I am switching a 20 mesh node from olsrd but I have some problem in routing. I have no gateway node because I use openvpn to have a tunnel with PC. All nodes have: batman -g 0 -r 3 -o 3000 <interface>
node C has: batman -g 0 -r 3 -o 3000 -a 10.0.0.0/24 <interface>
I have several case like this:
A----good----B----good-----C-----10.0.0.0/24----PC ---------------poor-------------/
three node can communicate with all others but radio link from A to C is poor.
When node A want to communicate to node C it goes directly to C because batman calculate a direct route to it. But if I manually set routes to use node B connection from A to C is good.
What is my mistake?
-r parameter in batmand daemon works only in searching gateway node? ...or it works every time, also with normal node?
Hi -
which version of batman are you using? And you should provide us with more details. Just saying Link is 'poor' or 'good' is very unprecise. Remember: A direct route with 6 Megabit performs similar to a two-hop link with 12 Megabits on each link, since no retransmissions have to be made.
If you set the routes manually, it would be interesting to know the transfer performance of the following:
A->C A->B A->B->C C->A C->B C->B->A
How many OGMs does A count directly from C and via B? (And vice versa) By the way: -o 3000 is quite slow for sending Originator messages if you have 20 nodes only. The default should be fine.
cu elektra
I am switching a 20 mesh node from olsrd but I have some problem in routing. I have no gateway node because I use openvpn to have a tunnel with PC. All nodes have: batman -g 0 -r 3 -o 3000 <interface>
node C has: batman -g 0 -r 3 -o 3000 -a 10.0.0.0/24 <interface>
I have several case like this:
A----good----B----good-----C-----10.0.0.0/24----PC ---------------poor-------------/
three node can communicate with all others but radio link from A to C is poor.
When node A want to communicate to node C it goes directly to C because batman calculate a direct route to it. But if I manually set routes to use node B connection from A to C is good.
What is my mistake?
-r parameter in batmand daemon works only in searching gateway node? ...or it works every time, also with normal node?
Hi,
which version of batman are you using? And you should provide us with more details. Just saying Link is 'poor' or 'good' is very unprecise. Remember: A direct route with 6 Megabit performs similar to a two-hop link with 12 Megabits on each link, since no retransmissions have to be made.
Yes, this is true; anyway suppose this scenario
A----> B ----> C
where: A --> B and B --> are 800 kbps links and: A---->C is a 500 kbps link
Suppose we have to send 100 packtes form A to C
if the direct link A---->C is chosen we suppose a 100 packets transmission while chosing B as router (repeater) we would expect a 100+100 packets transmission! What above is well right using that bandwidht values (6Mb) but with poor/lossy links we have also to consider the IP datagrams loss at network layer ---> which will cause TCP retransmits at higher layers (think to http connection) just based on that links. For this reason maybe a kind of "bandwidth threshold" can help in preferring a 500_Kb per link mulit-hop path rather than a 300_Kb link direct path.
This is a my opinion elektra, no criticism... all what we want is only give hints and tips in order to improve batman. Ok?
-- Antonio
What above is well right using that bandwidht values (6Mb) but with poor/lossy links we have also to consider the IP datagrams loss at network layer ---> which will cause TCP retransmits at higher layers (think to http connection) just based on that links. For this reason maybe a kind of "bandwidth threshold" can help in preferring a 500_Kb per link mulit-hop path rather than a 300_Kb link direct path.
Well, you certainly have a point here. The goal of a routing protocol should be to achive the maximum achievable bandwidth for all nodes using the network. There is a fancy word for this condition that one can use to brag around and sound like a scientist: equilibrium.
A route can consist of a large number of very good links - this would be one extreme. Or consist of a minimum of lousy links with maximum packet loss. The first option would consume a very high amount of available bandwidth since there will be many retransimissions disturbing others and it is likely to be relatively slow if your machines use one wireless interface only. The latter is likely to be completely unusable for anything more than transfering a few bytes.
The protocol should find the most effective compromise, of course.
With OLSR and ETX a two hop route with ETX=1,1 on each link won't be used if there is a direct link with ETX=2,1. The idea of ETX is to find the best compromise regarding loss and retransmissions. One has to note that this approach is only useful for wireless networks. ETX on wired connections sucks.
We are doing basically the same with Batman, but it is inherit in the algorithm. Usually a shorter route has a smaller propagation delay - so packets are approaching faster at the node that is counting. Only if the longer - and slower - route looses significant less packets Batman will choose the longer path. Batman has a small benefit on wired connections because they are usually much faster than wireless links and thus tend to be preferred.
In the previous example OLSR will prefer a single hop route with more than 50% packetloss, rather than the two-hop path with approx. 17% packetloss.
There are some people suggesting that Batman preferres shorter routes too much, so it is interesting to collect such reports. But misconfigurations have to be ruled out when collecting such data.
Something that could help to improve the situation as a workaround in this case is to increase the broadcast rate in the wireless settings of the cards. This will reduce the range of broadcasts and can improve the result, because the number of OGMs on stretched links will decrease.
cu elektra
Thank for reply I just read it but maybe is late in the night or maybe I'm too tired... but some statements are puzzling me. Sure tomorrow morning I'll have a more clean mind and take a look more deeper to your scripts.
ciao
Antonio
What above is well right using that bandwidht values (6Mb) but with poor/lossy links we have also to consider the IP datagrams loss at network layer ---> which will cause TCP retransmits at higher layers (think to http connection) just based on that links. For this reason maybe a kind of "bandwidth threshold" can help in preferring a 500_Kb per link mulit-hop path rather than a 300_Kb link direct path.
