40 lines
2.2 KiB
Plaintext
40 lines
2.2 KiB
Plaintext
include::{commondir}/chapters/osmux/osmux.adoc[]
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=== Osmux Support in {program-name}
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Osmux usage in {program-name} in managed through the VTY commands in node
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`osmux`. Command `use (on|off|only)` is used to configure use policy of Osmux
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within {program-name}. Once enabled (`on` or `only`), {program-name} will
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announce the _OSMUX_ BTS feature towards the BSC over OML. This way, the BSC
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becomes aware that this BTS supports using Osmux to transfer voice call user
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data when the AMR codec is selected.
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It is then up to the BSC to decide whether to use Osmux or not when establishing
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a new call. If the BSC decides to use Osmux for a given call, then the _IPACC
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CRCX/MDCX_ messages sent by the BSC will contain an extra _Osmux CID_ IE
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appended, which contains the Osmux CID to be used by the BTS to send Osmux
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frames to the co-located BSC MGW (aka the BSC MGW' local CID, or {program-name}'
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remote CID). The IP address and port provided in the same messages refer to the
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address and port where Osmux frames with the provided CID are expected to be
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received. Similarly, {program-name} appends an _Osmux CID_ IE to the _IPACC
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CRCX/MDCX ACK_ message it generates, this time with its own local Osmux CID.
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Same goes for the BTS' local IP address and port where Osmux frames are expected
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to be received.
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{program-name} will behave differently during call set up based on the VTY
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command `use (on|off|only)` presented above:
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* `off`: If _IPACC CRCX_ from BSC contains _Osmux CID_ IE, meaning
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BSC wants to use Osmux for this call, then {program-name} will reject the
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request and the call set up will fail.
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* `on`: {program-name} will support and accept both Osmux and non-Osmux (RTP)
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upon call set up. If _IPACC CRCX_ from BSC contains the _Osmux CID_ IE on a
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AMR call (`Channel Mode GSM3`), it will set up an Osmux stream on its end and
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provide the BSC with the BTS-local CID. If the BSC provides no _Osmux CID_ IE,
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then {program-name} will set up a regular RTP based call.
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* `only`: Same as per `on`, except that {program-name} will accept only Osmux
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calls on the CN-side, this is, if _IPACC CRCX_ from BSC doesn't
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contain an _Osmux CID_ IE, it will reject the assignment and the call set up
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will fail. This means also that only AMR calls (`Channel Mode GSM3`) are
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allowed.
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