[Mip4] RE: Issue 3: Diameter MIP4 Application vs. RADIUS Architecture

["McCann Peter-A001034" <pete.mccann at motorola.com>]

Hi, Ahmad,

Ahmad Muhanna wrote:
>> If we can increase the timer so that 99% of the time the registration
>> completes (or fails) within the new timeout value, then we will have
>> the initial RRP back to the MN before it retransmits (or, in the case
>> of failure, the retransmission will be really necessary).  This seems
>> to solve the issue.  I don't think we should go re-architecting the
>> MIP4 Diameter application because of a mismatched timeout value.
> 
> [Ahmad]
> Ok, I think this is an important step. I think what you are trying to
> say is that you agree with the analysis that the draft presented and
> you are trying to propose solutions for the issue without any change
> to the Diameter Mobile IPv4 Application, RFC4004. Is that a fair
> statement?    

I agree that if the Diameter infrastructure takes too long to
respond to the MN before it retransmits, this would potentially
put a second, uneccessary AMR into the network, causing more
traffic.  The registration process itself would be delayed a
bit because the MN would be waiting for a response to its most
recently transmitted RRQ.  However, RFC3344 specifies an
exponentially increasing timeout value so eventually the MN
would get registered.

I think that summarizes the problem you raised; it could have
been sent to the list in that form rather than writing an
entire draft with call flows comparing RADIUS to Diameter.

I agree that a Diameter (or RADIUS, for that matter) infrastructure
might take more than 1 second to respond to an AMR or an Access-Request.
It seems that the solution is to recommend a longer timeout value
for the initial retransmission.  Another solution would be to allow
the MN to complete its registration successfully by receiving an
RRP matching a previous RRQ (not just the most recently retransmitted
one).

I don't think we should turn the MIP4 Diameter application into a
2-round-trips protocol.  The goal of RFC4004 is to provide MIP
registration in one round-trip.

-Pete


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