Trying to understand multicast packet IP routing - why src IP address affects reception ??//

[Lev Olshvang]

Shahar ,
Thanks ....

see below :
Shachar Shemesh wrote:
> I'll just point out that my Multicast understanding is a bit tenuous.
>
> Lev Olshvang wrote:
>> Evening all,
>>
>>
>> But if I change the interface IP address to  other network, these 
>> packets are ignored at IP layer  (data link layer got it since RX 
>> count is running according to ifconfig )
>> I have tcp ip forwarding set to 1 and application sets  multicast 
>> socket option  to join the multicast group.
>>
> Did you change the IP address after the socket is up? Multicast needs 
> to perform some handshaking before it can start sending data, and this 
> handshake might be done only at the "start".
>

   Since this is my network driver , I  reload it and set IP after 
reload, as well I put some printk in it  so I see data link accepts 
packages in either case.  tcpdump also shows these packets.
> Also, I would start the debugging by running a sniffer and seeing 
> whether the packets actually leave the machine, and if so, with what 
> destination MAC address.
>
  I have no problem with MAC ( driver gets the packets), I put also some 
printk in net/ipv4/route.c and I see this packets are discarded at IP layer.
> Shachar
> -- 
> Shachar Shemesh
> Lingnu Open Source Consulting Ltd.
> http://www.lingnu.com
>   


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