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Re: [lwip-users] DHCP usage with latest git code version
From: |
Bram Peeters |
Subject: |
Re: [lwip-users] DHCP usage with latest git code version |
Date: |
Fri, 11 Sep 2015 09:10:28 +0000 |
Thanks for the clarification!
I had to add
#define LWIP_DHCP_CHECK_LINK_UP 1
as well to make
>netif_set_up(&gnetif);
>dhcp_start(&gnetif);
>Then DHCP will start if netif is already "link up" or at the next "link up"
>event.
work with the netif initially in link down
Otherwise the DCHP state was in DHCP_STATE_OFF mode, and stayed in that mode
when dhcp_network_changed(struct netif *netif) was called when link up occurred.
-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Sylvain Rochet
Sent: donderdag 10 september 2015 14:53
To: Mailing list for lwIP users
Subject: Re: [lwip-users] DHCP usage with latest git code version
Hi Bram,
On Thu, Sep 10, 2015 at 11:01:37AM +0000, Bram Peeters wrote:
> Hi,
>
> What is the recommended sequence to start DHCP with the latest git
> sources (anno 20150910) ? In the past dhcp_start() would automatically
> bring up the interface, and there is still a lot of references
> floating around to that way of working.
The behavior changed, an interface must be administratively up before starting
DHCP, which makes more sense than the previous behavior.
> So that note is wrong now because dhcp_start has an error on a down
> interface:
> if (netif_is_link_up(&gnetif))
> {
> /* When the netif is fully configured this function must be called */
> netif_set_up(&gnetif);
"netif link up" and "netif up" events are orthogonal properties,
coupling these events are wrong.
netif link up = hardware state, whether cable is plugged or unplugged
netif up = software administrative state, whether interface should be
used for routing or not
So, a interface must be administratively up before starting DHCP, so:
netif_set_up(&gnetif);
dhcp_start(&gnetif);
Then DHCP will start if netif is already "link up" or at the next "link
up" event.
If your port does not support link down/up events, you also need to call
netif_set_linkup() on your netif, but you'll lose the link status
signaling which makes DHCP fast.
Sylvain