Administrator’s Guide for the Polycom RealPresence Group Series Networks
Polycom, Inc. 47
In environments set up behind a firewall, firewall administrators can choose to limit access to TCP
connections only. Although TCP is an accurate and reliable method of data delivery that incorporates
error-checking, it is not a fast method. For this reason, real-time media streams often use UDP, which offers
speed but not necessarily accuracy. Within an environment behind a firewall, where firewall administrator
has restricted media access to TCP ports, calls can be completed using a TCP connection instead of UDP.
H.460 NAT Firewall Traversal
You can configure RealPresence Group systems to use standards-based H.460.18 and H.460.19 firewall
traversal, which allows video systems to more easily establish IP connections across firewalls.
The following illustration shows how a service provider might provide H.460 firewall traversal between two
enterprise locations. In this example the Polycom Video Border Proxy™ (VBP
®
) firewall traversal device is
on the edge of the service provider network and facilitates IP calls between RealPresence Group systems
behind different firewalls.
NAT Public (WAN)
Address
Displays the address that callers from outside the LAN use to call your system. If you
chose to configure the NAT manually, enter the NAT Public Address here.
This field is editable only when NAT Configuration is set to Manual.
NAT is H.323
Compatible
Specifies that the system is behind a NAT that is capable of translating H.323 traffic.
This field is visible only when NAT Configuration is set to Auto or Manual.
Address Displayed in
Global Directory
Lets you choose whether to display this system’s public or private address in the global
directory.
This field is visible only when NAT Configuration is set to Auto or Manual.
Enable SIP Keep-Alive
Messages
Specifies whether to regularly transmit keep-alive messages on the SIP signaling
channel and on all RTP sessions that are part of SIP calls. Keep-alive messages keep
connections open through NAT/Firewall devices that are often used at the edges of both
home and enterprise networks.
When a RealPresence Group system is deployed or registered in an Avaya SIP
environment, Polycom recommends that you disable this setting to allow calls to
connect fully.
Systems deployed outside a firewall are potentially vulnerable to unauthorized access. Visit the
Polycom Security section of the Knowledge Base at support.polycom.com for timely security
information. You can also register to receive periodic email updates and advisories.
Setting Description
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