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Webex Sunday Session 24 March 2013 Educational non-profit purpose only
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Introduction into Mobile Core Network
WebEx Sunday Session24 March 2013
• Goal– Introduction into 2G/3G and 4G core
network element in Telco technology, particular for non-Telco person.
– Overview of call establishment process– Experience sharing of 4G EPC project
delivery from existing Mobile Network Operator.
• What is not covered here…– Wireless and radio related part.– Detail and ‘deep dive’ of each network
element.– Detail procedure for call establishment.
• Disclaimer– All material presented here is solely for non-profit
educational purpose.
About this presentation
Node and Interface in Telco
• What is a Node ?Node is a network component that is capable of receiving, sending or forwarding electronic information over the designated communication link. For example BSC, RNC, SGSN, MSC, HLR.Known as Network Element too..
• What is an Interface ?In telecommunication, an interface is a logical link connection or a reference point, between two components in telecommunication infrastructure, for example, Gn interface is a reference point between SGSN and a GGSN.
However, Telecommunication also use term ‘interface’ as a device or program of that enabling a communication between user and a computing device.
2G and 3G Network Architecture
User planeControl plane
SGSN GGSN
Packet Data Networke..g Internet
GiGn
IuPS
Gb
BSC
BTSMS
Abis
RNC
NodeB
MSIub
HLR
SMSC
DNS
RADIUS
DHCP
Charging Centre
NMS / OSS
Service & subscriber management
PCRF
Gx/Gz
Gz/Gs/Gr/Gf/Gd
MGW
MSS/VLR
MGW
MSS/VLR
PSTNOther PLMN
IuCS
Nb
A
Nc
Mc Mc
Packet Core Domain
Circuit Core Domain
Acronym used in Telco..
MS Mobile Subscriber A mobile phone with SIM card
BTS Base Transceiver Station Air interface toward MS in 2G
BSC Base Station Controller Controlling BTS
NodeB n/a Air interface toward MS in 3G
RNC Radio Network Controller Controlling NodeB
MSS Mobile Switching Server Mobility Management for CS Domain
VLR Visitor Location Register Manage temporary subscriber information within an MSS
HLR Home Location Register Manage permanent subscriber Database
MGW Media Gateway Manage user plane traffic
SGSN Support GPRS Service Node Mobility Management for PS Domain
GGSN Gateway GPRS Service Node Session Management , IP address allocation, QoS enforcement, Routing toward internet.
Circuit Switching vs. Packet Switching
• Circuit Switching–Mostly used in the voice call.–Whenever a call is being made, a dedicated logical link needs to be established.–Network resource is allocated and reserved for the subscriber for entire duration of the call.
• Packet Switching–Mostly used in the Packet Data Connection.. . e.g. internet browsing–Whenever an MS sends or receives data, data is organized into packet and each packet has source / destination ID.
Signaling Plane vs. User Plane
• User Plane is the user traffic that contain the conversation between 2 or more user peers.– Carried over the core network as a bearer– Example. Voice call or Browsing data traffic through GPRS
• Control Plane is signaling communication used to control the bearer traffic.– Involving of sending and receiving messages between 2 nodes.– Example. Communication between SGSN and HLR.
A Simplified 2G/3G PS Call Flow…(1/3)
SGSN GGSN
Packet Data Networke..g Internet
GnGb IuPS
BSCRNC
BTS / NodebMS
Abis / Iub
HLR Gn DNS
Attach request..
Attach accepted..
Get info for this subscriber
Herewith the info
I am attached to the
network and want to
browse, by activating
PDP context
Reference : TS 23.060TS 24.008TS 29.060
Internet DNS
Note :All procedures here are simplified for overview
only. Reader should refer to above reference for detail procedures.
1
2
3
4
5
A Simplified 2G/3G PS Call Flow…(2/3)
SGSN GGSN
Packet Data Networke..g Internet
GiGn
Gb -IuPSBSCRNC
BTS / NodebMS
Abis - Iub
HLR Gn DNS
PDP context activation received from MS,
What is the IP address of the GGSN that serving this APN ? ?
Herewith the IP address of GGSN
Create PDP
Context Request
Create PDP Context
accepted
Create PDP context accepted, send this
info to MS
Reference : TS 23.060TS 24.008TS 29.060
Internet DNS
Note :All procedures here are simplified for overview
only. Reader should refer to above reference for detail procedures.
I am attached to the
network and want to
browse , by activating
PDP context
5
6
7
8 9
10
PDP context activation accepted, now browse
towww.google.com.au
11
A Simplified 2G/3G PS Call Flow…(3/3)
SGSN GGSN
Packet Data Networke..g Internet
GiGn
Gb -IuPSBSCRNC
BTS / NodebMS
Abis - Iub
HLR Gn DNS
Reference : TS 23.060TS 24.008TS 29.060
Internet DNS
Note :All procedures here are simplified for overview
only. Reader should refer to above reference for detail procedures.
