Ich würde als nächstes versuchen, einen statischen Eintrag in die ARP-Tabelle mit der MAC-Adresse des SPA machen und dann versuchen, diesen darüber anzusprechen.
Hab ich schon versucht, hat leider nichts gebracht:
gateway:~ # ip a l dev vlan24
21: vlan24@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 00:25:90:30:d8:40 brd ff:ff:ff:ff:ff:ff
inet 10.10.24.227/24 brd 10.10.24.255 scope global vlan24
valid_lft forever preferred_lft forever
inet6 fe80::225:90ff:fe30:d840/64 scope link
valid_lft forever preferred_lft forever
gateway:~ # ip neigh replace to 10.10.24.88 dev vlan24 lladdr 70:1f:53:0a:50:65
gateway:~ # ip neigh | grep vlan24
10.10.24.88 dev vlan24 lladdr 70:1f:53:0a:50:65 PERMANENT
gateway:~ # ping 10.10.24.88
PING 10.10.24.88 (10.10.24.88) 56(84) bytes of data.
^C
--- 10.10.24.88 ping statistics ---
7 packets transmitted, 0 received, 100% packet loss, time 6125ms
gateway:~ # tcpdump -i vlan24
12:16:06.905397 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 1, length 64
12:16:07.910432 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 2, length 64
12:16:08.934433 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 3, length 64
12:16:09.958425 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 4, length 64
12:16:10.982431 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 5, length 64
12:16:12.006436 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 6, length 64
12:16:13.030436 IP gw-voip.hauihau.home > spa112.hauihau.home: ICMP echo request, id 24389, seq 7, length 64