Composite ring network having an increased redundancy for restoring communication path

A composite ring network, comprising:

• first and second ring networks each including a plurality of nodes;
• each of said nodes having first and second paths extending therefrom for carrying an information signal, said first and second paths being connected to other nodes of said ring network, each of said nodes comprising:
• a cross connect switch connected to said first and second paths for establishing a cross connection therebetween;
• a channel part connected to said cross connect switch and capable for sending an information signal on both of said first and second paths simultaneously via said cross connect switch, said channel part selectively receiving an information signal from one of said first and second paths via said cross connect switch, said channel part including a path switch for selecting one of said first and second paths;
• said first ring network carrying signals with a first signal format;
• said second ring network carrying signals with a second, different format;
• said first and second ring networks being connected with each other at a pair of nodes, one of said pair of nodes being included in said first ring network and the other being included in said second ring network, by a bridging path;
• said bridging path receiving a first signal from said first ring network with said first signal format at a first end connected to said first ring network for sending a second signal to said second ring network with said second signal format at a second end connected to said second ring network, by converting the signal format of said first signal from said first signal format to said second signal format, said bridging path receiving a third signal from said second ring network at said second end with said second signal format for sending a fourth signal on said first ring network at said first end with said first signal format, by converting the signal format of said third signal from said second signal format to said first signal format;
• wherein said bridging path includes a converter for converting the signal format of a failure signal, which is issued in said bridging path upon a failure in said bridging path, to said first signal format and sending said failure signal thus converted to said first ring network, said converter converts the signal format of said failure signal to said second signal format and sending said failure signal thus converted to said second ring network, such that said path switch of said nodes is activated in response to said failure signal to select one of said first and second paths in response thereto.