APS can operate in a single chassis configuration (SC-APS) or in a multi-chassis configuration (MC-APS).
An SC-APS group can span multiple ports, MDAs or IOMs within a single node whereas as MC-APS can span two separate nodes as shown in Table: SC-APS versus MC-APS protection.
| Single chassis APS | Multi-chassis APS | |
|---|---|---|
Short form name |
SC-APS |
MC-APS |
Link failure protection (including intermediate transmission equipment failure) |
Yes |
Yes |
Optical/electrical module (SPF, XFP) failure protection |
Yes |
Yes |
MDA failure protection |
Yes |
Yes |
IOM failure protection |
Yes |
Yes |
Node failure protection |
No |
Yes |
The support of SC-APS and MC-APS depends on switching modes, 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.