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Re: [lwip-users] Handling sudden disappearance of network i/f
From: |
Kieran Mansley |
Subject: |
Re: [lwip-users] Handling sudden disappearance of network i/f |
Date: |
Thu, 21 Sep 2006 08:49:30 +0100 |
On Wed, 2006-09-20 at 23:51 +0100, Clive Wilson wrote:
> If the serial link
> that LwIP's PPP layer depends upon suddenly disappears, then on this event
> I call pppSigHUP to inform PPP of the low-level link's absence. This in
> turn calls netif_remove as you mention. However, if a socket call such as
> read(), write() etc is made after the serial link dies, I don't see these
> calls returning with an error to indicate a timeout waiting for response.
OK, I understand your problem better now, but I'm afraid I'm not 100%
sure what the correct behaviour is in this case either. I just tried it
with linux by establishing an ssh connection across an ethernet
interface, then taking that interface down. The connection didn't
immediately terminate, and when I brought the interface back up, the
connection resumed where it had left off - the data I had tried to send
while the interface was down was then sent.
I think the connection would eventually time out (once the right number
of retransmission timeouts had passed without it getting a response, it
would give up).
So, looks like lwIP is doing approximately the right thing. Socket
calls aren't made aware that the physical network has gone away.
Kieran
- [lwip-users] Handling sudden disappearance of network i/f, clive, 2006/09/18
- Re: [lwip-users] Handling sudden disappearance of network i/f, Kieran Mansley, 2006/09/19
- Re: [lwip-users] Handling sudden disappearance of network i/f, Clive Wilson, 2006/09/20
- Re: [lwip-users] Handling sudden disappearance of network i/f,
Kieran Mansley <=
- [lwip-users] LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);, Mumtaz Ahmad, 2006/09/21
- Re: [lwip-users] LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);, Kieran Mansley, 2006/09/21
- Re: [lwip-users] LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);, Mumtaz Ahmad, 2006/09/22
- Re: [lwip-users] Handling sudden disappearance of network i/f, Pedro Alves, 2006/09/25
- Re: [lwip-users] Handling sudden disappearance of network i/f, Janusz U., 2006/09/25
- Re: [lwip-users] Handling sudden disappearance of network i/f, Kieran Mansley, 2006/09/25
- Re: [lwip-users] Handling sudden disappearance of network i/f, Janusz U., 2006/09/25
- Re: [lwip-users] Handling sudden disappearance of network i/f, Janusz U., 2006/09/25
- Re: [lwip-users] Handling sudden disappearance of network i/f, Kieran Mansley, 2006/09/25
- Re: [lwip-users] Handling sudden disappearance of network i/f, Janusz U., 2006/09/25