Subject: Advanced Network Technologies

Topic: Network Design

Difficulty: Medium

The access layer ensures that packets are delivered to end user devices. This layer is sometimes referred to as the desktop layer, because it focuses on connecting client nodes to the network. Access layer devices include hubs, multi-station access units and switches.

Physical Connectivity

Is there any existing network? If so what are the physical and logical configurations and why?Sometimes the access network is designed based on what is available verses what is desired.The widest variance of any connectivity requirements are the physical media level.Copper, fibre and air are the three most common media for physical connectivity. The access layer design needs to accommodate user-side premises interfaces such as Ethernet, Token-Rings and ATM LANs hosts.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.

Protocols:

Networks that have been around for a long time are typically multiprotocol and requires some consolidation for optimal design.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.As IP became dominant networking protocol, many vendors joined the bandwagon by supporting IP versions of systems.

Switching versus Routing:

LAN switches have become very popular in IP address. Earlier LAN switches were in Layer2 devices but now LAN switches exist in Layer 4-plus that can make Layer 2 and 3 switching and routing decisions based on Layer 4 protocols. Routers are typically Layer3 devices .Switching in LAN provides many advantages like reducing collision domains, increasing between hosts, providing full duplex communicates and flexibility to support different speed interfaces.Routing divide the network into various broadcast domains.

QOS:

Which of your applications need support QOS and upto what level of QOS? Being able to prioritize traffic in both LAN and WAN it is becoming more important every year as voice and video traffic migrate to data network. Some access devices such as routers, switches and multiplexers allow prioritization of user traffic. Prioritization can be arranged through WAN side of access device and can be performed at packet level of IP services Ethernet switches can support various class of service settings (COS)