Re: open 80211s on XO 1.5
On Fri, Oct 30, 2009 at 11:50 AM, Ed McNierney e...@laptop.org wrote: On Oct 30, 2009, at 3:32 PM, Sameer Verma wrote: scenarios of a handful of XOs in the under-a-tree model Sameer - Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet forwarding from node A to node B, where such nodes cannot normally communicate with one another directly. Packets are forwarded through node C, visible to both A and B, or through multiple such intermediate nodes. If A can communicate with B, mesh is neither helpful nor advisable. It just confuses things, which is the problem we see with large numbers of children in a classroom. The mesh efforts to keep track of how to get from A to B can quickly saturate the RF spectrum with a lot of unhelpful traffic. Hi Ed, I've given this some thought and have come up with this. Let me know if this makes sense. Its more like talking to myself, but it helps to voice it out. We have the TCP/IP layer model, somewhat modified, as follows. I've expanded the subnet layer to Data Link and Physical as in the OSI model for more detail: Application (5) Transport (4) Network (3) Data Link (2) Physical (1) A) The Sugar business and gabble/salut collaboration happens in the Application layer, oblivious to how the network is set up. In a network where clients are somehow visible to each other (same subnet, vLAN, etc.), we simply use salut, and if not, we use gabble via a Jabber/XMPP server, also at the Application layer. How the network layer handles addressing is something that Sugar and Telepathy do not care about. B) We could choose to use 802.3 (Ethernet) or 802.11a/b/g/n (Wi-Fi) and the collaboration would still work. For 802.3 (Ethernet), we would use a USB dongle. For 802.11a/b/g/n (Wi-Fi) we would use an appropriate Wireless Access Point. These would network using a star topology at the Physical layer. We typically use DHCP and DNS for this setup, where DHCP and DNS servers run on the AP or on the school server. http://en.wikipedia.org/wiki/Network_topology#Star With XO-1, the radio would also use 802.11s in mesh topology and in combination with link local IP addresses and mDNS, where the volume of mDNS traffic would drown the real traffic as the number of nodes increase. http://en.wikipedia.org/wiki/Mesh_networking In the Under a tree model, we want a small number of XOs to somehow connect at layer 2 and address each other at layer 3. What you are saying is that 802.11s is not the only way to achieve this because ad-hoc 802.11a/b/g/n will allow for one hop visibility, and in the under a tree model, we really won't be seeing two hops, and hence don't need any hopping at layer 2 (802.11s). So, if the extent of hopping is 1 hop, and we still use link local for IP addressing, and as long as the Sugar guys can solve the issue of icons and picking an ad-hoc name easily, we can achieve under a tree collaboration with ad-hoc at layer 2. If all this is correct, then my interest, which was in seeing if the Marvell chip will do open80211s, was only to see if open80211s could be enabled some time in the future (even if it is only to showcase something cool). cheers, Sameer -- Dr. Sameer Verma, Ph.D. Associate Professor, Information Systems Director, Center for Business Solutions San Francisco State University http://verma.sfsu.edu/ http://cbs.sfsu.edu/ http://is.sfsu.edu/ I can't tell what it is you're doing at your meetings when your users all use mesh. At a typical in-person meeting, you have a number of people using XOs all in the same room. Any XO in the room can communicate over WiFi directly with every other machine in the room (except in extremely unusual circumstances, or too many attendees wearing their tinfoil hats). There's no need for or value to mesh network - A doesn't need C to forward packets to B because A can see B directly as another ad hoc node. If there's an AP providing routing to the Internet or other external networks, there's no mesh required there, either, presuming that each XO can communicate with the AP directly. I can't answer your question about whether those scenarios use ad hoc networking because I don't quite see what it is the users are doing in those scenarios. What (lowercase) activity are users engaged in when you say they all use mesh? What do you think they would be unable to do if they all stopped using mesh? Thanks for the info. - Ed ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Fri, Oct 30, 2009 at 8:50 PM, Ed McNierney e...