Hierarchical internetworking model
Encyclopedia
The Hierarchical internetworking model, or three-layer model, is a network design model first proposed by Cisco
. The
three-layer model divides enterprise networks into three layers: core, distribution, and access layer. Each layer provides different
services to end-stations and servers.
platforms, and may or may not provide layer 3
switching services. The traditional focus at the access layer is minimizing
"cost-per-port": the amount of investment the enterprise must make for each provisioned Ethernet
port.
distribution layer. Distribution layer devices also often manage individual branch-office WAN
connections.
different regions of the network. Core switches and routers are usually the most powerful, in terms of raw forwarding power, in the
enterprise; core network devices manage the highest-speed connections, such as 10 Gigabit Ethernet
.
Cisco
Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...
. The
three-layer model divides enterprise networks into three layers: core, distribution, and access layer. Each layer provides different
services to end-stations and servers.
Access layer
End-stations and servers connect to the enterprise at the access layer. Access layer devices are usually commodity switchingplatforms, and may or may not provide layer 3
Network Layer
The network layer is layer 3 of the seven-layer OSI model of computer networking.The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.The network...
switching services. The traditional focus at the access layer is minimizing
"cost-per-port": the amount of investment the enterprise must make for each provisioned Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
port.
Distribution layer
The distribution layer is the "smart" layer in the three-layer model. Routing, filtering, and QoS policies are managed at thedistribution layer. Distribution layer devices also often manage individual branch-office WAN
Wide area network
A wide area network is a telecommunication network that covers a broad area . Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations...
connections.
Core layer
The core network provides high-speed, highly-redundant forwarding services to move packets between distribution-layer devices indifferent regions of the network. Core switches and routers are usually the most powerful, in terms of raw forwarding power, in the
enterprise; core network devices manage the highest-speed connections, such as 10 Gigabit Ethernet
10 Gigabit Ethernet
The 10 gigabit Ethernet computer networking standard was first published in 2002. It defines a version of Ethernet with a nominal data rate of 10 Gbit/s , ten times faster than gigabit Ethernet.10 gigabit Ethernet defines only full duplex point to point links which are generally connected by...
.