Subject: [MEXT] draft-wakikawa-mext-cr-consideration-00.txt

From: marcelo bagnulo braun <[email-masked]>
Date: Tue, 22 Jul 2008 16:25:27 +0200

Hi Ryuji,

thanks for writing this down
i think this is exactly the disucssion we need to have at this point.

Some questions:

in section 2.1.  Triggering Route Optimization you state:

   The home agent distribution such as the global HAHA [ID-HAHAINTEROP]
   [ID-HAHA] is much simpler.  The mobile router or the mobile node are
   not involving the route optimization trigger.  The trigger is given
   by the home agent.

But, the HA is also a middle box so the same problems that apply to the 
CR/MR based ro triggering applies to the HA. I mean, how do you 
configure the policies int he HA? (i understadn that in the same way you 
configure them in the CR)

As i see it, the HA approach is simpler cause you always do RO, in the 
sense that you always use the MNN-MR-HA-HA-CN path, whcih is always as 
optimum as the HAHA approach provides, or am i missing something?

Later on, it reads:

2.3.  Registering Binding to Correspondent Router

   The Correspondent Router and the mobile router are not belong to the
   same administrative domain, there are several security concerns.

I don't think this is a concern in the aviation case, since we have 
assumed that it is posible to establish trust between the MR and a 
mobility anchor point near to the CN, so this shouldn't be an issues (or 
at least we have assumed that this is not an issue)

similarly with the rest of the issues in this section. If the trust can 
be assumed, i think these are non issues.

later on, it states:    MR-CR Route Management:

   Therefore, even if one direction is optimized, there is no guarantee
   that the reverse path is also optimized (Figure 2).

I don't understand how this could happen
I understand that asymmetric routing is quite common, but mostly in the 
core. I fail to see how a you could end up with a non optimized path in 
only one direction and i fail to see how you could possibly do better. 
Could you expand on this, for instance with an example of topology that 
would end up in this situation?

regards, marcelo

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From: Ryuji Wakikawa <[email-masked]>
Date: Wed, 23 Jul 2008 16:30:12 +0900

Hi Marcelo,

Thanks  for your comments.

marcelo bagnulo braun wrote:
> But, the HA is also a middle box so the same problems that apply to 
> the CR/MR based ro triggering applies to the HA. I mean, how do you 
> configure the policies int he HA? (i understadn that in the same way 
> you configure them in the CR)
right. Currently, in globalHAHA, RO states are always exchanged and no 
dynamic.
We can also design a global HAHA with the similar triggering issue of CR;-)
> optimum as the HAHA approach provides, or am i missing something?
after writing my comment above, i found the same answer here:-)

> mobility anchor point near to the CN, so this shouldn't be an issues 
> (or at least we have assumed that this is not an issue)
OK...
This document is not specific to aviation case, but I tried to explain 
general CR issues.

It is very important for operators(who deploy CR) to understand this 
security aspects.
To me, having trust between MR and all CRs is strong requirements.

> similarly with the rest of the issues in this section. If the trust 
> can be assumed, i think these are non issues.
>
> I understand that asymmetric routing is quite common, but mostly in 
> the core. I fail to see how a you could end up with a non optimized 
> path in only one direction and i fail to see how you could possibly do 
> better. Could you expand on this, for instance with an example of 
> topology that would end up in this situation?
It depends on size of AS and location of CR.

How can you guarantee that the packets destined to MR are intercepted by 
CR in AS?

see the WIDE AS topology in this URL.
http://two.wide.ad.jp/

Let's assume that CR is located at fujisawa (middle of the topology map).

how can you guarantee that the packets to MR are re-directed to that CR?
By OSPF routing, the packets are routed to one of peering points but  
not to CR.

If CN is located in the fukuoka (left upper in the map), the packets are 
routed to the Internet from Dojima  (left down in the map and peering 
point) by OSPF.
In that case, CR cannot be involved in the path from CN to MR... The 
packet are not route-optimized and routed to the MR's HA at the end.

regards,
ryuji