Static routing vs OLSR/AODV for multiple interfaces

Mahesh

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Feb 8, 2018, 1:34:55 AM2/8/18

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Hi all,

I am looking to simulate the attached scripts in which multiple interfaces (NetDeviceContainer instances) are present on a node. I want to compare the effect of static routing vs OLSR/AODV.

When I use static routing, the interfaces through which packets have to be routed work as intended. However, when I am using OLSR/AODV protocols, all the packets from node 0 get routed through the same interface. I came across few posts which talk about OLSR/AODV being incapable of handling multi-interface nodes.

How do I make my simulation work in multi-interface scenario with OLSR/AODV? Looking forward to your kind reply.

Thanks,

Mahesh

olsr.cc

static-routing.cc

Mahesh

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Feb 10, 2018, 12:52:30 PM2/10/18

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Can anyone please point me on how to make OLSR/AODV work with multiple interfaces?

N0----N1----N2

|

N3

For example, in the above sample wireless topology, if N3----N1 link is already being used through one interface, then I would like to route packets between N3----N0 through a different interface. Similar for N3----N2. Routing should work based on shortest path first.

- Mahesh

Tommaso Pecorella

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Feb 10, 2018, 3:34:36 PM2/10/18

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Hi,

both AODV and OLSR should be able to handle multiple interfaces.

Try debugging your code and especially the OLSR (or AODV) protocols. It's also possible that you found a bug...

T.

Mahesh

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Feb 11, 2018, 1:13:55 PM2/11/18

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Hi Tommaso,

Thanks for your reply. I thought maybe my attached script itself has a fault. I have the following topology:

N1

|

Ch. 1 |

|

Ch.2 | Ch. 4

N2------------------------N0------------------------N4

|

Ch. 3 |

|

N3

Node 0 has 4 interfaces (one each for communicating with nodes 1 to 4) with IP addresses: 10.1.1.1, 10.1.1.3, 10.1.1.5, 10.1.1.7

Node 1 has 1 interface with IP: 10.1.1.2

Node 2 has 1 interface with IP: 10.1.1.4

Node 3 has 1 interface with IP: 10.1.1.6

Node 4 has 1 interface with IP: 10.1.1.8

Now I setup 4 flows between node 0 and nodes 1 to 4 which are on 4 different channels. When I install the sourceHelper on node 0, how will OLSR/AODV "decide" that it has to use 4 different interfaces on node 0 for communicating with the nodes 1 to 4?

sourceApp[i] = sourceHelper.Install (nc_wireless.Get(0));

I am confused regarding this part. Kindly reply.

- Mahesh

olsr.cc

Tommaso Pecorella

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Feb 11, 2018, 4:40:25 PM2/11/18

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Hi,

well, N0 should send its route discovery packets on all the interfaces. If it doesn't it's a bug.

T.

Mahesh

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Feb 12, 2018, 2:09:53 AM2/12/18

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Hi Tommaso,

I ran my script on ns-3-dev and ns-3.26. In both the versions, OLSR is not working with multiple interfaces. I am attaching the script herewith. N0 has 4 interfaces. There are 2 scenarios:

Scenario 1 (all interfaces on node 0 are on same channel):

N1

|

Ch. 1 |

|

Ch. 1 | Ch. 1

N2------------------------N0------------------------N4

|

Ch. 1 |

|

N3

Scenario 2 (all interfaces on node 0 are on different channels):

N1

|

Ch. 1 |

|

Ch. 2 | Ch. 4

N2------------------------N0------------------------N4

|

Ch. 3 |

|

N3

N0 is not sending its route discovery packets on all the interfaces. I am attaching the neighbors, routes and throughput stats of scenario 1 and 2's executions. Kindly check at your end and let me know.

Thanks,

Mahesh

olsr.cc

olsr_same_ch_dev.txt

olsr_same_ch_dev.routes

olsr_same_ch_dev.neighbors

olsr_diff_ch_dev.txt

olsr_diff_ch_dev.routes

olsr_diff_ch_dev.neighbors

Mahesh

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Feb 15, 2018, 4:17:26 AM2/15/18

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Hi,

Can anyone please look into this issue? Awaiting your kind reply.

- Mahesh

Mahesh

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Feb 19, 2018, 2:41:08 PM2/19/18

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Hi Tommaso and ns3 community,

I have attached the script in my previous post which shows non-working of OLSR with multiple interfaces.

Can you please review if it is indeed a bug in ns3?

Thanks,

Mahesh

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Mahesh

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Feb 20, 2018, 2:19:43 PM2/20/18

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Someone please look into this issue/bug.

Tommaso Pecorella

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Feb 21, 2018, 11:55:03 PM2/21/18

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Hi,

I'm sorry, I was quite busy. I'll look at the issue as soon as I can.

T.

Tommaso Pecorella

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Feb 22, 2018, 12:58:03 AM2/22/18

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Hi,

ok, I thought it was a bug in OLSR, but it isn't.

It's actually bad design (not in OLSR, in the setup).

First and foremost: you're trying to send flows from the central node to the other nodes. As a consequence, OLSR doesn't have anything to do with it.

Second: it works when all the nodes are in the same channel by sheer luck: they're all connected in a big, huge, mesh.

And now the design issue.

When you have a node with multiple IP interfaces, you have to have a "normal" routing protocol. OLSR, AODV, or whatever, won't work.

In your case, the sender node (which has multiple interfaces) is picking up the wrong one to send all the traffic, purely because when it goes through the routing table it finds the first one first.

The solution is: bridge the interfaces, i.e., use BridgeNetDevice to connect all the interfaces in node 0.

T.

Mahesh

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Feb 24, 2018, 1:30:31 PM2/24/18

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Thanks for your kind reply, Tommaso. I tried linking the interfaces on central node (node 0) through BridgeNetDevice by following csma-bridge-one-hop.cc file. I read that bridging does not work in adhoc wifi mode so I made the central node as AP and the other nodes as STAs.

However, when I run the script, there seems to be no flow of packets. Can you please tell where I am going wrong?

Thanks,

Mahesh

5-nodes-bridge.cc

Mahesh

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Feb 27, 2018, 12:30:54 PM2/27/18

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Please guide where I am going wrong, Tommaso.

Thanks,

Mahesh

Tommaso Pecorella

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Mar 3, 2018, 10:58:44 PM3/3/18

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There should be only ONE node with bridged interfaces, i.e., the central node.

T.

Mahesh

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Mar 7, 2018, 10:15:28 AM3/7/18

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In my script, the central node is bridged to 4 BridgeDevices each through a separate interface. The other 4 nodes are all configured on a channel so as to receive the packets. Something like this:

N1

|

| Ch. 38

|

Ch. 46 ___ Ch. 62

N2----------|-N0-|----------N4

___

|

| Ch. 54

|

N3

Still no packets are being transferred, why? Kindly tell.

- Mahesh

Mahesh

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Apr 17, 2018, 12:14:56 PM4/17/18

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Up.

Also, I wanted to ask why does ns-3 not support bridging in adhoc mode?

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