Why Is the 3G Link Frequently Disconnected When the 3G Cellular Interface Is Used for Network Access?
An enterprise branch uses a router as the egress gateway and connects to a network through 3G cellular interfaces. The NMS of the headquarters detects that the 3G link of the branch is frequently disconnected.
The possible causes are as follows:
- The signal of the network provided by the carrier is unstable.
- The 3G hardware is faulty.
- The configuration is incorrect.
Use the following check methods:
- Run the display cellular interface-number radio command to check the Current RSSI field and received signal strength. If the RSSI is larger than or equal to -85 dBm, signals are stable and reliable.
- Check whether the 3G interface card and SIM, USIM, or UIM card are damaged or not properly installed.
Run the display dialer interface cellular interface-number command to check the Idle field and check whether the maximum idle time of the 3G link is manually shortened.
If a branch connects to a network through a 3G cellular interface and requires a long online duration, on-demand dial-up is not necessary for the branch. If on-demand dial-up is configured to reduce data traffic, run the dialer timer idle seconds command to set the link idle time of a 3G link to 600 seconds or longer.