Subject: Re: ICMP Tunnel error processing and reporting( was Re: [nemo] Last call for draft-ietf-nemo-basic-support-01.txt)

From: "S. Felix Wu" <[email-masked]>
Date: Wed, 12 Nov 2003 13:58:21 -0800

Dear Vijay,

Vijay Devarapalli wrote:

> good, this is the kind of detailed threat analysis I like to see.
Thanks. Yes, I agree that we should look for something more specific
to the nemo itself.

> I am missing something here....
> 
> if there is a problem with the outer header, the response goes back
> to the MR. the MNN will not get the ICMP error.
> 
> if there is a problem with the inner header, it means the Home Agent
> has already stripped the outer header and some node (could be the
> Home Agent also) is trying processing the inner packet. in this case,
> the nodes send the ICMP error back to the MNN. the Home Agent, when it
> tries to send the ICMP error back to the MNN, tunnels the error to the
> MR. the MR removes the outer tunnel headers and forwards the ICMP error
> alone to the MNN. the MNN will not get information about the tunnel
> between the MR and the HA.

according to the RFC, in some situations, the ICMP message should
also be forwarded to the MNN. But, later (after I sent out my first
email -- appologize for that), I also found that even under these
cases (i.e., the MR needs to send/forward ICMP messages to MNN, the
source of the original packet), the tunnel header information will
be removed according to the same rfc.

Thanks.
-Felix

-- 
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Dr. S. (Shyhtsun) Felix Wu                           [email-masked]
Associate Professor                      http://www.cs.ucdavis.edu/~wu
Computer Science Department                     office: 1-530-754-7070
University of California at Davis               fax:    1-530-752-4767
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