MPLS - what is fate sharing
Fate sharing is a concept that is involved with the use of shared risk link groups (SRLGs) in MPLS. SRLGs are defined in situations where links in a network share a common fiber or a common physical path. These links have shared risk, and thus when one link fails, other links in the group also fail.
In SRLG fate sharing, links are assigned one or more numbers to represent risks. When two links are assigned a common number, then this indicates that these two links are sharing fate. If one of those links fails, then the others, which share the same fate, will also be excluded from the topology.
Fate sharing and SRLGs are a part of the broader discipline of MPLS traffic engineering.