Transcript PowerPoint 簡報

Wireless and Mobile All-IP Networks
Yi-Bing Lin
[email protected]
1
From Traditional Telecom to All-IP

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Circuit-Switched vs Packet-Switched:
Intellient Network (IN) vs. IP Multimedia Core
Network Subsystem (IMS)
Example: Video Phone
All-IP Telecom Services : New Technologies vs.
New Services
VoIP: Numbering, Number Portability
Service Creation: Dictatorship vs. Democracy
Peer-to-Peer, Web 2.0
2
All-IP Architecture
3
Issues on Mobile All-IP Network
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Short Message Service (SMS) and IP Network
Integration
SMS is considered as the application level signaling
mechanism.
Mobility Management
GSM: Location Area (LA) tracking
GPRS: Routing Area (RA), cell tracking
UMTS: RA, UTRAN RA (URA), cell tracking
Session Management
PDP context is introduced.
4
Issues on Mobile All-IP Network
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Mobile Core Networks that Support All-IP:
UMTS: GPRS
cdma2000: PDSN (Packet Data Support Node)
UMTS Charging Protocol
On-line Charging System (OCS)
Mobile All-IP Network Signaling
Traditional: SS7 is supported by MTP
(Message Transfer Part)
All-IP: SS7 is supported by SCTP
(Stream Control Transport Protocol)
5
Issues on Mobile All-IP Network
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UMTS Security and Availability Issues
Virus, fraudulent Usage, Redundant
Authentication
Multicast for Mobile Multimedia Messaging
Service
UMTS All-IP Network
SIP (Session Initiation Protocol)
IPv6
6
Identities in UMTS
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Why is identity management important?
Billing, Security, Service
ANSI 41: MDN = MIN
GSM MAP: MDN ≠ MIN
How are identities assigned in UMTS PS
service domain?
Service: APN
MS: IP address
7
Access Point Name (APN)
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An APN is used in UMTS/GPRS as a reference
point to external PDN that supports the
services to be accessed by an MS.
The APN information is permanently
distributed and maintained in the HLR, the
GGSN and the Domain Name Server (DNS).
8
APN Allocation
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A set of APN labels is defined in the HLR.
Each mobile user can subscribe to one or more APNs
from this set.
The labels of these subscribed APNs are then stored in
the MS at the subscription time.
Among the subscribed APNs, there is one default APN.
If a user attempts to access a service without specifying
the APN, then the default APN is used.
Additionally, the HLR may also define a wild card APN
``*", which allows an MS to access any unsubscribed
APNs.
For each APN, the DNS keeps an IP address list of the
GGSNs associated with this APN label.
9
APN Configurations
(2) WAP
HLR
(12)
UTRAN
(11)
(6)
RADIUS
server
NAT
(13)
SGSN
GGSN
DNS
DHCP
server
(7)
(1) INTERNET
FW
(5)
(8)
Signaling
Signaling and data
DHCP: Dynamic Host Configuration Protocol
FW: Firewall
GGSN: Gateway GPRS Support Node
MS: Mobile Station
RADIUS
server
DHCP
server
(9)
RADIUS
server
(10)
(4) COMPANY
(3) ISP
NAT: Network Address translator
RADIUS: Remote Authentication Dial-In User Service
UMTS: Universal Mobile Telecommunication Service
UTRAN: UMTS Terrestrial Radio Access Network
10
IP Address Allocation: Access Modes
Based on the APN setting specified in 3GPP TS
29.060, the GGSN provides two access modes
for IP address allocation to an MS
 Transparent
 Non-transparent
11
Transparent Access Mode
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In the transparent access mode, the mobile
operator acts as an Internet service provider,
and an MS is given an IP address from the
operator's IP address space.
The IP address can be allocated statically at the
subscription time or dynamically at the
activation of the PDP context.
The transparent access mode is exercised if the
requested APN INTERNET.
