Change in osmo-gsm-manuals[master]: GSUP: document inter-MSC handover additions

[osmith]

Hello Vadim Yanitskiy, Pau Espin Pedrol, Neels Hofmeyr, Harald Welte, Jenkins Builder, 

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

    https://gerrit.osmocom.org/14096

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

Change subject: GSUP: document inter-MSC handover additions
......................................................................

GSUP: document inter-MSC handover additions

Message formats of the new messages look mostly the same (IMSI,
Message Class, Source Name, Destination Name, AN-APDU). That is, because
AN-APDU is storing results, error reasons etc. This can be seen clearly
in osmo-msc.git:
* src/libmsc/msc_a_remote.c:msc_a_remote_fsm_communicating()
* src/libmsc/msc_i_remote.c:msc_i_remote_fsm_ready()

The message squence charts in the E Procedures section are directly
based on Neels' interMSC_HO_GSUP_msgs.txt [1].

It seems that using AN-APDU made some other new IEs redundant: RR Cause,
BSSAP Cause, Session Management Cause had been added to GSUP for the MSC
handover, and are documented now, but they are currently not used in
osmo-msc.git. The new message OSMO_GSUP_MSGT_E_ABORT is not used either,
so I left a stub for it in the message format section.

I mentioned in the Source Name IE section, that source and destination
names are sent as nul-terminated strings. This is for legacy reasons,
Neels wrote a nice summary in the commit message of [2].

[1] https://osmocom.org/attachments/3720/interMSC_HO_GSUP_msgs.txt
[2] Change-Id: I9ca8c9eef104519ed1ea46e2fef46dcdc0d554eb (osmo-msc)

Related: OS#3774, OS#3619
Change-Id: I6b9f23d08cfe53c8b77f51c6afb900c2badc9e2c
---
M common/chapters/gsup.adoc
1 file changed, 410 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-gsm-manuals refs/changes/96/14096/3
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Gerrit-Project: osmo-gsm-manuals
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I6b9f23d08cfe53c8b77f51c6afb900c2badc9e2c
Gerrit-Change-Number: 14096
Gerrit-PatchSet: 3
Gerrit-Owner: osmith <osmith at sysmocom.de>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder (1000002)
Gerrit-Reviewer: Neels Hofmeyr <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Pau Espin Pedrol <pespin at sysmocom.de>
Gerrit-Reviewer: Vadim Yanitskiy <axilirator at gmail.com>
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