Re: [B.A.T.M.A.N.] Batman-Adv : Hops and Throughput with Collocated dual-radio

[Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>]

[-- Attachment #1: Type: text/plain, Size: 1748 bytes --]

Hi Zaki/Jack,

On Fri, Oct 11, 2013 at 11:11:04AM +0800, Zaki wrote:
> Hi,
> 
> I am a newbie in batman-adv.  I got a question regarding Hops and
> Throughput, especially in regards with a collocated dual-radio device.
>  Hopefully somebody could offer some help here for me to fully
> understand batman-adv operation.  I have 3 devices, namely A, B and C.
> 
> A is only having single radio (operating at Freq 5.20G in AdHoc mode).
>  Put this under bat0.  Bridge bat0 with eth0.
> B is having dual-radio (radio1 operates at 5.20G in AdHoc mode, radio2
> is at 5.24G in AdHoc mode). Put these under bat0. Bridge bat0 with
> eth0
> C is like A (single radio, operating at 5.24G in AdHoc mode). Put this
> under bat0.  Bridge bat0 with eth0.
> 
> So, the wireless link will be like this :
> 
> [A]::::::::::::::: [B(radio1)---B(radio2)]::::::::::::::::[C]
> 
> 1) If i were to ping from A to C, how many hops is it considered?.  Is
> it 2 hops or 3 hops?.

that would be two hops. One hop is considered traversing one link, and
you have two links here.

> 2) If my Iperf TCP throughput from A to B is 40Mbps, what is the
> expected throughput of Iperf from A to C ?.

That depends. If the links are not interferring, you should get approx.
the maximum of both link throughputs. So if one link is 30 mbit/s, the second
is 25 mbit/s, that whole path would yield 25 mbit/s - there might be tcp
effects further decreasing throughput (latency etc).

However you use two frequencies adjacent to each other. If you use omni
antennas, expect a lot of interferences (even if the channels are not
overlapping). If you use directional antennas you should be fine.

Cheers,
	Simon


> 
> Thanks a lot.
> 
> Jack.

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 198 bytes --]