCP media.
Default is 2777.
Default is 2777.
H.323 Assent call signaling port
Port used for Assent signaling.
Default is 2776.
Default is 2776.
H.323 H.460.18 call signaling port
Port used for H.460.18 signaling.
Default is 2777.
Default is 2777.
See
for more information.
About ICE and TURN services
About ICE
ICE (Interactive Connectivity Establishment) provides a mechanism for SIP client NAT traversal. ICE
is not a protocol, but a framework which pulls together a number of different techniques such as TURN
and STUN.
is not a protocol, but a framework which pulls together a number of different techniques such as TURN
and STUN.
It allows endpoints (clients) residing behind NAT devices to discover paths through which they can
pass media, verify peer-to-peer connectivity via each of these paths and then select the optimum
media connection path. The available paths typically depend on any inbound and outbound connection
restrictions that have been configured on the NAT device. Such behavior is described in RFC 4787
[
pass media, verify peer-to-peer connectivity via each of these paths and then select the optimum
media connection path. The available paths typically depend on any inbound and outbound connection
restrictions that have been configured on the NAT device. Such behavior is described in RFC 4787
[
].
An example usage of ICE is two home workers communicating via the internet. If the two endpoints
can communicate via ICE the Cisco VCS Expressway may (depending on how the NAT devices are
configured) only need to take the signaling and not take the media (and is therefore a non-traversal
call). If the initiating ICE client attempts to call a non-ICE client, the call set-up process reverts to a
conventional SIP call requiring NAT traversal via media latching where the Cisco VCS also takes the
media and thus requires a traversal licence.
can communicate via ICE the Cisco VCS Expressway may (depending on how the NAT devices are
configured) only need to take the signaling and not take the media (and is therefore a non-traversal
call). If the initiating ICE client attempts to call a non-ICE client, the call set-up process reverts to a
conventional SIP call requiring NAT traversal via media latching where the Cisco VCS also takes the
media and thus requires a traversal licence.
For more information about ICE, refer to RFC 5245 [
].
Cisco VCS Administrator Guide (X6)
Page 178 of 295