Re: [netlmm] Consensus call: RFC5107 based DHCP message intercept at MAG

Hi Rajeev,
If the MAG does not intercept DHCP messages, it will be unaware of any DHCP state changes (e.g., lease termination, IP address change/release, etc.) for the MN.  We don't have mandatory defined behavior in the LMA to avoid such potential state changes.  So, short of using RFC5107, the MAG needs to intercept DHCP messages to figure this out. 

I also want to highlight the difference between using and not using RFC5107 behavior.  The use of RFC5107 will allow the MAG to do normal forwarding.  If not, the MAG will need to inspect on the {destination IP address, protocol, port} tuple to trap the DHCP packets destined to the server.  

Vidya

> -----Original Message-----
> From: netlmm-bounces@ietf.org [mailto:netlmm-bounces@ietf.org] On
> Behalf Of Koodli, Rajeev
> Sent: Thursday, April 09, 2009 10:51 PM
> To: netlmm@ietf.org
> Subject: Re: [netlmm] Consensus call: RFC5107 based DHCP message
> intercept at MAG
> 
> 
> Hi Vidya,
> 
> question for my clarification: why does the MAG need to intercept DHCP
> messages?
> 
> Thanks,
> 
> -Rajeev
> 
> 
> ________________________________
> 
> From: netlmm-bounces@ietf.org on behalf of Narayanan, Vidya
> Sent: Thu 4/9/2009 9:48 PM
> To: netlmm@ietf.org
> Subject: [netlmm] Consensus call: RFC5107 based DHCP message intercept
> at MAG
> 
> 
> 
> An issue has been raised on the inclusion of the DHCP Server Identifier
> Override sub-option (specified in RFC5107) as a means for the MAG to
> intercept the MN's DHCP messages sent to the DHCP server.  This option
> allows the relay (MAG) to act like the DHCP server and more directly
> get the MN to even address the RENEW DHCP requests to itself, so that
> the MAG can include the Relay Agent option in those messages as well.
> Without this option, the relay in the MAG would need to intercept all
> DHCP messages.
> 
> In PMIPv6, all packets from the MN will go through the MAG - from an
> implementation perspective, my interpretation is that the use of
> RFC5107 is likely to make a difference in the extent of hardware based
> forwarding that is made feasible in the MAG.  Otherwise, functionally,
> the MAG should be able to intercept all DHCP messages even without this
> option.
> 
> The issue raised is primarily from an IPR perspective - please see the
> following link for the IPR terms associated with RFC5107:
> 
> https://datatracker.ietf.org/ipr/124/
> 
> I would like to hear WG input on whether you prefer to keep the option
> in the document or take it out.  If you can provide an explanation for
> the choice you make (IPR and/or technical), it will be useful.
> 
> Please respond to the list by April 15th, 2009.
> 
> Thanks,
> Vidya <as co-chair>
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