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FAQs
Contents:
- Introduction
- What is a "packet" based access system?
- How does PurePacket enable carriers to transition to packet-based networks?
- What are the elements of the PurePacket System?
- What services does PurePacket™ support?
- Does the Integral Access PurePacket™ System comply with open standards?
- How does this compare with ATM, IP, or TDM based technologies?
- What is MPLS?
- What is the Role of MPLS in Integrated Multi-Service Access Networks?
- With what other systems and networks can the Integral Access PurePacket™ system interwork?
- How does Integral Access support third party CPE devices and equipment?
- How are optical rings created using PurePacket™?
- What are the advantages in using optical rings based on PurePacket™ technology?
- How does this compare with SONET/SDH rings, ATM rings defined in Telecordia GR-2837, rings based on a "thin layer of ATM", or on Cisco's Dynamic Packet Transport technology?
- How does PurePacket™ work with the Internet Protocol and with routers?
- How will PurePacket™ interwork with emerging MPLS devices in the core network?
- How does the PurePacket™ system support Virtual Private Networks?
Introduction
The new century requires new networking technologies and systems to cope with the unprecedented surge in data traffic, much of this traffic due to the increasing popularity of the Internet for
- commerce,
- information dissemination, and
- communication.
Technologies developed and implemented in the 20th century did not anticipate that the Internet Protocol would be the predominant protocol type and Internet traffic the predominant traffic type as we enter the new century.
The first digital telecommunications technology, Time Division Multiplexing, or TDM, was eminently suitable to transform the voice telecommunications network from analog to digital from the early 1970s. TDM, however, is an inflexible point-to-point technology, with no sharing of fixed bandwidth allocations by traffic type. Voice traffic based on fixed 64 kbit/s connection-oriented circuits, transported between switching systems and to the end-user, have been well served by TDM. But this technology cannot efficiently cope with the dynamic, connectionless, and high-bandwidth traffic synonymous with the Internet.
Telecommunications planners envisioned that the network would be required to transport and switch more than just voice, and, subsequently developed the concept of the broadband integrated services digital network, or BISDN, to facilitate multi-services communication. The BISDN was designed for implementation using asynchronous transfer mode (ATM) technology, with the use of a compromise 48-byte cell payload with a 5-byte header. This cell size was selected based on the known and projected traffic types in the early 1980s, well before the Internet and the World Wide Web. ATM has its own management, addressing scheme, and quality of service mechanisms, each different to those used by the Internet Protocol.
Narrowband ISDN at 128 kbit/s was implemented in the local loop as the precursor to the BISDN, but has met with limited success for a wide variety of reasons, including that it no longer able to cope with the data traffic demands of the Internet and the responsiveness demanded by the Internet generation.
The 21st century will see the introduction of the All Digital Loop (ADL)-based on packet technology closely aligned to the Internet and the Internet Protocol. Both TDM and ATM technologies can transport IP, but have significant drawbacks both in efficiency and cost-effectiveness in doing so. Integral Access' PurePacket™ technology, on the other hand, is optimized for the transport and interaction with IP, as well as being able to service 20th century traffic types, which will continue to be with us well into the next century.
What is a "packet" based access system?
A packet based access system is a system that packetizes all traffic and transmits all information through the system in packet format. Packets contain a header or label with source/destination addresses and other parameters, along with the payload, and are able to be switched on a packet-by-packet basis from system ingress to system egress. Forward-looking packet schemes, such as the one used by Integral Access, also classifies traffic with quality of service parameters so that the network serves higher priority traffic before lower priority traffic. The PurePacket™ access system operates in the access layer of the network and is optimized for bringing traffic from customer premise to the central office in an efficient manner. The system is fully interoperable with third party equipment using standard protocols over standard interfaces both in the customer premises and in the central office.
Packet access systems are bandwidth efficient, and leverage the service-rich features of IP routing, as well as the resilience of fiber transport systems, and do so at a fundamentally lower cost but with higher functionality than traditional access systems.
How does PurePacket™ enable carriers to transition to packet-based networks?
PurePacket™ uses an MPLS-based architecture to
- route, transport and switch voice and data transmissions in packet format;
- guarantee Quality of Service (QoS);
- enable Class of Service (CoS); and
- maximize the traffic carrying capacity of access networks.
