On Apr 1, 2014, at 7:48 AM, Rick Miller <vmil...@hostileadmin.com> wrote:
> On Mon, Mar 31, 2014 at 4:31 PM, Robert Huff <roberth...@rcn.com> wrote: > >> [Please keep me CC'd as I am not subscribed. Thanks.] >> >> I have a system, running r263263, where dhclient is misbehaving. >> (Yes - this is CURRENT, but I have no reason to believe this inherently a >> version-specific issue. I am also on current@, and nothing like this has >> been reported.) >> The system has an Intel Pro/1000 ethernet card, "em0", connected >> to a Arris CM820 cable modem. >> This is the relevant portion of dhclient.conf: >> >> http://users.rcn.com/dhclient.conf >> >> Upon execution, I get this: >> >> http://users.rcn.com/roberthuff/dhcp_offer > > > The conversation between a DHCP server and client consists of the initial > DHCP DISCOVER request from the client broadcasted to the network to which a > DHCP ACK is expected in reply from an available DHCP server. Upon receipt > of DHCP ACK, the client sends another DHCP DISCOVER to the server asking > for configuration information necessary to initialize networking. The > server's response is a DHCP OFFER containing all the information requested > by the client. > > I illustrate this in a sequence diagram describing a PXE workflow for > FreeBSD installation at > http://hostileadmin.com/images/FreeBSD_PXE_Install_Workflow.gif. The first > four steps in the sequence is the workflow's first DHCP conversation. The description of the DHCP packet flow is incorrect. DHCP packet flow is the following for clients requesting a new lease. Diagram below copied from RFC 2131. For clients renewing a lease, only the REQUEST and ACK steps are done. Server Client Server (not selected) (selected) v v v | | | | Begins initialization | | | | | _____________/|\____________ | |/DHCPDISCOVER | DHCPDISCOVER \| | | | Determines | Determines configuration | configuration | | | |\ | ____________/ | | \________ | /DHCPOFFER | | DHCPOFFER\ |/ | | \ | | | Collects replies | | \| | | Selects configuration | | | | | _____________/|\____________ | |/ DHCPREQUEST | DHCPREQUEST\ | | | | | | Commits configuration | | | | | _____________/| | |/ DHCPACK | | | | | Initialization complete | | | | . . . . . . | | | | Graceful shutdown | | | | | |\ ____________ | | | DHCPRELEASE \| | | | | | Discards lease | | | v v v Figure 3: Timeline diagram of messages exchanged between DHCP client and servers when allocating a new network address -- DaveD _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
