Wifi multicast routing problem

[cuikeqi...@gmail.com]

Hello,

I want to make a multicast tree, the topology and channel assignment result is like the picture below.

Node A,B,C are using the same group address ,

C should send packets to its child nodes, however,because B is receiving in channel 1,so packets will return to B,then B sends it to C again.

I don't know how to deal with it.

How can I make it work as I want ?? Can I keep the channel assignment??? 

If I didn't make myself clear, please tell me ,I'll say it more clearly.

Please help. Thanks.

Cui Keqiang.

[Tommaso Pecorella]

Hi,

you need a multicast routing protocol. I don't know what (ad-hoc) routing are you using, but it seems that it's not multicast-ready.

A simple solution is to update the protocol and make it multicast-friendly, but this isn't that simple or that obvious.

A quick and dirty solution is to maintain a cache of the recently forwarded packets and avoid to re-forward what has been recently seen. This should help mitigating the issue you're describing. However, the cache size is not that simple to decide, and if it is too short, you'll have the same problem again.

For the records, the cache should be large enough to hold any [multicast] packet received between the moment you forward a packet and the maximum time a forwarded packet may bounce back to you.

Cheers,

T.

[cuikeqi...@gmail.com]

Hi,

Thank you,

I've already used static routing protocol,and set the same multicast group address to all these nodes, 

is it because I set the address in a wrong way??

I uploaded my script and input files, I'd appreciate it if you take a look .Are there problems in my script???

I have another question.

Do you know how to solve this kind of problem in real life?? just out of curiosity

Cui.

在 2014年11月10日星期一UTC+8下午10时31分15秒，Tommaso Pecorella写道：

[Tommaso Pecorella]

Hi,

unfortunately I don't have time right now to check your script with the due attention. From a quick look I don't see major problems, but the IP assignments is rather strange, so it deserves some more checks to be understood.
About all the nodes having the same multicast address, it wouldn't be multicast if they would require a different group each, isn't it ?

Real life... there's a lot of literature on it, just search with google. The main point is that the multicast ad-hoc routing protocol (we don't have one right now) should take care ofyour problem. The solution is: when you have a routing protocol building the proper multicast tree, each router knows who's the node "above" and "below", and forwards only the packets from the proper nodes. I.e., you can use a MAC filtering.

Cheers,

T.

[cuikeqi...@gmail.com]

Hi,

Thanks a lot,

Is there a Mac (or IP) filtering system already ,or I should make one???

C.
在 2014年11月11日星期二UTC+8下午3时44分53秒，Tommaso Pecorella写道：

[Tommaso Pecorella]

Hi,

I fear you'll have to do it.

Cheers,

T.

[Nat P]

Il giorno martedì 11 novembre 2014 11:14:59 UTC+1, cuikeqi...@gmail.com ha scritto:

Hi,

Thanks a lot,

Is there a Mac (or IP) filtering system already ,or I should make one???

I'm developing one. Uhm, to said well, I've already developed it, but before publishing it I want to first complete my paper on a subsequent result, and then cleanup the code... Stay tuned here on ns-developers mailing list for updates.
 

[cuikeqi...@gmail.com]

Thank you anyway.

You're kind.

 :-)

Cui.

在 2014年11月11日星期二UTC+8下午6时39分10秒，Tommaso Pecorella写道：

[cuikeqi...@gmail.com]

Hello,

It's good to hear that.

But if you don't mind, could you please tell me   how long it will take??

Thank you.

Cui.

在 2014年11月11日星期二UTC+8下午7时16分48秒，Nat P写道：

[Nat P]

Il giorno martedì 11 novembre 2014 13:09:04 UTC+1, cuikeqi...@gmail.com ha scritto:

Hello,

It's good to hear that.

But if you don't mind, could you please tell me   how long it will take??

Thank you.

Cui.

Near first days of December for presentation; if you want a fully and integrated thing, I think the right period is near May 2015.

[cuikeqi...@gmail.com]

Thanks for answering questions.

在 2014年11月11日星期二UTC+8下午9时23分08秒，Nat P写道：

[cuikeqi...@gmail.com]

Hello,

I have a question , you said about   Stay tuned here on ns-developers mailing list for updates...

Did you mean the google groups, ns-3-user???

If not, what did you mean???

:-) 

thanks

Cui
 
在 2014年11月11日星期二UTC+8下午9时23分08秒，Nat P写道：

[pdbarnes]

The developers list is different from this google group which is the Users list.

The list of ns-3 lists, with information on subscribing, is here:
http://www.nsnam.org/support/mailing-list/

Peter

[cuikeqi...@gmail.com]

Thank you . 

:)