Cisco three layer hierarchical model and ping

Why we use the CISCO Model.

1.   High performance

2..  Efficient management and troubleshooting

3..   Policy creation

o      Enable to create policy and specify filters and rules

4.   Scalability

o       Enable the networks growth

5.   Behavior prediction

o       Enables you to determine what will happen to the network when new stresses are placed on it.

Three Layer Model

1, Core layer  (BACKBONE LAYER)

2. Distribution layer  (ROUTING LAYER)

        3. Access layer  (SWITCHING LAYER)

Core layer

Ø    Core layer is the main layer of the model.

Ø    It is responsible for the fast and reliable transportation of data across a network.

Ø    The core layer reduces the latency time in the delivery of packets.

Ø    It does not route traffic to the networks.

Ø    Components of the core layer are

o      Multiplexer

o      PBX

o      High speed WAN switches

Ø    If this layer is fail then every end user is affected.

Ø    It provides high reliability if the device is fail in the route then it will follow another route go deliver the data.

DISTRIBUTION LAYER

Ø    This layer acts as the intermediate in between the core layer and access layer.

Ø    Router is used on these layers.

Ø    Control broadcast and multicast.

o      It will serves as the boundary for broadcast and multicast domain.

Ø    Components used on distribution layer are

o      Routers

o      LAN routers

o      Layer 3 switches

o      Filters

o      Bridge

o      VPN access router

ACCESS LAYER

Ø    This layer deals with workgroup level users.

Ø    Components of access layers are

o      HUB

o      SWITCHES

o      COMPUTERS

o      EMAIL SERVER

o      REPEATER

  Ø    Its known as the desktop layer

 NOTE:   Router is known as layer 3 switches.

Ping commands

It is an echo request that is used to test the physical connectivity of an remote device with your device.

Trace route

It’s used to identify the best route that the packet will take to reach form source to destination. This command is used to trace the path.

Destination host unreachable

This message is appear when destination is not a member of your networks.

Request time out

This message is appear when the destination gets disconnected due to problem in wires hub switch ports or collision.