Software Defined Networking - Computerphile

What if the controller fails?

Make ipv6 detail video please

Wait what?

I love Computerphiles explanations. Easy to understand and put onto real life situations.

I want to start SDN. I want to know how to start and what is the first course I should study??
Plz guide me 🤝🌹

Thank you very much @Dr. Richard Mortier for that wonderful explanation and a big thank you @Sean Riley for filming all the Computerphile videos. I always recommend them to my students :D

How to control the any game package through Software Defined Network in a network

A very intelligent man, who finds a way to simplify a very complex concept, so that someone very unintelligent (me), can understand it.

Thank you sir.

I love this channel.

Great video guys.

Is anyone concerned about the controller in an SDN getting hacked and the implications?

So can we see the traditional tcp-ip routing mechanism as a specific case of openflow where the SDN algorithm implemented is spanning-tree?

Sir i need to know whether handoff reduction in cellular network is possible in iot sdn network

Question from 2020, what is considered the current status of SDN? Is a fair amount of public internet traffic running on SDN routers and switches now?

Is it true that we can actually specify the source IP and the action to it here but not in forwarding tables? (i.e: source IP cannot be specified in forwarding tables to apply actions accordingly, instead, you only use destination IP’s and ports to specify actions)

Aren't ACLs designed to permit or deny access based on the IP addresses?

Roooters 😆

Thanks for an amazing quality, love the vids with Dr. Mortier

Any possibility you could back up this video with an addendum that explains how you would implement some redundancy in an SDN?

What are the topics or problems in the networks that the researcher can work on in graduate studies?

Can someone tell me the names of the books on his shelf in the background?

This makes me wish there was a Telecomphile...

So is something like Cisco prime a form of SDN? I was reading on Cisco prime and they were talking about bootstrapping, etc to a network server. So the controller is basically like the config file for a switch, but it covers all the switches instead? Would something like this mean that say you have several Vlans and you bring a PC from Vlan 20 to the shop for work and you normally use vlan 10 will it be able to see the mac address at the controller then say this needs to be in vlan20?

Seems like the move towards a central control is a step backward to towards the police state! Why hasn't IPv6 been allowed out of its cage, the "its too expensive" is the lie the controllers aren't interested in freeing up the internet and giving it more address space anymore than they are interested in releasing the free energy of the quantum vacuum technology. We need smart switches alright but decentralize the switches with the smart contracts of block chain technology and let the internet become the source of an ethical economic system of open information to all humanity.

It almost seems like this just creates more overhead on switches, while this probably wouldn't cause a noticeable slow down in smaller settings, in big corporate offices where you would probably find these kinds of things, it may cause noticeable slow down for instance
If destination IP address is 10.10.10.2 send out of port 3, would require just as much processing time as most protocols, plus if it goes out of port 3, to say a switch with the IP 10.10.10.4 and then it's supposed to send that out of port 6 to 10.10.10.2, why not just use something like EIGRP to let the swiches/routers find everything themselves, not to mention if it has a controller it adds another point of failure that IT staff would need to be aware of and worry about

Do the switches typically get connected directly to the controller, as was shown in the diagram, or would they be connected through the network, and only one or two of the switches would be directly connected?

Look up WMvare NSX for an implementation of software defined networking.

Is this the reason why Googles virtual machines in asia and europe have IP addresses geolocated to the US?

Did he just say dynamically updating firewall rules. hmmmm

I usually use a rooter to clean my sewer pipes, and handle my internet traffic with a router.

I have a CCNA 1 networking exam tomorrow :O

Just so y'all know: By rooters, he means routers.

I hope this technology matures quickly. Although I enjoy the huge $$ as a Network Engineer, but as a Gamer, it's filthy to work with archaic technologies. XP

This gives Big Oppressive Government even easier abilities to censor, block, and degrade what they don't want Us to see.

Great into to the world of SDN. There's definitely enough material to do a mini series about this (SDN protocols like OpenFlow, POF, P4, issues related to centralization, security issues, applications to cloud computing, future internet protocols, alternatives like Contrail, NFV, and etc.). Judging from the comments I've seen so far people are itching for these to be discussed.

I love the 3D visualization of the network

Is the controller not then a single point of failure?

But then, Who, judges the merits of each router variant, for self-consistency, mutual-consistency, new-design consistency...

The main advantage I can see for this is stateful load balancing. Even if just implemented within a datacenter (as opposed to across the whole internet) this could be really advantageous.

Yeah, how about we don't do that for the internet?

Man in the middle attack.

This sounds like a terrible idea for data security and integrity.

Push a policy on to a server, "every time a password comes here send it to me and then i'll forward it" - simplified example.....

Nice! Now the large corporate ISPs can completely control content!

rip protocal

As this guy briefly mentioned, with the STP example, each bridge is essentially operating independently. A network isn't a "thing" it's a loose collection of things cooperating, and in the good days giving the illusion of order. The main reason that a network runs protocols like STP or OSPF is that you can't possibly have a centralized controller, and each device must be able to operate relatively independently.

What happens if the controller breaks? Make it redundant? Fine, what happens when the controllers lose connection between them and each of them thinks the peer is dead and assumes master role? You have a drawing there where the controller connects to the switches, that in itself is a network. How does that work? Is it a different network, or is it overlayed on top of the regular network? What happens when it fails? What happens when a centrally controlled network is split into multiple islands? Do they islands still operate independently? If they have connection to the controller maybe, but what if they don't? What happens when a device that has lost connection to the controller tries to collaborate with devices that are still connected to the controller (or does it give up trying to do anything altogether, that seems lackadaisical but it may be best)? I admit that in a datacenter, it would be possible to build a simple, reliable, robust, somewhat redundant network that would connect the controller to the network equipment, and then you would have simplified network by orders of magnitude, however, how do you do this if you are a service provider? Do you operate another control network to manage your data transfer network or do you overlay your control network over your data transfer network, in which case, what happens when something breaks, losing data transfer capability is one thing but loosing control over your network sounds much worse? In a datacenter it may be that the environment is stable and failures relatively rare, but in a network that spans a continent or more, failures will be a common thing. You can not try to avoid them, you must design a network that can operate despite these failures.

The most simple tasks, become unbelievingly complicated when they can not be solved by one device but rather a loose collection of devices cooperating, and each of them can loose connection, or malfunction in countless ways, not to mention wilful attempts to disrupt a networks operation.

Any one given device can fail, and it will not be the end of the world. If, let's say, there is a hardware failure of a memory module in a server, it is acceptable that that server will find itself in an irresolvable state of inconsistency, in which case it should stop, and possibly try to start again and if following the POST it is deemed that the server can safely operate with the remaining function components, then it should continue to do so. But what if a network controller fails? Then the entire network needs to be rebooted? That's unfathomable even in a datacenter or office network, let alone an ISP network or the entire internet? You probably plan to operate multiple controllers, but how do you ensure accurate and timely takeover of the role of a failed controller? And what do you do when the controllers disagree? Which of them is "right"? Do you run an odd number of controllers and then have them vote democratically? But who is the arbiter of that election? By doing this haven't you just shifted the problem to the arbiter? What happens when this fails?

This distributed nature of networking makes it such a difficult and interesting subject, if it were possibly to centrally control it would be very simple, but I can't for the life of me imagine how you can do that (though the fact that SDN exists means that this is possible and that I'm just lacking in imagination).

Any of the above questions I would like to see answered in future computerphile videos!

Sounds like Cisco iOS.

Good timing, I have an exam in this next Friday

>yaaaay woooo more centralized control on internet infrastructure

Yeah...how about no.

We just covered this subject in university today