Complex sentence: Shared risk resource group (commonly referred to as shared risk group or SRG) is a concept in Optical mesh network routing that different networks may suffer from a common failure if they share a common risk or a common SRG.
Split into simpler sentences: Shared Risk Resource Group (commonly referred to as only Shared Risk Group or SRG) is a concept used in Optical mesh network routing. SRG is the concept that different networks may suffer from a common failure if they are sharing a common risk or a common SRG.