<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
One can choose to require a router to generate a NACK in this case.
However, if this is a <br>
communication/transmission error, it's best for the consumer to
timeout and resend the interest. <br>
Otherwise, it could be due to:<br>
(1) an implementation bug at either router or consumer -- probably
best left alone,<br>
or<br>
(2) an attack -- adversary feeds incorrect content to router. If
this is an on-path adversary <br>
(e.g., a subverted/malicious upstream router), sending a NACK is
useless. A router that <br>
detects the error is better off trying another route.<br>
<br>
Another issue is how to secure the NACK itself. If not secured, this
kind of NACK can be<br>
used as a DoS attack (anyone can generate it). If secured (e.g.,
signed), the originating<br>
router would incur some non-negligible computational burden.<br>
<br>
Cheers,<br>
Gene<br>
<br>
p.s. FYI, for a discussion of some NACK-related issues in ICN, take
a look at:<br>
<a class="moz-txt-link-freetext" href="http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=7288477">http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=7288477</a><br>
or <a class="moz-txt-link-freetext" href="http://arxiv.org/pdf/1503.02123.pdf">http://arxiv.org/pdf/1503.02123.pdf</a><br>
<br>
<pre class="moz-signature" cols="72">======================
Gene Tsudik
Chancellor's Professor of Computer Science
University of California, Irvine
</pre>
<div class="moz-cite-prefix">On 6/28/16 1:47 AM, Tanusree Chatterjee
wrote:<br>
</div>
<blockquote
cite="mid:CAOeyPyQ=2H0-Xk2EW9bzN6J8nqHrLVGuQ4+grHBw5Voqw+m5ew@mail.gmail.com"
type="cite">
<div dir="ltr">If a data packet is modified and detected during
verification, can forwarder send a NACK. How the data can be
resend in this case? If consumer is not satisfied it has to send
the same interest again, is there any other way out to get the
data which may not been correctly received due to some
modification. <br clear="all">
<div><br>
</div>
-- Regards,<br>
<div class="gmail_signature" data-smartmail="gmail_signature">Tanusree
Chatterjee<br>
<br>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Ndn-interest mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Ndn-interest@lists.cs.ucla.edu">Ndn-interest@lists.cs.ucla.edu</a>
<a class="moz-txt-link-freetext" href="http://www.lists.cs.ucla.edu/mailman/listinfo/ndn-interest">http://www.lists.cs.ucla.edu/mailman/listinfo/ndn-interest</a>
</pre>
</blockquote>
<br>
</body>
</html>