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Altera_Forum's avatar
Altera_Forum
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9 years ago

Iniche stack - how found MAC address from IP

I'm using Nios II system to provide ethernet services (like ICMP, ARP etc. etc.) to an video over IP design. I'm using the uCOS II system with Nichestack.

My video to IP transmitter (hardware design) needs to known the MAC address of the receiver interface. Since the user didn't specify the MAC address but only the IP address, I need to find the MAC address from the IP.

I'm a newbie with uCOS and Nichestack.

How I can implement a function that search for IP in the ARP table and if doesn't exist make and ARP request and send back the MAC address? I can use some existing functions?

Thanks.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    Review the source in et_arp.c You'll need to write your own function to extract the MAC from the ARP table, but functions exist for sending the ARP request.

    The ARP table is in 

    
struct arptabent  arp_table;
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    Thanks,

    I've implemented a function that parse the ARP table up to find correspondance between my IP and IP contained in ARP table, then I extract the relative MAC address.

    //parse arp_table to find matching specified IP <-> IP in ARP table and then readback MAC address

    for (i=0; i<= MAXARPS; i++)

    {

    if (arp_table.t_pro_addr ==invert_addr_byte_order(udp_ip_tx_config[0].ipdestaddress))

    {

    mac_found = 1;

    mac_addr[0] = arp_table.t_phy_addr[0];

    MAC_addr[1] = arp_table.t_phy_addr[1];

    mac_addr[2] = arp_table.t_phy_addr[2];

    MAC_addr[3] = arp_table.t_phy_addr[3];

    mac_addr[4] = arp_table.t_phy_addr[4];

    MAC_addr[5] = arp_table[i].t_phy_addr[5];

    }

    }