Configuring Webrtc - AudioCodes Mediant 4000 SBC User Manual

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To keep a WebSocket session alive, it is sometimes necessary to send regular messages
to indicate that the channel is still being used. Some servers, browsers or proxies may
close an idle connection. The Ping-Pong WebSocket messages are designed to send non-
application level traffic that prevents the channel from being prematurely closed. You can
configure how
WebSocketProtocolKeepAlivePeriod parameter (see ''Configuring WebRTC'' on page 518).
The device always replies to ping control messages with a pong message.
Note: When the device operates in High-Availability (HA) mode, if a WebSocket
connection has been established and a switchover subsequently occurs, the
WebSocket session is not copied to the redundant device. As Chrome does not
renew the WebSocket connection with the device, WebRTC calls remain open
indefinitely; the Chrome side will stop the call, but the device will keep all of the call's
resources open and the other side will have an active call with no voice. To prevent
this, for the IP Profile associated with the WebRTC clients, configure the ' Broken
Connection Mode' parameter to Disconnect.

28.4.2 Configuring WebRTC

To support WebRTC, you need to perform special configuration settings for the device's
SBC leg interfacing with the WebRTC client (i.e., Web browser), as described in the
following procedure.
For the WebRTC deployment environment, you need to install a signed certificate by a
Certificate Authority (CA) on you Web server machine (hosting the WebRTC JavaScript)
and on your AudioCodes SBC device (i.e., WebSocket server).
Note:
•
Google announced a security policy change that impacts new versions of the
Chrome Web browser. Any Web site that has integrated WebRTC, geolocation
technology, screen-sharing and more, now requires to be served from a secure
(HTTPS) site, including WebRTC-based WebSocket servers (WSS instead of
WS). The configuration described below accommodates for this basic
requirement.
•
WebRTC JavaScript configuration is beyond the scope of this document.

To configure WebRTC:
1. Configure a TLS Context (certification):
a. Open the TLS Contexts table (see ''Configuring TLS Certificate Contexts'' on
page 95).
b. Add a new TLS Context (e.g., "WebRTC") or edit an existing one.
c. Create a certificate signing request (CSR) to request a digitally signed certificate
from a Certification Authority (CA).
d. Send the CSR to the CA for signing.
User's Manual
often the device pings
518
Mediant 4000 SBC
the WebSocket client,
Document #: LTRT-41729
using the