Subject: [nemo] About section 2.5 in ro-problem-statement

From: Julien Bournelle <[email-masked]>
Date: Wed, 6 Jul 2005 14:33:43 +0200

Hi all,

 I take a look at draft-ietf-nemo-ro-problem-statement-00.txt.

 I basically have 2 questions concerning section 2.5:

 In the first paragraph, it is written that:

 "When Mobile Routers have no prior knowledge of their peers..."

 In this sentence, "peers" means other MRs, MNNs, both ?

 Then it is written that: "In particular, it is possible to adopt a tit
 for tat (T4T) strategy and forward traffic unless the other party
 proves to be uncooperative when it is sollicited." 

 I don't clearly understand this sentence. If we consider the Figure 1.
 MR3 uses MR2. So MR2 forwards traffic for MR3. But I don't see how MR3
 can be uncooperative from MR2 perspective. Could you clarify this ?

 regards,

-- 
julien.bournelle at int-evry.fr

---

From: Chan-Wah Ng <[email-masked]>
Date: Wed, 06 Jul 2005 22:12:47 +0800

Hello Julien,

First of all, thanks for reading the draft, and bringing comments.
See my response in line (I would expect Pascal to give you better
answers, but let me attempt any way).

>  In this sentence, "peers" means other MRs, MNNs, both ?

Used in this context, "peers" should refer to other Mobile Routers who
are trying to do the same thing (i.e. trying to "cooperate to improve
the network availability for all parties").

>  can be uncooperative from MR2 perspective. Could you clarify this ?

What this sentence tries to illustrate is that mobile routers may wish
to relay each others packets to the Internet.  Remembering they are
mobile, there may be times when MR3 is attached to MR2, and times when
MR2 is attached to MR3.  So when MR3 is attached to MR2, should MR2
prove to refuse to provide connectivity to MR3, when the times comes to
MR2 attaching to MR3, MR3 may refuse to help.

/rgds
/cwng

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From: Julien Bournelle <[email-masked]>
Date: Wed, 6 Jul 2005 16:28:51 +0200

Hi,

 thanks for your quick answer,

 comments inline,

> the network availability for all parties").

 ok
> MR2 attaching to MR3, MR3 may refuse to help.

 how MR2 knows that it is forwarding traffic for MR3 and not from a
 MNNs ? I mean that your text implies that the MR2 is able to detect
 that MR3 is a Mobile Router and not a MNN. 

 (maybe by inspecting BUs sent from ingress network ?)

 regards,

---

From: Chan-Wah Ng <[email-masked]>
Date: Thu, 07 Jul 2005 10:17:11 +0800

>  that MR3 is a Mobile Router and not a MNN. 

Lots of ways.  Layer 2 identities, etc.

>  (maybe by inspecting BUs sent from ingress network ?)

Perhaps.  The point is that there are scenarios where security policy is
forbidding traffic from visitors to be tunneled into the home network,
and RO may be able to resolve this.  The T4T example is, just that, an
example.  The specifics of how the example will work is hypothetical at
best, and would be clouding the point of the sub-section.

/rgds
/cwng