The Intergalactic Research Network (IRN) is a technology that allows Research Labs from different planets to work together, decreasing research times. Each level of IRN combines the Lab where the research is actually being conducted with the Lab on one additional planet, effectively adding their Lab Levels together to compute research time. Joining labs together is completely automatic and transparent: the game will join labs in order of their level (highest first). Labs below the minimum level required to research a given technology will be excluded, regardless of IRN.
In order to function, the colony where the research is being conducted must have a Research Lab Level capable of conducting the research independently.
You have 4 planets, with Research Lab levels of 10, 8, 6, and 4. You want to research Shielding Technology which requires a level 6 research lab.
Level 2 IRN allows 3 research labs to work together, and your top 3 labs all have at least the required level 6.
Therefore, beginning research at any of those three labs will give the production time of a 10+8+6 = level 24 research lab.
You have 4 planets, with Research Lab levels of 10, 8, 6, and 4. You want to research Hyperspace Drive, which requires a level 7 research lab.
Level 2 IRN allows 3 research labs to be connected, but the level 6 and level 4 labs are excluded as they are not high enough to research Hyperspace Drive. Only two labs remain eligible.
Starting the research at either of the two possible labs, you will still get the benefits of a 10+8 = level 18 research lab.
You have 4 planets, with Research Lab levels of 10, 8, 6, and 4. You want to research Shielding Technology which requires a level 6 research lab.
Level 1 IRN allows 2 research labs to be connected. If you start the research at the level 6 lab, you will only get the benefits of a 6+10 = level 16 lab. However, If you start the research at either of the two higher labs, you will still get the benefits of a 10+8 = level 18 research lab.
Remember that lab where the research is started (the planet you have the resources on) is always part in the network. Therefore, as Example 3 shows, this sometimes means you should start the research on one of your higher level labs in order to gain the quickest possible research time.
The IRN is an extremely effective way to cut research time and is obviously a lot cheaper than upgrading one lab that high.