Networks would be empowering people to do their jobs, to communicate and collaborate, to teach and to learn. At their heart of the network lie the workhorses the often underappreciated switches as well as routers that would connect users to data centers. While every network is considered to be different and has to be crafted to the needs as well as the scale of the enterprise, some helpful patterns would have to have emerged that both network managers, as well as network equipment manufacturers, follow. When network designs which would be following these patterns, it’s easy to find a diverse mix of good products and, using those products, for building reliable and economic networks. To understand Layer 2 or 3 Design between the Core and Distribution, you are needed to go through the Hierarchical Network Design.
The Hierarchical network design includes:
- The Core (backbone) layer which provides optimal transport between sites
- The Distribution layer that which provides policy-based connectivity
- The Local-access layer that which provides workgroup/user access to the network
The function of the Core Layer:
The Core Layer is considered to be a high-speed switching backbone and should be designed to switch packets as fast as possible. This layer of the network shouldn’t perform any packet manipulation, like the access lists and filtering, which would slow down the switching of packets.
The function of the Distribution Layer:
The Distribution Layer of the network is considered to be the demarcation point between the access as well as core layers and helps to define and differentiate the core. The purpose of this layer is to provide a boundary definition and is also considered the place at which packet manipulation could take place. In the campus environment, the distribution layer could include several functions, like the following:
- Address or area aggregation
- Any media transitions that need to occur
- Broadcast/multicast domain definition
- Departmental or workgroup access
- Virtual LAN (VLAN) routing
Whereas in the non-campus situation, the distribution layer could be a redistribution point between routing domains or the demarcation between static as well as dynamic routing protocols. It could also be the point at which remote sites would be accessing the corporate network. The distribution layer could be summarized as the layer which is going to provide policy-based connectivity.
The function of the Access Layer:
The Access Layer is the point at which the local end users would be allowed into the network. This layer might also use the access lists or filters to further optimize the needs of a particular set of users. In the campus environment, access-layer functions could include the following:
- MAC layer filtering
- Shared bandwidth
- Switched bandwidth
Whereas in the non-campus situation, the access layer could give remote sites access to the corporate network via some wide-area technology, like Frame Relay, ISDN, or leased lines.
It is sometimes mistakenly thought that the three layers are needed to exist in clear and distinct physical entities, but this doesn’t have to be the case. The layers are defined to aid successful network design as well as to represent functionality that would be needed to exist in a network. The instantiation of each layer
- Can be indistinct routers or switches.
- Can be represented by physical media.
- Can be combined in a single device.
- Can be omitted altogether.
The way the layers are implemented would be dependent on the needs of the network being designed.
If you wish to have more information, you could, all you need to do is to join the courses offered by the SPOTO.