Subject: [Srcomp] Section 2.2.1 (Forwarding Efficiency)

From: Ron Bonica <[email-masked]>
Date: Thu, 3 Jun 2021 15:15:32 +0000

Folks,

I recommend that we make the following changes to Section 2.2.1 (Forwarding Efficiency). If we make these changes, we can delete much of the text that comes before it.

                                      Ron

New Text
-------------
        +-------------------+------+-----+---------+------+-------+
        | 16-bit            | CSID | CRH | CRH+TPF | VSID | UIDSR |
        +-------------------+------+-----+---------+------+-------+
        | PRS(48B.0T).V)    | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                   |      |     |         |      |       |
        | PRS(48B.1-4T).V)  | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                   |  [1] |CRH  | CRH     | SRH  | SRH   |
        |                   |      |     |         |      |       |
        | PRS(48B.5-15T).V) | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                   | SRH  |CRH  | CRH     | SRH  | SRH   |
        |                   |      |     |         |      |       |
        +-------------------+------+-----+---------+------+-------+

             Table 3: Headers parsed on transit nodes,
                      16-bit SIDs, 48B.0-15T.V

        +-------------------+------+-----+---------+------+-------+
        | 16-bit            | CSID | CRH | CRH+TPF | VSID | UIDSR |
        +-------------------+------+-----+---------+------+-------+
        | PRS(48B.0T).V)    | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                   |      |     |         |      |       |
        | PRS(48B.1-4T).V)  | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                   | [1]  |CRH  | CRH [2] | SRH  | SRH   |
        |                   |      |     | TPF     |      |       |
        |                   |      |     |         |      |       |
        | PRS(48B.5-15T).V) | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                   | SRH  |CRH  | CRH [2] | SRH  | SRH   |
        |                   |      |     | TPF     |      |       |
        +-------------------+------+-----+---------+------+-------+

             Table 4: Headers parsed on decapsulating nodes,
                      16-bit SIDs, 48B.0-15T.V

        +------------------+------+-----+---------+------+-------+
        | 32-bit           | CSID | CRH | CRH+TPF | VSID | UIDSR |
        +------------------+------+-----+---------+------+-------+
        | PRS(48B.0T.V)    | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                  |      |     |         |      |       |
        | PRS(48B.1-15T.V) | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                  | SRH  |CRH  | CRH     | SRH  | SRH   |
        +------------------+------+-----+---------+------+-------+

             Table 5: Headers parsed on transit nodes,
                      32-bit SIDs, 48B.0-15T.V

        +------------------+------+-----+---------+------+-------+
        | 32-bit           | CSID | CRH | CRH+TPF | VSID | UIDSR |
        +------------------+------+-----+---------+------+-------+
        | PRS(48B.0T.V)    | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                  |      |     |         |      |       |
        | PRS(48B.1-15T.V) | IPv6 |IPv6 | IPv6    | IPv6 | IPv6  |
        |                  | SRH  |CRH  | CRH [2] | SRH  | SRH   |
        |                  |      |     | TPF     |      |       |
        +------------------+------+-----+---------+------+-------+

             Table 6: Headers parsed on decapsulating nodes,
                      32-bit SIDs, 48B.0-15T.V

   [1] It may be necessary to include and parse an SRH if flags,tags
       Or TLVs are required. It also may be necessary to include
       And parse an SRH if all locator blocks are not drawn from the
       Same /48

   [2] Parsing can terminate after the 32 bits because the value of
       Segments left is zero.

   Conclusion: Tables 3,4,5 and 6 represents the number of headers parsed for each proposal. Overall, the CSID
               Parses the fewest headers.

               While one proposal may parse a greater number of headers than another, the total work required
               may be less because the header contains fewer fields. Furthermore, the impact of headers and fields
               parsed varies by implementation. Also, parsing a header generally requires fewer resources than processing it

Old Text
------------
        +-------------------+------+-----+---------+------+-------+
        | 16-bit            | CSID | CRH | CRH+TPF | VSID | UIDSR |
        +-------------------+------+-----+---------+------+-------+
        | PRS(48B.0T).V)    | *1*  | *1* | *1*     | *1*  | *1*   |
        | PRS(48B.1-4T).V)  | *1*  | 2   | 2 or 3  | 2    | 2     |
        | PRS(48B.5-15T).V) | *2*  | *2* | 2 or 3  | *2*  | *2*   |
        |                   |      |     |         |      |       |
        +-------------------+------+-----+---------+------+-------+

             Table 3: Headers parsed, 16-bit SIDs, 48B.0-15T.V

        +------------------+------+-----+---------+------+-------+
        | 32-bit           | CSID | CRH | CRH+TPF | VSID | UIDSR |
        +------------------+------+-----+---------+------+-------+
        | PRS(48B.0T.V)    | *1*  | *1* | *1*     | *1*  | *1*   |
        | PRS(48B.1-15T.V) | *2*  | *2* | 2 or 3  | *2*  | *2*   |
        +------------------+------+-----+---------+------+-------+

             Table 4: Headers parsed, 32-bit SIDs, 48B.0-15T.V

   Conclusion: CSID requires less header parsing than other proposals.

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