> Here are some facts:
>
> A. A mobile device transmitting data to a correspondent node will
> require forward and reverse tunneling through the home network
> unless it can establish a binding cache entry at the correspondent
> node.
>
> B. This can increase the total capacity requirement for the
> communications by an arbitrary amount, depending on the
> layout with respect to the home network. That could easily
> mean a factor of "thousands".
>
> Opinion:
>
> A typical multiplier for (B) will be about 2. The actual
> number depends on the relative placement of the nodes, and
> the multiplier will be higher whenever a mobile device needs to
> communicate with a local correspondent.
>
> Thus, the scenario where people would expect the most
> responsive communications will offer counterintuitive
> behavior.
>
> Solutions for this problem include:
> - restricted mobility
> - transient IP addresses
> = subcase: EIDs to replace IP addresses as identifiers
> - reengineering human intuition
> - proxy agents
>
> These are good for more startups and full employment (like
> NATs are), but most of them are bad for the Internet.
>
Those are all good points.
A correspndent node as a Server:
A correspondent node that serves a mobile node without route-optimization
is no different than any other IPv6 server. So what is the advantage
of using Mobile-IPv6 here other than using ipv6-addresses ?
Should not this promote more usage of NATs using existing MobileIPv4
protocol with private addresses ? What would be the advantage of
using MIPv6 rather than MIPV4 using co-located care-of-address with
reverse tunnel ?
One of the strong advantages of using MobileIPv6 is that route-optimization
is in-built in the protocol, if MobileIPv6 does not specify "Route Optimization"
as MUST behavior for CNs, we would be sending wrong messages to the
IPv6 node implementors, as we expect that a large number of mobile
devices will use MobileIPv6 in future.
Depending on the location of the server and the home-agent and the mobile
node the roundtrip time through the reverse tunnel could be much higher
compared to the roundtrip time between MN-CN if route-optimization is
used.
Correspondent Node as MNs:
In this case, imagine two MNs are visiting the same foreign network,
but since one of them does not support RO (since it's not mandatory),
they still communicate via their home-agent which is far away from
the foreign network. This situation will create un-necessary traffic
delay while mandatory route-optimization would have easily cut the
RTT short to a great length. If we transfer large amount of data, imagine
how compelling it would be to have the route-optimization feature in CN!
I believe, for successful deployment of MobileIPv6 and IPv6, route-optimization
should be MUST for all MIPv6 correspondent nodes and thus for all ipv6-nodes.
Thanks,
-Samita
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