Olsr-users Digest, Vol 75, Issue 2

Discussion:

Shyam B

2013-09-08 17:14:06 UTC

Hi Henning,

Thank you for your response.

I am trying to let each RPi see the other in the network and communicate
with each other.
The situation right now is that both Raspberry PI's have similar
connectivity, having:
ESSID, Channel 11 (2.457GHz), Ad-Hoc mode.
Each configured to a static IP in the same subnet.

I can see the other node via *iwlist scan* (that is I can sense the other
node in the network, I have tested with different ESSID's to verify).

To your question, I am unable to ping from one node to the other. (Note I
DO NOT have a gateway configured). This is what I am confused on, as to if
I should be able to.

It can communicate with a TP-Link router (which is configured as a router
by default), and packets can go through them.

My question is:
1) Is a gateway required for OLSR to route packets?
2) Right now, i have two (and later several) isolated nodes in the network.
No gateways. Can I not be able to communicate? If not, why not?
3) I have attached the olsr.conf file for the Rpi in the earlier mail.

Any details will certainly help me understand where I am going wrong.

Thanks in advance,
Shyam

----------------------------------------------------------------------
Message: 1
Date: Thu, 5 Sep 2013 13:42:46 +0200
Subject: Re: [Olsr-users] Fwd: Configuring two nodes directly (without
a gateway) - OLSR.
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Hi,
do you have already checked that you have direct IP connectivity? Can
you ping the other node over the network?
If you only have two nodes, ping will work with or without OLSR, because
you can only communicate with 1-hop neighbors without routing protocol.
If you cannot ping the other node, then you have trouble on layer-2
(wifi) or with your interface configuration.
Henning Rogge

Hi Al,
I am configuring _multiple RaspberryPI's_ as nodes in a mesh network. I
don't plan to use routers as gateway. Having installed OLSR on these
nodes (currently two to begin with), I am unable to communicate between
them.
The configuration was working with the routers.
_What I did_
Ad-Hoc mode, Channel 10 with same ESSID.
Tried to change hna, Ip4Broadcast to the same subnetwork as well.
Nothing works!
The iwconfig screenshot and olsrd.conf file attached. I have spent
multiple hours trying to get it to work!!
It would be of real help if someone can point out if communication
between two raw nodes is selected. If not why not, and what do I have to
do to make this setup work. Eagerly looking forward!

Henning Rogge
--
Diplom-Informatiker Henning Rogge , Fraunhofer-Institut f?r
Kommunikation, Informationsverarbeitung und Ergonomie FKIE
Kommunikationssysteme (KOM)
Fraunhofer Stra?e 20, 53343 Wachtberg, Germany
Telefon +49 228 9435-961, Fax +49 228 9435 685
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--
Best Regards,
Shyam

Shyam B

2013-09-09 17:17:06 UTC

Permalink

Hi Brian/ Others,

Thank you for your help so far. I am closer to the problem, I believe.

To summarize, I am using 2 Raspberry PI's in simple 'Ad-hoc mode', channel
10, *same* ESSID on both nodes. Setup for one Raspberry PIs, is perfectly
identical to the other one (I have crosschecked all parameters).

Device: Edimax EW-7811Un (One of the recommended dongle's with RPi -
enables Ad-Hoc mode: Ch 01:11)
Device driver does NOT seem to be a problem here. I can see the gateway
router of OLSR with Rpi over wlan0 but *NOT* another Rpi with same
configuration over wlan0.

Ok, first lets* DISABLE OLSR,* just simple Ad-hoc mode on two RPi's and try
to PING each other over wlan0. I am *able* to do this with RPi and a
TP-Link OpenWRT based router in Ad-hoc mode *with OR without OLSR*.

