|  |  |  |  |  |  |  |  |  |  |  |  | 
   
    | n | User services
    and terminals (as IN services: call last 
 |  | 
   
    |  | dialed...) 
 |  | 
   
    |  | 
   
    | n | Standards (IETF,
    IEEE, ITU-T ...) 
 |  | 
   
    |  | 
   
    | n | Routing and
    switching (unicast - multicast, devices) 
 |  | 
   
    |  | 
   
    | n | Transmission
    and links (as fibre, coax-cable.., RSVP) 
 |  | 
   
    |  | 
   
    | n | Access and
    transport (terminals, local-loop techniques..) 
 | 
   
    |  | 
   
    | n | Servers service
    (web,mail,ftp ...) 
 |  | 
   
    |  | 
   
    | n | Signaling (SS7, X.25, Frame relay ...) 
 |  | 
   
    |  | 
   
    | n | Network
    management (as OMAP of SS7...) 
 |  | 
   
    |  | 
   
    | n | Interworking
    between networks (gateways, bridges ...) 
 |  | 
   
    |  | 
   
    | n | Network planning 
 |  |