Due to production forecasts, support has been added to the StarOS for
one million S1-U connections on a single S-GW.
The S1-U interface is the user plane interface carrying user data
between an eNodeB and an S-GW received from the terminal. The StarOS now has
the capability to scale the number of S1-U peers to one million per VPN
A CLI command enables operators to set the number of S1-U peers for
which statistics should be collected. The limit is restricted to less than one
million peers (128k) due to StarOS memory limitations.
How it Works
The gtpumgr uses the following guidelines while allocating peers:
When a session installation comes from the Session Manager, a
peer is created. If statistics are maintained at the Session Manager, the
gtpumgr also creates the peer record with the statistics.
Peer records are maintained per service.
The number of peers is maintained at the gtpumgr instance level.
The limit is one million S1-U peers per gtpumgr instance.
If the limit of one million peers is exceeded, then peer creation
fails. It causes a call installation failure in the gtpumgr, which leads to an
audit failure if an audit is triggered.
The feature changes impact all the interfaces/services using the
gtpu-service including GGSN/S4-SGSN/S-GW/P-GW/SAEGW/ePDG/SaMOG/HNB-GW/HeNB-GW
The Gn and Gp interfaces of the General Packet Radio Service
The Iu, Gn, and Gp interfaces of the UMTS system
The S1-U, S2a, S2b, S4, S5, S8, and S12 interfaces of the Evolved
Packet System (EPS)
After a session manager/gtpumgr recovery or after an ICSR
switchover, the same set of peers configured for statistics collection is
Peers with 0 sessions and without statistics are not
Peers with 0 sessions and with statistics are recovered.
Peers with Extension Header Support disabled are recovered.
While upgrading from a previous release, ensure the newer release
gtpu peer statistics threshold is equal
to or greater than the previous release. This way the GTPU peer statistics are
preserved during the upgrade. For example, if you are upgrading from StarOS
release 19.0 to 20.2, and the StarOS 19.0 system has 17,000 GTPU sessions, then
configure the threshold on the StarOS 20.2 system to 17,000 as well.
Due to the large number of GTP-U entities connecting to the
StarOS, Cisco recommends disabling the GTP-U Path Management feature.
The configured threshold is not the hard upper limit for
statistics allocation because of the distributed nature of system. It is
possible that total GTP-U peers with statistics exceeds the configured
threshold value to some extent.
It is assumed that all 1 million peers are not connected to the
node in a point-to-point manner. They are connected through routers.
There will not be any ARP table size change for the StarOS to
support this feature.
This section describes how to
configure support for the One Million S1-U Peer Connections feature.