1 Network Models and Protocol Foundations Free Online FlashCards

What is a network model?

A network model organizes communication functions into layers; it is a guide, not itself a protocol.

What does a network protocol define?

A protocol is an agreed set of rules for exchanging information, including message formats, field meanings, and device responses.

What is a layer in a network model?

A layer groups related communication functions and provides services to the layer above it.

What is encapsulation?

Encapsulation occurs when each layer passes data downward and adds control information, such as a header or sometimes a trailer.

How do layers carry a browser's HTTP request across a network?

For a browser request, HTTP represents the request, TCP may carry it between processes, IP addresses and forwards it, and Ethernet or Wi-Fi carries it across the current link.

What are common data-unit names at the link, internet, and TCP transport layers?

Common data-unit names are frame at the link layer, packet at the internet layer, and segment for TCP at the transport layer.

What does a router do with an IP packet at the next link?

A router examines the IP packet to choose where to forward it, then places it in a new link-layer frame for the next link.

What delivery guarantees does IP provide?

IP provides a connectionless datagram service and does not guarantee that packets arrive, arrive only once, or arrive in order.

What layered order can guide network troubleshooting?

Check the local link, IP addressing and forwarding, transport communication, and then application-protocol behavior.

How does layering separate network responsibilities?

Layering separates responsibilities: an application can use transport services without managing Wi-Fi or Ethernet details.

How many layers do the OSI and Internet models commonly use?

The OSI model has seven layers. The Internet architecture commonly groups functions into four: application, transport, internet, and link.

Why is mapping Internet functions to OSI layers approximate?

The mapping is approximate: real protocols do not always fit neatly into a single model layer.