PDP context activation accepted, now browse
towww.google.com.au
11
12
13
HandoverAction of switching a call in progress from one radio channel to another to secure the continuity of an established call.
The purpose of handover control is to manage the mobility aspect of the Subscriber. This means keeping track of mobile stations (MS) as they move around in the network, and ensuring that their connections are uninterrupted and meet the negotiated Quality of Service requirements.
Move to 4G..???
• Wait…first, let see the widely involvement of IP protocol.
• Protocol used in the control plane messaging has evolved.– Changes in Transport Layer protocol
while keeping all the Application Layer remain unchanged.
– Completely changed at Transport and Application Layer.
• Transport Layer has changed dramatically from legacy protocol toward IP.
User planeControl plane
SGSN
RNCNodeBS4S12 DT
IuR8 3G
BSCBTS 2G SGSNGb R8 2G
General LTE Architecture
GnGn
BSC/RNCPre R8 2G/3G
SGSNBTS/NodeBGbIu
R7 DT
PCRF
Gx
S1-MME
S1-U S6a
HSS
eNodeB
S10MME
LTE
S5PGWSGW
SGi
SGi
S11
S3
SGs MSC
SGiInternet
Operator services
Basic EPS architecture defined in 3GPP TS 23.401
Acronym used in 4G
E-NodeB Air interface toward MS in 4G
MME Mobility Management Entity Mobility Management for 4G, Control Plane only
S-GW Serving Gateway Mobility Management for 4G for User Plane, Handover anchoring .
P-GW Packet Data Network Gateway Routing to Packet Data Network, Session Management, IP address Allocation. Function of P-GW is similar to GGSN in the 2G/3G network
HSS Home Subscriber Server Manage Permanent 4G subscriber data. Evolution of HLR.
Internet has driven operation model…(1/3)
SGSN GGSN
HLR
RNC
TDM
IP / MPLS
ATM
Internet
Operator Network
Multiple network type exist on Mobile Operator Network
Internet has driven operation model…(2/3)
SGSN GGSN
HLR
RNC
TDM
IP / MPLS
ATM
Internet
Operator Network
Driven by internet grows, Telco vendor is developing their product using IP as the transport media.
Internet has driven operation model…(3/3)
SGSN GGSN
HLR
RNC
IP / MPLS
Internet
Operator Network
Driven by internet grows, Telco vendor is developing their product using IP as the transport media. Mobile Operator needs to ‘simplify’ the O&M for many network type. New challenges and opportunities are on-board for IP (IT) and Telco engineer.
Protocol has been changed.. (1/2)
MTP Layer 1
MTP Layer 2
MTP Layer 3
INAP/CAPTUPISUP
BSSAPMAP
SCCP
TCAP
Legacy Gr InterfaceBetween SGSN – HLR Using MAP ApplicationSS7 protocol
Physical Layer
Data Link Layer
IP
SCTP
M3UA
Gr InterfaceBetween SGSN – HLR Using MAP ApplicationSS7 protocol transported over IP
Protocol has been changed… (2/2)
Physical Layer
Data Link Layer
IP
SCTP
Diameter Application
Physical Layer
Data Link Layer
IP
SCTP
M3UA
Gr InterfaceBetween SGSN – HLR Using MAP ApplicationSS7 protocol transported over IP
S6a InterfaceBetween MME – HSS Using Diameter ApplicationRFC 3588TS 29.272
IP is here…
PDCP
RLC
MAC
UE eNB MME
NAS NAS
RRC
SCTP
IP
L2
L1
S1AP
UDP
IP
L2
L1
GTP-Cv2
S-GW
Uu S1-MME S11
RLC
PHY
RRC
PHY
MAC
PDCP SCTP
L2
L1
S1AP
UDP
IP
L2
L1
GTP-Cv2PMIP
IP
PDCP
UE eNB S-GW
UDP
IP
L2
L1
UDP
IP
L2
L1
P-GW
Uu S1-U S5/S8
PHYPHY
PDCP
UDP
L2
L1
UDP
IP
L2
L1
IP
GTP-U
MAC
RLC
GTP-U GTP-U/GRE GTP-U/GRE
RLC
MACUse
r Pla
ne
Cont
rol P
lane
P-GW
UDP
IP
L2
L1
GTP-Cv2PMIP
S5/S8
…and here…
UDP
IP
L2
SGSN / MME
GTP-Cv2
S3/S4/S10/S16
L1
UDP
IP
L2
MME
GTP-Cv2
L1
Cont
rol P
lane
UDP
IP
L2
SGSN
GTP-U
S4/S12
L1
UDP
IP
L2
S-GW
GTP-U
L1
Use
r Pla
neSCTP/TCP
IP
L2
MME
Diameter
S6a/S6d/S13
L1
SCTP/TCP
IP
L2
HSS/EIR
Diameter
L1
Cont
rol P
lane
Reference : TS 29.281TS 23.401
…and everywhere…
VRF AVRF BVRF CVRF D
VRF S5VRF S1uVRF OAMVRF SGi
PEP-GW
•IP addressing scheme ? Private/public ? •Running OSPF between Node and PE• Area 0 or non-backbone ?• Stub or totally stub ? NSSA ?
