Packet filtering (firewalling): Processes packets and regulates the transmission of packets based on its source and destination information to create network borders.It also provides policy-based network connectivity, including: The distribution layer is responsible for routing. T-1 and E-1 lines, Frame relay connections, ATM networks, Switched Multimegabit Data Service (SMDS).Catalyst switches such as 6000, 5000, and 4000 (for LAN use).Examples of core layer Cisco equipment include: There are various equipments available for the core layer. Fewer and faster systems create a more efficient backbone. High reliability: Multiple data paths ensure high network fault tolerance if one path experiences a problem, then the device can quickly discover a new route.Īt the core layer, efficiency is the key term.Low latency period: The core layer typically uses high-speed low latency circuits which only forward packets and do not enforcing policy. One way that core networks enable high data transfer rates is through load sharing, where traffic can travel through multiple network connections. High data transfer rate: Speed is important at the core layer.The factors to be considered while designing devices to be used in the core layer are: Its purpose is to reduce the latency time in the delivery of packets. The core layer is often known as the backbone or foundation network because all other layers rely upon it. The core layer is responsible for fast and reliable transportation of data across a network. Behavior prediction: When planning or managing a network, the model allows you determine what will happen to the network when new stresses are placed on it.Scalability: You can grow the network easily by dividing your network into functional areas.Policy creation: You can easily create policies and specify filters and rules.Efficient management & troubleshooting: Allows you to efficiently organize network management and isolate causes of network trouble.High Performance: You can design high performance networks, where only certain layers are susceptible to congestion.When you implement these layers, each layer might comprise more than two devices or a single device might function across multiple layers.The benefits of the Cisco hierarchical model include: This layer ensures that packets are delivered to end user computers.įigure INT.2.1 displays the three layers of the Cisco hierarchical model. This layer is also called the desktop layer because it focuses on connecting client nodes, such as workstations to the network. This layer is also called the Workgroup layer.Īccess layer: This layer includes hubs and switches. This layer ensures that packets are properly routed between subnets and VLANs in your enterprise. Rather, this layer is concerned with speed and ensures reliable delivery of packets.ĭistribution layer: This layer includes LAN-based routers and layer 3 switches. In addition, no packet manipulation is done by devices in this layer. This layer of the network does not route traffic at the LAN. This model simplifies the task of building a reliable, scalable, and less expensive hierarchical internetwork because rather than focusing on packet construction, it focuses on the three functional areas, or layers, of your network:Ĭore layer: This layer is considered the backbone of the network and includes the high-end switches and high-speed cables such as fiber cables. The Cisco Three-Layered Hierarchical ModelĬisco has defined a hierarchical model known as the hierarchical internetworking model. Cisco Tutorial: The Cisco Three-Layered Hierarchical Model
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