Re: [DMM] Answer on raised questions for the proposed API

["Seil Jeon" <[e-mail]>]

Hi Danny,

 

See the inline please. I marked current replies with ">>" and previous
replies with ">" for you to catch them easily.

 

Regards,

Seil

 

 

From: Moses, Danny [ <mailto:[e-mail]>
mailto:[e-mail]] 
Sent: Thursday, April 02, 2015 2:16 PM
To: Seil Jeon
Cc:  <mailto:[e-mail]> [e-mail]
Subject: RE: [DMM] Answer on raised questions for the proposed API

 

Hi Seil,

 

Please see my replies (surrounded by  >>2) to yours.

 

Regards,

                /Danny

 

From: Seil Jeon [ <mailto:[e-mail]> mailto:[e-mail]] 
Sent: Tuesday, March 31, 2015 15:23
To: Moses, Danny
Cc:  <mailto:[e-mail]> [e-mail]
Subject: RE: [DMM] Answer on raised questions for the proposed API

 

Hi Danny,

 

See the inline please.

 

 

Seil Jeon 

 

 

From: Moses, Danny [ <mailto:[e-mail]>
mailto:[e-mail]] 
Sent: Monday, March 30, 2015 4:44 PM
To: Seil Jeon
Cc:  <mailto:[e-mail]> [e-mail]
Subject: RE: [DMM] Answer on raised questions for the proposed API

 

Hi Seil,

 

As to the potential of abuse:

Yes, I see your point and you are correct. If the IP stack will not request
a sustained IP address more than once after each movement to a new LAN (with
a different prefix), than there will be no abuse.

 

> Yes, it's true. Thanks for correction.

 

As to the second comment, please let me elaborate:

One potential implementation of the IP stack in the host, can be to request
a Nomadic IP address and a  Sustained IP address whenever connecting to a
network, and whenever moving to a new LAN, regardless if there are any
applications requesting any addresses. This way, whenever an application is
launched and requests either a Nomadic or Sustained IP address, the stack
can provide one without having to issue a request to the network. In this
case, there is no need for this flag from the application.

 

> Decision of which type of IP address by default will be depending on the
IP pool management policy by operators. You case may correspond to one of
them. What if only the Nomadic IP address is basically allocated upon a
network attachment? That is, a lot of applications require mere Internet
connectivity without session continuity support. So, the Sustained IP
address will be requested on demand, and the proposed flag will be used to
get a new Sustained IP address by expressing the explicit request by an
application.

 

>>2

As I mentioned at the beginning of the description - it is a description of
one alternative. I am not assuming it is the only scenario.

Yes, I agree that many apps require only Nomadic IP addresses, but in this
example, the IP stack in the host pre-allocates both Nomadic and Sustained
IP addresses upon attachment.

 

>> As I said, it could be, but not as general one. The proposed API is
useful through the explicit expression for any potential scenarios.

 

Yes, we can describe an alternative in which a Nomadic IP address is
pre-allocated upon NW connection (and after every movement to a new LAN) and
a Sustained (and/or Fixed) address is allocated on-demand. Even in such a
scenario, I do not see any use for this flag - see my reply to the second
item below.

>>2

 

>> My answer was already given in following answer in previous email.

 

Another potential implementation of the IP stack in the host is not to
request IP addresses in advance. In that case, it will issue a request for a
Nomadic IP address or a Sustained IP address the first time an application
requests one and use it for subsequent requests as long as it is not moving
to a different LAN. Once it moves, it will again request a new IP address
(Nomadic or Sustained - according to what is required) after receiving the
first request from any application. In this case as well, there is no need
for this flag.

 

> Another application requested just Sustained IP address while the IP stack
has already a Sustained IP address. Why should the IP stack try to get a new
one, though the application indicated simply "Sustained IP address type"?
You case took a step towards a solution where you want to draw. I don't
expect the action is generic when a Sustained IP address type is requested.

Besides, you assumption on IP address allocation seems not valid. A mobile
host would get an IP address whatever the allocated IP address type is when
it attaches at a network, regardless of an application's IP address request.

 

>>2 

Looks like I did not express myself well enough (and did not fully
understand your reply). Let me list some events that might help clarify.

 

Initial state: Mobile node is connected to a network; no Sustained IP
address is allocated. The IP stack sets a flag (SustainedIPAddressNeeded)
indicating that if an application requests a Sustained IP address, it will
have to request one from the network.

 

Event1: An application that requires a Sustained IP address is launched. 

APP action: App requests a Sustained IP address from the IP stack using the
proposed new API.

IP stack action: Since SustainedIPAddressNeeded is set, request one from the
network.

Network action: Assigned a Sustained IP address to the mobile node.

IP stack action: (1) Mark the new Sustained IP address as the one to be
associated to subsequent apps; (2) Reset SustainedIPAddressNeeded;
(3)Complete the API action and associate the marked Sustained IP address
with that port (app)

 

Event2: A new application that also required a Sustained IP address is
launched 

App action: App requests a Sustained IP address from the IP stack using the
proposed new API

IP Stack action: Since SustainedIPAddressNeeded  is not set, complete the
API action and associate the marked Sustained IP address with that port
(app)

 

Event3: The mobile node moves to a new LAN

IP Stack action: Set a flag indicating that the currently available
Sustained IP address is not optimized 

 

Event4: An application that requires a Sustained IP address is launched. 