@laptop.org wrote: Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet You guys are both right. At the SF meetings, if you have a bunch of XOs + an Active Antenna, you are using a combination of - 802.11s - Telepathy-based collaboration, using either Gabble (via ejabberd) or Salut (without XS) Now, in a small place, all machines can hear eachother's signals, so while you are using 802.11s, you are not enjoying any of its benefits. (And given what we know about 802.11s, you probably have less bandwidth to use, just because you are using 802.11s. Or, to put it another way, you'll have a saturated wifi with a small number of XOs, where 802.11g can handle more XOs.) Taking advantage of 802.11s not hard, but it doesn't happen often. You just have to have a few XOs far enough from the AA that they need to do routing. It works. (Of course, it doesn't work if you've saturated the spectrum.) Our XO-1s using 8.2.1 never actually use ad hoc. The driver reports it as such, but it's not ad hoc. Now, if you are all close enough, it's almost the same as using ad hoc mode. m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Mon, Nov 2, 2009 at 17:40, Martin Langhoff martin.langh...@gmail.com wrote: On Fri, Oct 30, 2009 at 8:50 PM, Ed McNierney e...@laptop.org wrote: Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet You guys are both right. At the SF meetings, if you have a bunch of XOs + an Active Antenna, you are using a combination of - 802.11s - Telepathy-based collaboration, using either Gabble (via ejabberd) or Salut (without XS) Also, I think using salut is much worst in the mesh case than gabble? Regards, Tomeu Now, in a small place, all machines can hear eachother's signals, so while you are using 802.11s, you are not enjoying any of its benefits. (And given what we know about 802.11s, you probably have less bandwidth to use, just because you are using 802.11s. Or, to put it another way, you'll have a saturated wifi with a small number of XOs, where 802.11g can handle more XOs.) Taking advantage of 802.11s not hard, but it doesn't happen often. You just have to have a few XOs far enough from the AA that they need to do routing. It works. (Of course, it doesn't work if you've saturated the spectrum.) Our XO-1s using 8.2.1 never actually use ad hoc. The driver reports it as such, but it's not ad hoc. Now, if you are all close enough, it's almost the same as using ad hoc mode. m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel -- «Sugar Labs is anyone who participates in improving and using Sugar. What Sugar Labs does is determined by the participants.» - David Farning ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Mon, Nov 2, 2009 at 6:26 PM, Sameer Verma sve...@sfsu.edu wrote: A) The Sugar business and gabble/salut collaboration happens in the Correct. B) We could choose to use 802.3 (Ethernet) or 802.11a/b/g/n (...) Correct again. There are 2 things at work - We are trying to make the under a tree user experience just work by using ad hoc instead of 802.11s, which has given us more pain than useful outcomes. Not entirely trivial, but doable. - We are trying to separate the concept of mesh (802.11s) from collaboration (telepathy, etc). Both concepts are mixed up in our communications, docs, etc. If all this is correct, then my interest, which was in seeing if the Marvell chip will do open80211s, was only to see if open80211s could be enabled some time in the future (even if it is only to showcase something cool). Yes. As you describe, we're sidestepping 802.11s, preferring a simpler approach based on ad-hoc networking for under a tree, and traditional 802.11a/b/g in spots where an AP is available. And we're encouraging people to tinker with alternative implementations -- such as open80211s -- but it's not in our roadmap. In terms of making it work, I see open80211s needs devices that have a 'mac80211' driver. I don't fully understand the softmac/hardmac/fullmac nomenclature, but we do have a softmac driver for our old libertas device. It was written against an older kernel -- may need a bit of TLC -- see http://wiki.laptop.org/go/Libertas_Thinfirmware_HOWTO . For the Libertas device on the XO-1.5, I do lobby for a similar softmac driver (to run it as a hostap device). But my influence is limited there -- the hot thing is the XO itself, not the XS ;-) cheers, m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Mon, Nov 2, 2009 at 6:50 PM, Tomeu Vizoso to...@sugarlabs.org wrote: Also, I think using salut is much worst in the mesh case than gabble? I suspect so, but I have never measured it (or seen it measured). m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Mon, Nov 2, 2009 at 18:02, Martin Langhoff martin.langh...