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| * ["M3UA"]: MEGACO can use ["M3UA"] as its transport protocol; if M3UA is used there is an indication in the M3UA part that this is MEGACO. | * ["M3UA"]: MEGACO can use ["M3UA"] as its transport protocol; MEGACO is indicated in M3UA by a Protocol user id of 14. |
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| XXX - Add example traffic here (as plain text or Ethereal screenshot). | H.248 [attachment:H.248decoded.gif decoded] by Ronnie Sahlbergs decoder in the 0.10.9-SVN-13213 build. |
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| If TCP is used there may be issues with desegmentation; such traces would be valuable. | If TCP is used there may be issues with desegmentation; such traces would be valuable. |
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| * You can change the PORTS on which MEGACO is dissected for UDP/TCP * Raw text output can be selected * Something else |
* You can change the ports on which MEGACO is dissected for UDP/TCP * You can specify whether the raw text of MEGACO packets is to be displayed * You can specify whether a detailed dissection of MEGACO packets is to be displayed |
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| * [http://www.ietf.org/rfc/rfc3525.txt?number=3525 RFC3525]: MEGACO version 2 * [http://www.iana.org/assignments/megaco-h248 IANA Megaco assignments]: * ITU-T Rec. H.248.1 |
Media Gateway Control Protocol (MEGACO/H.248.1)
MEGACO is used to control a Media Gateway in a VoIP system. MEGACO can be Text or Binary (ASN.1) encoded.
History
Protocol dependencies
- ["M3UA"]: MEGACO can use ["M3UA"] as its transport protocol; MEGACO is indicated in M3UA by a Protocol user id of 14.
- ["SCTP"]: Typically(?) MEGACO uses ["SCTP"] as its transport protocol; MEGACO is indicated in SCTP by a payload protocol ID of 7.
- ["TCP"]: MEGACO can use ["TCP"] as its transport protocol. The well known TCP port for MEGACO traffic is 2944; if TCP is used, a TPKT header must be included.
- ["UDP"]: MEGACO can use ["UDP"] as its transport protocol. The well known UDP port for MEGACO traffic is 2944
Example traffic
H.248 [attachment:H.248decoded.gif decoded] by Ronnie Sahlbergs decoder in the 0.10.9-SVN-13213 build.
Ethereal
The MEGACO dissector works for TEXT encoding of the protocol if EOL is used as SEParator. Dissection of binary encoding has recently been added (2004-10-25) as a separate dissector, but is currently only working if M3UA is used as transport.
If TCP is used there may be issues with desegmentation; such traces would be valuable.
Preference Settings
- You can change the ports on which MEGACO is dissected for UDP/TCP
- You can specify whether the raw text of MEGACO packets is to be displayed
- You can specify whether a detailed dissection of MEGACO packets is to be displayed
Example capture file
XXX - Add a simple example capture file to the SampleCaptures page and link from here. Keep it short, it's also a good idea to gzip it to make it even smaller, as Ethereal can open gzipped files automatically.
Display Filter
A complete list of MEGACO display filter fields can be found in the [http://www.ethereal.com/docs/dfref/MEGACO/MEGACO.html display filter reference]
Show only the MEGACO based traffic:
MEGACO
Capture Filter
You cannot directly filter MEGACO protocols while capturing. However, if you know the ["TCP"] or ["SCTP"] port used (see above), you can filter on that one.
External links
- add link to MEGACO specification and where to find additional info on the web about MEGACO
[http://www.ietf.org/rfc/rfc3015.txt?number=3015 RFC3015]: MEGACO version 1
[http://www.ietf.org/rfc/rfc3525.txt?number=3525 RFC3525]: MEGACO version 2
[http://www.iana.org/assignments/megaco-h248 IANA Megaco assignments]:
- ITU-T Rec. H.248.1