Well, you certainly have a point here. The goal of a routing protocol should be to achive the maximum achievable bandwidth for all nodes using the network. There is a fancy word for this condition that one can use to brag around and sound like a scientist: equilibrium.
A route can consist of a large number of very good links - this would be one extreme. Or consist of a minimum of lousy links with maximum packet loss. The first option would consume a very high amount of available bandwidth since there will be many retransimissions disturbing others and it is likely to be relatively slow if your machines use one wireless interface only. The latter is likely to be completely unusable for anything more than transfering a few bytes.
The protocol should find the most effective compromise, of course.
With OLSR and ETX a two hop route with ETX=1,1 on each link won't be used if there is a direct link with ETX=2,1. The idea of ETX is to find the best compromise regarding loss and retransmissions. One has to note that this approach is only useful for wireless networks. ETX on wired connections sucks.
We are doing basically the same with Batman, but it is inherit in the algorithm. Usually a shorter route has a smaller propagation delay - so packets are approaching faster at the node that is counting. Only if the longer - and slower - route looses significant less packets Batman will choose the longer path. Batman has a small benefit on wired connections because they are usually much faster than wireless links and thus tend to be preferred.
In the previous example OLSR will prefer a single hop route with more than 50% packetloss, rather than the two-hop path with approx. 17% packetloss.
There are some people suggesting that Batman preferres shorter routes too much, so it is interesting to collect such reports. But misconfigurations have to be ruled out when collecting such data.
Something that could help to improve the situation as a workaround in this case is to increase the broadcast rate in the wireless settings of the cards. This will reduce the range of broadcasts and can improve the result, because the number of OGMs on stretched links will decrease.
cu elektra _______________________________________________ B.A.T.M.A.N mailing list B.A.T.M.A.N@open-mesh.net https://list.open-mesh.net/mm/listinfo/b.a.t.m.a.n
Antonio,
I am continuing to have problems sshing into nodes. Currently, it is a repeater. Doing ifconfig eth1 (my wireless adapter) gives me this:
eth1 Link encap:Ethernet HWaddr 00:19:D2:03:D2:00 inet addr:10.19.66.100 Bcast:10.19.66.127 Mask:255.255.255.128
I am associated with the public AP.
So I then do:
ssh 10.19.66.1 -l root ssh: connect to host 10.19.66.1 port 22: No route to host
I never had problems to ssh into gateways or repeaters before.
What is wrong? This really worked in prior builds...
Mike
-----Original Message----- From: b.a.t.m.a.n-bounces@open-mesh.net on behalf of a.anselmi@oltrelinux.com Sent: Wed 9/19/2007 2:12 PM To: The list for a Better Approach To Mobile Ad-hoc Networking Subject: Re: [B.A.T.M.A.N.] batman routing clarification
Thank for reply I just read it but maybe is late in the night or maybe I'm too tired... but some statements are puzzling me. Sure tomorrow morning I'll have a more clean mind and take a look more deeper to your scripts.
ciao
Antonio
What above is well right using that bandwidht values (6Mb) but with poor/lossy links we have also to consider the IP datagrams loss at network layer ---> which will cause TCP retransmits at higher layers (think to http connection) just based on that links. For this reason maybe a kind of "bandwidth threshold" can help in preferring a 500_Kb per link mulit-hop path rather than a 300_Kb link direct path.
Well, you certainly have a point here. The goal of a routing protocol should be to achive the maximum achievable bandwidth for all nodes using the network. There is a fancy word for this condition that one can use to brag around and sound like a scientist: equilibrium.
A route can consist of a large number of very good links - this would be one extreme. Or consist of a minimum of lousy links with maximum packet loss. The first option would consume a very high amount of available bandwidth since there will be many retransimissions disturbing others and it is likely to be relatively slow if your machines use one wireless interface only. The latter is likely to be completely unusable for anything more than transfering a few bytes.
The protocol should find the most effective compromise, of course.
With OLSR and ETX a two hop route with ETX=1,1 on each link won't be used if there is a direct link with ETX=2,1. The idea of ETX is to find the best compromise regarding loss and retransmissions. One has to note that this approach is only useful for wireless networks. ETX on wired connections sucks.
We are doing basically the same with Batman, but it is inherit in the algorithm. Usually a shorter route has a smaller propagation delay - so packets are approaching faster at the node that is counting. Only if the longer - and slower - route looses significant less packets Batman will choose the longer path. Batman has a small benefit on wired connections because they are usually much faster than wireless links and thus tend to be preferred.
In the previous example OLSR will prefer a single hop route with more than 50% packetloss, rather than the two-hop path with approx. 17% packetloss.
There are some people suggesting that Batman preferres shorter routes too much, so it is interesting to collect such reports. But misconfigurations have to be ruled out when collecting such data.
Something that could help to improve the situation as a workaround in this case is to increase the broadcast rate in the wireless settings of the cards. This will reduce the range of broadcasts and can improve the result, because the number of OGMs on stretched links will decrease.
cu elektra _______________________________________________ B.A.T.M.A.N mailing list B.A.T.M.A.N@open-mesh.net https://list.open-mesh.net/mm/listinfo/b.a.t.m.a.n
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Stefano Scipioni