12
Non-transparent Access Mode
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In the non-transparent access mode, the mobile
operator only provides a user the access
channel to an Internet service provider (if the
APN is ISP) or a company (if the APN is
COMPANY).
The IP address pool is owned by the Internet
service provider or the corporate, and the IP
address for an MS is dynamically allocated.
13
IP Address Allocation (I)
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The IP addresses can be allocated by either the
GGSN, a Dynamic Host Configuration Protocol
(DHCP) server, or a Remote Authentication
Dial-In User Service (RADIUS) server.
In the transparent access mode, the GGSN may
allocate the IP address for a user by using its
own address pool.
In the current implementation, IPv6 addresses
can only be allocated by this alternative.
14
IP Address Allocation (II)
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In either the transparent or the nontransparent access modes, the GGSN may
negotiate with a DHCP server to allocate an IP
address from the address pool maintained by
this DHCP server.
Alternatively, the IP address of an MS may be
assigned by a RADIUS server, where the IP
address pool is maintained by this RADIUS
server.
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IP Address Allocation (III)
APN label
INTERNET
WAP
ISP
COMPANY
GGSN
access mode
Transparent
Transparent
Nontransparent
Nontransparent
IP address
allocator
GGSN/ DHCP
server
GGSN/ DHCP
server
DHCP server
RADIUS
RADIUS
IP address
type
IPv6/IPv4
IPv4
IPv4
IPv4
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PDP Context
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Before an MS can access any mobile data service, the
Packet Data Protocol (PDP) context for the service
must be activated.
The PDP context specifies the application-layer packet
data protocol and the routing information used for the
communication session.
The PDP context is maintained in the MS, the SGSN,
and the GGSN.
17
PDP Context Activation
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During the PDP context activation procedure , the
MS specifies a requested APN.
Then the SGSN uses this requested APN to select a
GGSN.
If the user does not specify any requested APN in the
activation procedure, the default APN is chosen by
the SGSN.
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PDP Context Activation: Step 1
MS
UTRAN
SGSN
DNS
GGSN
1. Activate PDP Context Request
The MS specifies the APN in the Activate PDP Context
Request message and sends it to the SGSN.
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PDP Context Activation: Step 2
MS
UTRAN
SGSN
DNS
GGSN
1. Activate PDP Context Request
2. Radio Access Bearer Assignment Procedure
The SGSN negotiates with the UTRAN to allocate the radio
bearer bandwidth for the data session.
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PDP Context Activation: Step 3
MS
UTRAN
SGSN
DNS
GGSN
1. Activate PDP Context Request
2. Radio Access Bearer Assignment Procedure
3. APN Query and response
The SGSN checks if the requested APN (obtained from the
Activate PDP Context Request message sent by the MS) is
specified in the APN list of the subscription data for the MS.
If not, the default APN is used.
Then the SGSN creates the PDP context for the user,
and sends the requested APN to the DNS server. The DNS
server uses this APN to derive the GGSN's IP address.
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PDP Context Activation: Step 4
MS
UTRAN
SGSN
DNS
GGSN
1. Activate PDP Context Request
2. Radio Access Bearer Assignment Procedure
3. APN Query and response
4. Create PDP Context Request
Based on the GGSN's IP address obtained from the DNS,
the SGSN sends the Create PDP Context Request message
to the GGSN to establish a GTP tunnel between the SGSN
and the GGSN, which will be used as the packet routing
path between the GGSN and the MS.
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Step 5. The GGSN creates a PDP context for the MS.
This PDP context records the requested APN, PDP type,
MSISDN, and IP address. The GGSN allocates an IP
address for the MS by using either transparent or nontransparent access mode, and determines the tunneling
mechanism to the destination external PDN.
