Cisco Certifications (CCNA | CCNP) -3

Layers                                           Do What ?
Trasport  layer (L4)                                     Port Addressing
Netwark layer (L3)                                      IP Addressing
Data  link layer (L2)                                    MAC Addressing


Note-
1-   IP Addressing ;is also Known as Logical Address/Software Address.
2 -  MAC Addressing is also Known as Physical Address or Hardware  Address.

Security -

   Layer 2- Security (Mac Base in Switch)

Layer 3- Security (IP Base in Router)

Series  of  Switch-  Cisco desgin for Switches
             1-Access Layer                 1900-2900  (CCNA)
             2-Distribution Layer       3000-5000 (CCNP)
             3-Core  Layer                   6000-8000 (CCIE)
When more traffic
             1-Head office  -         Core Layer Switch
             2-Regional office  -   Distribution Layer Switch 
             3-Branch office   -     Access Layer Switch