HP Coarse Wave Division Multiplexer - Manual (Page 14)

Figure 5 Point-to-point: 4-port (non-redundant)
Figure 6 Point-to-point: 8-port to 4-port (non-redundant)
Point-to-point redundant configurations (no single point of failure)
Typically, for redundant configurations, two HP CWDM 8-port MUX modules are installed in a chassis.
Two HP CWDM Slot A 4-port Add/Drop MUX modules or two HP CWDM Slot B 4-port Add/Drop MUX
modules can be installed in a chassis for redundancy. Additionally, a combination of an HP CWDM
8-port Multiplexer/Demultiplexer module and an HP CWDM Slot A 4-port and HP CWDM Slot B 4-port
Add/Drop MUX modules can be connected for a redundant configuration to create an environment
with no single point of failure.
14 About HP CWDM MUX modules and CWDM (SFP) transceivers