MS
UTRAN
SGSN
DNS
GGSN
1. Activate PDP Context Request
2. Radio Access Bearer Assignment Procedure
3. APN Query and response
4. Create PDP Context Request
5. Create PDP Context Response
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Step 6. Finally, the SGSN informs the MS that the session
setup is completed
MS
UTRAN
SGSN
DNS
GGSN
1. Activate PDP Context Request
2. Radio Access Bearer Assignment Procedure
3. APN Query and response
4. Create PDP Context Request
5. Create PDP Context Response
6. Activate PDP Context Accept
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All-IP Telecom. Trial
in Taiwan
NANKANG
Matsuh
County
NATIONAL SOFTWARE
MUSEUM PARK
OF
HISTORY
Taoyuan
County
TAIPAI
VOIP
Center
Hsinchu
County
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Under the MTaiwan Program,
FarEasTone is
developing IMS
Service Platform.
APTG is
conducting VoIP
Service Trial.
Keelung
City
Miaoli
County
Taichung
County
Taichung
City
Penghu
County
Hualien
County
Nantou
County
Yunlin
County
Taitung
County
Chiayi
County
Chiayi
City
Tainan
City
Tainan
County
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Call Setup in APTG Trial
(4) Taipei switch
Originating switch
(3) Caller
PSTN
(2) Proxy server
(CSCF)
APTG IP backbone
(5) Softswitch
(MGCF/MGW)
IP-PBX
(1) AP
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Performance Measurement
Mean Opinion Score (MOS)
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Conclusions
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The SIP protocol does not provide all features needed
to implement existing telecommunications services. For
example, the flash-hook signal for the call waiting
service is implemented proprietarily in the APTG trial.
There are too many kinds of IP CPEs. Some of them
may not be compatible with the networks, and may
show very poor performance. Furthermore, some CPEs
may be complicate to operate, and cannot be simply
“plug-and-play”.
Although the cost for deploying All-IP VoIP network is
lower than traditional PSTN network, it is not clear if
the same advantages are guaranteed for maintenance
and operations of the VoIP network.
28
Appendix A: IPv4 vs IPv6
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The above procedure assumes IPv4 IP address allocation.
For IPv6, the IP address allocation is different.
Support of public IP address is a major difference for
UMTS address allocation between IPv4 and IPv6.
For IPv4, the MS is typically allocated a private address
because of limited IPv4 address space.
For IPv6, the MS is always allocated a public address.
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IPv6 Address Allocation
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At Step 5 of the PDP context activation procedure, the
GGSN allocates a complete IP address for IPv4.
For IPv6, there are two alternatives for dynamic address
allocation: stateless address allocation and stateful address
allocation.
Like IPv4, the stateful IPv6 address is allocated by DHCP
server at Step 5.
On the other hand, in stateless address auto-configuration,
the GGSN allocates a part of the IPv6 address called linklocal address for the MS by using its own IPv6 address
pool at Step 5.
Then the MS generates the public IP address by combining
the link-local address and a network-prefix address.
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IPv6 Stateless Autoconfiguration Procedure
MS
UTRAN
SGSN
GGSN
1. PDP Context Activation Procedure
2. Router Solicitation
3. Router Advertisement
4. GGSN-Initiated PDP Context Modification Procedure
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Stateless Address Auto-configuration (I)
Step 1: the MS first obtains the link-local address in the PDP
context activation procedure.
Step 2: the MS activates the IPv6 address auto-configuration
by sending the Router Solicitation message to the GGSN.
Step 3: The GGSN replies with the Router Advertisement
message, which includes the network-prefix address.
After the MS has received the Router Advertisement message,
it obtains the IPv6 address by concatenating the link-local
address and the network-prefix address.
Step 4: Then the GGSN updates the IPv6 address of the PDP
contexts in the SGSN and the MS.
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Stateless Address Auto-configuration (II)
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To avoid conflict of link-local address assignment, the
GGSN shall exercise neighbor discovery with other
GGSNs.
Note that in traditional IPv6 stateless address allocation,
neighbor discovering is conducted by the mobile host. In
UMTS, neighbor discovery is exercised by the GGSNs.
