mobileip / netfilter

[Vikram]

hi,

i have a basic doubt as to the use of DNAT rules to simulate mobile ip
behaviour. i am very new to this , so please tolerate/explain glaring
omissions:


* host `home.netfilter.edu` and host `runaway.netfilter.edu` exist on the
  same subnet. the runaway node , runs away:) to another subnet and
  _changes_ its ip address [and hence dns name] to another address
  probably assigned via dhcp once it joined the new network.

* however runaway.netfilter.edu told home.netfilter.edu to proxy arp[1] for
  it and moreover `registered` with home.netfilter.edu its NEW ip address
  once it got it [after entering the new subnet].

* in the mobile ip implementation, the home.netfilter.edu receives
  packets for runaway.netfilter.edu because of proxy arp AND then tunnels
  these packets using a virtual device driver

my question is :

instead of tunnelling can the home.netfilter.edu just have a dynamic DNAT
rule which changes the destination address of the packet to the registered
ip address it should sent to . is there a problem with this ?

do reply. thank you,

	Vikram


[1] how does one proxy arp ? i tried to arp -s <hostname> <iface> pub
and tried to ping from some other host outside the subnet and it failed.
i thought the who-has request at the local subnet router will be answered
by the host which does proxy arp but then what went wrong here ?