Usr USR-GPRS232-701, Руководство пользователя

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GPRS DTU User Manual V1.3 http://en.usr.cn
Jinan USR IOT Technology Limited Page 13 of 31 tec@usr.cn
Class C: From 192.0.0.0 to 223.255.255.255, generally used for small companies,
campus network and research institutions,etc
Class D: From 224.0.0.0 to 239.255.255.255, used for special purpose, also called
“broadcast address”
Class E: From 240.0.0.0 to 255.255.255.255, Temporary retention
To judge if the computer has a public IP, you can operate like this to check:
Start- Run- input CMD- then Enter- input ”ipconfig/all”. As following picture: 180.186.12.99
is belong to Class B, it is an effective public IP address.
Generally, we can distinguish whether the IP is public IP through following method:
 Usually, the machine that Telecom and Netcom through adsl dial-up obtain IP
address, it should be public IP; Railtom broadband has NAT address translation, not
public IP.
 Cable modems for dial-up Internet IP address, also public IP.
 GPRS wireless card (for laptop wireless Internet), the IP is Mobile GPRS internal IP,
but because for GPRS DTU, they are from the same network, so they can also be
used for connectivity.
 If users access to Internet through a router, and the router address is not the public IP
through NAT translation, then we can adopt router port mapping, so the data can be
forwarded through a router to your computer (Specific application diagram reference
to chapter 5.2)
 If the machines IP is dynamic public IP, means the Internet IP is not fixed, it requires a