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MIT Roofnet article at TechnologyReview.com

>From a /. mention on Saturday, MIT's Technology Review site is carrying a story about Roofnet, "a project to create a self-organizing wireless network in which an amorphous, unmanaged collection of cheap Linux computers equipped with Wi-Fi cards collaborate to efficiently route data packets." The story can be found here: http://www.technologyreview.com/articles/wo_guizzo082903.asp?p=0 In case you're interested, the /. story and comments are here: http://slashdot.org/article.pl?sid=03/08/29/2320228&mode=thread I thought this was a neat article that would provide a good follow-up to Dave's email to cu-wireless about Roofnet in June. Nodes are Linux-based PCs with 802.11b wireless cards. As of 2003/08/29, the network has 30 nodes in a 4 sq-km area (cost for each node is ~$685). Also, a connectivity map is available at: http://www.pdos.lcs.mit.edu/roofnet/map.php Chase Phillips -- shepard at ameth.org ][ -111--0010-0-1100-101-000-01--10 http://www.ameth.org/ ][ 00-00-01-10--1-00-01-010111010-0 _______________________________________________ Cu-wireless mailing list Cu-wireless@xxxxxxxxxxxxxxxxxx http://lists.cu.groogroo.com/cgi-bin/listinfo/cu-wireless Project Page: http://cuwireless.ucimc.org

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Re: MIT Roofnet article at TechnologyReview.com

On Tue, Sep 02, 2003 at 01:58:52PM -0500, Sascha Meinrath wrote: > Just a quick follow-up -- the software is open source and available for > download at: http://www.pdos.lcs.mit.edu/grid/software.html > > It seems to me that we may want to have one of our Linux-savvy folks take > a look at it. I would also love to know if there are solutions that can > be implemented into our own software or whether we should have folks > working on a separate fork (if people are interested). > > Thoughts? AFAICT, the most important research outcome from the MIT Roofnet is ETX, a "routing metric." A routing metric is a way of assigning "scores" or "costs" to the links in a network in order to bias the routing algorithm's choice of paths. The ETX algorithm is simple, and it is equally applicable to an OSPF network as to the DSR-hybrid which Roofnet uses. Essentially, you weight links in the network using the formula 1 --------- df * dr where df is the proportion (between 0 and 1) of ten 802.11 broadcast packets that were received over the link in the "forward direction" in the last ten seconds, and dr is the proportion received in the "reverse" direction. It is a little more complicated. IIRC, they use an exponential weighted average of 1 / (df * dr) over time. I am not expert enough at OSPF to know how easily we can use ETX on our network, especially not in the point-to-multipoint mode. Maybe Stephane can comment? AFAIK, the only thing that OSPF lets us assign costs to is an "interface." Am I wrong? Incidentally, the benefits of ETX on our *current* network will be nil. However, with "fill in," we will definitely need ETX. MIT uses ETX with a very complicated routing protocol which they call SrcRR. It is a variant of Dynamic Source Routing (DSR). You can read more about it on their web page. I think CUW will do better by using ETX with a routing protocol such as Hazy-Sighted Link State (HSLS). HSLS admits a *much* more parsimonious implementation, and it is predicted to scale better than SrcRR. The work-conserving thing to do is to continue with the CUW software, adding ETX to our OSPF routing, or producing an HSLS daemon with ETX. Dave -- David Young OJC Technologies dyoung@xxxxxxxxxxx Urbana, IL * (217) 278-3933 _______________________________________________ Cu-wireless mailing list Cu-wireless@xxxxxxxxxxxxxxxxxx http://lists.cu.groogroo.com/cgi-bin/listinfo/cu-wireless Project Page: http://cuwireless.ucimc.org

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MIT Roofnet article at TechnologyReview.com

>From a /. mention on Saturday, MIT's Technology Review site is carrying a story about Roofnet, "a project to create a self-organizing wireless network in which an amorphous, unmanaged collection of cheap Linux computers equipped with Wi-Fi cards collaborate to efficiently route data packets." The story can be found here: http://www.technologyreview.com/articles/wo_guizzo082903.asp?p=0 In case you're interested, the /. story and comments are here: http://slashdot.org/article.pl?sid=03/08/29/2320228&mode=thread I thought this was a neat article that would provide a good follow-up to Dave's email to cu-wireless about Roofnet in June. Nodes are Linux-based PCs with 802.11b wireless cards. As of 2003/08/29, the network has 30 nodes in a 4 sq-km area (cost for each node is ~$685). Also, a connectivity map is available at: http://www.pdos.lcs.mit.edu/roofnet/map.php Chase Phillips -- shepard at ameth.org ][ -111--0010-0-1100-101-000-01--10 http://www.ameth.org/ ][ 00-00-01-10--1-00-01-010111010-0 _______________________________________________ Cu-wireless mailing list Cu-wireless@xxxxxxxxxxxxxxxxxx http://lists.cu.groogroo.com/cgi-bin/listinfo/cu-wireless Project Page: http://cuwireless.ucimc.org

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Re: MIT Roofnet article at TechnologyReview.com

On Tue, Sep 02, 2003 at 01:58:52PM -0500, Sascha Meinrath wrote: > Just a quick follow-up -- the software is open source and available for > download at: http://www.pdos.lcs.mit.edu/grid/software.html > > It seems to me that we may want to have one of our Linux-savvy folks take > a look at it. I would also love to know if there are solutions that can > be implemented into our own software or whether we should have folks > working on a separate fork (if people are interested). > > Thoughts? AFAICT, the most important research outcome from the MIT Roofnet is ETX, a "routing metric." A routing metric is a way of assigning "scores" or "costs" to the links in a network in order to bias the routing algorithm's choice of paths. The ETX algorithm is simple, and it is equally applicable to an OSPF network as to the DSR-hybrid which Roofnet uses. Essentially, you weight links in the network using the formula 1 --------- df * dr where df is the proportion (between 0 and 1) of ten 802.11 broadcast packets that were received over the link in the "forward direction" in the last ten seconds, and dr is the proportion received in the "reverse" direction. It is a little more complicated. IIRC, they use an exponential weighted average of 1 / (df * dr) over time. I am not expert enough at OSPF to know how easily we can use ETX on our network, especially not in the point-to-multipoint mode. Maybe Stephane can comment? AFAIK, the only thing that OSPF lets us assign costs to is an "interface." Am I wrong? Incidentally, the benefits of ETX on our *current* network will be nil. However, with "fill in," we will definitely need ETX. MIT uses ETX with a very complicated routing protocol which they call SrcRR. It is a variant of Dynamic Source Routing (DSR). You can read more about it on their web page. I think CUW will do better by using ETX with a routing protocol such as Hazy-Sighted Link State (HSLS). HSLS admits a *much* more parsimonious implementation, and it is predicted to scale better than SrcRR. The work-conserving thing to do is to continue with the CUW software, adding ETX to our OSPF routing, or producing an HSLS daemon with ETX. Dave -- David Young OJC Technologies dyoung@xxxxxxxxxxx Urbana, IL * (217) 278-3933 _______________________________________________ Cu-wireless mailing list Cu-wireless@xxxxxxxxxxxxxxxxxx http://lists.cu.groogroo.com/cgi-bin/listinfo/cu-wireless Project Page: http://cuwireless.ucimc.org