[c-nsp] carving TCAM on Engine 3 linecards due to exhausted IPv6 TCAM regions

[Per Carlson]

Hi Jan.

> But if I look into TCAM usage I see no difference/improvement except as
> for the RX_IPv6_128 region:
>
> #execute-on slot 1 sh controllers frfab alpha tcam carve
> ========= Line Card (Slot 1) =========
> Id  Region  % Curr/Carve/Dflt   Mask Blocks       Masks
> Value Cells
>                                 Total/Used(%)     Total/Used(%)
> Total/Used(%)
> -----------------------------------------------------------------------------
> 7  RX_IPv6_128  10.13/14.00/ 4.00  830/4     0.48%  1660/8      0.48%
> 26560/128    0.48%
> 8  RX_IPv6_127   0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 9  RX_IPv6_126   0.03/ 0.00/ 0.00    3/3    100.00%     6/6     100.00%
>  96/96    100.00%
> 10 RX_IPv6_125   0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 11 RX_IPv6_124   0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 14 RX_IPv6_121   0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 28 RX_IPv6_107   0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 29 RX_IPv6_106   0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 55 RX_IPv6_80    0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 71 RX_IPv6_64    0.04/ 0.00/ 0.00    4/3    75.00%     8/7     87.50%
> 128/112   87.50%
> 79 RX_IPv6_56    0.01/ 0.00/ 0.00    1/1    100.00%     2/2     100.00%
>  32/32    100.00%
> 86 RX_IPv6_49    0.01/ 0.00/ 0.00    1/0     0.00%     2/1     50.00%
> 32/16    50.00%
> 87 RX_IPv6_48    0.96/ 0.00/ 0.00   79/77   97.46%   158/154   97.46%
> 2528/2464  97.46%
> 88 RX_IPv6_47    0.02/ 0.00/ 0.00    2/1    50.00%     4/3     75.00%
> 64/48    75.00%
> 89 RX_IPv6_46    0.02/ 0.00/ 0.00    2/2    100.00%     4/4     100.00%
>  64/64    100.00%
> 90 RX_IPv6_45    0.01/ 0.00/ 0.00    1/1    100.00%     2/2     100.00%
>  32/32    100.00%
> 91 RX_IPv6_44    0.03/ 0.00/ 0.00    3/3    100.00%     6/6     100.00%
>  96/96    100.00%

The 128 region holds all TCAM resources for all IPv6 prefix lengths.
Resources are automatically moved to other prefix lengths when needed.

>From the Bug-description (referenced before as well):

"For the purposes of IPv6 scalability, the RX_IPv6 regions are the
ones we're interested in. Initially, all IPV6 cells are placed into
the /128 region. As we add other mask lengths into the ipv6 routing
table, we will "move" blocks of the TCAM into a new region that
corresponds to the mask length for that prefix."


-- 
Pelle

RFC1925, truth 11:
 Every old idea will be proposed again with a different name and
 a different presentation, regardless of whether it works.