@gmail.com wrote: On Mon, Nov 2, 2009 at 6:50 PM, Tomeu Vizoso to...@sugarlabs.org wrote: Also, I think using salut is much worst in the mesh case than gabble? I suspect so, but I have never measured it (or seen it measured). Sorry to be speaking from memory, but I think that it was mdns' use of multicast that caused the spectrum use go through the roof. I wouldn't expect that from gabble. Regards, Tomeu m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff -- «Sugar Labs is anyone who participates in improving and using Sugar. What Sugar Labs does is determined by the participants.» - David Farning ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Mon, Nov 2, 2009 at 8:02 PM, Tomeu Vizoso to...@sugarlabs.org wrote: On Mon, Nov 2, 2009 at 18:02, Martin Langhoff martin.langh...@gmail.com wrote: On Mon, Nov 2, 2009 at 6:50 PM, Tomeu Vizoso to...@sugarlabs.org wrote: Also, I think using salut is much worst in the mesh case than gabble? I suspect so, but I have never measured it (or seen it measured). Sorry to be speaking from memory, but I think that it was mdns' use of multicast that caused the spectrum use go through the roof. I wouldn't expect that from gabble. That'd make sense. If Salut uses mdns, that means that even on 802.11a/b/g it will saturate RF easily. Not as bad as on 802.11s, but still... m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
open 80211s on XO 1.5
On a whim, I posted to the open 80211s list to see if the wireless card on the XO1.5B2 will support open 80211s. Here's the thread. http://open80211s.com/pipermail/devel/2009-October/000368.html I must admit that my understanding of open 80211s is fairly limited, but I was hoping that the wireless card in the 1.5 could support open80211s to allow for meshing a la XO1. cheers, Sameer ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
Hi, Sameer ! Are you sure open802.11s can be made to support to the Marvell chipsets ? In any case, open802.11s implementation is certainly incompatible with the standard OLPC 802.11s driver, since they implemented different versions of the draft. It is interesting to read that Mesh networking is exceptionally difficult to use properly on an XO-1, and I'm not aware of any real-world installations of it., as Ed told us. All the best, hilton On Friday 30 October 2009 16:38:28 Ed McNierney wrote: On Oct 30, 2009, at 2:21 PM, Sameer Verma wrote: to allow for meshing a la XO1 Sameer - Are you in fact using 802.11s mesh networking on XO-1 machines? Or are you rather using ad-hoc networking and collaboration features? Mesh networking is exceptionally difficult to use properly on an XO-1, and I'm not aware of any real-world installations of it. - Ed ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel -- Hilton Garcia Fernandes Nucleo de Tecnologias sem Fio (NTSF) -- Wireless Technologies Team Lab de Sistemas Integraveis Tecnologico (LSI) -- Integrable Systems Lab Escola Politecnica (Poli) -- Engineering School Univ S Paulo (USP) Tel: (5511)3091-5311 (work) (5511)8131-5213 (mobile) Av. Prof. Luciano Gualberto,158 trav.3 CEP 05508-010 S. Paulo -- SP -- Brazil Pagina inicial: http://www.lsi.usp.br/~hgfernan ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Fri, Oct 30, 2009 at 11:38 AM, Ed McNierney e...@laptop.org wrote: On Oct 30, 2009, at 2:21 PM, Sameer Verma wrote: to allow for meshing a la XO1 Sameer - Are you in fact using 802.11s mesh networking on XO-1 machines? Or are you rather using ad-hoc networking and collaboration features? Mesh networking is exceptionally difficult to use properly on an XO-1, and I'm not aware of any real-world installations of it. - Ed Hi Ed, When we have meetings at OLPC-SF the XO-1 that people bring to the meetings (anywhere from 5 to 30+ machines) all use mesh (draft 80211s at layer 2, as far as I can tell). We also usually have a school server running on a XO1 (via SD card), which I believe is also using draft 80211s mesh. I do have a prototype mesh antenna, which when plugged into a (non-XO based) schoolserver provides a mesh node (draft 80211s). This is based on my impression and understanding of things. I don't think any of the above mentioned scenarios use ad-hoc mode. Is this correct? Real world scenarios will involve schools of several hundred XOs, but should also include scenarios of a handful of XOs in the under-a-tree model. The collaboration aspect is further up the layers, so I understand that it will be oblivious to how the network or data link layer creates the p2p network. My goal in posting to the 80211s list was to see if the current radio would possibly support open80211s at some point. cheers, Sameer -- Dr. Sameer Verma, Ph.D. Associate Professor, Information Systems Director, Center for Business Solutions San Francisco State University http://verma.sfsu.edu/ http://cbs.sfsu.edu/ http://is.sfsu.edu/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
