Someone is killing the Internet. Since you probably use the Internet everyday you might find this surprising. It almost sounds silly, and the reason is technical, but our crack team of networking experts has examined the patient and made the diagnosis. What did they find?
- Diagnostic team: the Packet Pushers gang (Greg Ferro, Jan Zorz, Ivan Pepelnjak) in the podcast How We Are Killing the Internet.
- Diagnosis: invasive tunnelation. (tubes anyone?)
- Prognosis: even Dr. House might not be able to help.
- Cure: go back to what the Internet was; kill the tunnels; route IPv4 and IPv6; have public addresses on everything; disrupt the telcos.
This is a classic story in a strange setting--the network--but the themes are universal: centralization vs. decentralization (that's where the telcos obviously come in), good vs. evil, order vs. disorder, tyranny vs. freedom, change vs. stasis, simplicity vs. complexity. And it's all being carried out on battlefield few get to see: the infrastructure of Internet.
Our emergency medics for this battle, in this free flowing and wide ranging podcast, pinpoint the problem: through IPv6 and telco domination we are losing the original beauty and simplicity of the Internet. In summary:
We've effectively turned the Internet into a place with a bunch of tunnels infected with many layers of translation points. This is not the Internet we were thinking of of 20 to 30 years ago. We are stuffing IPv4 and IPv6 packets into a buch of tunnels: MPLS, VPLS, PPoE, PPoA, etc. Just a bunch of tunnels going on. The IETF standards continually talk about tunnels, IPv6 over IPv4 tunnels, carrier grade NAT, 6RD, and even NAT.
In another post, Greg Ferro asks: Shouldn't we replace tunnels with routing and letting the network be a network, not a bunch of tunnels over the backbone? The alternative to tunnelling is routing and that's what the Internet has always been about. Why isn't the industry going back to what the Internet was? Let's have IPv4 and IPv6 on routers and let's have public addresses on everything.
So there are lots of issues here, but the main themes are: 1) tunnels suck 2) centralization vs decentralization.
What are Tunnels?
First, what are these tunnel things? From networking expert Ivan Pepelnjak:
You can talk about tunneling when a protocol that should be lower in the protocol stack gets encapsulated in a protocol that you’d usually find above or next to it. MAC-in-IP, IPv6-in-IPv4, IP-over-GRE-over-IP, MAC-over-VPLS-over-MPLS-over-GRE-over-IPsec-over-IP ... these are tunnels.
Why do Tunnels Suck?
- MTU issues. Different networks have different packets sizes so packets have to be fragmented and reconstituted as they flow through the network. This process is complex, slow, and error prone.
- Visibility. When packets are inside a tunnel you can’t apply your security policies to what is inside the payload.
- Load sharing. You can’t reorder packets inside a flow and within tunnels everything looks like one flow, so you can’t load share across flows.
- Suboptimal paths. Once you put a packet in a tunnel you can’t react to network changes so there’s no guarantee that your traffic is taking the optimal path. It could be taking the worst path, but you have no idea. Tunneling style networks won’t survive a catastrophe whereas the typical adaptive networking will.
- NAT - translation. Why do we have to do that? We are introducing another layer of NAT called carrier grade NAT (evil). NAT broke a security model based on unique IP addresses. The IP address is not a unique identifier for a user so there’s no way to identify who is doing the bad thing. All you can do is identify the organization where the IP address came from. We are just playing the blame shifting game.
- Complexity. Overlays, tunnels and NAT bring complexity into a network that creates failure, in multiple modes, in many different ways.
- Centralization. More on this in the next section.
Telephony Thinking is Killing the Internet
Tunneling is about centralization. The Internet is about decentralization. Tunneling creates distributed state because it must be tightly coupled to the core. If you want fast reroute on a failure, for example, you have to tightly couple the edges with the core.
You have to choose one or the other. Centralization or decentralization. The core business of carriers should be bandwidth: transport IP, lay cable, and peer everywhere. Focus on delivering packets instead of layering on higher margin complexity. More bandwidth everywhere. Stop having something over something. Instead, move intelligence to the edge and keep the core simple with fast switching.
The centralization push is coming from the carriers because complex services in the core are high margin services. Layer 2 vMotion, for example, is another example of trying create a high margin product through complexification and centralization.
And then the podcast wraps up with this call to action:
This telephony style thinking and demands to vendors is slowly killing the Internet. Carriers think telephony. They are trying to impose a telephony model over the Internet, which means centralization and complexity. What makes the Internet go around today is telcos connected to each other. We probably can't change telco thinking. Maybe it's time for telcos to close down and go somewhere else.
Related Articles
- CAMPFIRE: THE TRUE STORY OF MPLS and MPLS is Not Tunneling by Ivan Pepelnjak
- Greg Ferro's post on Google+
- BUSTING LAYER-2 DATA CENTER INTERCONNECT MYTHS by Ivan Pepelnjak