FDM 3 Layers

8/13/2019 FDM 3 Layers

1/16

The Cisco Three-Layer Hierarchical Model

Core layer: is known as backbone of network as it is on the topof the network and it is responsible to transfer heavy amount of

traffic in reliable and quick manner.

Distribution layer: provides policy-based connectivity.

Access layer: provides local and remote workgroup or user

access to the network.

1


2/16

Cisco Three Network Layer

Fig. 1 Fig. 22


3/16

Cisco Three Network Layer

Fig. 33


4/16

Access Layer

The purpose of the access layer is to grant user access to network

resources.

The access layer can include routers, switches, bridges, hubs, and

wireless access points.

Access layer devices control traffic by localizing service requests to

the access media, it is the concentration point at which clients

access the network.

Functions include MAC layer filtering and micro segmentation.

4


5/16

Access Layer

Catalyst 1900 and 2820 switches were effective for small campus

networks The 2950 series provides access for users and servers that require higher

bandwidth to use FastEthernet and Gigabit Ethernet ports

The 4000 and 5000 series include Gigabit Ethernet ports to effective in

large campus networks

5


6/16

The access layer includes switched LAN devices with ports that

provide connectivity for workstations and servers in the campusenvironment.

The access layer for remote sites or teleworkers provides access

to the corporate network across some wide-area technology,such as Frame Relay, MPLS, ISDN, leased lines, DSL over

traditional telephone copper lines, or coaxial cable in the WAN

environment.

Access Layer

6


7/16

Distribution Layer Separates the Access layer from the Core layer

Distribution layer devices control access that are available at thecore layer so that it use bandwidth efficiently.

This layer provides redundant connections for access devices so

that it provides the opportunity to load-balance between devices.

Distribution layer where routing and packet manipulation are

performed so that it represents a routing boundary between the

access and core layers.

It implements network policies, and provides many networking

services e.g. NAT, QoS, routing, Traffic loading, firewall protection

(Security). 7


8/16

Distribution Layer OverviewThe often used Cisco switches at distribution layer are

Catalyst 2926G, Catalyst 5000 series, Catalyst 6000 series

Current distribution layer switches areCatalyst 4500, Catalyst 4900, Catalyst 6500

8


9/16

Distribution Layer Overview

The primary function of the distribution layer is to provide

routing, filtering, and WAN access and to determine how packets

can access the core, if needed .

In a WAN environment, the distribution layer aggregates WAN

connections at the edge of the campus and provides policy-based

connectivity.

The distribution layer is often the layer that terminates access

layer VLANs (broadcast domains); however, this can also be done

at the access layer.

9


10/16

Core Layer

It is also known as the heart or backbone of the network. Responsible for switching large amounts of data quickly and

efficiently

The core layer is critical for interconnectivity between

distribution layer devices so that it is important for highlyavailable and redundant.

This layer should not be loaded with security or traffic control

measures or any unnecessary additional equipment which slow

down the network traffic. Core layer network devices manage the highest-speed

connections, such as 10 Gigabit Ethernet.

10


11/16

Core LayerExamples of core layer Cisco equipment include

- Cisco switches such as 7000, 7200, 7500, and 12000 (for WAN use)- Catalyst switches such as 6000, 5000, and 4000 (for LAN use)

- T-1 and E-1 lines, Frame relay connections, ATM networks, SMDS

11


12/16

Core Layer

The core devices must be able to implement scalable protocols

and technologies, and provide alternative paths and loadbalancing.

The core must be able to accommodate failures by rerouting traffic

and responding quickly to changes in network topology. A fullmesh is highly recommendation, and at least a well-connectedpartial mesh with multiple paths from each device is required.

Core layer switches support additional hardware redundancyfeatures like redundant power supplies that can be swapped while

the switch continues to operate. Core layer-capable switches have

the ability to swap cooling fans without having to turn the switch

off.

12


13/16

Summary

The access layer is to grant user access to network resources.

The switch operate at Layer 2 of the OSI model is use to access

local workstations and servers which can provide using shared or

switched media LANs; VLANs may be used to segment the

switched LANs.

Connectivity of workgroup through distribution layer

13


14/16

Summary Distribution layer provides policy-based connectivity

Implementations of access lists for filtering interesting traffic

and blocking uninteresting traffic.

Security and network policy implementation containing addresstranslation and firewalls.

Enabling routing between all VLANs

Defining broadcast and multicast domains.

Operate at both Layer 2 and Layer 3 of the OSI model(multilayer switches) 14


15/16

Summary

Core layer is known as backbone of network as it is on the topof the network and it is responsible to transfer heavy amountof traffic in reliable and quick manner.

Protect the network from slowing down the traffic, it

shouldnt use of access lists, routing between different VLANs

and Packet Filtering.

It should protect network from workgroup access support.

Prefer to select protocols with low convergence time and fast

redundant link connectivity.

15


16/16

References:

1)http://binarydelusions.com/2010/08/12/network-foundations-

part-1-the-models/2) http://www.ccnaguru.com/hierarchical-network-design.html

3)http://ciscodocuments.blogspot.co.uk/2011/06/chapter-2-

applying-methodology-to_5299.html

4)http://www.youtube.com/watch?feature=endscreen&NR=1&v=ziRevTIZtv8

5) http://www.tech-faq.com/understanding-the-cisco-three-

layer-hierarchical-model.html

6) http://wiki.hill.com/wiki/index.php?title=Hierarchical_model7) http://flylib.com/books/en/4.147.1.44/1/

16

Documents

FDM 3 Layers