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Bug #3013

closed

regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'

Added by neels about 6 years ago. Updated almost 6 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
Target version:
-
Start date:
02/27/2018
Due date:
% Done:

100%

Spec Reference:

Description

While testing code changes based on current osmo-pcu master, I have noticed severe service outage, symptom from the user experience: the remote hosts not responding. At first a web page may load, but soon after, loading any other pages will completely stop working -- the downlink completely stops for the remaining lifetime of the PDP Context.

Apparently receiving on GPRS_NS a FLOW-CONTROL-BVC + FLOW-CONTROL-BVC-ACK pair triggers the behavior, but that's just a hunch.

I have tried an earlier osmo-pcu version which not exhibiting this behavior, and bisected the failure down to:

commit 896574e92bea09ed8d39688b6fdf504e84521746
Author: Max <msuraev@sysmocom.de>
Date:   Tue Jan 9 18:45:41 2018 +0100

    Rewrite Packet Downlink Assignment

    Use bitvec_set_*() directly without external write pointer tracking to
    simplify the code. This is part of IA Rest Octets (3GPP TS 44.018
    ยง10.5.2.16) which is the last part of the message so it should not
    interfere with the rest of encoding functions.

    The tests are adjusted accordingly.

    Change-Id: I52ec9b07413daabba8cd5f1fba5c7b3af6a33389
    Related: OS#1526


Files

os3013_gprs_works__bts_master__pcu_neels-fix_regression-414fcbb0.pcapng os3013_gprs_works__bts_master__pcu_neels-fix_regression-414fcbb0.pcapng 2.31 MB after the reverts of branch neels/fix_regression: browsing osmocom.org works perfectly neels, 02/28/2018 12:11 AM
os3013_gprs_completely_unusable_1__bts_master__pcu_master_0.4.0.97-731e.pcapng os3013_gprs_completely_unusable_1__bts_master__pcu_master_0.4.0.97-731e.pcapng 2.67 MB osmo-pcu master (731e2bb3) -- can't get a single page to load. Note, from the moment of the PDP Context Accepts, I continuously refreshed osmocom.org / hofmeyr.de in the browser, nothing got through. Sometimes GMM messages go missing. neels, 02/28/2018 12:13 AM
os3013_gprs_almost_completely_unusable_2__bts_master__pcu_master_0.4.0.97-731e.pcapng os3013_gprs_almost_completely_unusable_2__bts_master__pcu_master_0.4.0.97-731e.pcapng 4.05 MB osmo-pcu master (731e2bb3) -- one osmocom.org page loaded, from then on nothing. Note, from the moment of the PDP Context Accepts on, I continuously refreshed osmocom.org / hofmeyr.de in the browser, only one worked. Sometimes GMM messages go missing. neels, 02/28/2018 12:13 AM

Related issues

Related to OsmoPCU - Feature #3014: fix re-apply patches reverted by #3013, related: UL and DL packet assignment, and Timing AdvanceResolvedmsuraev02/27/2018

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