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Ethernet History Deepdive – Why Do We Have Different Frame Types?

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Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#41

Post by FuriouslyAdrift »

londons_explore wrote: post #36

I wish layer 2 and layer 3 were 'refactored' to force all links to be point to point, which they effectively are in the modern world. When was the last time you saw ethernet frame collisions because you used a hub not a switch? We'd get rid of the idea of a broadcast domain. We'd get rid of Mac address and ARP. Switches and routers would become the same device. We'd just use ip addresses for routing, and the 'next ho…

All wifi is a giant collision domain. Also, each segment of a wired network is a collision domain.

What you are describing is more in line with MPLS or Infiniband.

I agree with you frustration. I prefer to design networks that start routing right at the access port or even using an agent, virtual network port, or VPN endpoint at the client or application (like QUIC), but that is very expensive from a resource standpoint.

IPv6 is also another way to get closer to what you are describing.

In my perfect world, we'd move to something like a mashup of MPLS and HIP (https://en.wikipedia.org/wiki/Host_Identity_Protocol)

If want to study something more "routed" and more point to point, look at private mobile networks (5G).

What we don't want is more layers of abstraction... that's making every slow, brittle and impossible to troubleshoot.

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#42

Post by FuriouslyAdrift »

akira2501 wrote: post #30
mannyv wrote: post #25

One thing that isn't mentioned is that the physical layer at the time was 'flat' ie: a network had a shared wire. That means bus arbitration (to prevent collisions) was a big deal. Token ring solved that by passing tokens, which presumably guarantees latency. I believe Ethernet just raised a line high, and it was up to everyone to respect that. Of course that changed when switches came out. I have a 10/100 hub in a c…

> I believe Ethernet just raised a line high, and it was up to everyone to respect that. It's actually much simpler than that. When you transmit you also listen. If what you hear is not what you sent, there is a collision, and you backoff.

Exactly. CSMA/CD (carrier sense multiple access with collision detection)

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#43

Post by addaon »

londons_explore wrote: post #36

I wish layer 2 and layer 3 were 'refactored' to force all links to be point to point, which they effectively are in the modern world. When was the last time you saw ethernet frame collisions because you used a hub not a switch? We'd get rid of the idea of a broadcast domain. We'd get rid of Mac address and ARP. Switches and routers would become the same device. We'd just use ip addresses for routing, and the 'next ho…

> When was the last time you saw ethernet frame collisions because you used a hub not a switch?

10base-T1S is just beginning to ramp up in the automotive industry, which modifies the super-successful 100base-T1 to be cheaper by (a) allowing cheaper PHYs; (b) allowing cheaper endpoints due to the lower data rate to handle; (c) allowing lower-spec single twisted pair wiring; and ... (d) allowing multi-drop. This is intended to allow Ethernet to push down into the space that CAN-FD is currently occupying, and looks likely to succeed, at least in some niches.

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#44

Post by Hikikomori »

p_l wrote: post #33
Hikikomori wrote: post #24

Earlier quoted context omitted.

Would call it stretch to say it was widely used by ISPs. Some old ones may still be using integrated IS-IS as their IGP (early OSPF had scaling issues and complicated solutions for that), but that's nothing like widely using the ISO stack. But they might have used IS-IS it to route NSAP in their network at some point in time to manage ATM-era equipment, the ISP I worked still had some ctunnels for that purpose, I dou…

It was still widely used for IPv4 and v6 in 2000s. ex telco engineer told us that two major reasons was that IS-IS was simply more efficient, and that they didn't require IP communication between routers - meaning troubleshooting and management was easier than providing p2p routes for IP-based protocols.

It's still widely used, among old ISPs because why switch when it's just as good or better than the alternative and your engineers know it best. But it's not the whole stack as implied in the first reply.

It was popular primarily because OSPF didn't scale well with hundreds to thousands of routers with the minimal CPU power even large core routers had.

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#45

Post by kridsdale3 »

thfuran wrote: post #21
throwup238 wrote: post #18

Earlier quoted context omitted.

> I wish we could have another and bump the packet size. That's why I'm in full support of a world ending apocalypse that allows society to restart from scratch. We've made so many bad decisions this time around, with packet sizes being some of the worst.

As long as we also make sure electrons are positively charged this time.

Then I'm going to be really confused about positrons!

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#46

Post by ninkendo »

londons_explore wrote: post #36

I wish layer 2 and layer 3 were 'refactored' to force all links to be point to point, which they effectively are in the modern world. When was the last time you saw ethernet frame collisions because you used a hub not a switch? We'd get rid of the idea of a broadcast domain. We'd get rid of Mac address and ARP. Switches and routers would become the same device. We'd just use ip addresses for routing, and the 'next ho…

A really interesting article covering this: “The world in which IPv6 was a good design” https://apenwarr.ca/log/20170810

It talks about how when IPv6 was being designed, they wanted to do exactly that: drop most of the layer 2 stuff, abandon the idea of a bus network, make everything point-to-point, all switches would be L3 routers, etc.

