Running GPRS/EDGE Data Services with Osmocom

Daniel Willmann <dwillmann@sysmocom.de>

April 21, 2017

sysmocom - s.f.m.c. GmbH

Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

Contents

GPRS structure

PCU

NITB

SGSN

GGSN

Running GPRS

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

Classic GPRS

Structure of a GSM network

CN: Core NetworkMS: Mobile Station

UE: UserEquipment

ME: MobileEquipment

ICCGERAN: GSM EDGE Radio

Access Network BSS: Base Station System GPRS PS:

Packet SwitchedPS & CS

CS: CircuitSwitched

AN: Access Network

MSC: MobileSwitching Centre HSSUm

SIM-ME

Abis

Gb

PSTN

A

Nb

Mc

Nc

E

B

CH

D

G

F

Gf,Sv

Gd

Gn

Gc

Gp

Gi

PSTN

Internet

1 2 3

4 5 6

7 8 9

# 0 *

BTS: BaseTransceiver

Station

BSC:Base Station

Controller

CS-MGW

SGSN

MT/TE

SIM

GGSN

VLR

EIR

MSC server

1 2 3

4 5 6

7 8 9

# 0 *

HLR AuC

SMS-GMSC

1 2 3

4 5 6

7 8 9

# 0 *

1 2 3

4 5 6

7 8 9

# 0 *

GMSC

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

Osmocom GPRS

Configuration needed for:

OsmoNITB

OsmoPCU (located at BTS level)

OsmoSGSN

OpenGGSN

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration

IP: y.y.y.y

Gb/IP

sysmoBTS direct PHY access

PCU Sock

SDR Hardware

OsmoTRX Transceiver

VTY

OsmoBTS

osmo-bts-trx osmo-bts-sysmo

CTRL

sysmoBTS PHYsysmoBTS Hardware

Abis/IP

VTY CTRL

OsmoSGSN

OsmoNITBVTY CTRL

Includes functionality of* BSC* MSC/VLR* HLR/AUC* SMSC

OsmoPCU

CTRLVTY

GTP/IP

OpenGGSN

IP: a.a.a.aIP: x.x.x.x

IP: b.b.b.b

IP: y.y.y.y

IP: c.c.c.c

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration (PCU)

Setup coding scheme (CS) and when to switch CS

Throughput optimizations (flow control, TBF idle time)

BSC/NITB configures the rest

pcu

cs 2

cs max 4

cs threshold 50 80

alloc -algorithm dynamic

dl -tbf -idle -time 1000

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration (NITB)

network

bts 0

gprs mode gprs

gprs routing area 1

gprs cell bvci 1234

gprs nsei 1234

gprs nsvc 0 nsvci 1234

gprs nsvc 0 local udp port 23001

gprs nsvc 0 remote udp port 23000

gprs nsvc 0 remote ip a.a.a.a

trx 0

timeslot 6

phys_chan_config TCH/F_TCH/H_PDCH

timeslot 7

phys_chan_config PDCH

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration (SGSN)

sgsn

gtp local -ip b.b.b.b

ggsn 0 remote -ip c.c.c.c

ggsn 0 gtp -version 1

auth -policy closed

imsi -acl add 12345678901234

!

ns

encapsulation udp local -ip a.a.a.a

encapsulation udp local -port 23000

encapsulation framerelay -gre enabled 0

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration (SGSN)

sgsn

gtp local -ip b.b.b.b

ggsn 0 remote -ip c.c.c.c

ggsn 0 gtp -version 1

auth -policy closed

imsi -acl add 12345678901234

!

ns

encapsulation udp local -ip a.a.a.a

encapsulation udp local -port 23000

encapsulation framerelay -gre enabled 0

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration (SGSN)

auth-policy can be accept-all, closed, acl-only, remote

auth-policy remote for authorization and encryption with osmo-hlr

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

GPRS configuration (GGSN)

listen c.c.c.c

net 10.23.42.0/24

pcodns1 8.8.8.8

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

Miscellaneous

Don’t forget masquerading/IP forwarding:

# echo 1 > /proc/sys/net/ipv4/ip_forward

# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Enable data roaming on your phone

APN might need to be set manually

Daniel Willmann | Running GPRS/EDGE Data Services with Osmocom | sysmocom - s.f.m.c. GmbH | 11

Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

Running it all

Demo

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Overview GPRS structure PCU NITB SGSN GGSN Running GPRS

Thank you

Questions?

https:

//osmocom.org/projects/cellular-infrastructure/wiki/OpenBSC_GPRS

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