On Wed, Dec 28, 2011 at 7:28 AM, TJ <trej...@gmail.com> wrote: > 2011/12/28 Masataka Ohta <mo...@necom830.hpcl.titech.ac.jp> > >> valdis.kletni...@vt.edu wrote: >> > > >> <SNIP> >> >> >> In this case, the following statement in RFC1883: >> >>> If the minimum time for rebooting the node is known (often more than >> >>> 6 seconds), >> >> is the wrong assumption which made RA annoying. >> > >> > Oddly enough, a lot of us are running on networks where assuming this >> about end >> > user gear is perfectly reasonable. >> >> That is because, as I wrote already in the previous mail, >> >> > Network configuration was mostly stationary >> >> For example, IPv6 might work well, if most of your end users >> are not moving rapidly between small mobile cells. >> >> However, assuming you change the cells every 100m in average >> and you are moving at 100km/h, you must change the cells every >> 3.6 seconds in average, which means you must be able to change >> the cells frequently, which means each cell change take a lot >> less than 3.6 seconds. >> > > To me, that sounds like an argument in favor of SLAAC. SLAAC is noticeably > faster in my experience than DHCP (v4 or v6). Also, RAs can be sent in the > ms range - for environments that expect that type of attachment-point-churn > ... > > Also: > Isn't 100m an arbitrarily tight range for a cel tower? > And for cellular, isn't the real churn happening more at the Layer2 side > ... no L3/IPv6/IPv4 interaction? > >
Correct. Cellular network mobility at the cell site level is all L1 and L2 magic. GSM / UTMS / LTE will never engage in SLAAC churn as a result of a normal mobility event. > >> > We haven't seen many consumer-grade >> > Windows, Macs, or Linux boxes that are able to reboot in much under 6 >> seconds. >> >> IPv6 is wrongly architected, not because it assumes nodes are >> able to reboot in much under 6 seconds, but because it assumes >> new configurations necessary only at boot time. >> > > Boot time, or anytime a change in network attachment point is detected ... > is that not sufficient? > > >> Yes, I know you can do it with careful tuning and throwing SSDs and other >> > hardware at it - doesn't mean it's common. >> >> Obviously, the IPv6 committee and you are assuming computers >> of immobile main frame computers or, at least, immobile >> workstations. >> >> However, in the real world, commonly available mobile phones >> are IP capable computers which wake up from dormant state >> within a second and needs handover often within a second. >> > > Again, if we are arguing about simple speed of address attainment - SLAAC > wins. > > > >> Masataka Ohta >> > > > /TJ
