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Hello Jenkins Builder,

I'd like you to reexamine a change. Please visit

https://gerrit.osmocom.org/c/osmo-bts/+/38557?usp=email

to look at the new patch set (#3).

The following approvals got outdated and were removed: Verified+1 by Jenkins Builder

Change subject: CSD NT modes: transmit properly aligned RLP frames on DL ......................................................................

CSD NT modes: transmit properly aligned RLP frames on DL

There are two levels of alignment inside clearmode RTP packets carrying CSData per TS 48.103 section 5.6:

1) Alignment of 2 or 4 V.110 (T) or pseudo-V.110 (NT) frames within one RTP packet of 160 octets of an imaginary ISDN B channel;

2) For NT modes only, alignment of 4 pseudo-V.110 frames to form a single 240-bit RLP frame.

Per previous patch, alignment 1 is to be treated as mandatory for RTP transport inside an Osmocom network. Alignment 2 _could_ be made mandatory for TCH/F9.6 NT, but the same is not possible for TCH/[FH]4.8 NT: in the best case of half-alignment, alternating RTP packets will carry alternating halves of RLP frames.

Implemented solution: allow arbitrary state of alignment 2 (aligned or misaligned) in the incoming RTP stream for all CSD NT modes, and perform the necessary alignment internally.

This approach is consistent with the world of E1 BTS: a TRAU in data mode is responsible for alignment 1 (with 20 ms TRAU frames taking the place of our clearmode RTP packets), but only the BTS can perform alignment 2, as the TRAU is agnostic to T vs NT distinction.

Related: OS#6579 Change-Id: Idaebfce6da13b23ba265a197502712d83991873e --- M include/osmo-bts/csd_rlp.h M include/osmo-bts/lchan.h M src/common/csd_rlp.c M src/common/l1sap.c 4 files changed, 301 insertions(+), 29 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/57/38557/3