12 Mobile Networks Support

Stingray SG can detect GTP-C traffic and extract subscriber parameters for the subscriber's IP and login binding from the GTP session creation requests. GTP-C versions 1 and 2 are supported. GTP support is enabled by parameters in fastdpi.conf:

# bras_enable=1
#
# GTP processing mode
# Values:
# 0 - (default) GTP processing is disabled
# 1 - [bind mode] In this mode, BNG/BRAS processes GTP-C packets of the session start and end,
# binding the IP-address issued to the subscriber with the login (IMSI or MSISDN is used as the login).
# At the end of the session, the login-IP connection is broken.
# 2 - [auth mode] authorization of GTP sessions is enabled. In this mode, BNG/BRAS processes GTP-C session start and end packets.
# Upon successful start of the GTP session, BRAS sends an L3 authorization request to PCRF,
# transmitting the subscriber's IP address, IMSI, MSISDN, IMEI and other parameters.
# At the end of the session, the login-IP connection is broken.
#bras_gtp_mode=0

When the bras_gtp_mode is enabled, it is assumed that mirrored GTP-C traffic between S-GW and P-GW is sent to the SSG: SSG drops all incoming GTP-C packets, when bras_gtp_mode=2 is enabled SSG acts as L3 BNG/BRAS, requesting policing and subscriber services from PCRF.

You should also set the maximum size of active GTP-sessions internal database in fastdpi.conf

# Max number of concurrent GTP-sessions
# We recommend setting this parameter 1.5-2 times more than the actual max number of sessions
# Default value: 10000 sessions, minimum value: 10000
#bras_gtp_session=10000

After receiving a request to create a GTP-C session, SSG waits for a packet of successful session creation. Only at this moment, upon receiving a successful response and issuing an IP address to the subscriber, connects the login and IP. The response timeout is set by a parameter in fastdpi.conf:

# Max time to wait for a response to a GTP session creation, seconds
# Default = 3 seconds
#bras_gtp_pending_timeout=3

IMSI or MSISDN can be used as a login, which is set by a parameter in fastdpi.conf:

# What is the subscriber's login for GTP:
# 0 - IMSI (by default)
# 1 - MSISDN
#bras_gtp_login=0

To detect GTP-U, you have to enable tunnel parsing:

# enable the tunnels parsing by dispatchers
check_tunnels=1
# enable the detection and parsing of GTP-U
detect_gtp_tunnel=1

When you enable parsing of GTP-U tunnels, SSG will work with the real IP-address of the subscriber, and not with the IP-address of the tunnel. That means that it becomes possible to apply filtering, services and policing to the GTP-subscriber.

SSG does not terminate GTP-U tunnels.

The internal database of GTP-sessions can be controlled with a special set of CLI-commands.