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Bug #3953

OsmoSGSN LLC implementation doesn't refuse ABM

Added by laforge 6 months ago. Updated 6 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
04/24/2019
Due date:
% Done:

100%

Spec Reference:

Description

the LLC layer has a (specified) Asynchronous Balanced Mode (ABM), which is very much like LAPDm. I don't think it's used much in production. In any case, the OsmoSGSN LLC code implements a very small fraction of that, without properly handling it.

The better option is to outright refuse any etablishment of ABM, and hence inform the peer (MS) that ABM is not supported by sending a DM frame. This is also what the spec states in Section 6.4.1.4 of 3GPP TS 04.64:

The DM unnumbered response shall be used by an LLE to report to its peer that the LLE is in a state such that ABM operation cannot be performed. An LLE shall transmit a DM response to any valid command received that it cannot action.

History

#2 Updated by laforge 6 months ago

  • % Done changed from 0 to 70

#3 Updated by laforge 6 months ago

  • Status changed from In Progress to Resolved
  • % Done changed from 70 to 100

patches merged

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