E.g. setup:

***@raspberrypi ~ $ cat /etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet dhcp
auto wlan0
iface wlan0 inet static
address 192.168.10.200
netmask 255.255.255.0
wireless-channel 10
wireless-essid irt-ah-inria
wireless-mode ad-hoc

***@raspberrypi ~ $ iwconfig wlan0
wlan0 IEEE 802.11bg ESSID:"irt-ah-inria" Nickname:"<***@WiFi>"
Mode:Ad-Hoc Frequency: 2.457 GHz Cell: 0E:75:4D:3C:D9:3A Bit
Rate:54 Mb/s
Tx-Power=20 dBm
Retry long limit: 7 RTS thr:off Fragment thr:off
Power Management:on

***@raspberrypi ~ $ sudo iwlist wlan0 scan
wlan0 Scan completed :
Cell 01 - Address: 02:11:87:FA:4A:02
ESSID:"irt-ah-inria"
Protocol:IEEE 802.11bg
Mode:Ad-Hoc
Frequency:2.457 GHz (Channel 10)
Encryption key:off
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s
48 Mb/s; 54 Mb/s

*Ip is 192.168.10.200* and *broadcast IP *is over all subnets: *
192.168.255.255*

*Conclusion:*
-------------
Everything is fine uptil this point. For the question raised earlier, here
is my observation.

(1) I am ABLE to ping between the two RPi via eth0 but not via wlan0 (seems
like a layer two issue - hard to believe)! I have multiple RPis and
dongles, tested with others - same issue!
(2) I am able to run OLSR on the eth0 interface - yes, this works. RPi can
see each other.
(3) I am NOT able to see the other RPi over wlan0. IF I am able to 'ping'
the two RPi's in simple Ad-Hoc mode (no rocket science), I am sure OLSR
must work then (as with eth0)..
(4) I ran 'arp-scan' to scan the device address over wlan0. This is not
able to identify the hw-MAC address of the other RPi wlan0 device.

I am certainly missing something really tiny. This must work! Have spent
countless hours figuring what's wrong. Maybe someone's expertise can help
me or maybe can do a similar setup.

Thanks in advance,
Shyam

Shyam,
Do you have the same SSID configured on both nodes? You indicate that
they are both on the same channel, both set to ad-hoc mode, and both
wireless interfaces are in the same subnet. If all those conditions are
true, and the SSIDs match, you don't need the routing protocol to ping
between the nodes.
Just to be sure - you're attempting to ping the other node's wireless
interface directly from the Rpi - NOT from a PC connected to the Rpi's
Ethernet port. Have you tried setting the source interface of the ping to
the wireless interface? "ping a.b.c.d -I wlan0" (or whatever your wireless
interface is called).
-Brian
Hi Henning,
Thank you for your response.
I am trying to let each RPi see the other in the network and communicate
with each other.
The situation right now is that both Raspberry PI's have similar
ESSID, Channel 11 (2.457GHz), Ad-Hoc mode.
Each configured to a static IP in the same subnet.
I can see the other node via *iwlist scan* (that is I can sense the
other node in the network, I have tested with different ESSID's to verify).
To your question, I am unable to ping from one node to the other. (Note
I DO NOT have a gateway configured). This is what I am confused on, as to
if I should be able to.
It can communicate with a TP-Link router (which is configured as a router
by default), and packets can go through them.
1) Is a gateway required for OLSR to route packets?
2) Right now, i have two (and later several) isolated nodes in the
network. No gateways. Can I not be able to communicate? If not, why not?
3) I have attached the olsr.conf file for the Rpi in the earlier mail.
Any details will certainly help me understand where I am going wrong.
Thanks in advance,
Shyam

--
Best Regards,
Shyam

Teco Boot

2013-09-09 19:53:28 UTC

Permalink

Post by Shyam B
Hi Brian/ Others,
Thank you for your help so far. I am closer to the problem, I believe.
To summarize, I am using 2 Raspberry PI's in simple 'Ad-hoc mode', channel 10

Why not channel 1, 6 or 11?

