Bug #1638: BVC RESET ignored - OsmoPCU - Open Source Mobile Communications

Custom queries

all-by-project

Actions

Copy link

Bug #1638

closed

BVC RESET ignored

Added by msuraev about 8 years ago. Updated over 6 years ago.

Status:

Closed

Priority:

Normal

Assignee:

msuraev

Target version:

Start date:

03/09/2016

Due date:

% Done:

100%

Spec Reference:

Description

Right now OsmoPCU always respond to BVC RESET with STATUS error message due to unknown BVCI.
See gprs_bssgp_pcu_rcvmsg() in src/gprs_bssgp_pcu.cpp for details.
Instead, BVC RESET procedure described in 3GPP TS 08.18 § 8.4 should happen.
The tests were made with "bvc reset nsei 101 bvci 0" command introduced into libosmocore (corresponding patches are under review ATM).
Note: it could as well be some bug with the test command.
Related bug - OW#1303.

Related issues

Related to OsmoPCU - Feature #1537: Move the BSSGP handling to libosmocore

New

02/22/2016

Actions

Issue # Delay: days Cancel

History
Notes
Property changes
Associated revisions

Actions

Copy link

Updated by laforge about 7 years ago

Assignee set to msuraev
Priority changed from Normal to Low

Actions

Copy link

Updated by laforge almost 7 years ago

Priority changed from Low to Normal

Actions

Copy link

Updated by msuraev almost 7 years ago

Related to Feature #1537: Move the BSSGP handling to libosmocore added

Actions

Copy link

Updated by msuraev almost 7 years ago

Status changed from New to In Progress

Test command:

bssgp bvc nsei 101 bvci 0 reset

Spec 3GPP TS 48.018 §8.4 details to consider:

before sending BVC-RESET, the operational status of the associated NS shall be obtained
start T2 after BVC-RESET sent (no PDU transmission)
stop T2 on BVC-RESET-ACK
after performing the BVC Reset procedure all affected BVCs are assumed to be unblocked at the SGSN
if T2 expires with no ACK than retry BVC-RESET-RETRIES times
after that mark all BVC as blocked
BVC-RESET with same BVCI equal BVC-RESET-ACK
BVC-RESET equal BVC-UNBLOCK-ACK (only at BSS)
BVC_RESET for signalling BVC overrides all pending procedures for PTP BVC

for PTP BVC:

BSS received BVC-RESET:

if BVC is in blocking than after BVC-RESET-ACK BSS should initiate blocking procedure

for signaling BVC:

BSS received BVC-RESET:

stop all traffic
complete BVC reset for singalling
start BVC reset procedure for corresponding PTP

The spec is unclear in this regard: §8.4.1 says that "after sending or receiving a BVC-RESET for the signalling BVC, the BSS shall initiate the BVC-RESET procedure for all corresponding PTP BVC." but "BSS must complete the BVC-RESET procedure for signalling BVC before starting PTP BVC-RESET procedures". So, does sending "BVC-RESET" by BSS counted as "initiate" (which should happen before BVC-RESET-ACK for signaling BVC) or as "start" (which should happen after BVC-RESET-ACK)?

If I interpret spec correctly, both SGSN and BSS can reset any (PTP or signaling) BVC, but if signaling BVC is reset than corresponding PTP BVC are reset by BSS regardless of who initiated the reset for signaling BVC.

Handling all the corner cases seems to tricky without rewriting corresponding state handling into proper FSM, but until than we can implement most common cases as a natural improvement upon current broken state.

Actions

Copy link