AudioCodes Mediant 4000 SBC User Manual page 431

User's Manual
Parameter
SDP Handle RTCP
sbc-sdp-handle-rtcp
[IpProfile_SBCSDPHandleR
TCPAttribute]
RTCP Mux
sbc-rtcp-mux
[IPProfile_SBCRTCPMux]
Version 7.2
Note: As ICE has been defined by the WebRTC standard as
mandatory, the support is important for deployments implementing
WebRTC. For more information on WebRTC, see WebRTC on page
566.
Enables the interworking of the RTCP attribute, 'a=rtcp' (RTCP) in the
SDP, for the SIP entity associated with the IP Profile. The RTCP
attribute is used to indicate the RTCP port for media when that port is
not the next higher port number following the RTP port specified in the
media line ('m=').
The parameter is useful for SIP entities that either require the attribute
or do not support the attribute. For example, Google Chrome and Web
RTC do not accept calls without the RTCP attribute in the SDP. In
Web RTC, Chrome (SDES) generates the SDP with 'a=rtcp', for
example:
m=audio 49170 RTP/AVP 0
a=rtcp:53020 IN IP6
2001:2345:6789:ABCD:EF01:2345:6789:ABCD

[0] Don't Care = (Default) The device forwards the SDP as is
without interfering in the RTCP attribute (regardless if present or
not).

[1] Add = The device adds the 'a=rtcp' attribute to the outgoing
SDP offer sent to the SIP entity if the attribute was not present in
the original incoming SDP offer.

[2] Remove = The device removes the 'a=rtcp' attribute, if present
in the incoming SDP offer received from the other SIP entity, before
sending the outgoing SDP offer to the SIP entity.
Note: As the RTCP attribute has been defined by the WebRTC
standard as mandatory, the support is important for deployments
implementing WebRTC. For more information on WebRTC, see
WebRTC on page 566.
Enables interworking of multiplexing of RTP and RTCP onto a single
local port, between SIP entities. The parameter enables multiplexing of
RTP and RTCP traffic onto a single local port, for the SIP entity
associated with the IP Profile.
Multiplexing of RTP data packets and RTCP packets onto a single
local UDP port is done for each RTP session (according to RFC 5761).
If multiplexing is not enabled, the device uses different (but adjacent)
ports for RTP and RTCP packets.
With the increased use of NAT and firewalls, maintaining multiple NAT
bindings can be costly and also complicate firewall administration
since multiple ports must be opened to allow RTP traffic. To reduce
these costs and session setup times, support for multiplexing RTP
data packets and RTCP packets onto a single port is advantageous.
For multiplexing, the initial SDP offer must include the "a=rtcp-mux"
attribute to request multiplexing of RTP and RTCP onto a single port. If
the SDP answer wishes to multiplex RTP and RTCP, it must also
include the "a=rtcp-mux" attribute. If the answer does not include the
attribute, the offerer must not multiplex RTP and RTCP packets. If
both ICE and multiplexed RTP-RTCP are used, the initial SDP offer
must also include the "a=candidate:" attribute for both RTP and RTCP
along with the "a=rtcp:" attribute, indicating a fallback port for RTCP in
case the answerer does not support RTP and RTCP multiplexing.
431
20. Coders and Profiles
Description
Mediant 4000 SBC