I may have a mistake because of my Inaccurate expression in bug #64145: ICMP reply error when using bridge.
Now i illustrate again.
when I use lwIP netif implementing an IEEE 802.1D MAC Bridge,I add two portif eth0 and eth1 ,also I set address and mac to bridge0 as host netif(192.168.1.5) when i set NULL address to portif eth0 and eth1.
I connected two devices to portif eth0 and eth1 in outside, the address are 192.168.1.6 and 192.168.1.7.
    But,when I ping host(192.168.1.5) from device(192.168.1.7),I get no reply.Then I debuged and found the issue point at function icmp_input(icmp.c#198) and bridgeif_send_to_port(bridgeif.c #257).
    In this case, icmp request from eth1(input pbuf->if_idx = netif->num + 1,here is 1,default is 0),but in function icmp_input,it reuse the input pbuf rather than alloc new one,so this pbuf->if_idx = netif->num + 1 = 1.Then function bridgeif_send_to_port use the pbuf->if_idx to prevent sending out to rx port(if (netif_get_index(portif) != p->if_idx)),at this time,icmp reply would never be forward to eth1,so icmp error.
    icmp replied success when I added statement(p->if_idx = 0) at icmp.c#248 before ip4_output_if.
You can see the network structure at file network structure.jpg.