Question

“The Cisco Enterprise Architecture divides the network into functional components while still maintaining the core, distribution, and access layers” – Class, do you agree with this statement – why/why not?

Answer 1

Yes,The Cisco Enterprise Architecture divides the network into functional components while still maintaining the core,distribution and access layer.The modularity of the Cisco architecture allows flexibility in network design and facilitates implementation and does troubleshooting.The Cisco Architecture reduces the network into physical,logical and functional boundaries ,to scale the hierarchical model.

1) The Core Layer: The core layer is core of infrastructure module.This gives the high performance and the switched backbone connects various parts of the infrastructure.It provides transport between the sites.This layer should not perform any packet manipulation,such as access lists and filtering that would slow down switching of packets.The core layer provides interconnectivity between the distribution layer devices.

Example:The campus core layer of the campus infrastructure module provides redundant and fast-converging connectivity between the buildings and with the server farm.

2)The Distribution Layer:The Distribution Layer aggregates the data received from the access layer before transmitting it to the core layer for routing to its final destination.The significance of Distribution Layer can be exemplified as routers,managed switches and firewalls along with all security features including policies and access listing.

Example: The building Distribution layer aggregates the building's wiring closets and gives connectivity to the Campus Core layer.

3)The Access Layer: The Access layer is the lowest layer of the protocol hierarchy. The protocol in this layer provide the means for the system to deliver data to other devices on a directly attached network.The functions provided by the Access layer are

a)Encapsulation of IP data-grams into frames transmitted by the network

b)Mapping of IP address to physical address used by the network.

Example: The building Access layer Located withing a campus building aggregates end users from different workgroups and provide uplinks to the building Distribution Layer.It contains end-user devices such as workstation, Cisco IP phones ,VLANs.