CHAPTER19 Coders and Profiles
Mediant 800 Gateway & E-SBC | User's Manual
Parameter Description
■ As DTLS has been defined by the WebRTC standard
as mandatory for encrypting media channels for SRTP
key exchange, the support is important for deployments
implementing WebRTC. For more information on
WebRTC, see WebRTC.
'Reset SRTP Upon Re-key'
reset-srtp-upon-re-key
[IpProfile_
ResetSRTPStateUponRekey]
Enables synchronization of the SRTP state between the
device and a server when a new SRTP key is generated
upon a SIP session expire. This feature ensures that the
roll-over counter (ROC), one of the parameters used in the
SRTP encryption/decryption process of the SRTP packets
is synchronized on both sides for transmit and receive
packets.
■ [0] Disable = (Default) ROC is not reset on the device
side.
■ [1] Enable = If the session expires causing a session
refresh through a re-INVITE, the device or server
generates a new key and the device resets the ROC
index (and other SRTP fields) as done by the server,
resulting in a synchronized SRTP.
Note:
■ If this feature is disabled and the server resets the ROC
upon a re-key generation, one-way voice may occur.
■ The corresponding global parameter is
ResetSRTPStateUponRekey.
'Generate SRTP Keys Mode'
generate-srtp-keys
[IpProfile_GenerateSRTPKeys]
Enables the device to generate a new SRTP key upon
receipt of a re-INVITE with the SIP entity associated with
the IP Profile.
■ [0] Only If Required = (Default) The device generates
an SRTP key only if necessary.
■ [1] Always = The device always generates a new
SRTP key.
'SBC Remove Crypto Lifetime
in SDP'
sbc-sdp-remove-crypto-
lifetime
[IpProfile_
SBCRemoveCryptoLifetimeInS
DP]
Defines the handling of the lifetime field in the 'a=crypto'
attribute of the SDP for the SIP entity associated with the
IP Profile. The SDP field defines the lifetime of the master
key as measured in maximum number of SRTP or SRTCP
packets using the master key.
■ [0] No = (Default) The device retains the lifetime field (if
present) in the SDP.
■ [1] Yes = The device removes the lifetime field from the
'a=crypto' attribute.
Note: If you configure the parameter to Yes, the following
IP Profile parameters must be configured as follows:
■ IpProfile_EnableSymmetricMKI configured to Enable
[1].
■ IpProfile_MKISize configured to 0.
■ IpProfile_SBCEnforceMKISize configured to Enforce
[1].
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