Post by Shyam B
, same ESSID on both nodes. Setup for one Raspberry PIs, is perfectly identical to the other one (I have crosschecked all parameters).

If "perfectly identical", you will never have connectivity (e.g dup IP addresses, mac addresses etc.).

Please provide all configs (for both RPi's)

Post by Shyam B
Device: Edimax EW-7811Un (One of the recommended dongle's with RPi - enables Ad-Hoc mode: Ch 01:11)

What is Ch 01:11?

Post by Shyam B
Device driver does NOT seem to be a problem here.

Please don't shout.
Why are you so certain? If it works, you are OK. If not, there is a problem somewhere.

Post by Shyam B
I can see the gateway router of OLSR

What is "gateway router of OLSR"?

Post by Shyam B
with Rpi over wlan0 but NOT another Rpi with same configuration over wlan0.
Ok, first lets DISABLE OLSR, just simple Ad-hoc mode on two RPi's and try to PING each other over wlan0. I am able to do this with RPi and a TP-Link OpenWRT based router in Ad-hoc mode with OR without OLSR.

Can't you test without that TP-link device? It just confuses me.

Post by Shyam B
auto lo
iface lo inet loopback
iface eth0 inet dhcp
auto walnut
iface wlan0 inet static
address 192.168.10.200
netmask 255.255.255.0
wireless-channel 10
wireless-essid irt-ah-inria
wireless-mode ad-hoc
Mode:Ad-Hoc Frequency: 2.457 GHz Cell: 0E:75:4D:3C:D9:3A Bit Rate:54 Mb/s
Tx-Power=20 dBm
Retry long limit: 7 RTS thr:off Fragment thr:off
Power Management:on
Cell 01 - Address: 02:11:87:FA:4A:02
ESSID:"irt-ah-inria"
Protocol:IEEE 802.11bg
Mode:Ad-Hoc
Frequency:2.457 GHz (Channel 10)
Encryption key:off
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s
48 Mb/s; 54 Mb/s

The BSSID's should be the same.
Maybe just configure with something like:
auto wlan0
iface wlan0 inet static
wireless-mode ad-hoc
wireless-channel 11
address 192.168.10.200
netmask 255.255.255.0
broadcast 255.255.255.255
up iw dev wlan0 ibss join "irt-ah-inria" 2462 02:11:87:FA:4A:02

The wireless-* statements are redundant. Doesn't harm, maybe it helps.

Post by Shyam B
Ip is 192.168.10.200 and broadcast IP is over all subnets: 192.168.255.255

Is wrong. 192.168.10.200/24 would use 192.168.10.255 (or 255.255.255.255 as you configured).

Post by Shyam B
-------------
Everything is fine uptil this point.

Maybe you made a mistake before this point...

Post by Shyam B
For the question raised earlier, here is my observation.
(1) I am ABLE to ping between the two RPi via eth0 but not via wlan0 (seems like a layer two issue - hard to believe)!

Don't believe, just find out what's wrong.

Post by Shyam B
I have multiple RPis and dongles, tested with others - same issue!
(2) I am able to run OLSR on the eth0 interface - yes, this works. RPi can see each other.

You did not provide any config for the ethernet interfaces. So we can only guess if it should work or should not work.

Post by Shyam B
(3) I am NOT able to see the other RPi over wlan0.

Just put the interface in monitor and you will see the other RPi.

Post by Shyam B
IF I am able to 'ping' the two RPi's in simple Ad-Hoc mode (no rocket science), I am sure OLSR must work then (as with eth0)..
(4) I ran 'arp-scan' to scan the device address over wlan0. This is not able to identify the hw-MAC address of the other RPi wlan0 device.
I am certainly missing something really tiny. This must work! Have spent countless hours figuring what's wrong. Maybe someone's expertise can help me or maybe can do a similar setup.

So you used tcpdump?
Used monitor mode?
There is so much fun to keep you busy ;).

