Hi Colin: I'd say that the backbone must be dimensioned to the needs, like any network.
For mission critical deployments, technologies like virtual switching system (VSS) provide high availability and aggregated bandwidth to scale to the needs. And you'll find that TRILL provides immense scaling properties, and that ND proxy make a lot of sense there. For all I know, edge routers can do TRILL on the back end. More below... >> Are you sure an Ethernet would support >> periodic NAs about the potentially very large number of nodes in the >> 6LoWPAN network? > >From RFC4861: > In such cases a node MAY send up to MAX_NEIGHBOR_ADVERTISEMENT > unsolicited Neighbor Advertisement messages to the all-nodes > multicast address. These advertisements MUST be separated by at > least RetransTimer seconds. > >Since they are a MAY we could just not transmit any. There probably isn't >any advantage to sending them, as I doubt ERs will store a large enough >table of previously received NAs, but just do a NS when they need to find >something. > >> Ethernet uses different cables from each machine, through a hub/switch, >> etc. which does scales. > >ND messages would be multicast anyway, so almost everyone would see them >through a switch. Hence I don't see the difference between 10000 computers >in a local subnet and 10000 sensor nodes in a local subnet. > >Assume we are at 10Mbits/second on Ethernet, through a hub so everything is >broadcast. > >NS is 24 bytes. Let's add some options to bring it up to 40 bytes. Add IPv6 >header for 80 bytes. Add Ethernet header for 96 bytes. Assume some overhead >for CRC, retransmission, sync, etc etc, let's say 2x overhead so I can't be >accused of underestimating: 192 bytes. 192 bytes = 1536 bits. > >10E6 / 1536 = 6510 NS messages/second. Yikes! Sure it's not a good estimate, >but it's so far above our requirements I don't see a need to get a better >estimate. > >I'm assuming the proper deployment for a extended LOWPAN network is to put >the entire LOWPAN behind a router. The only traffic to worry about is LOWPAN >traffic, which would pale in comparison to the traffic generated by even one >or two computers, with users watching YouTube and studiously downloading >copyrighted material. We do not need such assumptions. We need a proper network design with The backbone technology dimensioned to the needs. Also, we want and need a node to be able to move transparently within the LoWPAN. In particular the node might change its neighbors and even its edge router over time. So as you remarked, all the addresses should be globally unique across the domain defined by the subnet. Pascal _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
