Ip Address - Vivotek IP Surveillance Overview

Chap.4 IP Network
Router
A router connects different Ethernet networks to achieve network coverage. It can connect LANs that use different
network protocols or transmission methods. When a router receives a packet, it checks the destination address of
the packet, and designates an optimal path for it based on packet size and priority.

4.3 IP Address

Each network device has its own IP address. An IP address is like a doorplate of the device, helping data to be
delivered to the correct destination. An IP address contains 32 bits, which are divided into four parts, each part
separated by a dot, such as 255.255.255.0.
The following three blocks of the IP address space are reserved for private Internets (local networks):
•
10.0.0.0~10.255.255.255
•
172.16.0.0~172.31.255.255
•
192.168.0.0~192.168.255.255
However, with the number of network devices increasing, IP address shortage has become a problem. To solve the
problem, DHCP and NAT and IPv6 were developed.
DHCP
DHCP (Dynamic Host Configuration Protocol) automatically assigns a valid IP address to a network device on the
Internet. Allocating a fixed IP address for each device will result in idle IP addresses when the devices are not in
operation. Therefore, DHCP can make more efficient use of the IP addresses.
NAT
NAT (Network Address Transfer) uses translation tables to change a private IP address of an outgoing packet
from a client PC into a public IP address. In this way, multiple PCs can access the Internet through one public IP
address.
Internet
Figure 4.1 NAT enables multiple PCs to share one public IP address
NAT breaks the rule of one IP address for one network device. As a result, when multiple network devices are
transmitting a great deal of data simultaneously, serious delay and packet loss may occur.
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WAN
3 Target: Public IP
Source: Public IP
2
Router with NAT Server
LAN
4 Target: Private IP
Source: Private IP
1
Client A
Client B