Re: [Srcomp] REQ-7-27-COMPRESS-01

[Ron Bonica <[e-mail]>]

Darren,

I think that the goal is laudable. However, I think that there is a more solution-neutral way to measure compression efficiency. Consider that:


  *   An SR path is a series of segments.
  *   Each segment is an instruction.
  *   The information of an instruction can be measured in bits. For example:
     *   The information value of a service instruction is greater than 20 bits (REQ-7-27-SVC-SCALE-00)
     *   The information value of a node instruction is equal to the number of bits in a locator (between 48 and 128?)
     *   The information value of an adjacency instruction is equal to the number of bits in a locator (between 48 and 128?) plus 16 bits (REQ-7-27-LINK-SCALE-00)

So, the information value of an SR path (P) is equal to the sum of the information values of its segments.

A compression mechanism produces a particular compression header for a particular SR path. So, we can create a table with the following columns:


  *   Compression mechanism
  *   SR path (described as a sequence segment types)
  *   Compression header length
  *   Encoding efficiency

In this table, Encoding efficiency is equal to compression header length divided by P.

                                                                                                         Ron









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From: Srcomp <[e-mail]> On Behalf Of Darren Dukes (ddukes)
Sent: Tuesday, July 28, 2020 12:01 AM
To: [e-mail]
Subject: [Srcomp] REQ-7-27-COMPRESS-01

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COMPRESS, Encapsulation Compression

Description:
A solution to compress SR for the IPv6 data plane MUST support efficient SRv6 encapsulating header compression.

Rationale:
The compression of SRv6 is the primary goal of the SR compression design team.

Metric:
Compression is the ratio of the IPv6 encapsulation size of SRv6 as defined in RFC8402, RFC8754, draft-ietf-spring-srv6-network-programming vs the IPv6 encapsulation size of a given proposal.
The encapsulation savings of a compression proposal vs the SRv6 base is a useful measurement to compare proposals.
The encapsulation metric (E) records the number of bytes required for a proposal to encapsulate a packet given a specific segment list.
  I.e. E(proposal, segment list)
The encapsulation savings  (ES) records the encapsulation savings for a proposal to encapsulate a packet given a specific segment list.
  I.e. ES(proposal, segment list) = 1 - E(proposal, segment list)/E(SRv6 base, segment list)