Subject: [Seamoby] CARD - FMIPv6 protocol interworking

From: Singh Ajoy-ASINGH1 <[email-masked]>
Date: Fri, 20 Dec 2002 10:35:43 -0600

Hello All,

The CARD design team would like to solicit WG consensus about CARD 
and FMIPv6 protocol inter-working.  The selection of anyone method 
from the proposed list would help us to focus in the right direction 
during the next phase of the protocol design. The high-level description
of the various approaches with their relative merits and de-merits is 
listed below:
 
Tight Coupling Approach 
Intermediate Approach
Loose Coupling Approach 

Tight Coupling Approach: In this case, we can define CARD signaling as 
an extension to the FMIPv6 messages. This makes the CARD protocol tightly
coupled with FMIv6 protocol. 

The following are the PROS and CONS of this approach:

PROS: Enables inter-working of CARD and FMIPv6. Probably this will make 
CARD and FMIPv6 implementation less complicated. 

CONS: This approach restricts the deployment of CARD to FMIpv6 only.  
This approach may also require modification to the present FMIPv6 protocol. 

Intermediate Approach: In this approach, we can define CARD signaling as 
generic ICMP options. These ICMP options can be piggybacked upon any ICMP 
message including FMIPv6 signaling messages. Additionally, we can also define 
new CARD ICMP messages, which can be used when no outgoing ICMP messages are 
pending. 

The following are the PROS and CONS of this approach:

PROS: This approach enables the deployment of CARD along with any protocol 
including FMIPv6.  This also provides opportunity for additional optimization 
when deployed with FMIPv6 by exploiting the possibility of piggybacking CARD 
signaling over the FMIPv6 messages. 
 
CONS: The CARD protocol will be slightly more complex compared to the other 
approaches.

Loose Coupling Approach: We can define CARD signaling as new set of messages 
and prohibit the possibility of piggybacking upon any FMIPv6 messages. 

The following are the PROS and CONS of this approach:

PROS:De-couples CARD from any other protocol including FMIPv6. Probably this
is simpler to implement. 
 
CONS: Adds extra over the air messages during critical path of handoff which 
may not be desirable for the most wireless link. 

Please send your choice if any.

Regards,
Ajoy
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From: "James Kempf" <[email-masked]>
Date: Fri, 20 Dec 2002 09:40:04 -0800

> CARD and FMIPv6 implementation less complicated.

I favor this approach, for router to mobile communication, at least.

> This approach may also require modification to the present FMIPv6 protocol.

I don't see why this should restrict CARD To FMIPv6. FMIPv6 defines some
additional ICMP messages. If the CARD messages are extensions too, the
difference between the loose approach and tight approach isn't so great in my
view. The new ICMP messages can be used with or without handover. Those designed
to be used with handover are FMIPv6, those designed to be used without are CARD.

There has been a discussion in the MIP group about whether the FMIPv6
prehandover signaling should be completely decoupled from handover, but the
discussion has not reached any clear conclusion. One issue is whether decoupling
the signaling would also decouple any signaling between the mobile's current
access router and other access routers (i.e. HI/HAck). If no signaling occurs
between access routers when the FMIPv6 signaling occurs (that is, it is for
information only), then that would be the equivalent of CARD. If signaling does
occur, perhaps to pre-configure a care of address on the new subnet, then it
would be different.

I think a more pressing issue for CARD is whether the same protocol can be used
to exchange CARD information between routers. The current FMIPv6 approach isn't
defined for this, and there are some good arguments why this should be done
using a reliable transport, such as SCTP or TCP, rather than UDP, which came up
during the CT discussion.

> CONS: The CARD protocol will be slightly more complex compared to the other

I am opposed to this. It seems the least clean of all the approaches, both
architecturally and implementationally.

> PROS:De-couples CARD from any other protocol including FMIPv6. Probably this

I'm not sure I follow why. While implementing the protocol might be easier,
since FMIPv6 will be the principle consumer, it might be more complicated to
integrate the two.

> may not be desirable for the most wireless link.

Again, why would this be so? The CARD information can be exchanged between the
AR and MN at any time prior to the handover.

BTW, I think that the Loose Coupling approach might be appropriate for the
inter-router exchange protocol, presuming we want to tackle that. However, I
believe we would need to look at alternatives, such as including CARD
information in the IGP (though that might be messy, given the IETF has three
"standard" IGPs).

            jak

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From: "James Kempf" <[email-masked]>
Date: Fri, 20 Dec 2002 09:40:04 -0800

jak

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From: Rajeev Koodli <[email-masked]>
Date: Fri, 20 Dec 2002 12:03:08 -0800

Ajoy,

for MN - AR signaling, it would be good to have ICMP options.
So, I guess that means "Intermediate Approach" without
necessarily endorsing all the associated PROS and CONS.

