Announcing ethernet link state changes via route socket

[Vlad GALU]

On 3/16/07, Hasso Tepper <hasso at estpak.ee> wrote:
Announcing link state changes to the userspace via route socket is critical
to get routing related applications to work correctly - routing protocols
are most important, but other applications might benefit from it as well.
This code is adapted from OpenBSD and is only the first basic step in path
to get correct support. Only em(4) is tested because I don't have hardware
to test others, although bge(4) might get my attention as well in the
future.
There is one fundamental problem I'd like to get feedback about from
developers - how to make various kernel stuff react on link state changes?
  There's been an IRC conversation recently regarding that. FreeBSD
defines a EVFILT_NETDEV filter, which can have one of the following
event bits set: NOTE_LINKUP, NOTE_LINKDOWN, NOTE_LINKINV. It's a quite
clean interface. I don't know why OpenBSD chose to do it diferently.
For example various interfaces which are somehow attached to the interface
(bridges, carp, vlans etc) should react. Ideally routing table should react
as well (yes, no BSD or Linux kernel does that yet, but they should).
Personally I like the idea of the hooks OpenBSD uses, but as I'm not very
familiar of DragonFlyBSD, my personal opinion might be very far from good
solution ;).
regards,

--
Hasso Tepper



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