Fwd: Re: RPSL support for 32 bit ASN

Larry,


>     The big difference is that existing tools can potentially break if
>the syntax is changed in existing attributes.     I agree that adding new
>attributes is undesirable, but I see a couple alternatives.   The first would
>be to use straight integer notation for the AS numbers instead of the
>"." notations.

The IESG has asked for a standard notation for ASN32 when processing
draft-ietf-idr-as4bytes.  draft-michaelson-4byte-as-representation was
written to suggest the "x.y" notation.  This draft is likely to be
accepted soon.

My draft follows this "x.y" notation simply because I don't think that it
is a good idea to have 2 different formats for the same thing.  At least,
it'd drive me nuts if I had to type 1.0 in one place (my router CLI, for
example) and 65536 in another (an RPSL tool) when referring to the same
thing.

>  This is actually compatible with the RFC 2622 flex macro
>for AS numbers (as Mark Prior noted) and would likely be compatible
>with existing tools.

An AS has been a 16 bit number forever (in terms of the lifetime of the
Internet) and authors have implicitly used that when writing their tools.
That means: regular int's (or even short unsigned ints) in the code,
checks on input that numbers entered are below 65536 and/or 5 digits,
arrays dimensioned to 65536, etc.  All this code will have to be
checked and updated.  I would definitely not feel comfortable using
code with numbers outside the range of the original spec.


>   Note that RFC3779 uses a straight integer for 32-bit
>ASN's  (as opposed to the dotted character bitstrings for IPv4 numbers), so
>this is not unprecedented.

I seriously doubt that the authors of RFC3779 had ASN32 in mind when they
wrote that RFC.  I also think that this is a good example of why things
have to be checked; a regular C integer (31 bits plus sign bit) in your
code will fail for ASN 32768.0.  It should be an unsigned int.



Henk


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