Hi Raj,
On Thu, 2006-08-10 at 15:45 -0500, Basavaraj Patil wrote: > Hello Pars, > > Response inline: > > > On 8/10/06 12:38 PM, "ext Pars MUTAF" <[EMAIL PROTECTED]> wrote: > > > Selon Basavaraj Patil <[EMAIL PROTECTED]>: > > > >> > >> Inline: > >> > >> > >> On 8/10/06 8:52 AM, "ext Pars Mutaf" <[EMAIL PROTECTED]> wrote: > >> > >>> > >>> Hello, > >>> > >>> I'm still trying to understand the problem :-) > >>> Unless I missed an episode, the context is > >>> connection-oriented cellular networks under IP > >>> (whatever that means) > >>> > >>> You say that the RA packets (unicasted) will wake up > >>> 90% of hosts in the subnet. Because roughly %90 of > >>> hosts are dormant, in general. > >>> > >>> I still believe that 30 minutes is longtime. Thus > >>> the problem is not energy consumption perhaps > >>> (without justification). > >> > >> 30 minutes is a long time. But if you have to go through the process of > >> waking a host to simply deliver an RA, which in most instances has no value > >> for the host, it is a waste of resources which include power, radio and > >> possibly causing congestion as well. > >> From a power consumption perspective: > >> The host will wake up when paged and have to establish a traffic channel > >> which requires it to request allocation of resources from the network. > >> There > >> is power that is consumed. Now if you argue that doing this every 30 > >> minutes > >> is not a problem...... I cant really argue against that. But my point is > >> that why do you need to do this every 30 minutes in networks where you know > >> that the host is not going to change the AR and the RA has no value to the > >> host. > >> > >>> > >>> But there is a problem if you link-layer page > >>> many many hosts simultaneously to deliver an > >>> RA. The paging channels may be saturated. From L2 > >>> perspective, this would be similar to a situation > >>> where many many cellular users are called > >>> simultaneously, resulting in call setup delays. > >>> Personally, I suspect that this may be a much more > >>> serious problem than energy consumption. > >> > >> True. Paging a large number of dormant hosts simultaneously will be a > >> serious issue for operators and people who do network planning don't like > >> such broadcasts. So I agree that congesting the paging channel may be a > >> more > >> serious concern than power consumed by the host. > >> Additionally you have to note that in order to deliver the RA you have to > >> establish a traffic channel in most cases. Establishing this for a large > >> number of hosts every 30 minutes just to deliver an RA is an overhead and > >> waste of resources. > >> > >>> > >>> But, firstly, your draft doesn't make it clear, > >>> and secondly, I couldn't see how your draft solved > >>> this problem. > >> > >> Solution is fairly simple as stated in the I-D: > >> 1. Transmission of periodic RAs should be optional - It is a configurable > >> parameter and the RA will indicate this to the host when it first attaches > >> or solicits an RA. > >> 2. Interval between periodic RAs should be flexible, i.e > 1800 secs. It is > >> up to the deployment to determine what is an optimal interval. 1800 secs is > >> just as random a value as 600 seconds or 5400 secs. > >> > >> And if a host needs an RA for some reason, it can always solicit it from > >> the > >> AR. > > > > > > > > This is the only point that needs clarification IMveryHO: > > > > Are the periodic RAs useless for those cellular hosts? > > Ignoring cellular hosts for a moment, how are periodic RAs useful for any > host? RAs can be used as a means for detecting network attachment status or > to detect movement (prefix change). In the case of a stationary host (as an > example), periodic RAs really are of no benefit to the host (IMO). > In certain cellular networks (GPRS/UMTS) the host does not change the AR > (GGSN) that it is attached to frequently. In such cases there is no benefit > of receiving the periodic RA. > > A cellular host such as a mobile phone does not need periodic Ras. However > any laptop can also be considered as a cellular host when it connects to the > cellular network. Hence you cannot generalize what a cellular host means. If > you agree that movement detection and network attachment are not of serious > concern in certain environments, what other reasons are there which makes > the reception of the periodic RA critical? I would see the periodic RAs as a heartbeat signaling. There may be other information as well, in the RA. But I don't know what the cellular operator wants! (I'm actually wondering if they know for sure what they want ;-) > > A periodic RA can periodically show me that the paging > > subsystem still works, for example. I can sleep better. > > You don't verify today at regular intervals if the paging subsystem works > and I am sure that is not causing any sleeplessness ;) > > So why would you worry about whether the system works or not? This is not > required. Not at the IP layer at least. Again, I don't know what the cellular operator wants. All I know is that IPv6 takes care of its hosts ;-) >From IP point of view, the following may make sense. In the context of this discussion, there are 3 different paths between a router and a host: 1. AR ---> MH when the mobile host is active 2. MH ---> AR when the mobile host is active 3. AR ---> MH when the mobile host is 'dormant' The state of the 3th type (i.e. up or down) can only be checked using periodic RAs. Or, I missed something. My two cents! pars > -Raj > > > > > This makes sense in your context? (I'm not a > > connection-oriented specialist). > > > > > > > >>> > >>> The real solution, imho, is to distribute the > >>> unicast RAs over time. For example, if there are > >>> 5 hosts in the subnet and the RA period is 5 minutes, > >> > >> Staggered tranmission of RAs is one solution. There are others as well. > > > > > > I'm curious what are the others? (if/when you have time) > > > > Thanks! > > pars > > > > > > > >> > >>> then > >>> > >>> start: > >>> Min1 - send the 1st RA > >>> Min2 - send the 2nd RA > >>> ... > >>> Min5 - send the 5th RA > >>> > >>> and goto start. > >>> > >>> This makes sense? Sorry if this is already specified > >>> somewhere. > >>> > >>> Otherwise, you may want to filter the RAs at > >>> the paging agent. > >> > >> Thanks for your comment. > >> > >> -Raj > >> > >>> > >>> pars > >>> > >>> > >>> > >> > >> > > > > > > > > > > ---------------------------------------------------------------- > > This message was sent using IMP, the Internet Messaging Program. > -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
