Hi Danny,
>From your cases specified as follows; "I am thinking of two places that might require an update: 1. When an application chooses not to specify a source address (but request a specific type) 2. When an application wishes to choose the source address from a provided list. " I don't understand the meaning of the second case. Why should an application wish to choose a source address from a list? What I have talked about was about allowing the default source address selection rules, which will be determined in the IP stack when an application is initiated with the destination address. I think we don't need to touch it. The point is an application will totally assign the default source address selection mechanism based on only type request but with no preference, or will request with the preference of a new Sustained IP address as well as type request. In the former case, if there is one or multiple Sustained IP addresses, the IP stack will try to pick up one. Or the IP stack will try to get a new one. In the latter case, the IP stack will consider a newly obtained Sustained IP address all the time, if the requested preference value is not less than other preferences defined in the default source address selection rules. The need of the proposed flag and main criteria to be considered were already covered with case studies in the draft. http://tools.ietf.org/html/draft-sijeon-dmm-use-cases-api-source-00 So, for productive discussion, I would like to suggest that you check our draft again please and bring your questions if there is something weird or should be updated with additional cases. Best Regards, Seil Jeon From: Moses, Danny [mailto:danny.mo...@intel.com] Sent: Sunday, April 12, 2015 1:49 PM To: Seil Jeon Cc: dmm@ietf.org Subject: RE: [DMM] Answer on raised questions for the proposed API You have a good point here. Now I understand the need for the flag you are proposing !!! We need to take a better look at RFC 6724 and figure out if we need to update it. I am thinking of two places that might require an update: 1. When an application chooses not to specify a source address (but request a specific type) 2. When an application wishes to choose the source address from a provided list. When the application indicates the desired address type, but chooses not to specify the source address (from a list provided by the IP stack), the stack should allocate a source IP address according to the address-type requested by the application. In this case, we should consider adding text to describe the behavior for Sustained IP addresses. Specifically, if there are several Sustained IP addresses allocated to the mobile host, whether to choose one of them, or to have the mobile host request a new one from the network (as a result of a mobility event - for example). When an application wishes to chooses the source address from the available list (obtained by getaddrinfo()), there are some alternative approaches we should consider: 1. Enhance getaddrinfo() enabling the application to specify the required address type, and return the list of source addresses that are of that type (Nomadic, Sustained, Fixed or DontCare), or - 2. Provide the list of addresses with an indication of their type (Nomadic, Sustained, Fixed or TypeUnknown) and an indication of whether each address is New (allocated after the last handoff event) or Old (allocated before the last handoff event) 3. Some other approach. The flag is need here, to enable the application to request a new IP address (if the returned list only contain 'Old' addresses) !!! I agree that we should discuss this. How about bringing it to the next 'Mobility Exposure and Selection WT' call? Regards, /Danny From: Seil Jeon [mailto:seilj...@av.it.pt] Sent: Sunday, April 05, 2015 17:08 To: Moses, Danny Cc: dmm@ietf.org Subject: RE: [DMM] Answer on raised questions for the proposed API Hi Danny, Meeting is always good, even with you by f-to-f. But in the discussion, the main issue is whether we will allow the default source address selection rules defined in RFC6724 for selecting a Sustained IP address among several ones or fundamentally block them for a specific reason raised by a DMM need. The latter approach is not reasonable no matter how I try to think of.it. If an application has the specific preference of a newly obtained Sustained IP address, it uses the proposed API. Regards. Seil From: Moses, Danny [mailto:danny.mo...@intel.com] Sent: Sunday, April 05, 2015 12:23 PM To: Seil Jeon Cc: dmm@ietf.org Subject: RE: [DMM] Answer on raised questions for the proposed API Hi Seil, By now we have been discussing this for quite some time and clearly we did not succeed in convincing each other. I suggest we try again when we have a chance to meet face to face. Meanwhile, let's listen to what other people have to say on this matter. Regards, /Danny From: Seil Jeon [mailto:seilj...@av.it.pt] Sent: Sunday, April 05, 2015 01:16 To: Moses, Danny Cc: dmm@ietf.org Subject: RE: [DMM] Answer on raised questions for the proposed API Resent. Seil From: Seil Jeon [mailto:seilj...@av.it.pt] Sent: Saturday, April 04, 2015 1:35 PM To: 'Moses, Danny' Cc: 'dmm@ietf.org' Subject: RE: [DMM] Answer on raised questions for the proposed API 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:danny.mo...@intel.com> mailto:danny.mo...@intel.com] Sent: Thursday, April 02, 2015 2:16 PM To: Seil Jeon Cc: <mailto:dmm@ietf.org> dmm@ietf.org 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:seilj...@av.it.pt> mailto:seilj...@av.it.pt] Sent: Tuesday, March 31, 2015 15:23 To: Moses, Danny Cc: <mailto:dmm@ietf.org> dmm@ietf.org Subject: RE: [DMM] Answer on raised questions for the proposed API Hi Danny, See the inline please. Seil Jeon From: Moses, Danny [ <mailto:danny.mo...@intel.com> mailto:danny.mo...@intel.com] Sent: Monday, March 30, 2015 4:44 PM To: Seil Jeon Cc: <mailto:dmm@ietf.org> dmm@ietf.org 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:seilj...@av.it.pt> mailto:seilj...@av.it.pt] Sent: Monday, March 30, 2015 17:08 To: Moses, Danny Cc: <mailto:dmm@ietf.org> dmm@ietf.org Subject: FW: [DMM] Answer on raised questions for the proposed API Hi Danny, Any comments? Regards, Seil Jeon From: dmm [ <mailto:dmm-boun...@ietf.org> mailto:dmm-boun...@ietf.org] On Behalf Of Seil Jeon Sent: Thursday, March 26, 2015 8:08 PM To: <mailto:dmm@ietf.org> dmm@ietf.org 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 --------------------------------------------------------------------- A member of the Intel Corporation group of companies This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies. --------------------------------------------------------------------- A member of the Intel Corporation group of companies This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. 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