Access layer switches / Distribution layer overview

Access layer switches
5.2.2 Access layer switches operate at Layer 2 of the OSI model and provide services such as VLAN membership. The main purpose of an access layer switch is to allow end users into the network. An access layer switch should provide this functionality with low cost and high port density.
The following Cisco switches are commonly used at the access layer:

Catalyst 1900 series
Catalyst 2820 series
Catalyst 2950 series
Catalyst 4000 series
Catalyst 5000 series

The Catalyst 1900 or 2820 series switch is an effective access device for small or medium campus networks. The Catalyst 2950 series switch effectively provides access for servers and users that require higher bandwidth. This is achieved with Fast Ethernet capable switch ports. The Catalyst 4000 and 5000 series switches include Gigabit Ethernet ports and are effective access devices for a larger number of users in large campus networks.

The Interactive Media Activities will describe the features of the Cisco Catalyst 1912, 2950, and 4006 switches.
The next page will discuss the distribution layer.

Distribution layer overview

5.2.3 The distribution layer of the network is between the access and core layers. It helps to define and separate the core. The purpose of this layer is to provide a boundary definition in which packet manipulation can take place. Networks are segmented into broadcast domains by this layer. Policies can be applied and access control lists can filter packets. The distribution layer does not allow the problems to affect the core layer. The distribution layer also prevents these problems from affecting the core layer. Switches in this layer operate at Layer 2 and Layer 3. The following are some of the distribution layer functions in a switched network:

Aggregation of the wiring closet connections
Broadcast/multicast domain definition
VLAN routing
Any media transitions that need to occur
Security

The next page will discuss distribution layer switches.

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