http://mars.merhot.dk/w/index.php?action=history&feed=atom&title=Cisco_IOS_Wildcard_maskCisco IOS Wildcard mask - Revision history2026-06-10T21:04:22ZRevision history for this page on the wikiMediaWiki 1.29.0http://mars.merhot.dk/w/index.php?title=Cisco_IOS_Wildcard_mask&diff=23529&oldid=prevRael at 13:13, 5 September 20122012-09-05T13:13:41Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 13:13, 5 September 2012</td>
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<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Terry Slattery CCIE#1026 (The fist one to pass a CCIE exam)<ref>http://bigevilsciscoworld.wordpress.com/2011/04/16/wildcard-mask-how-and-why/</ref>:</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Terry Slattery CCIE#1026 (The fist one to pass a CCIE exam)<ref>http://bigevilsciscoworld.wordpress.com/2011/04/16/wildcard-mask-how-and-why/</ref>:<ins class="diffchange diffchange-inline"><br/></ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>"I had to jump in on the wildcard mask topic, because the idea of inverting the subnet mask has been around since the early days of Cisco training. I asked Kirk Lougheed, one of Cisco’s founders and the principal software developer at the begining, about why the wildcard mask uses the bits it does (i.e. 1 = don’t care). He told me that it was just a decision he made one day and that it could have gone either way."</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>"I had to jump in on the wildcard mask topic, because the idea of inverting the subnet mask has been around since the early days of Cisco training. I asked Kirk Lougheed, one of Cisco’s founders and the principal software developer at the begining, about why the wildcard mask uses the bits it does (i.e. 1 = don’t care). He told me that it was just a decision he made one day and that it could have gone either way."</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline"><br/><br/></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">Scott Morris<ref>https://learningnetwork.cisco.com/thread/3194</ref>:<br/></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">Access Lists actually came before subnet masks. Remember way back when we lived in an evil classful world. So back in like 1985, when access-lists came about it was actually easier to code in assembler to do a NAND operation instead of an AND. Thus the wildcarding.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline"><br/><br/></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">Francois Labreque<ref>http://www.velocityreviews.com/forums/t297267-why-does-ospf-use-wildcard-mask-bit.html</ref>:<br/></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">Access-lists and ospf areas use wildcard masks because back in the days of the AGSes, every CPU cycle counted and using a wilcard mask makes the logic of deciding if a packet matches a couple of cpu cycles faster.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>==References==</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>==References==</div></td></tr>
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</table>Raelhttp://mars.merhot.dk/w/index.php?title=Cisco_IOS_Wildcard_mask&diff=23528&oldid=prevRael: Created page with "Terry Slattery CCIE#1026 (The fist one to pass a CCIE exam)<ref>http://bigevilsciscoworld.wordpress.com/2011/04/16/wildcard-mask-how-and-why/</ref>: "I had to jump in on the wild..."2012-09-05T13:00:51Z<p>Created page with "Terry Slattery CCIE#1026 (The fist one to pass a CCIE exam)<ref>http://bigevilsciscoworld.wordpress.com/2011/04/16/wildcard-mask-how-and-why/</ref>: "I had to jump in on the wild..."</p>
<p><b>New page</b></p><div>Terry Slattery CCIE#1026 (The fist one to pass a CCIE exam)<ref>http://bigevilsciscoworld.wordpress.com/2011/04/16/wildcard-mask-how-and-why/</ref>:<br />
"I had to jump in on the wildcard mask topic, because the idea of inverting the subnet mask has been around since the early days of Cisco training. I asked Kirk Lougheed, one of Cisco’s founders and the principal software developer at the begining, about why the wildcard mask uses the bits it does (i.e. 1 = don’t care). He told me that it was just a decision he made one day and that it could have gone either way."<br />
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==References==<br />
<references/></div>Rael