Re: Keeping unconfigured Ethernet powered on [was Re: Detecting ethernet cable plugged in]
Re: Keeping unconfigured Ethernet powered on [was Re: Detecting ethernet cable plugged in]
- Subject: Re: Keeping unconfigured Ethernet powered on [was Re: Detecting ethernet cable plugged in]
- From: Josh Graessley <email@hidden>
- Date: Tue, 02 Oct 2007 09:24:26 -0700
On Oct 2, 2007, at 9:11 AM, Peter Sichel wrote:
On 10/2/07, Josh Graessley wrote:
You may see no active link status if there are no services using the
interface. In this case, the interface may be powered down to save
power. When the interface is powered down, the link is down whether
or
not the cable is connected.
I have an interface filter NKE that does Ethernet bridging and have
noticed it is necessary to configure the second Ethernet with an IP
address, to ensure the Ethernet stays up even though I don't need
it for bridging.
Is there any way to indicate an Ethernet should remain powered on
when no higher level service defined in the SCF is using it?
If there's an interface filter NKE attached to a data link,
AND the Ethernet driver for that link is set to promiscuous mode,
it seems a bit presumptuous to shut it down since somebody
(like me) could still be using it.
It's been a while since I've been spelunking in that area so my memory
is a little fuzzy. It might be possible to attach a protocol to the
interface to keep the interface powered up. From inside of the kernel,
you could probably attach a protocol that doesn't specify any ethernet
descriptors so you would never receive any packets. From user space,
you could probably just open a PF_NDRV socket and bind it to the
interface you wanted to keep awake.
Disclaimer: Doing so will incur a power penalty so the battery on a
laptop may drain faster. Even on a machine plugged in to the wall,
every milliwatt counts. Extra energy adds heat. Living in California,
the power we can draw isn't limitless, so every bit we save keeps us
that much further from rolling blackouts.
-josh
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Macnetworkprog mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden