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Hi all, In general problem is as following: I have a board with PPC cpu, embedded linux and DM9161A (Davicom) network chip. When I started to configure multicasts on it ...
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  1. 05-22-2009 #1
    Igrushkin
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    [SOLVED] Problem with multicasts

    Hi all,

    In general problem is as following: I have a board with PPC cpu, embedded linux and DM9161A (Davicom) network chip. When I started to configure multicasts on it I discovered a couple of strange things. The board sends IGMP requests and normal multicast packets but it doesn't receive any multicasts. I have tried to send different packets from the packeth and have discovered that board receives packets with its own MAC-address or broadcast (MAC = ff-ff-ff-ff-ff-ff) only. All the packets with other destination MAC-addresses are dropped (I can't see them in the tcpdump output). The exactly same situation with the multicast packets (MAC = 01-00-5e-xx-xx-xx). However, all the packets are come to the board and I can see them by blinking led on switch.
    I guess the problem is somewhere in the L2 layer configuration of the Linux. And iptables configuration is completely clean.

    Could you please tell me what is the possible problem? Where should I dig up? Is it driver's or hardware issue?
    Thank you in advance!
  2. 05-27-2009 #2
    Rubberman
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    What kernel version are you running? Also, what does the Davicom website say about support for multi-cast addressing? Also, a lot of routers won't forward multi-cast packets, though I don't think this is an issue for you here from what you say about your environment. In any case, it could be driver configuration, general tcp/ip configuration, or hardware that is at fault here. More investigation is required. Make sure you know ALL details of your system's network configuration settings, and understand what they do.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!
  3. 05-29-2009 #3
    Igrushkin
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    Thank you for your answers. The issue has been solved.

    After long digging up in the drivers and linux kernel I discovered than function set_multicast_list for FCC ENET network driver for ppc (arch/ppc/8260_io/fcc_enet.c) is commented (it sets promiscuous mode for the interface and multicast MAC address filtering).

    I can't understand the exact reason why it is commented but after I compiled kernel with this function issue with MAC addresses has disappeared
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