APS behavior and operation differs based on the switching mode configured for the APS group as shown in Table 1. 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.