APS behavior and operation differs based on the switching mode configured for the APS group as shown in Table: APS switching modes. Several switching modes are supported in the router.
The switching mode affects how the two directions of a link behave during failure scenarios and how APS tx operates.
Unidirectional / Bidirectional configuration must be the same at both sides of the APS group. The APS protocol (K byte messages) exchange switching mode information to ensure that both nodes can detect a configuration mismatch.
If one end of an APS group is configured in a Unidirectional mode (Uni 1+1 Sig APS or Uni 1+1 Sig+Data APS) then the other end must also be configured in a Unidirectional mode (Uni 1+1 Sig+Data APS).
If one end of an APS group is configured in a Bidirectional mode then the other end must also be configured in Bidirectional mode.
| Bidirectional 1+1 signaling APS | Unidirectional 1+1 signaling APS | Unidirectional 1+1 signaling and datapath APS | |
|---|---|---|---|
Short form name |
Bidir 1+1 Sig APS |
Uni 1+1 Sig APS |
Uni 1+1 Sig+Data APS |
CLI |
bidirectional |
unidirectional |
uni-1plus1 |
Interworks with a standards compliant APS implementation |
Yes |
Yes |
Yes |
Full 1+1 APS standards-based signaling |
Yes |
Yes |
Yes |
Data is transmitted simultaneously on both links/circuits (1+1 Data) |
No |
No |
Yes |
The support of switching modes depends on SC-APS/MC-APS, MDAs, port types and encaps. For a definitive description of the MDAs, port types, switching modes, bundles and encapsulations supported with APS, see APS applicability, restrictions, and interactions.