PurePacket™ provides a migration path to the pure IP networks of the future and supports SoftSwitch Call Control for transporting voice calls across IP core networks. To allow carriers to leverage their investments in existing TDM-based infrastructures, PurePacket™ also supports the GR-303 and V5.2 standards for seamless interoperability with Class 5 voice switches.
What are the elements of the PurePacket™ System?
The PurePacket™ platform comprises the following components:
- PurePacket™ Node resides in the carrier's network, at the Central Office, Collocation or Multi-Dwelling/Multi-Tenant Point of Presence
- PurePacket™ OUTburst is a family of Integrated Access Devices (IADs) for the customer premise. This IAD product family includes solutions for small-medium business (SMB) and small office/home office (SOHO) markets
- PurePacket™ Operations Management System (OMS) is a powerful management system for remote network and service provisioning, configuration, monitoring and management.
What services does PurePacket™ support?
Carriers need to boost access bandwidth and at the same time efficiently provide new-generation IP based services to end-users. PurePacket™ addresses these critical needs and also support customers with a wide range of legacy services such as TDM voice, digital PABX and IBM SDLC transport, all over a single access interface to the customer. The PurePacket™ system is an IP-optimized system for next generation networks, but also assists in network migration by providing efficient and effective interfaces into the embedded switch, transport, customer premises and services base.
Does the Integral Access PurePacket™ System comply with open standards?
PurePacket is MPLS-based and supports worldwide telecom-industry voice signaling and transport standards. Standardized interfaces into IP, frame relay, and ATM networks ensure that the PurePacket™ system seamlessly integrates into existing telecom and data communications networks.
How does this compare with ATM, IP, or TDM based technologies?
Access networks are characterized by the need to support large numbers of customers and service types as economically and efficiently as possible. ATM systems have the capability to transmit voice, data and video but have a large overhead and are relatively expensive and complex to implement for low customer and service densities and over low capacity links. IP networks are an important class of packet network, but are optimized for the transfer of IP (Internet Protocol) traffic alone and are ineffective in the transport of other traffic types, such as TDM voice, frame relay, SNA/SDLC, etc. TDM based systems can transport multiple traffic types, but are inflexible and not optimized for IP and other dynamic traffic types. A pure packet based system is native to most popular traffic types such as IP (including Voice over IP) and frame relay and can also transport circuit switched voice (TDM) traffic efficiently, when quality of service measures are applied. Packet based systems also transport voice over xDSL.
What is MPLS?
MPLS or Multi-Protocol Label Switching is an IETF initiative that integrates Layer 2 information about network links (bandwidth, latency, utilization) into Layer 3 (IP) in order to simplify and improve IP-packet exchange. MPLS gives network operators a great deal of flexibility to divert and route traffic around link failures, congestion, and bottlenecks. From a QoS standpoint, network operators will better be able to manage different kinds of data streams based on priority and service plan. For instance, those who subscribe to a premium service plan, or those who receive a lot of streaming media or high-bandwidth content, see minimal latency and packet loss.
What is the Role of MPLS in Integrated Multi-Service Access Networks?
The single biggest challenge for service providers is migrating their existing TDM-based access network to one that is optimized for delivering packet-based IP services while still delivering TDM-class voice services. MPLS provides the tools for network operators to manage traffic, implement QoS and provision secure data Virtual Private Networks (VPNs). Until now the majority of work around MPLS has concentrated on solving the backbone traffic engineering problems of large ISPs. The next step is to extend the reach of MPLS to the customer premises in order to enable enhanced QoS and VPN capabilities for delivering integrated voice and data services across packet-based access networks.
With what other systems and networks can the Integral Access PurePacket™ system interwork?
The PurePacket™ system can interwork with a wide range of customer premises and core network equipment such as
- analog POTS, ISDN,
- T1/E1,
- SONET/SDH, and
- ATM.
Voice switch interfaces are terminated using standard TR-08, GR-303 and V5.2 protocols which are supported by the major circuit-switched voice network suppliers such as Lucent, Nortel, Siemens, Alcatel and Ericsson. The system also operates as a Voice Access Gateway operating under 'SoftSwitch' control, passing voice traffic to the IP Backbone. A flexible interworking function within the PurePacket™ system allows the access network to communicate with standard routers and frame relay switches using MPLS and other protocols such as those supported by Cisco, Juniper and Lucent.
