On Thu, 2005-17-11 at 22:03 -0500, jamal wrote:
>
> I will attempt some ascii art shortly. Actually if you agree with it
> please include it in your patch so it is easier for people to make
> changes in the future.
>
ok, ascii art is hard - instead in pseudo code (please double check with
the RFC); i am sure the states can be optimized, but here goes:
switch oper state
case NP:
- If !stacked goto DOWN else goto LLD
case LLD:
- If told to go to up
goto UP if at least one child is up and mode=default
generate netlink event
- If told to go to dormant and mode=dormant
goto dormant if at least one child is dormant
case DOWN:
// netlink event when transitioning to UP
- if told to transition to UP and mode default, goto UP
- if told to transition to UP and mode to dormant, goto to DORMANT
case DORMANT
- if told to transition to up
if stacked goto UP if at least one child is up
if !stacked goto UP
generate netlink event on transition to UP??
- if told to transition to DOWN
if !stacked goto LLD if no children are up or dormant
else goto DOWN
generate netlink event either going to LLD or DOWN
case UP
- if told to goto DOWN go there if !stacked
else goto LLD if all children are oper down
emit netlink event for above transitions
- if told to goto to DORMANT goto DORMANT
"told to" is something along the lines of netif_carrier_down/up etc
comments:
-> I think NP state is useless mostly - thats why i left it as
immediately transitioning without having to be told to do so. Perhaps
some USB netdevices may find use for it; in typical big chasis routers
it is used to indicate presence of a network device but absence of
hardware.
-> UP->DORMANT; i am not sure if that transition is needed.
-> I didnt show UNKNOWN state; it's the default bizare state
-> And the other important piece is stacking as well defined in section
3.1.14. A stacked interface can never just be down; it can only be LLD
instead (because it depends on oper states of its children). Suggestion:
we may need a IFF_flag for indicating something is stacked. When this
flag is set together with IFF_RUNNING it implies UP; else if IFF_RUNNING
is not set it implies it is LLD.
cheers,
jamal
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