Also note that existing UMTS core network is developed
based on the IPv4 transport network.
Therefore, IPv6 packets are carried on top of the IPv4based GTP tunnel, which are invisible to the UMTS core
network.
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UMTS and External PDN Interworking
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The GGSN interworks the external data network through
the Gi interface. The interworking mechanisms may be
different for various APN configurations.
For the INTERNET and WAP APNs, the GGSN connects
to the external PDN directly through Ethernet or leased
lines.
For the ISP APN, the external PDN can be connected to
the GGSN either through the leased lines or the VPN. If
the Internet service provider connects to the GGSN
through VPN, then tunneling is required.
For the COMPANY APN, tunneling is always required for
interworking between the GGSN and the corporate intranet.
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Tunneling Methods
Three tunneling methods have been proposed for
UMTS.
 IP-in-IP tunneling.
 Generic Routing Encapsulation (GRE) tunneling
 Layer 2 Tunneling Protocol (L2TP) tunneling
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IP-in-IP Tunneling
Intranet of
a corporate
MS
GGSN
Internet
VPN
Gateway
Application
Server
Application
(2) IP
(1) IP
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Intranet of
a corporate
MS
GGSN
Internet
VPN
Gateway
Application
Server
Application
(3) PPP
(2) GRE
(1) IP
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Intranet of
a corporate
MS
GGSN
Internet
VPN
Gateway
Application
Server
Application
(5) IP
(4) PPP
(3) L2TP
(2) UDP
(1) IP
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Tunneling
method
Overhead
Multiprotocol
support
Transport
support
MS
support
IP-in-IP
low
no
IP
IP
GRE(PPTP)
medium
yes
IP
PPP
L2TP
high
yes
IP/UDP,
FR, ATM
IP
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Each of the above three methods can be used
together with IPsec to provide protection for packet
delivery.
If an MS supports both PPP and IP, then all these
three tunneling methods can be used to provide data
sessions to this MS.
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Quality of Service
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UMTS defines four QoS classes for user data traffic:
conversational, streaming, interactive, background
The conversational and the streaming classes support realtime traffic for services such as voice and streaming video.
The interactive and the background classes support non
real-time traffic for services such as web browsing and
email.
Each class defines parameters including maximum bit rate,
guaranteed bit rate, bit error ratio, transfer delay, etc.
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QoS: VoIP and Internet Access
QoS
parameter
VoIP
(conversational)
Internet access
(Interactive )
Maximum
bit rate
Guaranteed
bit rate
16 Kbps
128 Kbps
12.2 Kbps
100 Kbps
Bit error
ratio
Transfer
delay
104
10-6
100 ms
unguaranteed
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End-to-end IP QoS Models (I)
Scenario 1
2
3
4
5
MS
--
DS
RSVP
SBLP
GGSN
DS
DS
DS
RSVP
DS
DS
RSVP
DS
SBLP
External DS
PDN
Remote DS
host
DS
DS
DS
DS
DS
RSVP
DS
RSVP
DS
RSVP
DS
SBLP
RSVP: Resource Reservation Protocol
SBLP: Service-Based Local Policy
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End-to-end IP QoS Models (II)
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The end-to-end QoS for packet switched service is
negotiated among the MS, the GGSN and the remote host
located in the external PDN.
3GPP TS 23.207 assumes that the external PDN supports
Diffserv QoS mechanism, and the GGSN is required to
perform the Diffserv edge function in all scenarios.
Within the UMTS network (MS-UTRAN-SGSN-GGSN),
the IP QoS is translated and maintained by the UMTS QoS
mechanism where the QoS parameters are set in the PDP
contexts.
