BLSR

Bidirectional Line Switched Ring

Bidirectional Line Switched Ring (SONET/SDH)

Bidirectional Line-switched Self Healing Ring;
Bidirectional Line Switched Ring (BLSR)
benefits from 1:1 protection. In 1:1 protection, every link can carry both regular traffic and backup traffic at the same time and thus does not require dedicated backup links. On a link failure, the node upstream of the failed link wraps traffic from one ring to another ring in the reverse direction so that traffic still can reach its destination. BLSR is as fast as Unidirectional Path-Switched protection and does not waste as many resources, as there is no notion of dedicated primary and backup link. See also UPSR

Bi-directional Line-Switched Ring