Private VLAN’s and PVLAN Edge

Overview of attacks & countermeasures

  • IP spoofing – IP source guards, PACL
  • STP Spoofing – BPDU guard, Root guards
  • MAC Spoofing  – Port Security , Static CAM table entries
  • DHCP Server Spoofing – DHCP Snooping
  • ARP Spoofing – ARP inspection (ASA + IPS )
  • VLAN Hopping – Disable auto DTP *
  • CAM Floods – Port Security , 802.1x
  • DHCP Starvation – DHCP Rate limiting

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What Cisco Output Commands Are In A “Show Tech” On The Nexus 5000?

Have you ever wondered what commands were actually in a “show tech” on the Nexus 5000? Well, I did. There seems to be a lot of info in there, and there really is. I compiled a list of commands that a show tech runs on a Nexus 5000 and have listed them below. Enjoy!

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Switchport Errors – Determining the cause

Many times we (network engineers) hear the complaint “the network is working, but it is terribly slow”. This is often one user’s perception of a perfectly working network however, other times there is something to the complaint.  One thing to check is if that particular user’s switchport is reporting any errors.  Let’s take a look at the error counters on a typical switchport.

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ip local-proxy-arp

Recently, while trying to enable proxy arp on an interface, I noticed the presence of the sub interface command ‘ip local-proxy-arp’.  I was a little puzzled and the googling I did didn’t help me get a better understanding of the concept.  Bewildered, I turned to my favorite network forum, and asked if someone could help out with an explanation…

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BGP Looking Glass Database

Welcome to the biggest and most updated BGP Looking Glass and Traceroute list in internet You´ll find out 1150 Looking Glass Servers updated at 09/09/2017. If you find a broken link, or you want to announce a new looking glass site, please feel free to send us an email to

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