On Oct 30, 2009, at 3:32 PM, Sameer Verma wrote: scenarios of a handful of XOs in the under-a-tree model Sameer - Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet forwarding from node A to node B, where such nodes cannot normally communicate with one another directly. Packets are forwarded through node C, visible to both A and B, or through multiple such intermediate nodes. If A can communicate with B, mesh is neither helpful nor advisable. It just confuses things, which is the problem we see with large numbers of children in a classroom. The mesh efforts to keep track of how to get from A to B can quickly saturate the RF spectrum with a lot of unhelpful traffic. I can't tell what it is you're doing at your meetings when your users all use mesh. At a typical in-person meeting, you have a number of people using XOs all in the same room. Any XO in the room can communicate over WiFi directly with every other machine in the room (except in extremely unusual circumstances, or too many attendees wearing their tinfoil hats). There's no need for or value to mesh network - A doesn't need C to forward packets to B because A can see B directly as another ad hoc node. If there's an AP providing routing to the Internet or other external networks, there's no mesh required there, either, presuming that each XO can communicate with the AP directly. I can't answer your question about whether those scenarios use ad hoc networking because I don't quite see what it is the users are doing in those scenarios. What (lowercase) activity are users engaged in when you say they all use mesh? What do you think they would be unable to do if they all stopped using mesh? Thanks for the info. - Ed ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
I'd said to lots of people that the XO uses 802.11s mesh networking and eventually ran into someone rather geekie and otherwise impressively knowledgeable who corrected me that they didn't implement the whole standard (and people here say draft). The Marvel driver is said to be closed source, and RMS didn't like that, all of course rumor, and another rumor that the driver was open sourced. No rumors on the XO-1.5 yet, which is a shame. Even as hype and pre-release getting a buzz going would be nice. I don't have one, so can't test it to find out. Computer are supposed to be a Science, or so Knuth is credited by the ACM for helping to make that happen, documenting the fundamental algorithms and all... There are other mesh networking and someone once said to me that the 802.11s isn't that special that mesh OLR or somesuch protocols have been around for some time, but I'm guessing the XO is one of the bigger (~1 million XOs out there somewhere) publicly known implementations in that arena. So if someone / laptop.org wants to set the record straight and give definitive info, that would be great... On Fri, Oct 30, 2009 at 3:50 PM, Ed McNierney e...@laptop.org wrote: On Oct 30, 2009, at 3:32 PM, Sameer Verma wrote: scenarios of a handful of XOs in the under-a-tree model Sameer - Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet forwarding from node A to node B, where such nodes cannot normally communicate with one another directly. Packets are forwarded through node C, visible to both A and B, or through multiple such intermediate nodes. If A can communicate with B, mesh is neither helpful nor advisable. It just confuses things, which is the problem we see with large numbers of children in a classroom. The mesh efforts to keep track of how to get from A to B can quickly saturate the RF spectrum with a lot of unhelpful traffic. I can't tell what it is you're doing at your meetings when your users all use mesh. At a typical in-person meeting, you have a number of people using XOs all in the same room. Any XO in the room can communicate over WiFi directly with every other machine in the room (except in extremely unusual circumstances, or too many attendees wearing their tinfoil hats). There's no need for or value to mesh network - A doesn't need C to forward packets to B because A can see B directly as another ad hoc node. If there's an AP providing routing to the Internet or other external networks, there's no mesh required there, either, presuming that each XO can communicate with the AP directly. I can't answer your question about whether those scenarios use ad hoc networking because I don't quite see what it is the users are doing in those scenarios. What (lowercase) activity are users engaged in when you say they all use mesh? What do you think they would be unable to do if they all stopped using mesh? Thanks for the info. - Ed ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel -- DancesWithCars leave the wolves behind ;-) ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
