Re: [mpls] FW: New Version Notification for draft-jags-mpls-ps-mna-hdr-00.txt

Hi Greg,

> GIM2>> The PALS (PWE3 at that time) WG was faced with the result of allowing PW CW to be optional in Ethernet PW in the scenario you've described.  Because of the allocation of MACs with the first nibble 0x4 or 0x6, the payload was misinterpreted by a transit node as IPv4 or IPv6. And thus, the WG published RFC 8469 <https://www.rfc-editor.org/rfc/rfc8469.html>. But I only know of cases when a transit node mistakes the payload for IPv4 or IPv6. In principle, a transit node must not draw a conclusion about the payload type based on the value of the first nibble after the BoS LSE. If we agree on that, then using any value other than 0x4 and 0x6, e.g., 0x0, should be satisfactory. WDYT?


Again, I’m a big fan of simple and straightforward demultiplexing, without overloading.

But I await the collected wisdom of the first nibble draft.


>> Just for clear semantics. I am a very big fan of avoiding overloading.
> GIM2>> Considering the limited number of unused values, re-using what we can seems like a reasonable trade-off. 


Save one as an escape value and use the rest. :-)

T

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