Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Sat, Mar 10, 2012 at 05:37:00 -0800, Mitar wrote: Hi! Maybe you could perform some more tests in this direction at the next WBM in Athens? I don't think any of us are going to Athens. No? How come? Why? I'm wondering the same :(:(:( From the participant list it seems that all the French guys but one gave up on WBM :(:(:( this is sad Only a coincidence or there is something wrong this year? Cheers, -- Antonio Quartulli ..each of us alone is worth nothing.. Ernesto Che Guevara pgpmNuBpFK4zd.pgp Description: PGP signature
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
I don't think any of us are going to Athens. No? How come? Why? Gabriel and I are busy -- we're hard at work wrapping up some stuff we've been working on for the last four years, we hope to finish soon. I cannot speak for the others. There Ain't No Cabal, if that's what you mean. However, in my personal case, there's also the fact that WBM has been evolving in a direction that I don't feel comfortable with (less technical content, more self- promotion, tolerance for bomb-makers, etc.) -- Juliusz
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
Hi! However, in my personal case, there's also the fact that WBM has been evolving in a direction that I don't feel comfortable with (less technical content, more self- promotion, tolerance for bomb-makers, etc.) Self-promotion of good ideas is not necessary bad. And others are there to squash the bad ideas. ;-) But for technical content: I think you could easily volunteer to lead few round tables on the topic of protocol design. For example, this discussion we are now having on the mailing list about different aspects of routing protocols: oh, how I would love to have them in live, with everybody from all protocols together, sitting and explaining their approaches, their arguments and experiences why they are doing something in the way they are doing: is this theoretical argument, or is it simply a practical observation, can we find a theoretical reasoning behind it, can we maybe invalidate some theoretical argument with a practical (repeatable) experiment? Because I think I am not the only one who does not know much about how other protocols are doing things, what were the reasons they have chosen the given approach, ... And it would really help understanding each other, and maybe, maybe, we could in some years even agree on a common routing protocol. ;-) This would also be interesting for non-technical and new people, because they would be able to listen and understand how things work. But because Juliusz is afraid to come, I can volunteer to moderate (and mediate) such tables if others prepare me a list of topics to discuss. Mitar
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
Hey there, On Sun, Mar 11, 2012 at 09:02:54AM -0700, Mitar wrote: Hi! However, in my personal case, there's also the fact that WBM has been evolving in a direction that I don't feel comfortable with (less technical content, more self- promotion, tolerance for bomb-makers, etc.) Self-promotion of good ideas is not necessary bad. And others are there to squash the bad ideas. ;-) I definitly agree. If we promote bad ideas as the batman-adv-team, I'm sure we'll be shouted at very loud, and thats a great thing. But for technical content: I think you could easily volunteer to lead few round tables on the topic of protocol design. For example, this discussion we are now having on the mailing list about different aspects of routing protocols: oh, how I would love to have them in live, with everybody from all protocols together, sitting and explaining their approaches, their arguments and experiences why they are doing something in the way they are doing: is this theoretical argument, or is it simply a practical observation, can we find a theoretical reasoning behind it, can we maybe invalidate some theoretical argument with a practical (repeatable) experiment? Because I think I am not the only one who does not know much about how other protocols are doing things, what were the reasons they have chosen the given approach, ... And it would really help understanding each other, and maybe, maybe, we could in some years even agree on a common routing protocol. ;-) This would also be interesting for non-technical and new people, because they would be able to listen and understand how things work. But because Juliusz is afraid to come, I can volunteer to moderate (and mediate) such tables if others prepare me a list of topics to discuss. Sounds like a great idea! After some discussion with some other batman-adv devs, we would really like to join this. Actually I think its a good thing that we have some different routing protocols. Diversity gives birth to different approaches, which may succeed or fail, and in both events we can learn from each other. Anyway, maybe we should have put a list in the wiki what we want to dicuss? Do you want to put it as a side-event or more like a podium discussion thing? Cheers, Simon signature.asc Description: Digital signature
