Hi all, <br><br>I originally posted my message (see below) to the xorp-hackers list, but I think it might be more appropriate on this list, so I am sending it here also. <br><br>-Andreas<br><br><div class="gmail_quote">---------- Forwarded message ----------<br>
From: <b class="gmail_sendername">Andreas Voellmy</b> <<a href="mailto:andreas.voellmy@gmail.com">andreas.voellmy@gmail.com</a>><br>Date: Feb 6, 2008 2:25 PM<br>Subject: from and to blocks of policy terms<br>To: <a href="mailto:Xorp-hackers@icir.org">Xorp-hackers@icir.org</a><br>
<br><br>Hi, <br><br>I've read the XORP user manual and Bittau & Handley's paper on "Decoupling Policy from Protocols" and I am still a bit confused as to how the policy terms work. <br><br>I understand that policies that do route redistribution, like "from {protocol:rip} to {neighbor: <a href="http://192.168.1.2" target="_blank">192.168.1.2</a>} then {accept}" make sense as an export policy, but it's not clear to me why a policy term has both from and to blocks when it is not doing route redistribution. For example, take the following policy term: <br>
<br>from {} to {neighbor: <a href="http://192.168.1.2" target="_blank">192.168.1.2</a>} then {accept}<br><br>As an export policy I understand that it would advertise all routes to neighbor <a href="http://192.168.1.2" target="_blank">192.168.1.2</a>. However, if it were an IMPORT policy, what would it mean? More generally, what do any conditions in the to block mean in an import policy? <br>
<br>Similarly, what does "from {neighbor: <a href="http://192.168.1.2" target="_blank">192.168.1.2</a>} to {} then {accept}" mean as an export policy? What does any condition in the from block of an export policy mean? <br>
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Thanks!<br><font color="#888888"><br>-Andreas <br>
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