What does this picture describe?

enter image description here

Fa0/0 == Fast Ethernet port 0/0.

Fa0/1 == Fast Ethernet port 0/1. == IP Address of the PC of the bottom left. == IP Address of the PC of the bottom right. == Why is there only one IP Address between the routers?

.1, .2 == What are these values? Are they fractions or what?

S 0/0/0 == What does it mean? 0/0 port of Slot 0? Then why does 0/0 port of Slot 1 is written as 0/1/0?

DTE == Terminal?

DCE == Modem?

Why are 'Terminal' and 'Modem' information necessary?

4 Answers 4


Fa0/0 is the FastEthernet interface on slot 0, port 0.

Fa0/1 is the FastEthernet interface on slot 0, port 1.

The addresses,, and are address prefixes representing the subnets used on the respective link.

The .1 and .2 mean the specific addresses on that subnet (e.g. the .1 on the subnet means the address).

S0/0/0 means the serial interface on slot 0, card 0, port 0.

DTE means Data Terminal Equipment and DCE means Data Communications Equipment. Basically, serving the same purpose as male and female connectors; male connects to female, not another male. The DTE/DCE information is necessary for the configuration of the interfaces.


DCE=ISP DTE=customer side

they operate off of different standards which are not commonly used in many environments anymore.

Setting the bandwidth and clockrate for this type of setup is necessary and must match on both sides of the link if im not mistaken.

X25 and HDLC are common for this type of setup...the represents the network link of the serial connection between the two routers

.1 and .2 are equal to the last octet in the 192.168.0.x network (class c) and are on the same subnet. Both of these are private IP addresses not routable on the internet.

S0/0/0/0 refers to serial links in routers in Cisco hardware, Serial links are commonly used for connections to ISP at network boundaries or to WAN links of an ISP.


Actual format is Interface card/slot/port numberes

Some devices (like 2500's) it's just a port number (Serial0)

In modular devices, you may have a slot/port number (Serial 0/0)

In larger modular devices, you'll get card/slot/port numberes (Serial 0/0/0)


Fa0/0 --> slot 0, port 0

Fa0/1 --> slot 0, port 1

S0/0/0 --> slot 0, card 0, port 0

DTE --> Data Terminal Equipment DCE --> Data Communications Equipment

  • Please try to give more details, like in the accepted answer. The person asking the question may not understand well what is a slot, a port, etc. Jun 25, 2021 at 16:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.