44
GGSN QoS Architecture
GGSN
3 Packet
Classifier
Step
1
Incoming
IP
packets
Outgoing IP packets
Step 2
4 Traffic
Conditioner
External
Data Network
Step 9
Step 3
SGSN
2
Admission
Controller
5
Packet Mapper
QoS Control Signaling
Step 4
User data
1
Resource
Manager
Step 6
incoming GTP packets
outgoing GTP packets
6 Packet
Scheduler
Step 8
Step 5
7 GTP/IP Packet
Converter
Step 7
45
UMTS QoS vs DSCP
UMTS QoS
class
Conversational
DSCP codepoint
Delivery Priority
Expedited Forward
1 (high)
Streaming
Assured Forward
class 1
2
Interactive
Assured Forward
class 2
3
Background
Best Forward
4 (low)
46
Remarks on GGSN QoS
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The Resource Manager and the Admission
Controller are involved in PDP context activation.
The Packet Classifier, Traffic Conditioner, Packet
Mapper and Packet Scheduler are involved in
packet delivery.
47
Appendix B: Multicast for Mobile
Multimedia Messaging Service
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Short Message Service (SMS) allows mobile subscribers to
send and receive simple text message in 2G systems (e.g.
GSM).
Multimedia Message Service (MMS) is introduced to
deliver messages of sizes ranging from 30K bytes to 100K
bytes in 2.5G systems (e.g. GPRS) and 3G systems (e.g.
UMTS)
The content of an MMS can be text (just like SMS),
graphics (e.g., graphs, tables, charts, diagrams, maps,
sketches, plans and layouts), audio samples (e.g., MP3 files),
images (e.g., photos), video (e.g., 30-second video clips),
and so on.
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MMS Architecture [1/2]
49
MMS Architecture [2/2]
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The MMS user agent (a) resides in a Mobile Station (MS) or an
external device connected to the MS, which has an application layer
function to receive the MMS.
The MMS can be provided by the MMS value added service
applications (b) connected to the mobile networks or by the external
servers (d) (e.g., email server, fax server) in the IP network.
The MMS server (c) stores and processes incoming and outgoing
multimedia messages.
The MMS relay (e) transfers messages between different messaging
systems, and adapts messages to the capabilities of the receiving
devices. It also generates charging data for the billing purpose. The
MMS server and the relay can be separated or combined.
The MMS user database (f) contains user subscriber data and
configuration information.
The mobile network (g) can be a WAP (Wireless Application Protocol)
based 2G, 2.5G or 3G system. Connectivity between different mobile
networks is provided by the Internet protocol.
50
Short Message Multicast Architecture
MCH (HLR)
VLR1
1
VLR2
2
VLR3
0
MCV (VLR1)
MCV (VLR3)
LA5
0
LA6
0
MCV (VLR2)
LA1
0
LA3
0
LA2
1
LA4
2
51
Appendix C: Short Message Service and IP
Network Integration
GSM SMS Network Architecture
52
SMS-IP Integration: SM-SC-based
In most commercial implementations, SMS and IP networks
are integrated through SM-SC.
Mobile
Network
IP
Network
SM-SC
Gateway
53
NCTU-SMS
54
iSMS
55
Simple Tone Language (STL)
The regular expressions are used for the STL grammar. In STL,
a music tone is defined as
tone = [style] [tempo] [volume] [repeat] (note-expression)+
where style is of the format
style = “S” “0” (“0” | “1” | “2”)
S00: Natural Style (rest between notes)
S01: Continuous Style (no rest between notes)
S02: Staccato Style (shorter notes and longer rest period)
56
STL Representation for a Taiwanese Song
Notes:
STL: t13
3e 3f 5 3e 3f 5
2z 3f 1c
3e 5f 5e 6f 5
5e 6f 5e 3f 3
2z 3f 1c
57
Appendix C: GGSN Functionalities
The GGSN plays the role as a gateway, which controls user
data sessions and transfers the data packets between the
UMTS network and the external PDN.
The meta functions implemented in the GGSN are described
as follows:
 Network access control
 Packet routing and transfer

Mobility management
58
Functions of UMTS Network Elements
59