Subject: [dhcwg] Query regarding DHCPREQUEST time windows

From: Soumava Das <[email-masked]>
Date: Wed, 21 Sep 2005 22:43:36 -0700

Hello Evrybody,

            I need clarifications regarding the time windows for the
DHCPREQUEST messages.

1.	DHCPREQUEST (from INIT_REBOOT state): The RFC says this message is
send by the client to verify a previously allocated, cached configuration.
So, can such a message be send after the lease period has expired (and the
client is aware of this fact)?

2.	DHCPREQUEST (from RENEWING state): Can such a message be send after
the expiry of the T2 time? Is it a RFC violation if the message is send
after the T2 expiry? It seems neither the Windows 2003 DHCP server or ISC
dhcpd really cares.

3.	DHCPREQUEST (from REBINDING state): Can such a message be send
before T2 expiry? RFC does not clarify this point. It only mentions that the
clients may extent or renew the lease before T1 expiry.

I would be grateful if someone can provide a clarification on the above
issues.

Regards,

Soumava

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From: Andre Kostur <[email-masked]>
Date: Thu, 22 Sep 2005 12:19:38 -0700

Soumava Das wrote:

>    1. DHCPREQUEST (from INIT_REBOOT state): The RFC says this message
>       is send by the client to verify a previously allocated, cached
>       configuration. So, *can such a message be send after the lease
>       period has expired* (and the client is aware of this fact)?
>
No.  INIT-REBOOT is for when the client "knows" that its lease is still 
valid, but wishes to verify.  If the client "knows" that its lease has 
expired, it should use a Discover.

>  
>
>    2. DHCPREQUEST (from RENEWING state): *Can such a message be send
>       after the expiry of the T2 time?* Is it a RFC violation if the
>       message is send after the T2 expiry? It seems neither the
>       Windows 2003 DHCP server or ISC dhcpd really cares.
>
I don't see why not.  Although it's really for the client's benefit that 
they change from unicast to broadcast at T2.  (OK, I'm assuming that 
you're asking about sending a unicast Request after T2...)

>  
>
>    3. DHCPREQUEST (from REBINDING state): *Can such a message be send
>       before T2 expiry?* RFC does not clarify this point. It only
>       mentions that the clients may extent or renew the lease before
>       T1 expiry.
>
I'm not sure which type of Request you're talking about in this one.  
Unicast or Broadcast?  In either case, I don't see why not.  It would 
probably be "rude" behaviour to ignore the T1/T2 sent by the server, but 
almost everything in DHCP is unsolicited anyway....