Re: draft-ietf-rtgwg-segment-routing-ti-lfa Table 1 questions

["Francois Clad (fclad)" <[e-mail]>]

Hi Stewart,

Thank you for pointing that out.

The term circuits in the third column refers to bi-directional links. For the sake of clarity, we propose to replace it with “links” and multiply all values in the third column by 2.

It also appears that a glitch occurred when the link/node ratios were reported in this table 1.

Below is the updated table.

   +-------------+------------+------------+------------+------------+
   |   Network   |    Nodes   |    Links   |Link-to-Node| SRLG info? |
   |             |            |            |    Ratio   |            |
   +-------------+------------+------------+------------+------------+
   |    T1       |    408     |     1330   |    3.26    |    Yes     |
   +-------------+------------+------------+------------+------------+
   |    T2       |    587     |     2166   |    3.69    |     No     |
   +-------------+------------+------------+------------+------------+
   |    T3       |    93      |      802   |    8.62    |    Yes     |
   +-------------+------------+------------+------------+------------+
   |    T4       |    247     |      786   |    3.18    |    Yes     |
   +-------------+------------+------------+------------+------------+
   |    T5       |    34      |      192   |    5.65    |    Yes     |
   +-------------+------------+------------+------------+------------+
   |    T6       |    50      |      156   |    3.12    |     No     |
   +-------------+------------+------------+------------+------------+
   |    T7       |    82      |      586   |    7.15    |     No     |
   +-------------+------------+------------+------------+------------+
   |    T8       |    35      |      82    |    2.34    |    Yes     |
   +-------------+------------+------------+------------+------------+
   |    T9       |    177     |     2742   |    15.49   |    Yes     |
   +-------------+------------+------------+------------+------------+

Regards,
Francois

On 22/07/2019 12:00, "Stewart Bryant" <[e-mail]> wrote:

    I would like to understand what Table 1 in 
    draft-ietf-rtgwg-segment-routing-ti-lfa is telling us.
    
    It uses the terms links and circuits without distinguishing between the 
    two. I could speculate that a circuit is a group of links, but then the 
    ratio of nodes to circuits in T1 seems far too low at less than 1:1 in 
    network T1.
    
    Then the node to link ratio sounds quite high with fan outs of 84:1 in T2.
    
    Please could you explain what you mean by circuits and links in this table.
    
    What I would like to know is the average ratio of nodes to neighbours, 
    and the number of parallel links per neighbour.
    
    Best regards
    
    Stewart