If you don't know what a software-defined network is or how it works, read the linked post. These networks have wide-ranging implications, both positive and negative.
Example: Throttling and bandwidth quotas.
Implementing bandwidth quotas has been, in the past, something costly, inefficient, and a major consumer annoyance. But now, it comes practically out-of-the-box for internet service providers.
Example: Large-scale network setup and administration.
Now for the good part: network administration has never been easier! Forget the Cisco Certifications and other expensive, year-long training – now, even an amateur hobbyist should be able to set up a big-data-scale network cluster without much difficulty.
Now that's a big change in the IT landscape behind the scenes – and one that, in a time where data analysis and volume is of growing importance, is bound to change the competitive field!
Originally shared by +Guido Stepken
Software Defined Networking – Everybody needs it. Nobody understands it. We explain it!
Beginning with well known fact, that routers, switches can be configured to work in a fail save mode, being redundant (see BGP – Border Gateway Protocol) and several selected ports can be switched to build their own 'collision domain', called VLAN, there was an urgent need to have VLAN groups depending on protocol basis (e.g. port 80, http) for e.g. load balancing.
Directly after CISCO™, JUNIPER™ did implemented that, customers were asking for firewalling (IP masquerading, NAT), bandwidth control for realtime services, like video streaming (Netflix®), telephony (Skype™), video conferencing, decentralized server clusters. Things became complex, more and more software controlled. Good old ASICS, doing well in routers, switches until now, couldn't solve these complex tasks any longer.
So some CISCO® employees founded JUNIPER®, building up routers, switches with FreeBSD and ASICS as 10/100 GbE network card, gaining significant market share.
Now, something magic happend. Some guys did find out, that memory I/O of a simple INTEL® Core™ i5 is fast enough to care about everything running – Linux!
Have a look at next picture: Jetway NF9G-QM77 plus Jetway ADE4INLANG 4 Port PCI-E daughter board, together available for far under $300. (Available at: http://www.jetway.com.tw/jw/ipcboard_view.asp?productid=996&proname=NF9G-QM77 ). For more ports see cheap $20 TP-LINK 8 port switch (see diagram).
With that hardware you have everything in one: Router, switch, VLANs, redundancy, bandwidth control, firewall.
But not only that. Running isolated in secure LXC/Docker™ containers, you can start e.g. a 'silent, reversed proxy' like Varnish or Squid. Means: All bypassing traffic (http, ftp, video streaming) will be cached in the Linux machine, being internally rerouted (#ip route add…), massively reducing physical traffic going through your network of connected machines. Akamai® is known to offer such 'caching proxy' services, massively reducing traffic on servers e.g. at "patch day".
Why 6 ports? 6 ports are the minimum and sufficient number of physical ports needed to build up even largest redundant logical networks. See http://en.wikipedia.org/wiki/Network_topology
It's important to understand, that physical topology and logical topology, real traffic flow and logical trafic flow as well as real routing/switching and virtual routing/switching now totally have been decoupled. See diagram.
With , a physical port in california can build a logical, (firewalled) collision domain with some physical ports in europe, with or without proxy cache somewhere in between to reduce traffic. That's, why companies, like Netflix® with their global server farms and global million customer base can fullfil their business, do exist.
So, in fact, just by connecting some handful of these magic Linux SDN machines you can throw out almost all network hardware, you ever had.
Now you might ask: Who, the hell, is able to administrate such complex SDNs? From my point of view, you have exactly two choices:
Either install ™ ™, pay for expensive courses learning to administrate that stuff, or use OpenWRT zero administration machines. Based on B.A.T.M.A.N. protocol, just buy some new hardware, plug in, start and everything is configured automatically. It's building up a professional, highly redundant grid network – automatically. No special knowledge required.
Buying "ready to use" ® or ® hardware, IMHO, is no option. U.S. NSA is, in fact, spying everywhere (See E. papers), silently copying even your internal companies traffic onto servers in the U.S.A., (self) authorized by U.S. law (see U.S. 'patriot act'). Alternatively buy open sourced Linux machines.
What can not be combined on a single manuscript page, is not been thought through yet ready for decision. (Dwight David Eisenhower)