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New Member

backup bridged serial inteface with a bridged FE to avoid STP loops?

Current network setup:

(3640, serial) ------T1-----> (serial, 1721, FE) --> Branch LAN (hubs, switches from other vendors)

All devices on a single bridged network (vlan80)

New network requirment:

Branch LAN vlan80 will be extended to another building using point to point laser equipment (two end devices, each with a FE port). New Building will have a new 1700 (2x FE, 1x Serial) router using another T1 to connect to a different serial interface on the 3640 router. All three 1700 router interfaces will be bridged, but the Branch LAN has hubs and non-cisco switches interconnections, which will cause STP loop.

We are thinking of using "backup interface" command on the new 1700 router. The command will be configured on the serial (S0) interface: backup interface FE1. FE1 connects to laser FE port. FE0 will connect to the new building LAN, an extension of vlan80.

Is this workable? backuping bridged interfaces to prevent STP loops? Although backup interfaces are normally in "standby" mode, but will STP packets still be transmitted?


New Member

Re: backup bridged serial inteface with a bridged FE to avoid ST

Any update on this?

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