•or should BGP being used ??
Example : VRF Concept
A wake up call for Telco Engineer !!!
Multiple OSPF process
ISP A
ISP B
Costumer C
192.168.1.1/24
192.168.2.1/24
192.168.3.1/24
192.168.4.1/24
Client Role Server Role
Primary Path
Secondary Path
• Based on IETF - RFC 4960• Application always use 2 IPs from different subnet for each node.• Whenever there is a failure in primary path, the client and server automatically
switch the traffic into secondary path.• Applied for most signaling traffic, such diameter, Sigtran.• Telco engineer to make sure that Client – Server communicate correctly.• IP engineer to make sure that there is a path diversity within IP network and there is
NO unseen single point of failure may happen.
…While in telecommunication has another view about multihoming..
Customer – Provider
Multihoming Concept
A Simplified PS Call Flow with 4G…(1/2)
MME
S-GW
Packet Data Networke..g Internet
SGi
S11S1u
eNodeBMS
S1
HSS DNS
Attach request..
Get info for this subscriber
Herewith the info
I am attached to the network and
want to browse to www.google.com.
au
What is the S-GW IP Address ?What is the P-GW IP Address ?
Herewith the IP Addresses
Create Session Request with IP Address of S-GW and P-GW
Create Session Request response (Accept)
P-GW
Create Session Request with IP Address of P-GW
Create Session Request response (Accept)
Create Session Request response (Accept)
S5/S8
Reference : TS 29.281TS 23.401TS 29.274
Note :All procedures here are simplified for overview
only. Reader should refer to above reference for detail procedures.
1
2
3
4
5
6
7
8
9
10
11
A Simplified PS Call Flow with 4G… (2/2)
MME
S-GW
Packet Data Networke..g Internet
SGi
S11S1u
eNodeBMS
S1
HSS DNS
I am attached to the network and
want to browse to www.google.com.
au
P-GWS5/S8
Reference : TS 29.281TS 23.401TS 29.274
Note :All procedures here are simplified for overview
only. Reader should refer to above reference for detail procedures.
11 12
Internet DNS
13
LTE QoS Concept Overview• Admission Control
– Prioritize bearers based on QoS parameter– Protect network element in case of congestion or overload.
• Traffic Control– Traffic classification (queuing, scheduling)– Traffic policing and shaping
EPC Project Delivery• Client : one of live mobile operator • Duration : Jan 2012- November 2012• Involving 3 areas of expertise :
– PS Core– CS Core – IP
Prepare
Plan
Design
Implement
Operate
Optimization
User planeControl plane
Network Assessment : Current 2G/3G Mobile Packet Core
S6a
S1-MME
S1-UeNodeB
S10MME
LTE S5
PGWSGW
S11
SGs MSC
SGi
GGSN
GnGn
BSC/RNC
Pre R8 2G/3G
SGSNBTS/NodeBGbIu
R7 DT
Internet
Operator services
HLR/HSS
Gi
Gr
Project Delivery: EPC Node Commissioning and IntegrationNetwork Target : LTE & 2G/3G interworking
• It is a new technology..– New network elements, protocols and
procedures.– Everyone involve may have their own
interpretation during planning, commissioning and integration.
– Limited reference from available production network.
– Always refer to International Standard. 3GPP, RFC and GSMA.
Lessons learned and Challenges...
It is all IP..– A complexity of client MPLS network.– Design and Planning is taking an
important step.– Requires an intensive collaboration
work with IP team. – Things worth to note…
• L1 implementation. Wrong cable positioning• VLAN and IP addressing, public/private ??• Pay attention into any node limitation : port type,
MTU, active/standby behavior, Load Balance concept, Client-Server role
Diameter Routing Planning..
MME MME
HSS EIR
MME MME
DRA
HSS EIRHSS HSS HSS
Roaming Partner /GRX
DRA
Without DRADRA=Diameter Routing Agent With DRA
Some screenshots from 4G handset
Some speed test in various location.
Upcoming technical challenges with LTE
More InformationTechnical Specification and Standard. Readable and downloadable for
public • www.3gpp.org/specification-numbering• www.ietf.org• http://www.gsma.com/newsroom/technical-documents
EPC Product Knowledge. Also readable and downloadable for public • http://www.cisco.com/en/US/products/ps11072/products_installatio
n_and_configuration_guides_list.html
Further discussion
• Parakontel • Indocisco
…ready to ‘take-off’ now ?
…then please fasten your seatbelt…
Thank You….
Images Creditshttp://wallpoper.com/wallpaper/board-circuit-253188http://forzamotorsport.net/en-US/fm4/tracks.aspx?t=Circuit_de_Catalunyahttp://www.certshelp.com/blog/wp-content/uploads/2012/10/ip-address.jpghttp://coachgiorgio.com/wp-content/uploads/2011/05/teamwork4.jpg
Further discussion.