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
That was our intuition too, but experiments we did in Brussels using 802.11n multiradio routers, with Benjamin and Juliusz, seemed to show that packet loss (as measured by babel at least) is not always correlated to throughput. I do not claim to understand how this is possible. It's not magic, and I don't think it's due to .11n. We currently measure using multicast, which in 802.11 is sent at a low rate. Minstrel, the rate adaptation algorithm used by Linux, uses unicast probes at the higher data rates to find out the optimum rate. What we have shown is that under some conditions, the multicast packet loss is zero, while Minstrel detects data loss at the higher data rates. As Benjamin rightly noted, this implies that, for that particular class of links, multicast packet loss rate is a poor predictor of link quality. (Duh. It's constant zero.) We've got various ideas about how to solve this issue. Dave suggested hooking into the data structures that Minstrel is using. For Babel, that'd be a cross-layer indication, which is something that makes me nervous, but it should be no problem for a layer 2 protocol. While I like Dave's suggestion, I also like to keep Babel lower-layer agnostic, and I'm considering the use of a different predictor which has the advantage of also making sense on wired links. I'm not telling more right now, I want to implement and test first. -- Juliusz
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
Maybe you could perform some more tests in this direction at the next WBM in Athens? I don't think any of us are going to Athens. -- Juliusz
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
Hi! Maybe you could perform some more tests in this direction at the next WBM in Athens? I don't think any of us are going to Athens. No? How come? Why? Mitar
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN [was: Battlemesh v5 tests]
Consider the following topology (all links assumed lossless), where we're trying to route from A to S: B---C / \\ / \\ A S \/ \ / B'---*C' (C' has just a single interface) In Babel, even with just Z1,the diversity information is encoded in the metric, and so B announces a smaller metric than B'; this causes A to prefer the ABCS route to the AB'C'S route. Unless I'm misunderstanding something, in BATMAN no information is propagated to A -- the information about the extra diversity in the upper route is purely local to C. Hi Juliusz I'm no expert here, but if Simon happens to fall on his head. The metric is simply based on TQ. C=S will probably have a better local TQ than C'-S because of the load balancing over the two links, meaning there are less packets in the air, and so probably less collisions, etc.. A gets to know the complete link path TQ going both ways around the loop, so does get some idea that C=S is better than C'-S, assuming it is actually better. Andrew
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
The metric is simply based on TQ. C=S will probably have a better local TQ than C'-S because of the load balancing over the two links, Sorry for the confusion, I used « = » to mark a different frequency than « - ». There's only the one link between C and S, it's just using a different (non-interfering) frequency. -- Juliusz
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Fri, Mar 09, 2012 at 02:10:02PM +0100, Juliusz Chroboczek wrote: The metric is simply based on TQ. C=S will probably have a better local TQ than C'-S because of the load balancing over the two links, Sorry for the confusion, I used « = » to mark a different frequency than « - ». There's only the one link between C and S, it's just using a different (non-interfering) frequency. Then the route over the = link will probably have a better TQ due to less packet loss (as it doesn't interfere with any neighbouring link). But there is no explicit coding of this better freq in the metric. Cheers, -- Juliusz -- Antonio Quartulli ..each of us alone is worth nothing.. Ernesto Che Guevara pgpufMJR3vWLD.pgp Description: PGP signature
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
