[ECOS] BOOTP/DHCP delay question

[John Newlin]

Another possiblity, is some switches do checks for network loops when
a port comes active, and this can take a couple of seconds.



On Mon, 31 Jan 2005 23:26:18 +0100, Andrew Lunn <andrew@lunn.ch> wrote:
> On Mon, Jan 31, 2005 at 06:07:10PM +0100, Ilko Iliev wrote:
> > Hi,
> > I use BOOTP and DHCP to configure my target IP, in both cases this
> > process takes about 5 secs.
> > So the questions are:
> > 1. What is the purpose of this delay?
> > 2. Can this be made immediately, i.e. not waiting for a timeout?
> 
> Look at the packets being transfered. I've seen a few different things
> happen:
> 
> 1) The dhcp server allocates an IP address and then sends out an ARP
> for that address to see if anybody else is already using it. It then
> waits a couple of seconds to see if anybody replies to the ARP before
> giving the IP address to the dhcp client.
> 
> 2) The dhcp client code passes the first packet to the ethernet device
> before it is fully initialised. The ethernet device then drops the
> packet. Some time later the dhcp client does a retry which does make
> it out onto the wire.
> 
> It could be one of these is happening.
> 
>         Andrew
> 
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> 
>

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