Subject: [Mip4] Does it still make sense to save MIPv4 address space?

From: zhen <[email-masked]>
Date: Thu, 6 Oct 2005 16:50:42 -0300

Hi, All,

Recently I found some idea about saving home address usage in MIPv4. 
Because each MN has to possess a public address, this is a huge 
consumption of IPv4 address space. Somebody told me it's no longer 
valid because people are soon using MIPv6 in wireless network. I'm not 
sure because in order to support IPv6, all hosts and routers must be 
updated. In my point of view, IPv4 will be still in use for quite a 
while. In wireless networking, such as 3G, within the network surely 
each terminal can use IPv6 address, but in order to communicate with 
IPv4 world, one IPv4 home address may still be necessary, so the waste 
of IPv4 address still exists.

looking forward to other opinions.

regards

Zhen

-- 
Mip4 mailing list: [email-masked]
    Web interface: https://www1.ietf.org/mailman/listinfo/mip4
     Charter page: http://www.ietf.org/html.charters/mip4-charter.html
Supplemental site: http://www.mip4.org/

---

From: Hans Sjostrand <[email-masked]>
Date: Mon, 10 Oct 2005 10:16:46 +0200

Hi Zhen,

There's nothing that mandates a MN to possess a public IP address. Thats 
a misunderstanding. Almost all installations I've seen are using private 
IPv4 addresses for the MN's.

Best regards
/// Hasse

---

From: Zhen Zhen <[email-masked]>
Date: Sat, 15 Oct 2005 15:26:10 -0300 (ADT)

Then how do the computers outside of the network find the MN?

---

From: Hans Sjostrand <[email-masked]>
Date: Mon, 17 Oct 2005 10:27:16 +0200

Hi Zhen,

When I wrote "nothing that mandates a MN to possess a public IP address" 
I meant nothing in the Mobile IP specifications or the protocol. Then 
there are deployment considerations and the nature of IPv4 addressing 
and NATs that of course are still valid. And some implementation 
limitations that may exist in the MN or HA.

To answer your question.
- how do the computers outside of the network find the MN?
In the case with private MN address, they don't. Since the traffic from 
the MN is natted out from the private address space to the public 
address space; the MN needs to find the computer outside the network.

In a corporate deployments this is in most cases what you want. The home 
network is inside the intranet, all computers on the intranet can 
directly find the MN and no computer outside the intranet should ever 
setup a connection against the MN.

In several public deployments the operator have chosen to place all home 
networks as "virtual" home networks with private addresses, and then nat 
out the traffic. This is the same scenario as in several other offers 
and the reason is in most cases a scarcity of IP addresses.

In some deployments the operator actually wants the global reachability. 
The MN then needs to have a public address. But in my mind, this is not 
a limitation imposed by Mobile IP, it's the nature of IPv4.

Best regards
/// Hasse

---

From: Zhen Zhen <[email-masked]>
Date: Fri, 21 Oct 2005 12:48:12 -0300 (ADT)

May I ask that if the MN is using a private address, then what is in the
"home address" field of Registration Request message? If it's also a
private address, how to guarantee that it is not conflicted with other
hosts in the foreign network?

rgds

---

From: Hans Sjostrand <[email-masked]>
Date: Mon, 24 Oct 2005 11:45:43 +0200

Read "RFC 3024 Reverse Tunneling for Mobile IP, revised    January 2001 
Appendix A: Disparate Address Space Support" to get an understanding how 
FA's nees to cope with this issue.

Regards
/// Hasse