[ntpwg] ntp extension

[Brian Haberman]

Greg,
      Works for me.  Any objections?

Regards,
Brian

Greg Dowd wrote:
> 
>   _NTP Extensions Field_
> 
>  
> 
> TLV = Type, Length and Value
> 
>  
> 
>  
> 
> Autokey is currently using ALL 65,535 types.  This violates the TLV 
> principle.  The reason for this is that Autokey has redefined the Type 
> field as a structure containing version and flag fields along with the 
> original type id. 
> 
>  
> 
> Current type definition in the NTP document
> 
> The Field Type field is specific to the defined function and is not
> 
> elaborated here.  
> 
>  
> 
> Suggested definition in NTP document.
> 
> The Field Type field is specific to the defined function and is not
> 
> elaborated here.  TLV types are IANA registered numbers.  
> 
>  
> 
> Current type definition in the Autokey document
> 
> The 8-bit Code field specifies the request or response operation,
> 
> while the 4-bit Version Number (VN) field is 2 for the current
> 
> protocol version.  There are four flag bits: bit 0 is the Response
> 
> Flag (R) and bit 1 is the Error Flag (E); the other two bits are
> 
> presently unused and should be set to 0.  The remaining fields will
> 
> be described later.
> 
>  
> 
> If we take the presently unused flag bits and force them to 0, we could 
> recover some space for future use.
> 
>  
> 
> Note that the 48000 TLVs currently in use by Autokey support about 20 
> commands.  This is wasting 99.96% of the allocated space.  This is due 
> to Autokey’s usage of the Type field as a compound structure 
> incorporating not only commands but also a version and flags field.
> 
>  
> 
> Types currently in use by Autokey (if flag fields are capped)
> 
>  
> 
> 0x0000 – 0x0FFF
> 
> 0x4000 – 0xFFFF
> 
>  
> 
> Available for future use (if flag fields are capped)
> 
>  
> 
> 0x1000 – 0x3FFF
> 
>  
> 
> Result is that at least 25% of the space will be available for 
> extensions of the protocol, which will be backwards compatible with the 
> current proposed version.
> 
>  
> 
>  
> 
>  
>  
> Greg Dowd
> gdowd at symmetricom dot com (antispam format)
> Symmetricom, Inc.
> www.symmetricom.com <blocked::http://www.symmetricom.com/>
> "Everything should be made as simple as possible, but no simpler" Albert 
> Einstein
>  
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> ntpwg mailing list
> ntpwg at lists.ntp.org
> https://lists.ntp.org/mailman/listinfo/ntpwg