D-4 User’s Reference Guide

WWW Server

 

Netopia Router

Workstations

ISP Router

LAN: 192.168.5.1

163.176.4.32

A & B

200.1.1.1

WAN: 200.1.1.40

 

 

 

 

 

 

Router

Netopia

ISP Router to WWW Src IP: 200.1.1.40 Dst IP: 163.176.4.32 Src Port:: 5001 Dst Port:: 80

ISP Router to WWW Src IP: 200.1.1.40 Dst IP: 163.176.4.32 Src Port:: 5002 Dst Port:: 80

WWWto ISP Router Src IP: 163.176.4.32 Dst IP: 200.1.1.40 Src Port:: 80

Dst Port:: 5002

WWWto ISP Router Src IP: 163.176.4.32 Dst IP: 200.1.1.40 Src Port:: 80

Dst Port:: 5001

Netopia to ISP Router Src IP: 200.1.1.40 Dst IP: 163.176.4.32 Src Port:: 5001

Dst Port:: 80

Netopia to ISP Router Src IP: 200.1.1.40 Dst IP: 163.176.4.32 Src Port:: 5002

Dst Port:: 80

ISP Router to Netopia Src IP: 163.176.4.32 Dst IP: 200.1.1.40 Src Port:: 80

Dst Port:: 5002

ISP Router to Netopia Src IP: 163.176.4.32 Dst IP: 200.1.1.40 Src Port:: 80

Dst Port:: 5001

Wkstn A to Netopia Src IP: 192.168.5.2 Dst IP: 163.176.4.32 Src Port:: 400

Dst Port:: 80

Wkstn B to Netopia Src IP: 192.168.5.3 Dst IP: 163.176.4.32 Src Port:: 400

Dst Port:: 80

Netopia to Wkstn B Src IP: 163.176.4.32 Dst IP: 192.168.5.3 Src Port:: 80

Dst Port:: 400

Netopia to Wkstn A Src IP: 163.176.4.32 Dst IP: 192.168.5.2 Src Port:: 80

Dst Port:: 400

As you can see, when Workstation A and Workstation B transmit an IP packet to the WWW Server on the Internet, they have unique source IP addresses on the LAN interface but potentially the same source ports, which in this case is 400. When the Netopia R2121 receives these packets, the source IP addresses are substituted with the single globally unique IP address that was acquired on the WAN interface which is 200.1.1.40.

Now both IP packets have the exact same source IP address (200.1.1.40) and source ports (400). The way the Netopia R2121 is then able to distinguish between the two IP packets is to change the source TCP or UDP ports and keep this information in an internal table. As seen above, the source port for Workstation A has been changed to 5001 and the source port for Workstation B has been changed to 5002.

If you were to look at the internal port mapping table that is maintained by the Netopia R2121, it would look similar to the following:

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Netopia R2121 manual Router Netopia

R2121 specifications

The Netopia R2121 is a powerful and versatile router designed for both home and office environments, providing seamless connectivity and robust performance for various networking needs. This device offers a range of features and technologies that cater to the demands of modern users seeking reliable internet access, speed, and security.

One of the standout characteristics of the Netopia R2121 is its dual-band technology, which operates on both the 2.4 GHz and 5 GHz frequency bands. This capability allows users to enjoy faster speeds and less interference, as the 5 GHz band is typically less congested than the traditional 2.4 GHz band. With the ability to support multiple devices simultaneously, the R2121 ensures that users can stream videos, play online games, and conduct video conferences without experiencing lag or connectivity issues.

The router is equipped with advanced security features, including WPA3 encryption, which provides enhanced protection against unauthorized access and data breaches. The R2121 also supports a robust firewall system that guards against external threats, ensuring that the user's network remains secure. Additionally, the router includes parental controls, allowing users to manage and restrict internet access for specific devices or set time limits for usage, making it an excellent choice for families.

Another significant advantage of the Netopia R2121 is its extensive coverage area. With high-gain antennas and advanced beamforming technology, the router can deliver strong and stable Wi-Fi signals even in larger homes or office spaces. This technology focuses the Wi-Fi signal directly toward connected devices, minimizing dead zones and improving overall connectivity.

The R2121 also supports both IPv4 and IPv6, ensuring compatibility with current and future internet technologies. This forward-thinking design makes it a future-proof solution for users looking to invest in a reliable router.

In terms of setup and management, the Netopia R2121 features a user-friendly web interface that allows users to easily customize settings, monitor network performance, and manage connected devices. The inclusion of mobile app support further enhances the user experience, enabling remote monitoring and control of the network from anywhere.

Overall, the Netopia R2121 stands out as a robust and reliable router that combines advanced features, enhanced security, and excellent performance, making it an ideal choice for home and business users alike. With its focus on delivering seamless connectivity and comprehensive management options, the R2121 is well-suited for today's connected lifestyles.