Thanks Jonas.
Juniper just came back to me and confirmed that distances reachable out of a 4x10GBAseSR coming from a splitted SR4 QSFP are much lower than distances reachable with native 10GBaseSR SFP+.
They even advise not to go for SR4 optics but ESR4 instead, as SR4 optics send a initial signal that can exceed normal 10GBaseSR signal ranges, and cause warning on the peer equipment.
But ESR4 optics are much (much!) more expensive than SR4.
To summarize :
- QSFP+ SR4, 40G mode : 100m@om3, 150m@om4
- QSFP+ SR4, 4x10GBaseSR mode : 100m@om3, 150m@om4, not recommended (signal strength)
- QSFP+ESR4, 40G mode : 300m@om3, 400m@om4, no support for om2
- QSFP+ ESR4, 4x10GGBaseSR mode : 300m@om3, 400m@om4, no support for om2
- SFP+ 10GBAseSR : 82m @om2, 300m@om3, 400m@om4.
Pascal