And today we can't do that? That's what I mean by, obsolete before it was deployed. IPV6 was designed in an age of lesser storage/higher cost memory and embedded processor power.
And no, not every one. Store the ones routed thru you. That's all you need. Look them up and keep a cache.
Every node on a local network would need to be able to know whether another node is on the local network (unless you want all traffic to go through a router). So do you send arp requests for every ip you try to contact? Distribute a list through DHCP?
All upstream routers needs to know about your node. So every time someone somewhere in the world connects a new device a message gets sent up to the core routers of the internet? And the core routers needs to keep track of routing tables in the size of billions and be able to look entries up in nano seconds.
Thanks, yes those seem like possible algorithms that would work great with today's technology.
And yes, every time new traffic appears at a 'core' router, entering it into a cache would be another great algorithm. But they do that now, so no patents for us.
I love it when somebody 'objects' to a plan, then proceeds to describe the solution succinctly.
> every time new traffic appears at a 'core' router, entering it into a cache
How does that new traffic appear in the core router? I has to appear in every core router, otherwise hosts connected to a a core router which didn't receive that traffic recently wouldn't know how to route to your host. So the answer would be flooding, which is extremely wasteful of bandwidth and processing power. Also, it's a cache, which means it expires, so you have to flood the host announcements constantly (and even if it doesn't expire, you have core routers going down and being replaced). Once you think over all the details on how to fix these issues, what you end up with is basically a routing algorithm, like BGP or others, only replacing the "network" by a single host.
And once you arrive at a routing algorithm, consider that routing algorithms have a long history, and have already received a lot of research. That naive "flooding" algorithm is basically RIP, one of the oldest routing algorithms; there are good reasons why most people don't use RIP anymore.
Sure, lots of history. Which is why new solutions are such a hard sell - everybody quote an authority and concludes 'it has to be this way'.
Traffic appears at core routers because it already gets send there by peripheral routers as a gateway. Sharing routing information between peer routers is not unsolvable nor likely onerous.
Strawman solutions (flood constantly) are being deliberately dense. I suspect because, folks are so very comfortable with what they know, and so very unwilling to extend themselves. How we got IPV6 in the first place. Which isn't working either.
> Traffic appears at core routers because it already gets send there by peripheral routers as a gateway. Sharing routing information between peer routers is not unsolvable nor likely onerous. Strawman solutions (flood constantly) are being deliberately dense.
If by "sharing routing information between peer routers" you mean that, when a router learn of a new host, it shares that information with its peer routers, which then share that information with their peer routers, that is flooding. Without flooding, the traffic would not appear at every core router, which means most routers would not know of your host.
> I suspect because, folks are so very comfortable with what they know, and so very unwilling to extend themselves.
I once seriously considered how to make an Internet-scale non-hierarchical routing protocol, where the host identifier was a cryptographic hash of its cryptographic public key. The reverse path is easy; once A has successfully sent a packet to B, all routers in the middle know how to get from B to A. The forward path (from A to B) is the hard one. Every router knowing every host is non-viable; consider, for instance, what happens when my phone roams from the WiFi to the LTE and back (which happens many times per day) - if every router had to know of that change, for every roaming phone in the world, it would be enough to overwhelm all the links between them, not to mention their CPUs. I came to the conclusion that the amount of propagation of the route updates must be limited for it to be viable, so having every router know of every host is not possible. Either the routing information must be summarized somehow (which is what the hierarchical routing used with IPv4 and IPv6 does), or some other way which does not involve the routers (for instance, path routing, like MPLS) must be used.
That is, I'm not rejecting your idea because I "feel comfortable" with hierarchical routing, I'm rejecting your idea because I've already given it (or something like it) serious consideration, and found it harder than what I had initially thought.
No I don't mean the worst interpretation thinkable, when I say 'share that information'.
Glad to see you've thought of the issues. Now lets brainstorm solutions.
A DNS-style authority with the answer to the routers' questions perhaps. Updated by the leaf router with some route coloring info for a new leaf node perhaps. Inquired upon cache miss by core routers? Aged out for frequent updating (roaming, unique ID per connect, and other short-lived routes).
lookup complexity is a very real cost factor for routing equipment and it's increasing faster (because interface speeds are increasing and prefixes are getting smaller) than hardware capabilities are .
so no, we can't make every router cache every host id.
Sure we can. Especially UUIDS. They have a normal distribution of values (bits are random) so an associative cache would match entries faster than current devices can match highly-repetitive prefixes.
This is an example of what the IPV6 folks suffered from. They could only see the issues of previous implementations, and took an incremental step along those solution axes. Instead of considering future trends (cheaper memory/processing power) and "skating toward the puck". Instead they followed the puck, and ended up well behind.
A cache with a few billion devices in it will be too large, and as soon as your cache may be large enough you will have even more devices.
Also, for routing an address hierarchy is nice because of the O(log n) properties the address tree gives you. UUIDs do not do that, but subnets do. For the endpoints and smaller routers near the edges it is even more advantageous, those only need to know a few local prefixes, the rest goes to the next gateway. With UUIDs, every devices needs to learn all the addresses behind it, quite an impossible task, even if the lookup were fast and small enough for its cache.
Again, for core routers, not at all. The UUID is random; it has the same order of lookup or better; endpoints need only the local routing info in the same way. Caches need only hold active routes, which is orders of magnitude smaller.
The idea that its 'impossible' is 20 year old thinking. That's my whole point. We've wandered into a disappointing, underpowered solution that's not gaining traction. While real future-proof solutions exist right in front of us.
It doesn't, prefix lookup is solved faster and cheaper in hardware via CAM or TCAM, maybe combined with hashing, because you can limit yourself to a prefix, discarding the rest of the address.
Even if you are right about the endpoints (which only need to know all devices in their specific subtree), as soon as you get to a part of the network where there is no longer just a limited tree below a given router hierarchically, you need a global view of all addresses. This view has to be current, correct and total. That is impossible to achieve, even if the lookup itself would work (which it won't, a conservative estimate of 4 billion active internet devices take up 64GB just for their addresses, not even including routes and metrics). You just cannot search those 64GB fast enough for each packet you are passing through your links (remember, even saturating 10GE in software is hard, and routers do have a lot of those ports in 40 or 100GE...).
Nobody suggests 'just searching' 64GB (which is not an unreasonable amount of memory today for a core router). Associative lookup is required, as is the case today. Nothing very new is required to create even larger (hashed) associative memories to manage this problem.
> Caches need only hold active routes, which is orders of magnitude smaller.
What do you do when there's no active route? If a router receives a packet from 192.0.2.1 to 198.51.100.2, but the router has never received a packet from 198.51.100.2, how does it know to which of its neighbors it should send the packet?
We resolve arbitrary names with DNS to a global identifier (an IP address), but for routing, what you need is a local identifier (which neighbor router to send the packet to), which means every router or set of routers would need its own database, and each database would need to know about every host in the world. This is exactly what we have nowadays with BGP, only with networks instead of hosts: every core router or set of core routers has a database which knows about every network in the world, and tells which neighbor AS to send the packet to.
Also, DNS caches are just locally used small subsets. Global lookups are again hierarchical, thats why it is called _domain_ name system. Thats why there are dots in the adresses. Also, DNS lookups are rare compared to IP route lookups, you look at DNS for every connection at most, limited by the TTL for caches. Route lookups happen for every packet.
And no, not every one. Store the ones routed thru you. That's all you need. Look them up and keep a cache.