This article covers the specifics of the S101 platform as relates to the 40G interfaces on this platform. The article on recommended SFPs still applies to this platform and should be read in conjunction with this article.
The 40G interfaces on the S101 platform support 40G QSFPs or 10G SFPs (with adapter if required) that fully comply with all standards. Deployments may freely connect any combination of these ports, including multiple 40G ports in combination with multiple 10G ports.
When using multiple ports where the total Ethernet bandwidth available exceeds 40G the total traffic throughput of the system across all ports should not be allowed to exceed 40G.
The 40G interfaces on the S101 platform with a 40G QSFP may only be configured as a single port using all four 10G lanes.
40gb QSFP breakout cables are supported, but they have extremely limited use cases and are unlikely to be a practical option. The use of breakout cables require that all 4 SFP+ modules be connected to a single switch with the four ports configured to operate as a single 40G interface. Typically a single 40Gb QSFP link or individual 10Gb links across multiple interfaces will be a superior solution.
For this reason there is usually no benefit in connecting breakout cables to the 40G interfaces. Breakout cables may still be used but only where the four 10G lanes are connected to an appropriate endpoint also configured in 1x40G mode. The four 10G lanes cannot be configured in 4 x 10G mode as four separate interfaces.
For customers requiring four 10G interfaces the S101 may be configured to use the two 10G ports in 10G mode and the two 40G interfaces in 10G mode using appropriate 10G SFPs. Vectra does not provide any recommendations for 10G SFPs compatible with 40G QSFP ports and whether any adapters may be required, however Vectra does expect for any high quality solutions from well reputed vendors to work without issue.
It is exceptionally important to note the comments in the above linked article regarding cheaper, cloned or non-standard SFPs. Third party SFPs have an increased chance of being non-compliant with standards and an increased chance of interface instability or errors. Vectra cannot recommend the use of any SFPs not fully compliant with all relevant SFP standards.