PDF of this tutorialHow Is an Enterprise Connected?
With DTM, service providers are able to provide large enterprises with all their communication needs via one network-access point. DTM allows services to be integrated on a transport level and thus optimizes the utilization of network access. The solution for the large enterprise is a DTM access device that provides service access via several Ethernet ports and some E1/T1 ports on the same device. The upper link runs DTM directly on fiber from the access device toward the network. That gives the network provider a simple network structure with DTM as the only protocol needed in the aggregation loops for all services offered.
Bandwidth between 512 Kbps and Full Link Bandwidth
With the integration of services on the transport level, QoS is kept clean and simple without the use of any complex priority schemes. The high granularity (steps of 512 kbps) and bandwidth scalability (from 512 kbps to 850 Mbps) of DTM channels also allows for flexible price differentiation. When using the DTM access device, it is even possible to provide company control of its bandwidth resources and then bill upon resource (bandwidth) utilization. Typical services for enterprises that can be offered through the access device are voice VPN via private branch exchange (PBX) interconnection, corporate data network solutions, Internet access, and firewall solutions.
Voice Interconnect
The voice VPN is simply built by interconnecting PBXs via the PDH transport service. By interconnecting PBXs via a transparent PDH architecture on an E1/T1 basis, voice quality is preserved and all types of signaling protocols used for different voice solutions are supported transparently.
Figure 4. Interconnection of PBXs
Private Data Networking
Corporate data networks can simply be built by interconnecting office LANs with DLE service. The DLE service provides a flexible high-speed LAN–to–LAN network which is Level-3 independent and, hence, could be used for many kinds of protocols and applications supporting Ethernet. Supporting DTM short-cut establishment with channel isolation ensures high-quality communication with short delays that preserves communication security. The DLE service is therefore ideal for demanding applications such as videoconferences.
Because the DLE service supports Ethernet transparently, most office LAN architectures can be preserved, and interoperability, with all kinds of standard Ethernet equipment, is ensured. When using an access device at the customer premises, no additional equipment with gateway functions (such as a router) is actually needed for LAN interconnection, and thus much of the network management can be reduced.
For larger data networks it may, for manageability reasons, be desirable to build hierarchical networks using routers. The DLE service and any standard router with Ethernet support may be used for that purpose.
Figure 5. Corporate Data Network using the DTM LAN Emulation (DLE) Service
By combining the DLE service with an IP–routing solution, the same Ethernet access may be used for both the corporate-data network and the company's Internet access. The IP–routing solution has a built-in firewall that permits the same access to be used. Because the DLE service isolates DTM channels for flows between different Ethernet segments, all Internet communication will be separated from corporate data, even though these are defined on the same DLE segment. It is thereby possible to separate the Internet from corporate-data traffic completely.
Figure 6. Corporate Data Network Combined with an Internet Connection
Benefits of the access device as a service integration device include the following:
- One network layer exists between the user and the service access points.
- Synchronous circuit switching enables a guarantee for QoS to customers.
- High granularity and scalability in bandwidth allow for pricing differentiation.
- Customers can be guaranteed control of bandwidth and can be billed for it.
- Transparent support of PDH ensures voice quality and interoperability.
- Layer-3–independent data link escape (DLE) service ensures interoperability and preserves existing LAN architectures.
- DTM short-cut establishment ensures high-quality communication for special needs such as video conferences.
- Internet traffic can be controlled so as not to interfere with the corporate-data network.