I can't quite understand the desire for definitive info combined with your disappointment that you don't have 1.5 rumors. I don't think we need rumors, and I and many other folks have been providing definitive info about 1.5 for some time. And about the mesh, etc. You don't say what topic it is on which you want the record set straight - if you need info, just ask. http://wiki.laptop.org/go/XO-1.5 http://wiki.laptop.org/go/Mesh_Network_Details - Ed P.S. The 802.11s draft standard has certainly been implemented on other devices; no one suggests it is unique to the XO-1. What is special about the XO-1, AFAIK, is its ability to continue to operate as a mesh node (or MPP, mesh portal point) and forward packets while the laptop is otherwise shut down. The fundamental limitations on the utility of 802.11s in typical XO-1 scenarios, however, limit the value of this unique (I think) laptop feature. On Oct 30, 2009, at 4:12 PM, DancesWithCars wrote: I'd said to lots of people that the XO uses 802.11s mesh networking and eventually ran into someone rather geekie and otherwise impressively knowledgeable who corrected me that they didn't implement the whole standard (and people here say draft). The Marvel driver is said to be closed source, and RMS didn't like that, all of course rumor, and another rumor that the driver was open sourced. No rumors on the XO-1.5 yet, which is a shame. Even as hype and pre-release getting a buzz going would be nice. I don't have one, so can't test it to find out. Computer are supposed to be a Science, or so Knuth is credited by the ACM for helping to make that happen, documenting the fundamental algorithms and all... There are other mesh networking and someone once said to me that the 802.11s isn't that special that mesh OLR or somesuch protocols have been around for some time, but I'm guessing the XO is one of the bigger (~1 million XOs out there somewhere) publicly known implementations in that arena. So if someone / laptop.org wants to set the record straight and give definitive info, that would be great... On Fri, Oct 30, 2009 at 3:50 PM, Ed McNierney e...@laptop.org wrote: On Oct 30, 2009, at 3:32 PM, Sameer Verma wrote: scenarios of a handful of XOs in the under-a-tree model Sameer - Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet forwarding from node A to node B, where such nodes cannot normally communicate with one another directly. Packets are forwarded through node C, visible to both A and B, or through multiple such intermediate nodes. If A can communicate with B, mesh is neither helpful nor advisable. It just confuses things, which is the problem we see with large numbers of children in a classroom. The mesh efforts to keep track of how to get from A to B can quickly saturate the RF spectrum with a lot of unhelpful traffic. I can't tell what it is you're doing at your meetings when your users all use mesh. At a typical in-person meeting, you have a number of people using XOs all in the same room. Any XO in the room can communicate over WiFi directly with every other machine in the room (except in extremely unusual circumstances, or too many attendees wearing their tinfoil hats). There's no need for or value to mesh network - A doesn't need C to forward packets to B because A can see B directly as another ad hoc node. If there's an AP providing routing to the Internet or other external networks, there's no mesh required there, either, presuming that each XO can communicate with the AP directly. I can't answer your question about whether those scenarios use ad hoc networking because I don't quite see what it is the users are doing in those scenarios. What (lowercase) activity are users engaged in when you say they all use mesh? What do you think they would be unable to do if they all stopped using mesh? Thanks for the info. - Ed ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel -- DancesWithCars leave the wolves behind ;-) ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: open 80211s on XO 1.5