APP action: App requests a Sustained IP address from the IP stack using the
proposed new API.

IP stack action: Since SustainedIPAddressNeeded is set, request one from the
network.

Network action: Assigned a Sustained IP address to the mobile node.

IP stack action: (1) Mark the new Sustained IP address as the one to be
associated to subsequent apps; (2) Reset SustainedIPAddressNeeded;
(3)Complete the API action and associate the marked Sustained IP address
with that port (app)

 

Note that the behavior of the IP stack in Event4 is exactly like the one in
Event1.

 

I believe that this event is the one we have different of opinions: I think
that the default behavior of the IP stack is to request a new Sustained IP
address since it moved to a new LAN, and you think that it should do so only
if the application specifically requests a new Sustained IP address via the
flag you are proposing.

>>2

 

>> You can see my answer at the lowest ">>" in this mail.

 

As a matter of fact, if such a flag is defined, I cannot think of an example
where it will not be used. It seems to me that applications will always
request a refreshed Sustained IP address (when requesting a Sustained IP
address). If this is correct, the flag is redundant.

 

> Some applications, e.g. email, that are not relatively restricted from
optimal routing would consider a Sustained IP address without issuing the
new flag. More applications based on such network characteristic can be
thought more than expected.

And such use of existing Sustained IP address is not extraordinary, since IP
address is a resource, even in the consideration of IPv6 deployment. If as
many as applications require new Sustained IP address, it will end up in a
lot of network resource consumption in the mobility routers where the
Sustained IP addresses are anchored as the terminal moves.

>>2

I am sorry but I disagree with the email example. I categorize it as an
example of an application that will request a Nomadic address since it does
not break when the mobile node moves to a new LAN and the source IP address
is changed. It simply restarts the socket and continue with the new source
IP address (the user will not even notice this).

 

>> The example was given as a benefit when the existing Sustained IP address
is used. You could get some insight from such kind of application not caring
much the routing distance even on the Sustained IP address.

 

I did not understand the other text regarding resource consumption. I
thought we agreed that even of a new Sustained IP address is requested upon
each movement to a new LAN, the effect on IP address allocation is not
significant. Otherwise, my initial comment on applications abusing the
network using your proposed flag, becomes valid again

>>2

 

>> No, our draft didn't say so. Our idea is that a new Sustained IP address
is requested upon receiving *new* flag from an application, as a preference
for a source address selection. You need to read our draft classifying the
categories of IP address request again.

 

Besides, I don't understand what is abused. Delivering its preference cannot
be abuse. Regarding "abuse", I see it in your default behavior you're
assuming here. In your scenario, a new app initiated in a new network will
be forced to use a newly obtained Sustained IP address. You see that? You
totally block the possibility to be considered by the default source address
selection rules defined in RFC6724. But in our draft, in case the need of a
newly obtained Sustained IP address is prioritized, the proposed *new* flag
can be used by app's request, thus it will be selected with priority.

 

Can you provide a scenario in which an application will not request to
refresh the Sustained IP address?

 

> It was mentioned in the former comments.

 

 

Regards,

                /Danny

From: Seil Jeon [ <mailto:[e-mail]> mailto:[e-mail]] 
Sent: Monday, March 30, 2015 17:08
To: Moses, Danny
Cc:  <mailto:[e-mail]> [e-mail]
Subject: FW: [DMM] Answer on raised questions for the proposed API

 

Hi Danny,

 

Any comments?

 

Regards,

Seil Jeon

 

 

From: dmm [ <mailto:[e-mail]> mailto:[e-mail]] On
Behalf Of Seil Jeon
Sent: Thursday, March 26, 2015 8:08 PM
To:  <mailto:[e-mail]> [e-mail]
Subject: [DMM] Answer on raised questions for the proposed API

 

Hi,

 

I could attend DMM Thursday meeting via MeetEcho.

I could also hear some raised comments by Danny and Someone. Here goes
answers to the raised questions.

 

 

First, regarding the need of the proposed API (IPV6_PREFER_SRC_NEW),

 

The use of the proposed API is suggested in the SUSTAINED IP address case in
the draft. On receiving this API with the SUSTAINED IP address type at the
IP stack, it will try to get a new SUSTAINED IP address if there is no
available in the currently attached access network. So, actual obtaining of
the IP address will be tried one time while attached at a specific access
network. Even some applications put this API after, the already obtained
SUSTAINED IP will be used. So, no worries about abuse.

 

Second question sounded to me like that this API is not needed because the
host can get a new SUSTAINED IP address, right?

If the question is right, I don't understand what the question is meant,
that is how the host can get a new SUSTAINED IP address?

Based on the definition of three types of IP address, an application should
show its requirement with an API among them. If it is the SUSTAINED IP
address, how do we expect the IP stack will try to get a new SUSTAINED IP
address?

 

Besides, the propsoed API is not used alone but with the three type APIs. 

 

 

 

Regards,

 

Seil Jeon

 

 

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