-Original Message- From: battlemesh-boun...@ml.ninux.org [mailto:battlemesh- boun...@ml.ninux.org] On Behalf Of Juliusz Chroboczek Sent: Friday, March 09, 2012 2:10 PM To: Battle of the Mesh Mailing List Cc: b.a.t.m.a.n@lists.open-mesh.org Subject: Re: [Battlemesh] Diversity in BATMAN The metric is simply based on TQ. C=S will probably have a better local TQ than C'-S because of the load balancing over the two links, Sorry for the confusion, I used = to mark a different frequency than - . There's only the one link between C and S, it's just using a different (non-interfering) frequency. Ah, O.K. Humm, the answer stays the same :-) C=S will probably have a better TQ if it is not getting as much interference due to collisions. A will get to know about this in the path TQ. Better still, B-C will also probably have a better TQ, since the link C=S is not interfering with it. So the path TQ is even better. A gets all this. Andrew
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Fri, Mar 9, 2012 at 2:36 PM, andrew.l...@ascom.com wrote: -Original Message- From: battlemesh-boun...@ml.ninux.org [mailto:battlemesh- boun...@ml.ninux.org] On Behalf Of Juliusz Chroboczek Sent: Friday, March 09, 2012 2:10 PM To: Battle of the Mesh Mailing List Cc: b.a.t.m.a.n@lists.open-mesh.org Subject: Re: [Battlemesh] Diversity in BATMAN The metric is simply based on TQ. C=S will probably have a better local TQ than C'-S because of the load balancing over the two links, Sorry for the confusion, I used = to mark a different frequency than - . There's only the one link between C and S, it's just using a different (non-interfering) frequency. Ah, O.K. Humm, the answer stays the same :-) C=S will probably have a better TQ if it is not getting as much interference due to collisions. A will get to know about this in the path TQ. Better still, B-C will also probably have a better TQ, since the link C=S is not interfering with it. So the path TQ is even better. A gets all this. How do you compute the TQ? -- Benjamin Henrion bhenrion at ffii.org FFII Brussels - +32-484-566109 - +32-2-3500762 In July 2005, after several failed attempts to legalise software patents in Europe, the patent establishment changed its strategy. Instead of explicitly seeking to sanction the patentability of software, they are now seeking to create a central European patent court, which would establish and enforce patentability rules in their favor, without any possibility of correction by competing courts or democratically elected legislators.
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Friday, March 09, 2012 22:07:37 Benjamin Henrion wrote: C=S will probably have a better TQ if it is not getting as much interference due to collisions. A will get to know about this in the path TQ. Better still, B-C will also probably have a better TQ, since the link C=S is not interfering with it. So the path TQ is even better. A gets all this. How do you compute the TQ? I suggest reading chapter 3.1 (specifically 3.1.3) of the excellent network coding paper[1] written by our catwoman specialists. It is very well written and contains the most comprehensive general overview about batman-adv in existence. Regards, Marek [1] http://downloads.open-mesh.org/batman/papers/batman-adv_network_coding.pdf
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Fri, Mar 9, 2012 at 3:36 PM, Marek Lindner lindner_ma...@yahoo.de wrote: On Friday, March 09, 2012 22:07:37 Benjamin Henrion wrote: C=S will probably have a better TQ if it is not getting as much interference due to collisions. A will get to know about this in the path TQ. Better still, B-C will also probably have a better TQ, since the link C=S is not interfering with it. So the path TQ is even better. A gets all this. How do you compute the TQ? I suggest reading chapter 3.1 (specifically 3.1.3) of the excellent network coding paper[1] written by our catwoman specialists. It is very well written and contains the most comprehensive general overview about batman-adv in existence. TQ is based on packet-loss only, so it is doomed to fail to detect fast interfaces. With such metric, you don't make any difference between a 56K telephone line and a 10Ge NIC. If you 10Ge has 5pc packet loss and your 56K line has 0pc, your TQ will be prefer the 56k link. -- Benjamin Henrion bhenrion at ffii.org FFII Brussels - +32-484-566109 - +32-2-3500762 In July 2005, after several failed attempts to legalise software patents in Europe, the patent establishment changed its strategy. Instead of explicitly seeking to sanction the patentability of software, they are now seeking to create a central European patent court, which would establish and enforce patentability rules in their favor, without any possibility of correction by competing courts or democratically elected legislators.
