Tag Archives: routing

Cisco Switch Wireshark Packet Capture

Posted on September 23, 2018 by

One of the most fundamental troubleshooting concepts in all of IT is to capture packets and review the data as it flows over the wire. Historically the easiest way to do this was to configure some type of SPAN port on a switch to copy the traffic to your pack capture device. With today’s less expensive and more powerful hardware it should come as no surprise that this functionality is now available on network hardware it’s self. Continue reading →

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Understanding Prefix Lists

Posted on April 3, 2014 by

When filtering and manipulating routing protocols and routing updates there are a number of options on the Cisco platforms we as engineers can take advantage of.  In a previous post I briefly discussed the use of standard ACL’s to filter updates.  ACLs filter every packet, or in this case advertised network, that falls within the range is specifies.  This is useful for all or nothing or specific inclusions but does not allow us to us easily filter or permit based on the actual prefix length, ie subnet mask length.  Enter prefix lists. To begin the discussion lets establish a topology … Continue reading →

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EIGRP Route Filtering with ACLs

Posted on March 11, 2014 by

There are a number of reasons to implement route filtering. The filters can be used to control what routes are sent as well as what routes are learned from a neighbor. With ACLs the configuration is very flexible so just about anything is possible! Continue reading →

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