From: Stefano Salsano <stefano.salsano@uniroma2•it>
To: Stephen Hemminger <shemminger@vyatta•com>,
Sri Ram Vemulpali <sri.ram.gmu06@gmail•com>
Cc: linux-netdev <netdev@vger•kernel.org>
Subject: Re: Question on DHCP
Date: Wed, 13 Oct 2010 09:31:34 +0200 [thread overview]
Message-ID: <4CB56056.2040704@uniroma2.it> (raw)
In-Reply-To: <20101012184543.55ebf503@nehalam>
Stephen Hemminger wrote:
> On Tue, 12 Oct 2010 21:33:25 -0400
> Sri Ram Vemulpali <sri.ram.gmu06@gmail•com> wrote:
>
>> Hi All,
>>
>> I have very basic stupid doubt. Can anyone help to resolve this.
>>
>> DHCP, is used for dynamically configuring IP address, mask, MTU, DNS
>> domain, .... for a host. DHCP is a application layer protocol, but the
>> values it configures are related to IP layer. How come DHCP can
>> configure when its data packet in embedded in to IP datagram, which
>> are disparate layers. I am little confused. Please clarify. Thanks.
>>
>
> DHCP client uses UDP to send broadcast packet and find the nearest
> server. The Linux DHCP client ends up using a AF_PACKET socket because
> it wants to seem MAC address of server.
you may also want to refer to RFC 2131 (Dynamic Host Configuration
Protocol), in section 2 it states:
In the case of a client using DHCP for initial configuration (before
the client's TCP/IP software has been completely configured), DHCP
requires creative use of the client's TCP/IP software and liberal
interpretation of RFC 1122. The TCP/IP software SHOULD accept and
forward to the IP layer any IP packets delivered to the client's
hardware address before the IP address is configured;
--
*******************************************************************
Stefano Salsano
Dipartimento Ingegneria Elettronica
Universita' di Roma "Tor Vergata"
Via del Politecnico, 1 - 00133 Roma - ITALY
http://netgroup.uniroma2.it/Stefano_Salsano/
E-mail : stefano.salsano@uniroma2•it
Cell. : +39 320 4307310
Office : (Tel.) +39 06 72597770 (Fax.) +39 06 72597435
*******************************************************************
prev parent reply other threads:[~2010-10-13 7:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-13 1:33 Question on DHCP Sri Ram Vemulpali
2010-10-13 1:45 ` Stephen Hemminger
2010-10-13 7:31 ` Stefano Salsano [this message]
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