Teco
(mainly offline a few days)

Post by Shyam B
Thanks in advance,
Shyam
Shyam,
Do you have the same SSID configured on both nodes? You indicate that they are both on the same channel, both set to ad-hoc mode, and both wireless interfaces are in the same subnet. If all those conditions are true, and the SSIDs match, you don't need the routing protocol to ping between the nodes.
Just to be sure - you're attempting to ping the other node's wireless interface directly from the Rpi - NOT from a PC connected to the Rpi's Ethernet port. Have you tried setting the source interface of the ping to the wireless interface? "ping a.b.c.d -I wlan0" (or whatever your wireless interface is called).
-Brian

Post by Shyam B
Hi Henning,
Thank you for your response.
I am trying to let each RPi see the other in the network and communicate with each other.
ESSID, Channel 11 (2.457GHz), Ad-Hoc mode.
Each configured to a static IP in the same subnet.
I can see the other node via iwlist scan (that is I can sense the other node in the network, I have tested with different ESSID's to verify).
To your question, I am unable to ping from one node to the other. (Note I DO NOT have a gateway configured). This is what I am confused on, as to if I should be able to.
It can communicate with a TP-Link router (which is configured as a router by default), and packets can go through them.
1) Is a gateway required for OLSR to route packets?
2) Right now, i have two (and later several) isolated nodes in the network. No gateways. Can I not be able to communicate? If not, why not?
3) I have attached the olsr.conf file for the Rpi in the earlier mail.
Any details will certainly help me understand where I am going wrong.
Thanks in advance,
Shyam
----------------------------------------------------------------------
Message: 1
Date: Thu, 5 Sep 2013 13:42:46 +0200
Subject: Re: [Olsr-users] Fwd: Configuring two nodes directly (without
a gateway) - OLSR.
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Hi,
do you have already checked that you have direct IP connectivity? Can
you ping the other node over the network?
If you only have two nodes, ping will work with or without OLSR, because
you can only communicate with 1-hop neighbors without routing protocol.
If you cannot ping the other node, then you have trouble on layer-2
(wifi) or with your interface configuration.
Henning Rogge

Henning Rogge
--
Diplom-Informatiker Henning Rogge , Fraunhofer-Institut f?r
Kommunikation, Informationsverarbeitung und Ergonomie FKIE
Kommunikationssysteme (KOM)
Fraunhofer Stra?e 20, 53343 Wachtberg, Germany
Telefon +49 228 9435-961, Fax +49 228 9435 685
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*****************************************
--
Best Regards,
Shyam

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Best Regards,
Shyam
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Henning Rogge

2013-09-10 05:33:04 UTC

Permalink

Hi,

Ok, first lets*DISABLE OLSR,* just simple Ad-hoc mode

Good plan. :)

Always good to start testing the lower layers before moving to the upper
layers.

on two RPi's and
try to PING each other over wlan0. I am _able_ to do this with RPi and a
TP-Link OpenWRT based router in Ad-hoc mode _with OR without OLSR_.

Pinging direct neighbors is independent of running OLSR. So your first
tests should work fine without routing protocol.

auto lo
iface lo inet loopback
iface eth0 inet dhcp
auto wlan0
iface wlan0 inet static
address 192.168.10.200
netmask 255.255.255.0
wireless-channel 10
wireless-essid irt-ah-inria
wireless-mode ad-hoc

Can you post the output of "ifconfig" and "iw wlan0 station dump" on
both the sender and the receiver of your ping?

Henning Rogge

--
Diplom-Informatiker Henning Rogge , Fraunhofer-Institut für
Kommunikation, Informationsverarbeitung und Ergonomie FKIE
Kommunikationssysteme (KOM)
Fraunhofer Straße 20, 53343 Wachtberg, Germany
Telefon +49 228 9435-961, Fax +49 228 9435 685
mailto:***@fkie.fraunhofer.de http://www.fkie.fraunhofer.de