diff options
| author | Harald Welte <laforge@osmocom.org> | 2020-12-12 19:02:16 +0100 |
|---|---|---|
| committer | Harald Welte <laforge@osmocom.org> | 2020-12-12 19:12:18 +0100 |
| commit | 9e917647aef4679b6fd6eabbe77651bb50b60da8 (patch) | |
| tree | 252f5697b6bb1621e87df9e8eb0c9560d5f598c0 /doc | |
| parent | 784c59f87e6966ac3dc7e03fad2bbb9ceee8592a (diff) | |
gbproxy: Implement scaling of BVC flow control in SGSN pool
When there are multiple SGSNs inside a pool, we need to decide
how much of the per-BVC capacity advertised by the BSS in its
BVC-FLOW-CONTROL we should announce to each of the pool members.
A conservative approach would be to advertise 1/num_sgsn, but
there may also be use case where over-provisioning (announcing more
than an equal share of the capacity) is useful.
Hence, let's introduce "pool bvc-flow-control-ratio <1-100>" in order
to allow the administrator to decide.
Related: OS#4891
Change-Id: Ibe5addf657e7237499ca0205bacfe999ecd1e771
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/manuals/chapters/gbproxy-configuration.adoc | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/doc/manuals/chapters/gbproxy-configuration.adoc b/doc/manuals/chapters/gbproxy-configuration.adoc index 599b3f7ba..e61af48b4 100644 --- a/doc/manuals/chapters/gbproxy-configuration.adoc +++ b/doc/manuals/chapters/gbproxy-configuration.adoc @@ -4,3 +4,29 @@ TBD. Unfortunately this chapter of the manual still needs to be written. Osmocom has very limited funding and support resources; Feel free to help us completing this documentation by contributing with code, documentation or by supporting the developers financially. + + +=== 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. |