Access Layer Design involves selecting or modifying LAN, MAN, dial or dedicated access topology.
There are five key areas which need to understand while designing the access layer.
1. Physical Connectivity:
The access layer design needs to accommodate user-side premises interfaces such as Ethernet, Token-Rings and ATM LANs hosts.Equipment is shared between to premises and access layer.
The interface from access layer design into backbone layer is typically on a router or switch using serial or telephony interfaces.
The typical options of building wiring are UTP, STP, thin and thick coax and glass or plastic fibre optic media. The UTP is widely used.
Protocol support can range from providing transparent transport for a homogeneous protocol to multiple protocols.
Each protocol that operates over each interfaces must be defined by identifying syntax, semantics, timing, implementations and peculiarity.
Determine which portion of protocol is used.The amount of access device to application interactions will be different depending on the protocols being used.
There will be most likely be many dissimilar protocols in the application layer and most will not communicate with each other.
As IP became dominant networking protocol, many vendors such as Novell joined the bandwagon by supporting IP versions of systems. Novell Netware5 allows use IP or IPX to the user.
3. Switching versus Routing:
Implementing a switch over a hub sets up different collision domains. This increases network performance by reducing collision that require re-transmission and by reducing traffic an each segment.
Switches allow full-duplex interfaces when server are directly attached to the switch so twice the bandwidth.Routers divide network into various broadcasts domains. Almost every major enterprise implements router as their WAN access device.
4. Quality of Service (QOS):
When the user interfaces to the WAN through an access network device certain features, functions, and services are required over and above normal interface and protocol support.Some access devices such as routers, switches and intelligent multiplexers allows prioritisation of user traffic.