routerjockey

Using Deny ACEs in your PBR ACL on your Nexus 7k

Quite a while ago I had a need for some network duct tape… Policy Based Routing while useful should only IMHO be used as a temporary fix. But as you know, temporary things soon …

Cisco Nexus 2000: A Love/Hate Relationship

My feelings towards the Nexus 2000 Fabric Extender (FEX) are hardly a secret. The myriad of design choices and platform limitations present engineers with some rather difficult …

QinQ: IEEE 802.1Q Tunneling

In situations where service providers want to offer transparent LAN services that preserve a customers VLAN tags across your Layer-2 network, this amendment to the IEEE 802.1q …

Network Duct Tape Gone Wrong

As many of you may know, I’m in the middle of a huge network redesign, last week our new firewalls finally arrived and it became time for us to start migrating services onto the …

Nexus 7000 vPC Features

Next generation data centers across the world are taking advantage of Cisco’s Virtual PortChannel. As of recent, I’ve moved our core to a pair of Nexus 7010s running …

NX-OS 5.2(1) for the Nexus 7000

Rather quietly, at least I never heard anything, on July 29th, Cisco released NX-OS Version 5.2(1) for the Nexus 7000 platform. (and the world rejoiced) This long awaited revision …

SVI Autostate

Switch Virtual Interfaces, or SVIs on Cisco IOS use a feature called autostate to determine the interface availability. By default an SVI will show an up/down (Status / Protocol) …

Nexus 1000v – Out of Ports on a Virtual Switch?

Yesterday, work presented an interesting issue I wanted to share with everyone. While configuring a new virtual machine one of our systems engineers was presented with an issue he …

Introduction to the Nexus 1000V

The Nexus 1000V is a software-based Cisco NX-OS switch that integrates into VMware vSphere 4 and operates inside the VMware ESX hypervisor. With the 1000V your virtual servers have …

Nexus Virtual Port Channel (vPC)

The Nexus 7000 and 5000 series have taken port-channel functionality to the next level by enabling port-channels to exist between links that are connected to different devices. …

Introduction to Private VLANs

The concepts behind Private VLANs are in fact rather simple, but it is quite easy to get discombobulated in the details. In their simplest form, PVLANs can dissociate ports within …

Measuring Cable Lengths on a Catalyst Switch

A while back, I was playing on a 3750 switch in a customers lab and came across something I’ve never seen before. It seems that some Cisco switches have a built in …

Using Discontiguous Wildcard Masks in ACLs

Unlike subnet masks, wildcard masks allow you to use discontiguous bits which enable you to match on a range of values. Using these within routing protocols is typically frowned …

Switching