Hi Sven, On Tue, Aug 23, 2011 at 3:32 AM, Sven Eckelmann <sven(a)narfation.org> wrote: Thanks for pointing that out. I did not know there were that many versions. Noted. ?? By colliding I mean "come into conflict or opposition", not killing bunnies. And it happens to be the same verb that Simon Wunderlich used to explain why batman-adv had to change its ethertype (https://lists.open-mesh.org/pipermail/b.a.t.m.a.n/2009-August/001682.html). Of course it's not a big deal, but definitely something you need not worry about if your implementation is based on a spec that has been standardized. Nice. I see. If I understand correctly batman-adv works as a bridge, encapsulating mesh management info into data frames. In that case batman-adv routing must be based on hopcount and/or transmission failures as radio layer info is lost in the conversion to 802.3. By being in the 802.11 stack, 11s has more information about the quality of the links and can use that information to compute a finer-grained metric. The standard defines airtime as the default link metric but 11s can be extended to include other info like RSSI or SNR. A similar argument can be made about security. I assume batman-adv does not implement security but instead relies on whatever the lower layer provides. In 11s security is built from the ground up. Peers authenticate each other and exchange encryption keys at the same time they establish a peer link. Security becomes easier to manage and more robust than when using, for instance, WPA to secure peer links. No matter how silent or small the open80211s community is, batman-adv + open80211s will always be larger than batman-adv alone. That's what I meant by "larger". Why limit yourself there? There are definitely use cases for non-routers to join a mesh network. IEEE 802 also has its share of funny names... client mac propagation, roaming announcements = (802.11s, Sec. 7.3.2.116) Proxy Updates bridge loop avoidance = (802.1D, Sec. 17) Rapid Spanning Tree Protocol or my favorite: (802.11s, Sec 8.2a.1) Simultaneous Authentication of Equals Agree to that. openwrt rocks. You mean the same Wireless Battle of Mesh that year after year fails to decide on a winner? :) (My sixth point as well as the response above should be taken humorously, that's what the colon thingy at the end of the sentence meant) I could not help noticing a certain level of skepticism in your response. I'm not trying to sell anything nor asking anyone to dump batman in favor of anything else. I admire and respect what the batman project has achieved so far. Even people in open80211s' mailing list criticize that batman performs much better than open80211s ( http://open80211s.com/pipermail/devel/2011-August/000859.html). But my impression is that, maybe because they were ahead of their time, the batman community had to invent/reinvent things in their own unique way. And now that a standard is in place, everyone interested in mesh could benefit if there was a seventh (and final) version bump to bring it in line with IEEE 802.11s. Greetings and congratulations for your good work. Cheers, Javier -- Javier Cardona cozybit Inc. http://www.cozybit.com

Hi Andrew, On Wed, Aug 24, 2011 at 12:18 AM, Andrew Lunn <andrew(a)lunn.ch> wrote: I'm on equal footing regarding batman: thanks for taking the time to help me understand the differences between the two. 802.11s is designed to fit within the IEEE 802 family of protocols (it was approved by the IEEE 802 Executive Committee in July). You are correct in that 11s does restrict the mesh to be a wireless mesh. But it is designed to connect to external networks via 802.1D bridges. 802.1D bridges have been around for ages and are good at interconnecting diverse MAC types without routing loops. I read here (http://www.open-mesh.org/wiki/batman-adv/Bridge-loop-avoidance) that batman implements its own loop-avoidance protocol which, from my limited perspective, seems redundant. I can appreciate the benefits of supporting a diversity of link technologies. I'd have to understand better how a single metric definition can be used to quantify the quality of all link types, from 802.11 to homing pigeon. But I guess it's being done successfully. In 802.11 infrastructure mode you have only one authenticator (the AP) and many supplicants. You cannot use the same security model in a mesh, when there are no such role divisions. Does batman-adv provide a security layer above the link layer security (and below IP)? If so, where can I read more about that? Based on my current understanding it looks like you could establish a batman-adv network over 1-hop 11s links. Interesting. When I wrote my first e-mail to your list I was under the impression was that batman-adv's routing algorithm was more advanced than HWMP, mainly because it had incorporated improvements gathered from many deployments (... and mesh battles :). But it seems like batman's main strength is its ability to establish routes over heterogeneous links, not necessarily minimizing the spectrum utilization. Thanks a lot for sharing your thoughts on this. Cheers, Javier

STP, RSTP protocols are good when the networks are nearly perfect. However, wifi is no way near perfect, there is high packet loss. So when deciding to block ports, to resolve loops, you want to block the wireless part and keep the wired part working. It can be hard to make STP and RSTP do this, it often blocks the wired part, so making your overall network work badly. Read the page, it explains the concept quite well. BATMAN does not really care if the WiFi is in infrastructure mode of adhoc. However, generally, it is used in adhoc. Maybe the 802.11s authentication and encryption schemes don't make too much sense in infrastructure mode, but it would be nice to be able to use them in adhoc mode. Nope. That is a problem for some other layer, e.g. the link layer below, IPSEC above, TLS end to end etc... I expect it will also work over 42-hop 11s links. It probably won't have the "optimal" toplogy, by some definition of "optimal". Actually, most of the mesh protocols i listed try to minimizing the spectrum. They try to use wired as much as possible! Wired links give a much better goodput compared to wireless, so that it is better to take a longer low bandwidth looking path over wired than a shorter higher bandwidth looking path over wireless. I'm not a PHY person, but i've seen papers from coding/PHY people who actually say you should be maximizing spectrum utilization, not minimizing it. If i understand the research correctly, you get better overall mesh performance by sending for a long time a 6Mbps at lower power, compared to sending a short burst at 54Mbps at high power. To receive at 6Mbps you need a much lower SNR than at 54Mbps. So you can transmit at lower power, so causing less interference to others and receive in a noisier environment at 6Mbps, than receive a 54MBps frame which needs more transmit power and less background noise in order to receive it. So 6Mbps at lower power allows more links to be active at the same time, maximizing the overall mesh bandwidth/latency. But like i said, i'm not a PHY person, so i might have this all wrong. Most mesh protocols actually go partway towards this. They all roughly approximate to "least number of hops over good links", by some definition of "good link". Least hops generally means using long hops, which will naturally have less bits per symbol, i.e more medium time. All that is missing is power control in the wireless layer. Andrew