Cisco LAN

Campus Wired LAN

The LAN is the networking infrastructure that provides access to network communication services and resources for end users and devices spread over a single floor or building. You create a campus network by interconnecting a group of LANs that are spread over a local geographic area. Campus network design concepts include small networks that use a single LAN switch, up to very large networks with thousands of connections.

The campus wired LAN enables communications between devices in a building or group of buildings, as well as interconnection to the WAN and Internet edge at the network core.

Specifically, this design provides a network foundation and services that enable:

  • Tiered LAN connectivity.
  • Wired network access for employees.
  • IP Multicast for efficient data distribution.
  • Wired infrastructure ready for multimedia services.

Hierarchical design model

The campus wired LAN uses a hierarchical design model to break the design up into modular groups or layers. Breaking the design up into layers allows each layer to implement specific functions, which simplifies the network design and therefore the deployment and management of the network.

Modularity in network design allows you to create design elements that can be replicated throughout the network. Replication provides an easy way to scale the network as well as a consistent deployment method.

In flat or meshed network architectures, changes tend to affect a large number of systems. Hierarchical design helps constrain operational changes to a subset of the network, which makes it easy to manage as well as improve resiliency.

Modular structuring of the network into small, easy-to-understand elements also facilitates resiliency via improved fault isolation.

A hierarchical LAN design includes the following three layers:

  • Access layer—Provides endpoints and users direct access to the network
  • Distribution layer—Aggregates access layers and provides connectivity to services
  • Core layer—Provides connectivity between distribution layers for large LAN environments

Figure 1.   LAN hierarchical design

Cisco Software-Defined Access campus design

Another way to overcome the Layer 2 adjacency restrictions while still maintaining the advantages of the routed access layer design is by adding fabric capability to a Layer 3 access campus network design, supporting an overlay network with the required Layer 2 connectivity. Benefits of Cisco SD-Access technology are the decoupling of the Layer 2/Layer 3 forwarding plane of the endpoint/user from the underlay network, the unification of wired and wireless policies, and the advantage of not having to hair-pin wireless traffic to an overlay node such as WLC. 

The addition of the fabric overlay is automated using Cisco DNA Center to deploy Cisco SD-Access technology. The Cisco SD-Access design enables the use of virtual networks (overlay networks, or macro segmentation) running on a physical network (underlay network) in order to create alternative topologies to connect devices.

Beyond traditional network virtualization, Cisco SD-Access allows for software-defined segmentation and policy enforcement based on user identity and group membership, integrated with Cisco TrustSec technology to support group-based micro segmentation policies. Beyond support for the wired LAN and unlike any alternative virtualization technology, Cisco SD-Access also inherently supports integration of the wireless LAN for a common policy across the entire campus domain.