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
With such metric, you don't make any difference between a 56K telephone line and a 10Ge NIC. If you 10Ge has 5pc packet loss and your 56K line has 0pc, your TQ will be prefer the 56k link. If my 10Ge has 5% packet loss, its broken. I don't want to use it. Falling back to the 56K link is the right thing to do. There is a general rule of thumb. The higher the bandwidth, the less packet loss there is. This is because high bandwidth links are generally not wireless and so don't suffer high packet loss. As a side effect, BATMAN will tend to favor wired links over wireless links, because wired links tend to be reliable, wireless links drop packets. Andrew
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Fri, Mar 9, 2012 at 4:43 PM, Andrew Lunn and...@lunn.ch wrote: With such metric, you don't make any difference between a 56K telephone line and a 10Ge NIC. If you 10Ge has 5pc packet loss and your 56K line has 0pc, your TQ will be prefer the 56k link. If my 10Ge has 5% packet loss, its broken. I don't want to use it. Falling back to the 56K link is the right thing to do. There is a general rule of thumb. The higher the bandwidth, the less packet loss there is. This is because high bandwidth links are generally not wireless and so don't suffer high packet loss. As a side effect, BATMAN will tend to favor wired links over wireless links, because wired links tend to be reliable, wireless links drop packets. So compare a 1Mbits wireless link with a 54Mbits one. -- Benjamin Henrion bhenrion at ffii.org FFII Brussels - +32-484-566109 - +32-2-3500762 In July 2005, after several failed attempts to legalise software patents in Europe, the patent establishment changed its strategy. Instead of explicitly seeking to sanction the patentability of software, they are now seeking to create a central European patent court, which would establish and enforce patentability rules in their favor, without any possibility of correction by competing courts or democratically elected legislators.
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
On Fri, Mar 09, 2012 at 05:07:37PM +0100, Benjamin Henrion wrote: On Fri, Mar 9, 2012 at 4:43 PM, Andrew Lunn and...@lunn.ch wrote: With such metric, you don't make any difference between a 56K telephone line and a 10Ge NIC. If you 10Ge has 5pc packet loss and your 56K line has 0pc, your TQ will be prefer the 56k link. If my 10Ge has 5% packet loss, its broken. I don't want to use it. Falling back to the 56K link is the right thing to do. There is a general rule of thumb. The higher the bandwidth, the less packet loss there is. This is because high bandwidth links are generally not wireless and so don't suffer high packet loss. As a side effect, BATMAN will tend to favor wired links over wireless links, because wired links tend to be reliable, wireless links drop packets. So compare a 1Mbits wireless link with a 54Mbits one. The 54Mbps link probably has a very low packet error rate. Otherwise it would not be running at 54 Mbps. The automatic rate selection algorithm would take it down to a lower rate if it had high packet loss. On the other hand, any link running at 1Mbit probably has quite a high packet error rate. It must be a bad link, otherwise it would not be using the lowest possible coding rate. So when comparing a 1Mbps and a 54Mbps link, probably the TQ for the 54Mbps link will be better than the 1Mbps link. Andrew
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
So when comparing a 1Mbps and a 54Mbps link, probably the TQ for the 54Mbps link will be better than the 1Mbps link. That was our intuition too, but experiments we did in Brussels using 802.11n multiradio routers, with Benjamin and Juliusz, seemed to show that packet loss (as measured by babel at least) is not always correlated to throughput. I do not claim to understand how this is possible. How do you define throughput? Do you mean the coding rate the wifi driver has chosen to use, or iperf/netperf measurements of throughput? Also, does babel perform its measurements using unicast or broadcast/multicast packets/frames? It was in a limited setup, however, and we would be glad to get more results proving or disproving this hypothesis. Do you have any actual experimental results to share on this topic? I've got no results on 11n. I've done most of my work on 11g. I will see if i've got any results for 11g which might be appropriate. Maybe
Re: [B.A.T.M.A.N.] [Battlemesh] Diversity in BATMAN
I've got no results on 11n. I've done most of my work on 11g. I will see if i've got any results for 11g which might be appropriate. Maybe Upps. Got side tracked, disrupted, and hit send Maybe you could perform some more tests in this direction at the next WBM in Athens? Andrew
