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Bug #3659

LCLS directly between BTSs

Added by laforge 28 days ago. Updated 6 days ago.

Status:
In Progress
Priority:
Urgent
Assignee:
Category:
RTP/Media
Start date:
10/17/2018
Due date:
% Done:

20%

Spec Reference:

Description

So far, we have implemented LCLS on the BSC level, i.e. in case of a local switch, the RTP stream still goes from BTS A to the BSC-colocated MGW and from there to BTS B. This removes the RTP/voice from A, but not from the Abis side.

In deployments where there are e.g. 3 BTS (A,B,C) at one site, back-hauled via Abis to a BSC in a remote data center, we want the voice to go directly between BTS A and BTS B, without going to the MGW at the BSC.

This basically means that we close the loop not inside our osmo-mgw via MGCP, but that we close it between the two involved BTSs.

Even in a single-remote-BTS use case, this helps in cases where both calling and called subscribers are attached to that same BTS.


Related issues

Related to OsmoBSC - Feature #1602: BSC side of LCLS (local call local switching) as per the 3GPP specsResolved2016-02-23

Related to OsmoBSC - Bug #3413: TC_lcls_connect_clear does not pass anymore.In Progress2018-07-23

Related to OsmoMSC - Feature #2487: MSC side of LCLS (local call local switching) as per the 3GPP specsIn Progress2017-09-03

History

#1 Updated by laforge 28 days ago

  • Priority changed from Normal to Urgent

#2 Updated by msuraev 23 days ago

  • Related to Feature #1602: BSC side of LCLS (local call local switching) as per the 3GPP specs added

#3 Updated by msuraev 21 days ago

  • Status changed from New to In Progress

Preparing test setup using fake_trx/virtphy to check signalling locally.

#4 Updated by msuraev 16 days ago

On a related note: right now TTCN-3 TC_lcls_connect_clear() fails due to commit 6fe125294b219a519c77f7140de26870d17bf40a in OsmoBSC. Reverting just this commit doesn't fix it though so it's also affected by some changes in related commits as well.

The failing part in TC_lcls_connect_clear is probably CONN_A.receive(tr_RSL_DATA_REQ(?, tr_RslLinkID_DCCH(0), l3_rr_chan_rel)) due to missing "DATA REQuest (DTAP) (RR) Channel Release" packet - see difference in .pcap from https://jenkins.osmocom.org/jenkins/view/TTCN3/job/ttcn3-bsc-test/369/ and https://jenkins.osmocom.org/jenkins/view/TTCN3/job/ttcn3-bsc-test/370/

#5 Updated by msuraev 13 days ago

  • % Done changed from 0 to 30

Implemented "lcls-mode bts-loop" in gerrit 11552, corresponding tests are in 11559 - WIP. Related preparation patches are under review.

#6 Updated by msuraev 13 days ago

  • Related to Bug #3413: TC_lcls_connect_clear does not pass anymore. added

#7 Updated by msuraev 13 days ago

  • Related to Feature #2487: MSC side of LCLS (local call local switching) as per the 3GPP specs added

#8 Updated by msuraev 6 days ago

  • Checklist item add TTCN tests for RSL MDCX added
  • Checklist item add RSL MDCX to BSC LCLS added
  • Checklist item handle LCLS-MGW in handover added
  • Checklist item handle LCLS-BTS in handover added
  • Checklist item add TCCN test handover with LCLS-MGW added
  • Checklist item add TCCN test handover with LCLS-BTS added
  • % Done changed from 30 to 20

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