# Computer Networks - Computer Performance Indicators

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Rate conversion in real network

2. Bandwidth

3. Throughput

4. Delay

The difference between transmission delay and propagation delay

5. Delay-bandwidth product

6. Round-trip time

Seven, network bandwidth utilization

Computer performance indicators: rate, bandwidth, throughput, delay, delay-bandwidth product, round-trip time, utilization # 1. Broadband speed

The rate at which a host connected to a computer network transmits data bits on a digital channel, also known as data rate or bit rate

Units are b/s kb/s Mb/s Gb/s

bit is the smallest unit of information, called binary Bit; generally represented by 0 and 1.

Byte It is called a byte, which consists of 8 bits (8bit) to form a byte (1Byte), which is used to represent a character in the computer.

Conversion between bit and Byte can be performed, and the conversion relationship is: 1Byte=8bit (or abbreviated as: 1B=8b); in practical applications, the abbreviation is generally used, that is, 1bit is abbreviated as 1b (note that it is a lowercase English letter b), 1Byte Abbreviated as 1B (note the capital letter B)

## Rate conversion in real network

In computer networks or network operators, the unit of general broadband rate is expressed in bps (or b/s); bps means bits per second, which means how many bits of information are transmitted per second, which is the abbreviation of bit per second.

1M bandwidth actually means 1Mbps (it's megabits per second Mbps not megabytes per second MBps).

Conversion formula:

1B=8b 1B/s=8b/s (or 1Bps=8bps)

Specification Tip:

In the actual writing specification, B should represent Byte (byte), and b should represent bit (bit), but in the usual actual writing, bit and Byte are mixed as b. Mixed with Mb/s, causing people to make mistakes due to confusion of units in actual calculations.

Example: In our actual network applications, when downloading software, we often see that the download speed is displayed as 128 KBps (KB/s), 103KB/s and other broadband rate size words, because the unit of line bandwidth provided by ISP is bits, and the general download software displays bytes (1 byte = 8 bits), so it needs to be converted by conversion. , to get the actual value.

Convert it according to the conversion formula:

128KB/s = 128×8(Kb/s) = 1024Kb/s = 1Mb/s ie 128KB/s = 1Mbps,

1Mbps = 1024Kbps = 1024/8KBps = 128KB/s

Channel icon: # 2. Bandwidth

Bandwidth refers to the highest data rate that a digital channel can transmit in the field of data communication

Units are b/s kb/s Mb/s Gb/s View the current bandwidth of the network used # 3. Throughput

Throughput: The amount of data passing through a network per unit of time

Units are b/s kb/s Mb/s Gb/s # 4. Delay Sending delay: refers to the time when the data is sent from the sender (the beginning of the data packet to the end of the data packet)

time delay diagram ## The difference between transmission delay and propagation delay

The sending delay is related to the bandwidth. The higher the bandwidth, the larger the amount of data sent at one time, and the smaller the sending delay.

The propagation delay is related to the propagation medium. The faster the propagation speed of the propagation medium, the smaller the propagation delay. # 5. Delay-bandwidth product

Delay-bandwidth product: the maximum number of bits on the link, also known as the link length in bits. Indicates the maximum amount of data on this network at a particular time.

Latency Bandwidth Product = data link capacity (bits per second) multiplied by round-trip communication delay # 6. Round-trip time

From sender sending data to sender receiving receiver acknowledgment

ping the local computer gateway, domestic website and foreign website respectively below, we can see that the round-trip time of the network is different.

```ping 192.168.43.1   // ping gateway - LAN

is Ping 192.168.43.1 Has 32 bytes of data:
from 192.168.43.1 's reply: byte=32 time=4ms TTL=64
from 192.168.43.1 's reply: byte=32 time=4ms TTL=64
from 192.168.43.1 's reply: byte=32 time=5ms TTL=64
from 192.168.43.1 's reply: byte=32 time=4ms TTL=64

192.168.43.1 of Ping Statistics:
data pack: Has been sent = 4，Received = 4，lost = 0 (0% lost)，
Estimated time for the round trip(in milliseconds):
shortest = 4ms，longest = 5ms，average = 4ms
--------------------------------------------------------
ping www.baidu.com // ping domestic server - Internet

is Ping www.a.shifen.com [112.80.248.75] Has 32 bytes of data:
from 112.80.248.75 's reply: byte=32 time=25ms TTL=53
from 112.80.248.75 's reply: byte=32 time=39ms TTL=53
from 112.80.248.75 's reply: byte=32 time=37ms TTL=53
from 112.80.248.75 's reply: byte=32 time=40ms TTL=53

112.80.248.75 of Ping Statistics:
data pack: Has been sent = 4，Received = 4，lost = 0 (0% lost)，
Estimated time for the round trip(in milliseconds):
shortest = 25ms，longest = 40ms，average = 35ms
----------------------------------------------------------
ping 8.8.8.8  // ping foreign servers - Internet

is Ping 8.8.8.8 Has 32 bytes of data:
from 8.8.8.8 's reply: byte=32 time=117ms TTL=113
from 8.8.8.8 's reply: byte=32 time=105ms TTL=113
from 8.8.8.8 's reply: byte=32 time=115ms TTL=113
from 8.8.8.8 's reply: byte=32 time=96ms TTL=113

8.8.8.8 of Ping Statistics:
data pack: Has been sent = 4，Received = 4，lost = 0 (0% lost)，
Estimated time for the round trip(in milliseconds):
shortest = 96ms，longest = 117ms，average = 108ms```

# Seven, network bandwidth utilization

Network bandwidth utilization: The efficiency of bandwidth receiving and sending information per second.

Channel utilization: time with data passing / (with + without) data passing time

Network Utilization: Weighted Average of Channel Utilization Just like the daily highway, the more cars on the highway, the higher the utilization efficiency of the highway per unit time. Posted by igorek on Wed, 18 May 2022 06:42:55 +0300