AudioCodes Mediant 4000 SBC User Manual page 445

User's Manual
Parameter
Media IP Version Preference
media-ip-version-preference
[IpProfile_MediaIPVersionPr
eference]
RTP Redundancy Depth
rtp-redundancy-depth
Version 7.2
Defines the preferred RTP media IP addressing version for outgoing
SIP calls (according to RFC 4091 and RFC 4092). The RFCs concern
Alternative Network Address Types (ANAT) semantics in the SDP to
offer groups of network addresses (IPv4 and IPv6) and the IP address
version preference to establish the media stream. The IP address is
indicated in the "c=" field (Connection) of the SDP.

[0] Only IPv4 = (Default) SDP offer includes only IPv4 media IP
addresses.

[1] Only IPv6 = SDP offer includes only IPv6 media IP addresses.

[2] Prefer IPv4 = SDP offer includes IPv4 and IPv6 media IP
addresses, but the first (preferred) media is IPv4.

[3] Prefer IPv6 = SDP offer includes IPv4 and IPv6 media IP
addresses, but the first (preferred) media is IPv6.
To indicate ANAT support, the device uses the SIP Allow header or to
enforce ANAT it uses the Require header:
Require: sdp-anat
In the outgoing SDP, each 'm=' field is associated with an ANAT
group. This is done using the 'a=mid:' and 'a=group:ANAT' fields.
Each 'm=' field appears under a unique 'a=mid:' number, for example:
a=mid:1
m=audio 63288 RTP/AVP 0 8 18 101
c=IN IP6 3000::290:8fff:fe40:3e21
The 'a=group:ANAT' field shows the 'm=' fields belonging to it, using
the number of the 'a=mid:' field. In addition, the ANAT group with the
preferred 'm=' fields appears first. For example, the preferred group
includes 'm=' fields under 'a=mid:1' and 'a=mid3':
a=group:ANAT 1 3
a=group:ANAT 2 4
If you configure the parameter to a "prefer" option, the outgoing SDP
offer contains two medias which are the same except for the "c=" field.
The first media is the preferred address type (and this type is also on
the session level "c=" field), while the second media has its "c=" field
with the other address type. Both medias are grouped by ANAT. For
example, if the incoming SDP contains two medias, one secured and
the other non-secured, the device sends the outgoing SDP with four
medias:

Two secured medias grouped in the first ANAT group, one with
IPv4 and the other with IPv6. The first is the preferred type.

Two non-secured medias grouped in the second ANAT group, one
with IPv4 and the other with IPv6. The first is the preferred type.
Note:

The parameter is applicable only when the device offers an SDP.

The IP addressing version is determined according to the first SDP
"m=" field.

The feature is applicable to any type of media (e.g., audio and
video) that has an IP address.

The corresponding global parameter is MediaIPVersionPreference.
Enables the device to generate RFC 2198 redundant packets. This
can be used for packet loss where the missing information (audio) can
be reconstructed at the receiver's end from the redundant data that
445
20. Coders and Profiles
Description
Mediant 4000 SBC