OsmoPCU Debugging » History » Version 1
laforge, 07/28/2017 01:18 PM
| 1 | 1 | laforge | h1. OsmoPCU Debugging |
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| 3 | In order to debug issues with [[OsmoPCU]], it is important to have protocol traces from all related interfaces. |
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| 4 | |||
| 5 | Fundamentally, this includes |
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| 6 | # the Gb interface (NS-over-IP from PCU to SGSN, showing NS/BSSGP/LLC and higher layer protocols) |
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| 7 | #* this one is easy, you just have to capture the UDP traffic on the ip/port as specified in your configuration for this NS-VC (from [[OsmoBSC:]] or [[OsmoNITB:]] |
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| 8 | # the Um interface (RLC/MAC between MS and PCU) |
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| 9 | #* Um frames transmitted/received via OsmoPCU (on PACCH, PTCCH, PDTCH) |
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| 10 | #* Um frames transmitted/received via OsmoBTS on behalf of OsmoPCU (on PCH and AGCH) |
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| 11 | |||
| 12 | The instructions below will help you to set this up |
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| 13 | |||
| 14 | h2. Setting up capturing |
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| 15 | |||
| 16 | h3. NS-over-IP traffic |
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| 17 | |||
| 18 | FIXME |
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| 19 | |||
| 20 | h3. Um frames of OsmoPCU via GSMTAP |
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| 22 | You must call the specific [[OsmoPCU:]] binary for your BTS hardware with the @-i@ option to enable GSMTAP and specify a remote IP address where to send it to[1]. |
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| 23 | The IP address could be the localhost/loopback device, in case you want to capture packets locally. |
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| 24 | |||
| 25 | For example, on a sysmoBTS device the normal command to start osmo-bts (by the systemd service) is: |
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| 26 | |||
| 27 | /usr/bin/osmo-pcu -c /etc/osmocom/osmo-pcu.cfg |
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| 28 | |||
| 29 | but we now need to start it as |
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| 30 | |||
| 31 | /usr/bin/osmo-pcu -c /etc/osmocom/osmo-pcu.cfg -i 127.0.0.1 |
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| 33 | fn1. As of this writing, OsmoPCU actually will send GSMTAP automatically by default to 127.0.0.1 but this is scheduled to change. Explicitly specifying the GSMTAP via the command-line argument as described here will work with both older and future versions of [[OsmoPCU:]] |
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| 34 | |||
| 35 | h3. Um frames of OsmoBTS via GSMTAP |
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| 36 | |||
| 37 | You must call the specific [[OsmoBTS:]] binary for your BTS hardware with the @-i@ option to enable GSMTAP and specify a remote IP address where to send it to. |
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| 38 | The IP address could be the localhost/loopback device, in case you want to capture packets locally. |
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| 39 | |||
| 40 | For example, on a sysmoBTS device the normal command to start osmo-bts (by the systemd service) is: |
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| 41 | |||
| 42 | /usr/bin/osmo-bts-sysmo -s -c /etc/osmocom/osmo-bts.cfg -M |
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| 43 | |||
| 44 | but we now need to start it as |
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| 45 | |||
| 46 | /usr/bin/osmo-bts-sysmo -s -c /etc/osmocom/osmo-bts.cfg -M -i 127.0.0.1 |
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| 47 | |||
| 48 | In osmo-bts.cfg you need to enable the following gsmtap SAPIs: |
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| 49 | <pre> |
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| 50 | bts 0 |
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| 51 | ... |
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| 52 | gsmtap-sapi ccch |
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| 53 | gsmtap-sapi rach |
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| 54 | gsmtap-sapi agch |
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| 55 | gsmtap-sapi pch |
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| 56 | ... |
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| 57 | </pre> |
