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manuals/gbproxy: Move pooling to separate chapter 

Change-Id: Ie2ad652c8261ce56cb2ed1a6f16a81486ccdf063
Related: SYS#5115, SYS#5005
This commit is contained in:
Daniel Willmann 2021-01-27 19:32:33 +01:00
parent ae303b40fc
commit 852ebadd44
2 changed files with 25 additions and 24 deletions
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24
doc/manuals/chapters/gbproxy-configuration.adoc
View File

@ -39,27 +39,3 @@ sgsn 101 <1>
<1> Each SGSN is identified by its NSEI (same as in the NS configuration)
<2> An SGSN can optionally have a name. If none is set a default name will be used.
=== SGSN pool support
In a SGSN pool, osmo-gbproxy is facing the problem of dividing the downlink
capacity of a cell towards the SGSN. The BSS advertises the per-BVC capacity
by means of the BSSGP FLOW-CONTROL-BVC messages, but as there are multiple
SGSN in a pool, they all have to share / divide that total capacity.
By default, osmo-gbproxy advertises the full capacity to _each_ of the SGSN
pool members, which results in significant over-provisioning and can lead to
overload situations.
The administrator can configure the _percentage_ of the overall BSS-advertised
capacity that shall be reported to each pool member SGSN using the
`pool bvc-flow-control-ratio <1-100>` configuration command.
A setting of 100 means that each pool member is informed of 100% of the
BSS side capacity.
A setting of 25 means that each pool member is informed of 25% of the
BSS side capacity. This would make most sense in a set-up with four
SGSN of equal share.
More complex capacity division schemes are so far not supported by
osmo-gbproxy.

25
doc/manuals/chapters/gbproxy-sgsnpool.adoc
View File

@ -192,3 +192,28 @@ To re-enable an SGSN for attaching new subscribers:
sgsn nsei 1
allow-attach
----
==== Traffic allocation
In a SGSN pool, osmo-gbproxy is facing the problem of dividing the downlink
capacity of a cell towards the SGSN. The BSS advertises the per-BVC capacity
by means of the BSSGP FLOW-CONTROL-BVC messages, but as there are multiple
SGSN in a pool, they all have to share / divide that total capacity.
By default, osmo-gbproxy advertises the full capacity to _each_ of the SGSN
pool members, which results in significant over-provisioning and can lead to
overload situations.
The administrator can configure the _percentage_ of the overall BSS-advertised
capacity that shall be reported to each pool member SGSN using the
`pool bvc-flow-control-ratio <1-100>` configuration command.
A setting of 100 means that each pool member is informed of 100% of the
BSS side capacity.
A setting of 25 means that each pool member is informed of 25% of the
BSS side capacity. This would make most sense in a set-up with four
SGSN of equal share.
More complex capacity division schemes are so far not supported by
osmo-gbproxy.