RE: Compressed Routing Header idea

Pascal, thanks I did not know about this but at first glance I do not believe RFC8138 fully
satisfies what I need. First, I want to be able to support both left-side (most significant
bits) and right-side (least significant bits) compression. Second, I want to be able to
compress to the byte granularity for any length from 0 to 16 bytes. And, third, I want
to be able to include an ancillary piece of information (e.g., an application port number)
with each IPv6 address. So, I submitted a short draft showing the format that I would
see as being flexible to support my use case and I think perhaps many other:

https://datatracker.ietf.org/doc/draft-templin-6man-crh-variable/

I did include a reference to RFC8138 - let me know your thoughts.

Fred

> -----Original Message-----
> From: Pascal Thubert (pthubert) [mailto:pthubert@cisco.com]
> Sent: Monday, May 18, 2020 7:55 AM
> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>; IPv6 List <ipv6@ietf.org>
> Subject: RE: Compressed Routing Header idea
> 
> Hello Fred:
> 
> Are you aware of RFC 8138? See https://tools.ietf.org/html/rfc8138#section-5.1
> The addresses in the source route header can be compressed as follows:
> 
> "
> 
>      +-----------+----------------------+
>      |   6LoRH   | Length of compressed |
>      |   Type    | IPv6 address (bytes) |
>      +-----------+----------------------+
>      |    0      |       1              |
>      |    1      |       2              |
>      |    2      |       4              |
>      |    3      |       8              |
>      |    4      |      16              |
>      +-----------+----------------------+
> 
>                        Figure 7: The SRH-6LoRH Types
> 
> "
> You need multiple SRH-6loRH if you have different sizes to accommodate.
> 
> Keep safe
> 
> Pascal
> 
> > -----Original Message-----
> > From: ipv6 <ipv6-bounces@ietf.org> On Behalf Of Templin (US), Fred L
> > Sent: lundi 18 mai 2020 16:04
> > To: IPv6 List <ipv6@ietf.org>
> > Subject: Compressed Routing Header idea
> >
> > Hi, I have a use case where some IPv6 addresses that would go into a routing
> > header are more compressible than others and so I am wondering if some kind
> > of "hybrid" compressed routing header would be possible. For example, if one
> > address can be compressed down to
> > 16 bits, then include only those 16 bits; if a different address can only be
> > compressed down to 32 bits, then include the 32 bits; if yet a different address
> > cannot be compressed at all, then include all 128 bits. And, there may be many
> > more sizes in between.
> >
> > RFC4191 Section 2.3 shows an example of how an IPv6 prefix/address can be
> > compressed to a variable length. Essentially, a length byte followed by a
> > variable-length prefix. That way there would still be "pretty good compression"
> > albeit with an extra byte per prefix. And, it would be a generalized form that
> > would only require a single routing header type value.
> > How would it be if we did something like that?
> >
> > Fred
> >
> >
> >
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