SONET vs DWDM for Metro Rings

I like the multiple fibre optic option where there is always some slack in the system. The ring network is ok for big network suppliers where continuity of data transmission is a requirement. It suits a backplane environment. I work at the end of the line.

Actually, I tend to think of WDM as a physical layer thing - you can run just about anything over it. While SONET is more like a data-link protocol because of its packetization of data.

WDM is cool because it gives you several channels over the same fiber And while WDM and SONET are ring topologies, they don't participate in any kind of nasty token passing, such as Token Ring or FDDI. Instead, if they use Spacial Reuse Protocol (Cisco PRP), they hit the fiber in the same way Ethernet works CSMACD. However, at the same time, they have a resilient double-ring structure that can compensate for downed links.