Previously, the service provider's network relied on a hierarchical topology that relied on the access layer, edge layer, and core layer. This topology is often necessary because the routers at that time have a low density of distribution and a lifetime of only two years.
Although tiering provides a modular design approach, too much speciality in access points (PoPs) occupies a large portion of expensive PoP intranet ports, squeezing WANs that may carry revenue-generating traffic. Ports, which increase the complexity and cost of the interconnect and cause maintenance, configuration, and operational challenges.
Figure 1 shows a traditional layered PoP. Service providers have deployed redundant routers to increase availability.
In Figure 1, routers are placed in their respective layers according to the roles they play as cores, aggregations, and edge devices. The capacity of each layer can be adjusted by adding additional routers at the expense of adding interconnect links around the layers. Each layer of routers has some specific functionality, so managing these routers may require unique configurations and tasks.
Increasing devices in this way can increase resiliency, but cross-connections between redundant systems can reduce the revenue-generating ports. The increasing complexity of layered architectures and the deployment of bandwidth-intensive, high-performance applications are pushing this traditional topology to the limit.
Providers need to effectively provide a range of profitable IP services in the edge network to increase ARPU (average revenue per user). However, due to the increasing investment cost of configuring and managing multiple physically added routers to run new services, it is difficult to increase profitability for strictly tiered PoPs.
To handle customer service level agreements and ensure high availability, service providers typically use multiple PoP locations to build huge networks. To provide quality of service and performance levels and maintain network maintainability, a simplified design makes it easier to create resilient networks with greater availability and flexibility. Since PoPs themselves tend to be unified, the entire backbone network can be simplified.
With high-density, flexible routers with the richest interface types (copper and optical interfaces), service providers can flatten traditional multi-layer network topologies (Figure 2) while relying on product and service differentiation to establish a competitive advantage in the marketplace.
Edge, aggregation, and core layer integration allow for fewer routers to be used in the network, correspondingly reducing capital and operational overhead. Services are also easier to provide because there are fewer business nodes to configure.
Figure 1: Traditional Hierarchical PoP
Figure 2: Flattened core alternative
To build a flat PoP architecture, the router preferably has the following features:
1. IP service functions in the core router
2. Rich interface types
3. Density and high availability
4. Physical and logical scalability
5. Maintainability and reliability
Edge function in the core routerIn general, the requirements for edge and core routers are different. Core IP/MPLS routers tend to play a simpler role; the primary consideration is direct forwarding speed, and most service creation and other forms of network intelligence will come from the edge of the network.
Although core routers also involve traffic engineering decisions, interpretation of QoS markings, filter-based forwarding 1 and many other traffic processing functions, multi-service edge routers allow providers to unify multiple different ATM and Frame Relay networks into a single IP/ On top of the MPLS infrastructure, it leverages leading IP services to generate new revenue.
The necessary functions include the aggregation and distribution of services.
These edge routers need to support the configuration of various Layer 2 and Layer 3 services. They may also need to emulate ATM and Frame Relay services, or Ethernet services, over an MPLS network. Edge routers therefore require a wide variety of interface types, and both circuit and trunk interfaces are required.
Figure 3 shows the difference in edge and core functionality expected by the service provider.
Figure 3: Edge and core features of the router
Service providers and other operators are increasingly aware that they need functional overlap in order to scale and build their PoP designs in a predictable manner. For example, IP edge functionality is listed in the table as a requirement for core routers, and QoS requirements are required for both core and edge routers.
Rich interface typeIn order to further unify the functions, the old rules that only need a certain type of interface for the edge router and the core router needs other interfaces must be revised. It is generally believed that the core router only needs to implement a large optical interface and does not require a high-density, low-capacity interface. In fact, this limitation has led to a lack of flexibility in core routers and has quickly been phased out.
Density and high availability
D-sub Connector Contacts
A D-sub connector is a form of connector commonly found in electronic and computer systems. It consists of a D shaped metal band and two or more parallel rows of either pin contacts (male) or socket contacts (female). D-sub connector contacts can vary in size, material, current rating, length and resistance.
The most common type of connector is the crimp contact. These are assembled by inserting a stripped wire end into the cavity at the rear of the contact. The cavity is then crushed using a crimp tool, gripping the contact to the wire.
What are D-sub connector contacts used for?
The D-sub connector contacts carry the signal from the source to the destination across the D–sub connection.
Types of D-sub connector contacts
Most D-sub connectors are supplied with contacts ready in place. Contacts can be replaced if damaged or if the application of the D-sub connector is to be changed from the original design specification.
High-current, high-voltage, or co-axial inserts require larger contacts. The material of the D-sub connector contact can be changed if the robustness or quality of the connection needs to be improved.
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