With the wide deployment of the 40G network, it's worthwhile to consider how to connect the present 10G network to the 40G network. Currently, there are several adaptable solutions that can help to realize 40G-10G migration: 40G QSFP+ to 4x10G SFP+ DAC breakout cables, 40G QSFP+ to 4x10G SFP+ AOC breakout cables, MTP/MPO-LC breakout cables, and the CVR-QSFP-SFP10G modules. Among them, CVR-QSFP-SFP10G module can use the existing 10G cabling for a 40G-10G transition.
The CVR-QSFP-SFP10G module, also known as QSFP+ to SFP+ adapter or 40G-10G adapter, is a type of the QSA adapter. It is built in a QSFP+ form factor with a cage for the SFP+ module at the back. That is to say, a low-speed SFP+ transceiver can be plugged into its back, allowing single-channel SFP+ transceivers to connect to 4-channel QSFP+ ports. The QSFP+ to SFP+ adapter is acting as an interface for the SFP+ transceiver during the process. With this adapter, 40G-10G migration is allowed when the other end of the network is running at lower speeds.
CVR-QSFP-SFP10G features with low insertion loss, low crosstalk, secure latching mechanism, QSFP+ MSA compliant, and trouble-free installation and network bring-up. It also has wide applications in data servers, routers and switches, networked storage systems, data center networking, and InfiniBand (IB).
Figure1: CVR-QSFP-SFP10G Module
Since the QSFP+ to SFP+ adapter ensures smooth connectivity between 40G and 10G devices by using SFP+ based cabling, it has been considered as an effective solution for converting 40G ports to the 10G ports after launch.
CVR-QSFP-SFP10G supports all SFP+ cables and is compatible with mainstream switch models and SFP+ modules. A list of SFP+ transceiver modules that can be plugged into it is provided in the table below.
|Item||Product Name||Product Description|
|1||SFP-10G-SR||10GBASE-SR SFP+ module for multimode fiber|
|2||SFP-10G-LR||10GBASE-LR SFP+ module for single mode fiber|
|3||SFP-10G-ER||10GBASE-ER SFP+ module for single mode fiber|
|4||SFP-10G-ZR||10GBASE-ZR SFP+ module for single mode fiber|
|5||10G SFP+ copper cables||SFP+ copper cables (1m to 10m lengths)|
|6||10G SFP+ active optical cables||SFP+ active optical cables (1m to 100m lengths)|
Here is a typical 40G-10G application case: with the cooperation of two 10GBASE-SR SFP+ transceiver modules, an LC duplex multimode fiber patch, and one CVR-QSFP-SFP10G adapter, 40G to 10G migration will be realized smoothly.
Figure 2: Direct connection for QSFP+ to SFP+ adapter module
QSFP+ to SFP+ breakout cable consists of a QSFP+ connector on one end and four SFP+ connectors on the other end. Generally speaking, QSFP+ to SFP+ breakout cable can be divided into direct attach copper cable (DAC) and active optical cable (AOC). They are used to transmit 40Gbps data into four separate streams of 10Gbps data over a fan-out cable in a point-to-multipoint configuration.
As mentioned above, we can use a CVR-QSFP-SFP10G adapter to convert a QSFP+ port to an SFP+ port. Or adopting QSFP+ to 4x10G SFP+ breakout cables to split a 40G port between a switch or a server into four 10G ports. In a word, both QSFP+ to SFP+ adapter and QSFP+ breakout cables are providing adaptable options for the 40G-10G transition. But what's the difference between them? The distinctions of the two solutions will be analyzed in three aspects: performance, cost, and utilization.
Figure 3: DAC&AOC Breakout Cables
QSFP+ to 4x10G SFP+ breakout cables split the 40G channel into 4x 10G channel, which provides four times more data transmission than CVR-QSFP-SFP10G adapter that just provides connectivity only for a single 10G connection.
It's not difficult to find that a product's pricing is related to its popularity in the market to a certain extent. CVR-QSFP-SFP10G may be more expensive than expected on the market on account of the exclusive patent by some vendors. For short-reach transmission (<10m), DAC breakout cables provide the most cost-effective solution.
QSFP+ to 4x10G SFP+ breakout cables have mature technology compared to CVR-QSFP-SFP10G adapter, which hasn't been widely used yet for the aforementioned factors.
Figure 4: Direct Connection for 40G QSFP+ to 4SFP+ DAC
Considering the application in different scenarios, each solution has its adoptable point. If there is only one 10G device that needs to connect the switch, using a QSFP+ to SFP+ adapter is more appropriate. Or there are multiple 10G devices in dispersed locations that need to connect to 40G switches. In this case, the adapter also offers a cost-effective solution. However, if the distribution of these 10G devices is rather concentrated, QSFP+ breakout cables will be better for an optimal ROI.
Although CVR-QSFP-SFP10G modules can just perform a single 10G connection and may cost more for the exclusive patent by some vendors, they are the optimal choice for converting 40G ports to the 10G ports after launch. With CVR-QSFP-SFP10G adapter, which supports all SFP+ cables and is compatible with mainstream switch models and SFP+ modules, smooth connectivity between devices that use 40G QSFP+ port and 10G SFP+ port will be realized.