From what I understand so far, the equipment installed on the BTS that TD-LTE routers receive internet from is different from the equipment that mobile phones receive internet from. I want to know how a router that can connect to both TD-LTE network and mobile phone network can determine which type of equipment to connect to?
1 Answer
Metrics.
Each interface has a value called the metric that determine the priority.
When an interface is disconnected, obviously it is not taken into account (technically: the routes associated to this interface are removed from the forwarding table).
If several interfaces are connected at the same time and you have the same route (usually in your case the default route 0.0.0.0/0) pointing to both interfaces, then the metric of the interfaces are used to choose which one to use.
A default metric is configured for each interface, and usually -depending of the exact device- can be altered by the admin.
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Does the router connect to which equipment depends on the type of SIM card that is placed inside the router?– SEPEHRCommented Mar 5 at 17:40