FreeBSD 7.3 i386

1. Local tunnel end is not configured as ip on other interfaces.
IP from same network as remote tunnel end ip is configured on ethernet interface.
Works.

# ifconfig le0 
le0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=8<VLAN_MTU>
	ether 08:00:27:e0:ea:60
	inet 192.168.2.103 netmask 0xffffff00 broadcast 192.168.2.255
	media: Ethernet autoselect
	status: active
# kldload ng_iface
# ngctl mkpeer . iface foobar inet
# ifconfig ng0 192.168.2.10/32 192.168.2.15
# ifconfig ng0 
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1500
	inet 192.168.2.10 --> 192.168.2.15 netmask 0xffffffff
# arp -s 192.168.2.15 08:00:27:e0:ea:60 pub
# arp 192.168.2.15
? (192.168.2.15) at 08:00:27:e0:ea:60 on le0 permanent published (proxy only) [ethernet]

2.  Local tunnel end is configured on ethernet interface. Works

# ifconfig le0
le0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=8<VLAN_MTU>
	ether 08:00:27:e0:ea:60
	inet 192.168.2.103 netmask 0xffffff00 broadcast 192.168.2.255
	inet 192.168.2.10 netmask 0xffffffff broadcast 192.168.2.10
	media: Ethernet autoselect
	status: active
# ifconfig ng0 192.168.2.10/32 192.168.2.15
# ifconfig ng0
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1500
	inet 192.168.2.10 --> 192.168.2.15 netmask 0xffffffff
# arp -s 192.168.2.15 08:00:27:e0:ea:60 pub
# arp 192.168.2.15
? (192.168.2.15) at 08:00:27:e0:ea:60 on le0 permanent published (proxy only) [ethernet]

3. Local tunnel end is configured on carp(4) interface. Works
# ifconfig carp0 192.168.2.10/32 pass igwywa vhid 10 advskew 200
# ifconfig carp0
carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500
        inet 192.168.2.10 netmask 0xffffffff 
        carp: MASTER vhid 10 advbase 1 advskew 200
# ifconfig ng0 192.168.2.10/32 192.168.2.15
# ifconfig ng0 
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1500
	inet 192.168.2.10 --> 192.168.2.15 netmask 0xffffffff
# arp -s 192.168.2.15 08:00:27:e0:ea:60 pub
# arp 192.168.2.15
? (192.168.2.15) at 08:00:27:e0:ea:60 on le0 permanent published (proxy only) [ethernet]

4. Local tunnel end is not configured as ip on other intrfaces.
IP from same network as remote tunnel end ip is configured on vlan(4) interface.

# ifconfig vlan7
vlan7: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	ether 08:00:27:e0:ea:60
	inet 172.16.0.1 netmask 0xffffff00 broadcast 172.16.0.255
	media: Ethernet autoselect
	status: active
	vlan: 7 parent interface: le0
# ifconfig ng0 172.16.0.10/32 172.16.0.15
# ifconfig ng0 
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1500
	inet 172.16.0.10 --> 172.16.0.15 netmask 0xffffffff
# arp -s 172.16.0.15 08:00:27:e0:ea:60 pub
# arp 172.16.0.15 
? (172.16.0.15) at 08:00:27:e0:ea:60 on vlan7 permanent published (proxy only) [vlan]

so on FreeBSD 7 work all this 4 varioants of ng0 tunnel and proxy arp
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Same tests for unpatched FreeBSD 8.0-STABLE i386

1. Local tunnel end is not configured as ip on other interfaces.
IP from same network as remote tunnel end ip is configured on ethernet interface.
Don't work
# arp -s 192.168.2.15 08:00:27:28:28:f5 pub
cannot intuit interface index and type for 192.168.2.15
# arp -s 192.168.2.15 auto pub
using interface le0 for proxy with address 08:00:27:28:28:f5
cannot intuit interface index and type for 192.168.2.15

2. Local tunnel end is configured on ethernet interface. Works.

3. Local tunnel end is configured on carp(4) interface. Don't work
# ifconfig carp0
carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500
	inet 192.168.2.10 netmask 0xffffffff 
	carp: MASTER vhid 10 advbase 1 advskew 200
# ifconfig ng0 192.168.2.10/32 192.168.2.15
ifconfig: ioctl (SIOCAIFADDR): File exists
but strange, that 192.168.2.10 seems to be configured:
# ifconfig ng0 
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1500
	inet 192.168.2.10 --> 192.168.2.15 netmask 0xffffffff

4. Local tunnel end is not configured as ip on other interfaces.
IP from same network as remote tunnel end ip is configured on vlan(4) interface.
Don't work

# arp -s 172.16.0.15 08:00:27:28:28:f5 pub
cannot intuit interface index and type for 172.16.0.15
# arp -s 172.16.0.15 auto pub
using interface vlan7 for proxy with address 08:00:27:28:28:f5
cannot intuit interface index and type for 172.16.0.15
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Same tests on patched FreeBSD 8.0-STABLE i386
patch: http://people.freebsd.org/~qingli/ng-patch.diff

1.  Local tunnel end is not configured as ip on other interfaces.
IP from same network as remote tunnel end ip is configured on ethernet interface.
Works.

2. Local tunnel end is configured on ethernet interface. Works

3. Local tunnel end is configured on carp(4) interface. Don't work

# ifconfig ng0 192.168.2.10/32 192.168.2.15
ifconfig: ioctl (SIOCAIFADDR): File exists

4. Local tunnel end is not configured as ip on other interfaces.
IP from same network as remote tunnel end ip is configured on vlan(4) interface.
Works.