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Source : Network Insight
Emerging Services for Wireless Carrier Networks--Design Abstract
Core Network is also known as :
Communications Network,
Mobile Communications,
Mobile Communications Network,
Mobile Network,
Access Network,
Aggregation,
Core Network Performs,
Gateways,
Telecommunications,
Local Area Network,
Wireless LAN ,
Wide Area Network,
Router,
Subnet.
Table of Contents
- The Transition to IP
- Enabling Next Generation Services
- Voice over IP (VoIP)
- Virtual Private Networks
- IPv6
- SS7oIP
- Conclusion
- Acronyms
The Transition to IP
A wireless carriers national or regional next generation core network will be an all-IP
network in the sense that IP will be the network layer (L3) protocol. MPLS
(Multiprotocol Label Switching) will be the transport protocol for all IP-based services,
applications, and control and management traffic in the network. In other words, IP will
be used as the common network layer to support all of the carrier's application and
service networks (corporate data, customer data, VoIP, Internet access, etc.), and
management networks.
It is assumed that the Layer 1 and Layer 2 core network is a shared transport network
infrastructure that is characterized by high speed, high reliability, high availability
andhigh performance. This new IP- based network must meet the business,
architectural and functional requirements that a national or regional wireless carrier
have come to expect.
Enabling Next Generation Services
This section describes some of the features and functionality that may be added to the
core network to meet the business and technical needs of the corporation. The core
network must be capable of supporting each of the following services:
Voice over IP (VoIP)
Voice over IP (VoIP) defines a way to carry voice calls over an IP network including the
digitization and packetization of the voice streams. IP telephony utilizes the VoIP
standards to create a telephony system where higher level features such as advanced
call routing, voice mail, call/contact centers, etc., can be utilized.
The long-distance Voice over IP (VoIP) network solution is a set of network design and
configuration strategies that provide trunk-level transport of global switched telephone
traffic distributed over VoIP. Calls may originate from the Public Switched Telephone
Network (PSTN) or the (Mobile Switching Center) MSC, and are handed off to the IP
network for transport, providing for toll bypass of customer voice traffic, voicemail, and
customer care/ call center traffic. Thus allowing for enormous operational cost savings.
Virtual Private Networks
Virtual Private Networks (VPNs) provide private IP closed user group(s). A VPN
simulates the operation of a private wide area network (WAN) over a common
infrastructure. MPLS allows the creation of Layer 3 VPNs across an MPLS
infrastructure, providing a simple, flexible, and powerful tunneling mechanism. These
tunnels provide transport service and enable the use of:
- Segregation of traffic such as voice and VoIP, signaling traffic, public/customer
data services, as well as private data services such as billing and provisioning,
and Corporate IT traffic such that can be maintained as separate administrative
domains.
- QoS parameters applied to each VPN independently
- Overlapping private address space across various VPNs
Moreover, MPLS allows Layer 2 VPNs and Circuit Emulation Service (CES) over MPLS.
This allows Layer 2 interface information to be bound to labels and advertised (signaled)
across a network. As such, the following Layer 2 encapsulation types may be tunneled
over an intervening MPLS core:
- Frame Relay
- ATM AAL5 PDUs and cell relay
- PPP
- HDLC
- Ethernet
- Ethernet VLAN
Layer2 and Layer3 VPNs may allow additional services to be transported across the
core network. VPN's may also reduce operating cost by minimizing or eliminating
leased line circuit costs.
IPv6
Internet Protocol version 6 (IPv6) is the "next generation" protocol designed by the IETF
to replace the current version Internet Protocol, IP version 4 (IPv4). IPv4 has been
remarkably resilient in spite of its age, but its lack of scalability in terms of addressing
and the addressing structure are now being seen throughout enterprise networks and
the Internet. Most importantly, there is a growing shortage of IPv4 addresses due to the
large increase in users, subscribers and customers that need IP connectivity, especially
for wireless carriers.
