Re: [lwip-users] ARP forwarding

[Eric Koldeweij]

Hello,

You would need to implement a switch/bridge. LWIP is an IP stack which is something quite different.

Implementing a L2 bridge is not difficult but you do need to know the theory and I suggest a lot of reading. I have implemented bridges on Xilinx FPGA's many times, with or without LWIP. If you need to receive/send IP packets LWIP can be placed on top of your switch code.

I can recommend "The Switch Book" by Rich Seifert, ISBN 0-471-34586-5. Everything you need to know about Ethernet switching and much much more.

Regards,

Eric.

On 13-12-2022 17:50, Александр via lwip-users wrote:

Hello!

I am trying to implement dual ethernet interface device on Xilinx baremetal logic. I’v already implement receiving data from both of two interfaces but now I want to realize forwarding from one interface to another. I’v connected to 1st interface and try to ping the second one. On wireshark I see arp requests that have no responses.

May be problem is in forwarding of broadcast messages?

 

#if IP_FORWARD

    /* non-broadcast packet? */

    if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), inp)) {

      /* try to forward IP packet on (other) interfaces */

      ip4_forward(p, (struct ip_hdr *)p->payload, inp);

    } else

#endif /* IP_FORWARD */

 

I can not understand this part. Why do we forward only unicast messages?

Sorry, i am niewbe in this stuff

 

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