Normally end to end connection have the same bandwidth, let's say 1G link connect to 1G link, 10G link connect to 10G link and so on. When Core or Distribution Layer capacity upgraded to 40G or 100G port, it will change planning capacity in the Access Layer, maybe some POP can follow to upgrade to 40G/100G port but another POP still enough with 10G port. How to solve this issue?
Picture 1. Core, Distribution and Access Layer port connection
From the picture above we can see Access Layer equipment that still use 10G port can't connect to Distribution Layer, since the Distribution equipment port only use 40G and 100G. Equipment vendor give solution about this issue with breakout connection solution. You can ask your vendor how to activate breakout connection. When you activate break connection on your equipment, the equipment will automatically create virtual interface 4x10G or 4x25G.
Picture 2. Virtual interface allocation when activate breakout
Breakout connection can separate 40G to 4x10G and 100G to 4x25G. How this solution work in the terms of optical level? Breakout solution can work because each link have different physical connection, since the physical connection are different so we can use only 1 wavelength on the optical cable. See the picture below :
Picture 3. Breakout connection 40G to 4x10G (Direct Connect type)
|1||SFP+ 10G 850nm LC||Breakout Cable MPO Female to LC 8 Fibers||QSFP+ 40G 850nm MPO|
|2||SFP+ 10G 1310nm LC||Breakout Cable MPO Female to LC 8 Fibers||QSFP+ 40G 1310nm MPO|
Table 1. Information Breakout connection from picture 3
Multimode only use 850nm and Singlemode only use 1310nm wavelength. And since there are 4 links, we need minimum 8 optic cable (4 pair), so QSFP port need use MPO type, because MPO port support up to 12 optical cable.
There are 2 types breakout connection, direct connect (already explain in the picture and table above) and interconnect. The difference for interconnect add 1 passive equipment that is MPO Cassette, the function same like OTB so you can get flexibility distance. Because breakout cable has standard that "joint section" distance is 0,5 meter from LC connector.
Picture 4. Breakout cable structure
Picture 5. Breakout Connection Interconnect Type
There is a case equipment with 100G port only can support breakout 4x10G can't do 4x25G, in this case if your QSFP28 100G already support multirate function there is no need to replace QSFP28 100G to QSFP+ 40G*. QoniTech product already support multirate function.
*You must check your equipment also, some equipment are very strict that you must use 100G transceiver on 100G port and use 40G transceiver on 40G port. But some equipment are very flexible that you can use QSFP28 or QSFP+ on 40G port.
- Breakout Connection is the solution to support 10G connection or 25G connection, when the other side use 40G/100G port.
- There are 2 types of breakout connection, Direct Connect and Inter Connect.
- Breakout use different physical for each link and use only 1 wavelength.
- At QSFP side we need MPO Connector so we can get 8 fibers or more.