Pv6 fixes a number of issues in IPv4, such as the limited number of available
addresses. It also adds many improvements to IPv4 in areas such as routing, security,
network auto-configuration, multicasting, QoS and additional support for traffic
engineering. While IPv6 is expected to replace IPv4, the two will coexist for a number
of years during a transition period. IPv6 also offers other features that facilitate mobility.
Mobility is essentially built in, and any node can support it as needed, in contrast to IPv4,
in which mobility must be specifically provided for. It is expected that IPv6 protocol
stacks will be supported in all phones, PDAs, and wireless NIC cards in the coming
years. As peer-to-peer services become more critical to the success of a wireless
carrier's capabilities, IPv6 will be the key enabler of these services.
SS7oIP
Signaling System 7 (SS7) provides the call setup and other important signaling
functions required by mobile wireless networks and the public switched telephone
network (PSTN). Like other technologies that have moved from TDM to IP packet
networks, SS7 over IP (SS7oIP) is quickly gaining momentum. Dramatic advances
across several fronts, from standards work in the Internet Engineering Task Force
(IETF) to much higher levels of reliability and availability, are laying the groundwork.
SS7 is the ubiquitous standard used by phone companies worldwide to enable call
setup, control, routing, billing, and information exchange. SS7 defines the protocols and
procedures by which elements of the PSTN exchange information over a digital
signaling network. Traditionally, the SS7 network has been comprised of an out-of-band
series of dedicated links that are bidirectional 56- or 64-kbps. These links have typically
run over leased-line TDM networks.
In recent years, however, SS7 has increasingly taken on the burden of handling more
than call control signaling. New features built into the SS7 protocols have allowed other
capabilities such as subscriber authentication, text messaging and number portability.
SS7oIP provides a mechanism by which operators can migrate SS7 traffic off of costly
TDM links to their exisiting WAN backbones. The core network must provide the
required architecture, QoS support and provisioning methodologies necessary to enable
a SIGTRAN-based IP transport of SS7 traffic. SS7 over IP will greatly reduce operating
costs by leveraging the core network instead of a leased TDM based infrastructure.
Conclusion
This document provides an introductory overview of emerging services for wireless
carrier core networks. With the correctly architected core network and applicable
servces, the IP- based core network will support a carrier's corporate and subscriber
growth for the forseeable future. It is also expected to provide a cost-effective solution
for high-speed, wireless data and facilitate emerging wireless services and standards
such as VoIP, VPN's, IPv6 and SS7oIP.
The next generation core network will be an all-IP network, with Multiprotocol Label
Switching (MPLS) providing transport for all IP-based services. MPLS, will also provide
transport of control and management traffic across the network and next-generation
network application and services, such as traffic engineering, Quality of Service, and
traffic protection.
The core network must be capable of supporting the convergence of voice, video, data
and data 3G/4G services, as well as mission-critical applications, over a common IP
infrastructure in order to gain operating efficiences and substantial cost reduction
For more information regarding MPLS please refer to Network Insight's White Paper.
Acronyms
3G ITU specification for the third generation of mobile communications technology
4G ITU specification for the fourth generation of mobile communications technology
AAL5 ATM Adaption Layer 5
ATM Asynchronous Transfer Mode
CES Circuit Emulation Service
HDLC High Level Data Link Control
IETF Internet Engineering Task Force
IP Internet Protocol
IPv4 Internet Protocol Version 4
IPv6 Internet Protocol Version 6
MPLS Multi-Protocol Label Switching
MSC Mobile Switching Center
NIC Network Interface Card
PDA Personal Digital Assistant
PDU Protocol Data Unit
PPP Point-to-Point Protocol
PSTN Public Switched Telephone Network
QoS Quality of Service
SIGTRAN IETF Signaling Transport Working Group
SS7 Signaling System #7
SS7oIP Signaling System #7 over IP
TDM Time Division Multiplexing
VoIP Voice Over Internet Protocol
VLAN Virtual Local Area Network
VPN Virtual Private Network
WAN Wide Area Network
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