Computer Networks Manual
OSI REFERNCE MODEL
OSI LAYERS PROTOCOL
EQUIPMENT AT THE LAYERS
Some of the layers use equipment to support the identified functions.
Hub related activity is “Layer One”.
The naming of some devices designates the functional layer such as “Layer Two Switch” or “Layer Three Switch”.
Router functions focus on “Layer Three”.
User workstations and servers are often identified with “Layer Seven”.
HUB
Hub is a hardware device that contains multiple, independent ports that match the cable type of the network. Most common hubs interconnect Category 3 or 5 twisted-pair cable with RJ-45 ends, although Coax BNC and Fiber Optic BNC hubs also exist.
Ethernet Hubs
An Ethernet hub is also called a multiport repeater. A repeater is a device that amplifies a signal as it passes through it, to counteract the effects of attenuation.
Multistation Access Unit
A Multistation Access Unit (MAU) is a special type of hub used for token ring networks.
Switches
Switches are a special type of hub that offers an additional layer of intelligence to basic, physical-layer repeater hubs. A switch must be able to read the MAC address of each frame it receives. This information allows switches to repeat incoming data frames only to the computer or computers to which a frame is addressed. This speeds up the network and reduces congestion
Bridges
A bridge is used to join two network segments together, it allows computers on either segment to access resources on the other. They can also be used to divide large networks into smaller segments.
Routers
Routers are networking devices used to extend or segment networks by forwarding packets from one logical network to another. Routers are most often used in large internetworks that use the TCP/IP protocol suite and for
OSI LAYERS PROTOCOL
EQUIPMENT AT THE LAYERS
Some of the layers use equipment to support the identified functions.
Hub related activity is “Layer One”.
The naming of some devices designates the functional layer such as “Layer Two Switch” or “Layer Three Switch”.
Router functions focus on “Layer Three”.
User workstations and servers are often identified with “Layer Seven”.
HUB
Hub is a hardware device that contains multiple, independent ports that match the cable type of the network. Most common hubs interconnect Category 3 or 5 twisted-pair cable with RJ-45 ends, although Coax BNC and Fiber Optic BNC hubs also exist.
Ethernet Hubs
An Ethernet hub is also called a multiport repeater. A repeater is a device that amplifies a signal as it passes through it, to counteract the effects of attenuation.
Multistation Access Unit
A Multistation Access Unit (MAU) is a special type of hub used for token ring networks.
Switches
Switches are a special type of hub that offers an additional layer of intelligence to basic, physical-layer repeater hubs. A switch must be able to read the MAC address of each frame it receives. This information allows switches to repeat incoming data frames only to the computer or computers to which a frame is addressed. This speeds up the network and reduces congestion
Bridges
A bridge is used to join two network segments together, it allows computers on either segment to access resources on the other. They can also be used to divide large networks into smaller segments.
Routers
Routers are networking devices used to extend or segment networks by forwarding packets from one logical network to another. Routers are most often used in large internetworks that use the TCP/IP protocol suite and for