IP with version number 5 is dedicated to the Internet Stream Protocol. Can you send such a packet on the internet at large, or will it be blocked/discarded?


No. A packet marked with v5 likely won't even be accepted by your WAN router. I don't think there are any somewhat current hardware devices with v5 support.

Some engineers just didn't give up but v5 was a dead end. It's much more practical to solve most problems on the transport layer and throw more bandwidth at it for the rest.

  • That's too bad. I thought it would be a fun exercise. Apr 17 '20 at 22:07
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    To my knowledge, 0110 and 0100 are the only valid binary values for the IP version field. Apr 17 '20 at 23:33
  • @RossJacobs On the Internet that is (also depending on ISP and data plan) - in your own network you can use what you like, if your gear can handle it.
    – Zac67
    Apr 18 '20 at 6:49
  • @Zac67 This is technically true, but the implied context here is traffic sent over networks and to a destination you do not control. Your gear won’t be able to handle it unless you modify all networking stacks for this educational exercise. At which point it seems like overkill, unless you’re testing this in a virtual environment. Apr 18 '20 at 7:00

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