Thank you. And yes I'm conflicted. Your summary and experience give a good overview and I'll point people to the wiki.laptop.org if they need more info. Re: the XO 1.5 mesh implementation, compatibility with other XO 1.0 and an open source driver would be nice. Not that I plan on hacking it, as I'm not nearly that good, just sometimes around people who are rather good, and don't want to pass along bad info, if I can help it. On Fri, Oct 30, 2009 at 4:23 PM, Ed McNierney e...@laptop.org wrote: I can't quite understand the desire for definitive info combined with your disappointment that you don't have 1.5 rumors. I don't think we need rumors, and I and many other folks have been providing definitive info about 1.5 for some time. And about the mesh, etc. You don't say what topic it is on which you want the record set straight - if you need info, just ask. http://wiki.laptop.org/go/XO-1.5 http://wiki.laptop.org/go/Mesh_Network_Details - Ed P.S. The 802.11s draft standard has certainly been implemented on other devices; no one suggests it is unique to the XO-1. What is special about the XO-1, AFAIK, is its ability to continue to operate as a mesh node (or MPP, mesh portal point) and forward packets while the laptop is otherwise shut down. The fundamental limitations on the utility of 802.11s in typical XO-1 scenarios, however, limit the value of this unique (I think) laptop feature. On Oct 30, 2009, at 4:12 PM, DancesWithCars wrote: I'd said to lots of people that the XO uses 802.11s mesh networking and eventually ran into someone rather geekie and otherwise impressively knowledgeable who corrected me that they didn't implement the whole standard (and people here say draft). The Marvel driver is said to be closed source, and RMS didn't like that, all of course rumor, and another rumor that the driver was open sourced. No rumors on the XO-1.5 yet, which is a shame. Even as hype and pre-release getting a buzz going would be nice. I don't have one, so can't test it to find out. Computer are supposed to be a Science, or so Knuth is credited by the ACM for helping to make that happen, documenting the fundamental algorithms and all... There are other mesh networking and someone once said to me that the 802.11s isn't that special that mesh OLR or somesuch protocols have been around for some time, but I'm guessing the XO is one of the bigger (~1 million XOs out there somewhere) publicly known implementations in that arena. So if someone / laptop.org wants to set the record straight and give definitive info, that would be great... On Fri, Oct 30, 2009 at 3:50 PM, Ed McNierney e...@laptop.org wrote: On Oct 30, 2009, at 3:32 PM, Sameer Verma wrote: scenarios of a handful of XOs in the under-a-tree model Sameer - Under a tree, using mesh networking is pointless (unless, I suppose, it is an extraordinarily large tree). Mesh networking allows packet forwarding from node A to node B, where such nodes cannot normally communicate with one another directly. Packets are forwarded through node C, visible to both A and B, or through multiple such intermediate nodes. If A can communicate with B, mesh is neither helpful nor advisable. It just confuses things, which is the problem we see with large numbers of children in a classroom. The mesh efforts to keep track of how to get from A to B can quickly saturate the RF spectrum with a lot of unhelpful traffic. I can't tell what it is you're doing at your meetings when your users all use mesh. At a typical in-person meeting, you have a number of people using XOs all in the same room. Any XO in the room can communicate over WiFi directly with every other machine in the room (except in extremely unusual circumstances, or too many attendees wearing their tinfoil hats). There's no need for or value to mesh network - A doesn't need C to forward packets to B because A can see B directly as another ad hoc node. If there's an AP providing routing to the Internet or other external networks, there's no mesh required there, either, presuming that each XO can communicate with the AP directly. I can't answer your question about whether those scenarios use ad hoc networking because I don't quite see what it is the users are doing in those scenarios. What (lowercase) activity are users engaged in when you say they all use mesh? What do you think they would be unable to do if they all stopped using mesh? Thanks for the info. - Ed ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel -- DancesWithCars leave the wolves behind ;-) -- DancesWithCars leave the wolves behind ;-) ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
