RE: [lwip-users] using loopback

[Pettinato, Jim]

Your netif may not support loopback, but your driver hardware might...
many MAC/PHY chips do. If you can afford to miss incoming packets long
enough to change the chip's mode, issue your test packet, and return the
chip to normal operation that could be a potential solution.

-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf
Of Ben Bobbitt
Sent: Friday, June 06, 2008 11:35 AM
To: Mailing list for lwIP users
Cc: Mailing list for lwIP users
Subject: Re: [lwip-users] using loopback

Yes, It would be more accurate to say that I need to check that a thread
is running. It sounds like there is no current capability to use the
loopback to do that. The thread that I want to monitor this way will be
blocked on a netconn read call using a netif that is not a loopif type. 

Ben Bobbitt
ESR


On Jun 6, 2008, at 9:46 AM, "address@hidden" <address@hidden> wrote:

I don't think I fully understand what you want to achieve: do you want
to check if your an ethernet interface is up or if a thread is running?
If you want to check the ethernet interface, loopif.c won't help you
much: it is designed to be an additional lwip netif that passes packets
to/from 127.0.0.1. However, there is some work going on to get loopif
functionality into _all_ netifs, but that is not supported in 1.3.0 and
it might take a while until it is finished in CVS.

Simon

Ben Bobbitt schrieb:

I'm trying to use a loopback mechanism on a periodic basis as a way of
checking that an interface is still up and running. 

It appears that loopback capability is included in the loopif.c module
with the LWIP_HAVE_LOOPIF option in opt.h set... however,  I'm not clear
on how one would actually use that.  Does the netif that you want to
periodically test with a loopback message have to be initialized under a
new model?   

I'm using the netconn api, and I simply want to have another thread
periodically send a ping to the port that another thread is listening to
- but since it's a blocking read, I can't really test that the thread is
still up unless he receives data.  Hopefully that makes sense. 

Thanks.



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