>>> I still have the following comments: >>> >>> 1. Regarding the definition of “fixed IP address” in the draft: >>> >>> “- Fixed IP Address >>> This is what standard Mobile IP provides with a Home Address (HoA). >>> The mobile host is configures a HoA from a centrally-located Home >>> Network. Both IP session continuity and IP address reachability are >>> provided to the mobile host with the help of a router in the Home >>> Network (Home Agent, HA). This router acts as an anchor for the IP >>> address of the mobile host.” >>> >>> If this is equal to HoA, then RFC5014 already cover that. We do not >>> need to repeat it here with another name. >>> >> >> >> This is not equal to "HoA". >> This is equal to "HoA permanently allocated on a HA in the core network" [1] >> (as opposed to "HoA temporarily allocated on a HA in the access network") [2] > > So that's a HoA, and RFC5014 already covers that, right?
No. I tried to explain it below, that it's not just "HoA". [1] provides a fixed IP address, [2] provides a sustained IP address. That distinction is not captured when you call it "HoA". > >>> 2. Regarding the definition of “sustained IP address” in the draft: >>> >>> "- Sustained IP Address >>> >>> This type of IP address provides IP session continuity but not IP >>> address reachability. It is achieved by ensuring that the IP address >>> used at the beginning of the session remains usable despite the >>> movement of the mobile host. The IP address may change after the >>> termination of the IP session(s), therefore it does not exhibit >>> persistence. >>> " >>> There is no clear dividing line between fixed IP address and sustained >>> IP address. Whether the IP address is used for reachability is not >>> determined by the IP address itself. For example, even when the MN get >>> a HoA, after it moves to another location of the network, it may >>> decide to release current HoA and get another HoA, in this case the >>> "fixed IP address" becomes a "sustained IP address". >>> >> >> If the IP stack on the host releases the IP address, then of course it's >> not a "fixed IP address". >> Please see the definitions of these terms in the I-D. >> >> >>> Further more, the reachability normally is implemented by domain name >>> instead of IP address. For example, we reach “Google” by its domain >>> name, never by it’s server’s IP address. >>> >>> Using temporary private IP address we can also achieve the goal of >>> “reachability”. For example, using dynamic DNS, as shown in >>> http://hsk.oray.com/ , it can provide reachability even the host get >>> a private IP address. >>> >> >> You had said this before, and I had explained it. >> Nevertheless, let me recap: >> You cannot ensure an ongoing IP flow continues w/o interruption if you >> simply rely on dynamic DNS. Ongoing flows break even if you update the DNS. > > But Dapeng talks about reachability, not about session continuity. In that > sense he's right, no? (DNS updates ensure reachability upon address change). it's not "IP address" reachability. When the host releases its IP address, that IP address is no longer reachable. > > Even I would go as far as to say that _some_ application flows will resist to > changes in that IP address and get restarted with the new address if that DNS > update process was performed. > > This is because the concept of 'flow' is very much ambiguous. Very rarely a > read in packet dump can show 'flows' as we talk commonly about them in the > DMM discussions. It is for this reason that there is no option in Wireshark > that groups packets in 'flows', like a mail reader would group messages into > 'conversations' or 'threads'. > > It is for this reason too that firewall rules trying to be smart and identify > 'flows' before blocking them very often fail, even if we do Deep Packet > Inspection. People always find ways to 'drill' through these rules. > >> Furthermore, even if you ignore the ongoing flows, also note that DNS >> clients have a cache, hence a dynamic DNS update cannot be >> instantaneously reflected on the hosts. > > I can agree to that. I guess though there may be forced updates on these > caches, or that the timers can be configured shorter in domains supporting > mobility. Nope, not practical. You need to enforce that on all possible hosts that may be in comm. with the MN across the Internet. Can't do that. > >> So, you cannot provide full mobility solution by relying on dynamic DNS. > > We dont know what full mobility is, and DNS updates is a good tool to provide > reachability and session continuity, in some cases. > Full mobility is what you get out of Mobile IP. You cannot achieve the same effect using dynamic DNS. Alper > Alex > >> >> >>> 3. Regarding the definition of “nomadic IP address”: >>> >>> “- Nomadic IP Address >>> This type of IP address provides neither IP session continuity nor IP >>> address reachability. The IP address is obtained from the serving IP >>> gateway and it is not maintained across gateway changes. In other >>> words, the IP address may be released and replaced by a new IP >>> address when the IP gateway changes due to the movement of the mobile >>> host.” >>> >>> Seems this IP address is the IP address that we normally used in most >>> cases. If this is the case, why we need a new name for it? >>> >> >> >> If you don't name it, how would you refer to it in this context? >> >> >> Alper >> >> >>> >>> -- >>> Dapeng Liu >>> >>> 在 2015年3月25日 星期三，下午2:02，Alper Yegin 写道： >>> >>>> Hello Dapeng and Alex, >>>> >>>> I hope you had a chance to digest our responses to your comments and >>>> questions about the API work. >>>> If you have any remaining issues, please let us know over the email >>>> at your earliest convenience. >>>> It'd be good if you can articulate them in detail. >>>> >>>> >>>> Thanks. >>>> >>>> Alper >>> >> > > _______________________________________________ dmm mailing list [email protected] https://www.ietf.org/mailman/listinfo/dmm
