73 lines
2.4 KiB
Plaintext
73 lines
2.4 KiB
Plaintext
== MGCP Extensions
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The MGCP protocol is extendable. The following non-standard extensions are
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understood by OsmoMGW.
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=== `X-Osmo-IGN`
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`X-Osmo-IGN` indicates to OsmoMGW that specific items of an endpoint should be
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ignored, so that it is lenient on mismatching values that would normally
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indicate collisions or configuration errors.
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==== `X-Osmo-IGN` Format
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The value part of `X-Osmo-IGN` must be one or more items separated by one or more
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spaces. Each item consists of one or more non-whitespace characters.
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.Example: `X-Osmo-IGN` format with three ficticious items "X", "abc" and "123".
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----
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X-Osmo-IGN: X abc 123
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----
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`X-Osmo-IGN` must be issued in the MGCP header section (typically as its last item),
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before the SDP section starts.
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==== Supported `X-Osmo-IGN` Items
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Currently, the following `X-Osmo-IGN` items are supported:
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* `C`: ignore CallID mismatches, i.e. differing "C" values between connections
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on the same endpoint.
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.Note:
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`X-Osmo-IGN` does not support ignoring mismatches on the domain part of
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an endpoint name, e.g. ignoring a mismatch on "example.com" in
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`rtpbridge/123abc@example.com`. Instead, you may globally configure OsmoMGW
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with `mgcp` / `domain *` to permit all domain parts.
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===== `X-Osmo-IGN: C`
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By default, OsmoMGW verifies that all CallIDs ("C" values) match for all
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connections on any one given endpoint. To ignore CallID mismatches, pass a `C`
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in the `X-Osmo-IGN` header, for the first or the second `CRCX` on an endpoint.
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When the `X-Osmo-IGN: C` is sent for any one `CRCX` on an endpoint, CallID
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mismatches will be ignored for that and all subsequent messages for that
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endpoint. Hence this header only needs to be included once per endpoint, in any
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`CRCX` message that precedes or coincides with a CallID mismatch.
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This is particularly useful for a BSC that is connected to an A/SCCPlite MSC,
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where the BSC and MSC each are expected to configure their respective own
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connection on a shared endpoint. For A/SCCPlite, it is impossible for the BSC
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to know the CallID that the MSC will use, so CallID mismatches are inevitable.
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See also OsmoBSC, which will by default pass the `X-Osmo-IGN: C` header for
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endpoints associated with an A/SCCPlite MSC.
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.Example: `CRCX` message that instructs OsmoMGW to ignore CallID mismatches
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----
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CRCX 2 rtpbridge/123abc@mgw MGCP 1.0
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M: recvonly
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C: 2
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L: p:20
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X-Osmo-IGN: C
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v=0
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c=IN IP4 123.12.12.123
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m=audio 5904 RTP/AVP 97
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a=rtpmap:97 GSM-EFR/8000
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a=ptime:40
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----
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=== `X-Osmux`
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See <<mgcp-extension-osmux>>
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