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Bug #2718

ipaccess_bts_handle_ccm() gets ID_REQ/ID_RESP/ID_ACK wrong

Added by laforge 11 days ago.

Status:
New
Priority:
Normal
Assignee:
Target version:
-
Start date:
12/06/2017
Due date:
% Done:

0%

Spec Reference:

Description

We've never had any documentation for the IPA CCM sub-protocol, but logic dictates [tm] that the sequence is as follows:
  1. BTS<-BSC IPA_IDENTITY_REQ (requesting unit-id etc.)
  2. BTS->BSC IPA_IDENTITY_RESP (responding with unit-id etc.)
  3. BTS<-BSC IPA_IDENTITY_ACK (acknowledging that the identity is known/welcome)
  4. BTS->BSC IPA_IDENTITY_ACK (another ack to ack the ack?)
Now the code in libosmo-abis/src/input/ipaccess.c, specifically in ipaccess_bts_handle_ccm() does the following:
  1. wait for any IPA_IDENTITY_REQ
  2. respond with IPA_IDENTITY_RESP
  3. immediately send an IPA_IDENTITY_ACK, no matter if the BSC/server sends an ACK first

And this code is used in our OsmoBTS code base :/


Related issues

Related to OsmoBSC - Bug #2719: OsmoBSC doesn't send BCCH filling after RSL connection unless BTS sends unsolicited message New 12/06/2017

History

#1 Updated by laforge 11 days ago

  • Related to Bug #2719: OsmoBSC doesn't send BCCH filling after RSL connection unless BTS sends unsolicited message added

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