OSI and TCPIP Models

OSI model consists of seven layers.It's inverted starting at the top from layer seven to layer one.

OSI模型由七层组成，它是由顶端从第七层到第一层倒置的。

The OSI model includes application ,presentation,session,transport,network,data link and physical layer.

包括应用层，表示层，会话层，传输层，网络层，数据链路层和物理层。

Specific layer should talk to specific layer in ccna,but actually that doesn't always happen in reality.

在ccna考试中特定层应当与特定层对话，但实际上在现实中并不这样。

In TCP/IP models,layer 5 to layer 7 are combined as application.

在TCP/IP模型中，5到7层合并为应用层。

But we refer to the top layer as layer 7 because it originated from the OSI model.

但是称呼最高层为第七层，因为它起源于OSI模型。

Hups are layer 1 devices.

A hup is essentially  a multi por