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stoffi92 / rfc5575bis

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IESG Robert Wilton: SHOULD be set to 0 on encoding, and MUST be ignored #220

Closed stoffi92 closed 4 years ago

stoffi92 commented 4 years ago

I don't know if this is a valid discuss point, so happy to be educated that it is always written this way and I'll remove my discuss ...

I note that in 5 places this document has text that states the equivalent to "SHOULD be set to 0 on encoding, and MUST be ignored during decoding." (example given below).

Doesn't this make extending this in future more risky because if new meaning are given to these bits then there could be senders already transmitting non 0 values which a receiver might then misinterpret?

Hence, I was surprised that the constraints did not also include a MUST on the encoding side (i.e. be strict in what you send ...), i.e. "MUST be set to 0 on encoding, and MUST be ignored during decoding."

Example: The extended is encoded as follows:

  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |   reserved    |   reserved    |   reserved    |   reserved    |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |   reserved    | r.|    DSCP   |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 6: Traffic Marking Extended Community Encoding

o DSCP: new DSCP value for the transiting IP packet.

o reserved, r.: SHOULD be set to 0 on encoding, and MUST be ignored during decoding.

suehares commented 4 years ago

This is a won't fix. This is normal for IDR work.