Regards,

-Rajeev

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From: Rajeev Koodli <[email-masked]>
Date: Fri, 20 Dec 2002 12:03:08 -0800

Ajoy,

Regards,

-Rajeev

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From: Rajeev Koodli <[email-masked]>
Date: Fri, 20 Dec 2002 12:13:12 -0800

Hello Jim,

> discussion has not reached any clear conclusion. One issue is whether decoupling

On the [mobile ip] mailing list, I saw many folks favoring this "advance signaling"

prior toAtlanta IETF. During the fmip presentation at Atlanta on this issue, I
didn't hear any objections. I am willing to say that this is recommended in the
spec,
while the MN MAY also do it during handover if it so wishes (please see the ATL
slides).

> occur, perhaps to pre-configure a care of address on the new subnet, then it

The implication is that HI/HAck would take place upon receiving FBU. It probably
does not make sense to create and manage handover state without knowledge of
when exactly the MN is undergoing handover (again, see the ATL slides).

Regards,

-Rajeev

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From: Rajeev Koodli <[email-masked]>
Date: Fri, 20 Dec 2002 12:13:12 -0800

Hello Jim,

Regards,

-Rajeev

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From: Pat Calhoun <[email-masked]>
Date: 20 Dec 2002 13:19:53 -0800

> while the MN MAY also do it during handover if it so wishes (please see the ATL

Nothing is agreed upon in meetings - we can just gage consensus. We have
to get agreement on the mailing list to get closure.

PatC

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From: Pat Calhoun <[email-masked]>
Date: 20 Dec 2002 13:19:53 -0800

PatC

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From: "James Kempf" <[email-masked]>
Date: Fri, 20 Dec 2002 14:00:10 -0800

I've moved the discussion to the MIP list, because it concerns how FMIPv6
signaling is done.

            jak

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From: "James Kempf" <[email-masked]>
Date: Fri, 20 Dec 2002 14:00:10 -0800

jak

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From: Rajeev Koodli <[email-masked]>
Date: Fri, 20 Dec 2002 18:20:12 -0800

> to get agreement on the mailing list to get closure.

Agreed. However, my suggested changes are based on the discussion on
[mobile ip] list prior to Atlanta meeting. [See thread on "Thoughts on Extending
Handover Capability Extension"]

-Rajeev

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From: Rajeev Koodli <[email-masked]>
Date: Fri, 20 Dec 2002 18:20:12 -0800

-Rajeev

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From: "Robert C. Chalmers" <[email-masked]>
Date: Sun, 22 Dec 2002 12:26:28 -0800 (PST)

I'm in favor of the intermediate approach. If Fast MIPv6 is available, it
makes sense to allow CARD content to be exchanged inline since the two
protocols do have some overlap in the AR-MN signalling, but I'd hate to
see CARD only applicable to Fast MIPv6.

> Please send your choice if any.

/****************************************************************

 Robert Chalmers
 UCSB Computer Science Doctoral Candidate
 Network and Multimedia Systems Lab (NMSL)

 "My heart is in the code, but my soul lies in the process"
 
 | [email-masked] || http://www.cs.ucsb.edu/~robertc/ |

*****************************************************************/

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From: "Robert C. Chalmers" <[email-masked]>
Date: Sun, 22 Dec 2002 12:26:28 -0800 (PST)

Robert Chalmers

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From: "Xiaoming Wang" <[email-masked]>
Date: Mon, 23 Dec 2002 14:55:39 +0900

I think the criterion of choice is whether CARD is big enough to be a
seperate one.
It decides the value of profit vs cost.

I'm in favor of the first one: Tight Coupling Approach
And the second one is also OK.

Xiaoming Wang
=========================================================
Network Protocol Technical Group, i-Networking lab
Samsung Advanced Institute of Technology, South Korea

Phone: 82-31-280-9615
Fax:      82-31-280-9569
EMail:   [email-masked]
=========================================================

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From: "Xiaoming Wang" <[email-masked]>
Date: Mon, 23 Dec 2002 14:55:39 +0900

Xiaoming Wang

Phone: 82-31-280-9615
Fax:      82-31-280-9569