What is Software Defined Networking or SDN?

What is software Defined Networking:

Wikipedia Says This

I have found that all of the major players are bringing out products that qualify for a type of Software Defined Networking.  This is great because as Networking Administrators and Networking Engineers

we can use controller based configuration in order to deploy networks faster and with more ease. I’m also looking at this in terms of rolling out entire servers, complete with networking, in an environment in a short amount of time. I can’t wait until we get our hands on some of the SDN gear!

DreamHost Uses SDN

Cisco Open Network Environment – Cisco Systems.

Software Defined Networking for increased agility – Juniper Networks.

Error Device ae1 Not Found

I recently ran into a problem on an EX series switch – after already setting interfaces ae0 ae1 and ae2 up.


Here was my configuration:

[email protected]# show interfaces ae1
aggregated-ether-options {
    minimum-links 1;
    link-speed 10g;
    lacp {
        periodic fast;
unit 0 {
    description lab-mx1-ae1;
    family ethernet-switching {
        port-mode trunk;
        vlan {
            members 800;

The problem was that after I had set these interfaces up I was getting this error on ae0, ae1 and ae2

[email protected]# run show interfaces ae0 statistics
error: device ae0 not found

[email protected]# run show interfaces ae1 statistics
error: device ae1 not found

[email protected]# run show interfaces ae2 statistics
error: device ae2 not found

This is really easy to overlook but I had missed an important step. I needed to allow a certain amount of aggregate devices.

set chassis aggregated-devices ethernet device-count 100

I set this to 100 because I did not see any use in having to add more interfaces to this later on.

Problems after removing a node from a virtual chassis


After removing the EX-4500 from a virtual chassis configuration, I ran into a few problems within the config. I noticed something in the configuration that I thought was strange.

[email protected]# set system commit factory-settings reset-virtual-chassis-configuration

In order to get the node working properly after removing it from the cluster, I had to issue three commands. Again making sure that I am in configure mode.

A. Revert the system to factory default configuration
within the CLI.
[email protected]# load factory default

B. The key here is to make sure that this configuration
is ran in order for the configuration to take effect
[email protected]# delete system commit factory-settings

C. Commit the modified default configuration file:
[email protected]# commit

Juniper’s knowledgebase article is available here: http://kb.juniper.net/InfoCenter/index?page=content&id=KB11159