Search for “What if instead the world worked like this?” for the relevant part.

My question though, is how would IP assignment work for each of the intermediary devices between me and (say) my ISP’s gateway? My computer is plugged into a switch right now, which is plugged into another switch, which is plugged into my router, which has a point-to-point link to the ISP gateway. Would my router get a /64, then delegate a /68 to the next “router” (ie. The physical thing I currently call a switch), which would delegate a /72 to the next one, etc? How would it determine the optimal IP allocation? What if there’s a cycle? Aren’t we sorta reinventing spanning tree at this point? (I’m genuinely curious about this, because I don’t really grok all of the implications of an “everything is L3” world like this.)

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#47

Post by toast0 »

londons_explore wrote: post #36

I wish layer 2 and layer 3 were 'refactored' to force all links to be point to point, which they effectively are in the modern world. When was the last time you saw ethernet frame collisions because you used a hub not a switch? We'd get rid of the idea of a broadcast domain. We'd get rid of Mac address and ARP. Switches and routers would become the same device. We'd just use ip addresses for routing, and the 'next ho…

If you force all links to be conceptually point to point, you probably make it harder to do some things. Already 1G and higher force full duplex, and 100base-TX full duplex is very common. I've still got a couple 10baseT half duplex devices though.

I have redundant internet/nat routers at home (overkill!), and they communicate amongst each other to decide which is active and which isn't, but either way, the active one ARPs for the router address with 00-00-5E-00-01-01 as the mac address. The rest of the network just sends off-network packets to 00-00-5E-00-01-01, and failover happens because switches figure out what port is currently using that address.

I share a different mac address for the upstream connection, which is PPPoE (sadly), but same deal --- when failover happens, the new computer starts using the address and everything figures it out, because stations are allowed to move to different ports by design.

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#48

Post by kjellsbells »

dale_glass wrote: post #35
toast0 wrote: post #11

Earlier quoted context omitted.

I mean, larger packets (and working path MTU detection) could be useful, but with large (1500) byte packets and reasonable hardware, I never had trouble pushing 10G from the network side. Add TLS and some other processing, and older hardware wouldn't keep up, but not because of packetization. Small packets is also a different story. All my hardware at the time was xeon 2690, v1-4. Nics were Intel x520/x540 or similar…

I discovered that putting a 10G interface into a bridge implies a very significant slowdown. Linux has to do stuff on the CPU to do the bridging, so that turns off a large part of the card's acceleration. That's not a good thing for a server that runs a bunch of VMs. Fortunately SR-IOV exists, but it seems a tad silly to me that I have to do all this weird PCIe passthrough stuff just for this. It's nice, don't get me…

I always found it ironic that virtualization made me have to care about the hardware more than I ever had to before.

2013 me: slap the app on a Dell. It'll be fine.

2017 me: aw crap, the nic doesnt support SR-IOV. What do you mean, I need a special driver? Oh lordy, I'm pinning a whole damn CPU just so DPDK can pull packets off the wire?

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#49

Post by thfuran »

kridsdale3 wrote: post #45
thfuran wrote: post #21

Earlier quoted context omitted.

As long as we also make sure electrons are positively charged this time.

Then I'm going to be really confused about positrons!

Oh, but have you heard the news about negatrons?

Re: Ethernet History Deepdive – Why Do We Have Different Frame Types?

#50

Post by zamadatix »

toast0 wrote: post #47
londons_explore wrote: post #36

I wish layer 2 and layer 3 were 'refactored' to force all links to be point to point, which they effectively are in the modern world. When was the last time you saw ethernet frame collisions because you used a hub not a switch? We'd get rid of the idea of a broadcast domain. We'd get rid of Mac address and ARP. Switches and routers would become the same device. We'd just use ip addresses for routing, and the 'next ho…

If you force all links to be conceptually point to point, you probably make it harder to do some things. Already 1G and higher force full duplex, and 100base-TX full duplex is very common. I've still got a couple 10baseT half duplex devices though. I have redundant internet/nat routers at home (overkill!), and they communicate amongst each other to decide which is active and which isn't, but either way, the active on…

You can pretty much 1:1 what you describe in the redundancy case with IP, just replace the "relearn which port the MAC address associated with that IP is on" with "relearn which port the next hop for that IP is on".

Things tend to get a little messier than people expect in figuring out the "what values do I use for the point to point links and how do they get assigned" step of things, though there are some clever answers there too.

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