Fibre ring topology
A fibre ring topology can provide resilience in the even of a fibre break. This is achieved by running multiple redundant geographically different fibre paths to the cabinet.
Although traditional network infrastructure works on a start topology it is possible to build an ethernet network as a ring. This topology has the advantage of providing redundant paths if a fibre is broken.
A good example of this is laid out in the diagram below. You can see that there are six distinct blocks on our diagram CAB A to CAB F, in CAB A sits a core switch and in each of the other cabs an access switch with a minimum of 2 x 10Gbps SFP+ ports plus access ports for client devices. Each of the blocks has a network cabinet and two twelve core OM4 fibres running to each.
Each of the access switches is linked back to the core via two 10Gbps trunked ports effectively giving each switch an uplink bandwidth of 20Gbps.
It is sometimes easier to think of this as two separate fibre runs one going clockwise, the other going anti-clockwise. It is in effect a star topology achieved with a ring infrastructure.
Fibre ring topology diagram
In the event of one of the twelve core fibres breaking, traffic would continue to flow to all switches in the network due to the geographically diverse fibres routes, albeit traffic would be flowing at a reduced rate of 10Gbps per switch.