How does Integral Access support third party CPE devices and equipment?
With standard physical interfaces for POTS, ISDN, xDSL and T1/E1 CPE, equipment using these types of interfaces can easily be interfaced to a PurePacket™ system. Inherent support for TDM, frame relay and other data link layer protocols, ensures that the majority of network protocols can be natively transported and concentrated with the added benefit of quality of service being applied.
How are optical rings created using PurePacket™?
Integral Access has a patent pending, redundant path data communications technique for creating optical rings and other multiple path topologies, including point-to-point and mesh. This approach includes the capability of sending packets over multiple paths and for the receiver to determine which sent packet to accept. By sending packets over more than one path to the receiver, hitless levels of redundancy can be achieved very economically.
What are the advantages in using optical rings based on PurePacket™technology?
One of the significant advantages of the Integral Access packet optical ring is the ability to protect traffic on a services and customer basis, rather than on a physical or logical facility basis which is the case with SONET/SDH and other traditional technologies. Customers that pay for full protection can have their traffic protected using dual paths, while unprotected traffic can use the balance of the dual path connection bandwidth. In the event of a path failure, the protection traffic is guaranteed to continue on a hitless basis, with other traffic transported on the remaining bandwidth based on traffic priority levels.
How does this compare with SONET/SDH rings, ATM rings defined in Telecordia GR-2837, rings based on a "thin layer of ATM", or on Cisco's Dynamic Packet Transport technology?
SONET/SDH rings have dedicated protection capacity and typically reserve as much network capacity for the protection circuit as it does for the revenue-generating payload. The SONET/SDH rings are also based on TDM technology and are provisioned point-to-point with no sharing possible of this provisioned capacity. While providing a high level of resilience with sub 50ms switchover in the event of a fiber ring cut, the rings are bandwidth inefficient.
ATM and derivative rings typically utilize some SONET/SDH framing and place ATM cells in SONET containers leading to multiple layers of overhead and management. ATM routing protocols alone are unable to provide the level of network protection and automatic protection switching that is provided in standard SONET/SDH facilities.
Cisco's DPT technology is suitable for packet level transport at the OC-3 level and above, but does not scale down to bandwidths below that which are the most prevalent in the access network. The Integral Access PurePacket™ system provides:
- The network level protection of standard SONET/SDH,
- Bandwidth efficiency synonymous with packet oriented systems through statistical multiplexing gains, and
- Effective operation on low speed links, which are predominant in the access network.
How does PurePacket™ work with the Internet Protocol and with routers?
PurePacket™ provides both layer two and layer three transport services for IP. Layer two transport through the access network is especially useful in cases where the administration of the IP network is not the responsibility of the access network provider. A layer two access network is fully transparent to IP and the need to coordinate configuration between the two administrations is minimized. Layer three transport requires coordination at the IP level but provides more advanced tools for traffic management and troubleshooting. Both IP transport modes are suitable for public Internet Access and for the provisioning of secure corporate LAN-IC services. The connection towards the IP backbone router can be based either on Ethernet, PPP over SONET, MPLS or ATM.
How will PurePacket™ interwork with emerging MPLS devices in the core network?
Most of the effort around MPLS has concentrated on solving the traffic management problems of the IP backbones of large ISPs. While MPLS is a very good tool for that purpose, MPLS also enables the IP networks to provide CoS and security comparable to that provided by Frame Relay and ATM, which are currently used for provisioning corporate LAN-IC services. Integral Access PurePacket™ provides the access solution required between the MPLS enabled IP backbone and the sites of small and medium size enterprises or the regional/branch offices of large corporations. Integral Access PurePacket™ can be used both in cases where the customer has MPLS enabled equipment and in cases where the customer's equipment only supports IP and the labeling of traffic is carried out by the PurePacket™ access network.
How does the PurePacket™ system support Virtual Private Networks?
Secure, flexible and economical data VPN services present a huge revenue opportunity for public network operators. MPLS is a protocol that allows provisioning of VPNs over the same infrastructure that is used for providing public Internet services. The use of MPLS makes VPNs secure and allows provisioning of guaranteed bandwidth thus enabling the use of these VPNs in mission critical applications. PurePacket™ is an optimized tool for extending MPLS VPNs to the customer premises while simultaneously being able to support the customer's voice access needs over the same packet access infrastructure.
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