Subject: [dhcwg] rfc2131 clarifications for few statements

From: [email-masked]
Date: Sun, 17 Jul 2005 23:02:28 -0600

Hi Everyone,

I would highly appreciate if you could shed some light on the following issues:

In section 3.2 page 18 

'Servers with knowledge of the client's configuration parameters
respond with a DHCPACK message to the client.  Servers SHOULD NOT
check that the client's network address is already in use; the
client may respond to ICMP Echo Request messages at this point.'

- What is exactly meant by at this point ? Is it the point when the client is
waiting for the
  DHCPACK Message from the server after sending DHCPREQUEST ?

rfc states that DHCPINFORM message will be sent by the client when it has been
assigned a static IP address and wants to know other network parameters (like
default router, dns server etc ?).
But I could not find any implementation available (tried both Windows client and
dhclient) which does that ? Is there any other case where the client can send
DHCPINFORM message. Also that in section 4.4.3, page 39 it says 'The client then
unicasts the DHCPINFORM to the DHCP server if it
   knows the server's address, otherwise it broadcasts the message to
   the limited (all 1s) broadcast address'
Can I conclude that the client can come to know the server ip address only once
it transits to BOUND state but that would mean the address has not been
externally assigned to the client.

What exactly a DHCP server has to know before it is started so that it responds
to BOOTP Requests relayed through a relay agent. It seems from various server
configurations that the interfaces on which it should listen is determinded from
the IP Address pools configured on the server. So, is it ok if configure IP Pool
of an offnet address range (to which none of the server interfaces belong) and
then expect it to offer addresses from that range to DISCOVER when giaddr is not
zero and belonging to that particular offnet IP pool network.

thanks and regards,
Rohan Sen

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From: Ralph Droms <[email-masked]>
Date: Tue, 26 Jul 2005 06:37:50 -0400

>   DHCPACK Message from the server after sending DHCPREQUEST ?

Yes, at this point the client has sent and the server has received the
DHCPREQUEST message and the server is composing the DHCPACK message.  

> externally assigned to the client.

I think there are situations in which a Windows host will send a
DHCPINFORM message after an interface has been manually configured with
an IP address.  Also, a host could send a separate DHCPINFORM message on
behalf of a specific application after using DHCP to obtain a
dynamically assigned address.

> zero and belonging to that particular offnet IP pool network.

If I understand your question correctly, the DHCP server must be
configured so that it has a pool of available addresses for the various
subnets through which it may receive requests from clients.  That is, a
request from a host on a non-local subnet will be identified by the
value in giaddr; the DHCP server must have a pool of available addresses
for that identified subnet.

> Rohan Sen

- Ralph Droms