A composition comprised of multiple lines connecting to arbitrary access points.
In cases of system failure, line and router switching enables users to maintain communications.
Redundant compositions are classified into three categories as below.

(1) 2-line redundant composition (different access points)
- Two lines connecting to different access points.
- Compositions where one line is the main line in normal operations (active/stand-by) and where a different line is used for each LAN segment (degenerate) are possible.

(2) 2-line redundant composition (single access point)
A composition comprised of two connecting lines with PE being dispersedly housed at an access point.
Compositions where one line is the main line in normal operations (active/stand-by) and where a different line will be used for each LAN segment (degenerate) are possible.

(3) 3-line redundant composition (not available for Japan Securities Depository Center)
A composition comprised of three connecting lines at arbitrary access points.