Cisco TelePresence Video Communication Server Administrator's Manual page 167

Bandwidth control
With a firewall
If the example deployment above is modified to include firewalls between the offices, we can use
Cisco's Expressway firewall traversal solution to maintain connectivity. We do this by adding a VCS
Expressway outside the firewall on the public internet, which will work in conjunction with the VCS
Control and Home and Branch office endpoints to traverse the firewalls.
In this example, shown below, the endpoints in the Head Office register with the VCS Control, while
those in the Branch and Home offices register with the VCS Expressway. The introduction of the
firewalls means that there is no longer any direct connectivity between the Branch and Home offices.
All traffic must be routed through the VCS Expressway. This is shown by the absence of a link
between the Home and Branch subzones.
The VCS Expressway has subzones configured for the Home Office and Branch Office. These are
linked to the VCS Expressway's Traversal Subzone, with pipes placed on each link. All calls from the
VCS Expressway to the VCS Control must go through the Traversal Subzone and will consume
bandwidth from this subzone. Note also that calls from the Home Office to the Branch Office must
also go through the Traversal Subzone, and will also consume bandwidth from this subzone as well as
the Home and Branch subzones and Home Office, Branch Office and Head Office pipes.
This example assumes that there is no bottleneck on the link between the VCS Expressway and the
Head Office network, so a pipe has not been placed on this link. If you want to limit the amount of
traffic flowing through your firewall, you could provision a pipe on this link.
Because the VCS Control is only managing endpoints on the Head Office LAN, its configuration is
simpler. All of the endpoints in the Head Office are assigned to the Default Subzone. This is linked to
the Traversal Subzone, through which all calls leaving the Head Office must pass.
Cisco VCS Administrator Guide (X6.1) Page 167 of 401