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From 1969 up through the early 80s, the Internet used general-purpose Honeywell minicomputers for its core routers. At some point after that, purpose-built machines started being used.

What was the first purpose-built core router? I'm interested in the name and year of course, but also if possible in technical specifics: what were the specifications of the machine, and how exactly did it get the performance boost that justified its invention, why did the Internet switch to dedicated routers then and not before or after.

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    Cisco routers, for example, have a lot of hardware that offloads much of the processing of packets and routing to ASICs instead of the CPU handling. OP may be asking what is the first router to perform some functions in specialized hardware versus the CPU.
    – LawrenceC
    Apr 27, 2017 at 17:26
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    @LawrenceC Right. An analogy from a domain with which I am more familiar: the Amiga (1985) was the first mass-market computer to feature graphics acceleration hardware (by a reasonable definition thereof) e.g. en.wikipedia.org/wiki/Blitter which was (I forget the exact number) times faster than the 68000 CPU at performing bitplane operations - that's the sort of answer I'm hoping for.
    – rwallace
    Apr 27, 2017 at 17:33
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    @rwallace I don't actually know what the first one was, but I'd bet that the 'special peripherals' were things like packet checksum offload, hardware-assisted fragmentation/reassembly, scatter/gather DMA (to allow a packet to be forwarded in-place without copying from a receive buffer to a transmit buffer), special buses or lattice switches (to allow packets to be moved quickly when accessing them in-place wasn't possible), and associative memories or hardware address hashing to allow for fast routing decisions (useful on routers with very large routing tables).
    – Ken Gober
    Apr 27, 2017 at 17:48
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    All active network components but the simplest types of unmanaged switch/hub/repeater are in the end computers with special coprocessors :) So it's computing isn't it? Apr 27, 2017 at 22:08
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    A "dedicated core router" would be different from a "computer mis-used as router" mainly by its specific hardware optimized for packet processing. TCP/IP was never designed for packet inspection in hardware, because that. was far out of the question when it was built. The first dedicated packet processing and protocol state machines likely coincide with the rise of complex ASIC technology in the late 1980s. Before that, there was simply no market and no suitable technology for such complex specialized circuitry .....
    – tofro
    Apr 15 at 15:03

2 Answers 2

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There are two well-documented computing devices that can lay claim to being the earliest examples of purpose-built Internet routers - The Stanford "Blue Box" router and the "Fuzzball" router.

The "Blue Box" is associated with Cisco Systems because the two founders of Cisco were Stanford employees, and used it as the basis for their first commercial product. It was originally developed by William Yeager as software for the PDP/11 to provide multi-protocol routing amongst networks on the Stanford Campus. Development began in 1981, but by 1985 the "Blue Box" router was running dedicated software developed by Yeager on dedicated Motorola 68000 CPU boards with 256KB of RAM also developed at Stanford by Andy Bechtolsheim, a future cofounder of Sun Microsystems. Also by 1985, Stanford was one of the major nodes on the growing ARPANET/NSFNet/Internet. While not particularly designated as "core" routing nodes, the "Blue Box" routers at Stanford likely handled as much traffic at the time as a core router, since they were gateways for the biggest edge node.

The "Fuzzball" router was also developed in 1985, and according to the U.S. National Science Foundation was the first true router for core usage. It was developed by David Mills under a grant from NSF and was used in backbone routing for NSFNet. Like with the "Blue Box", it was a specialty OS (which has the namesake "Fuzzball") purpose-built for routing and running on DEC LSI-11 hardware.

While both these early computers can satisfy being called the first dedicated router and a core router, it is mostly true that the "Blue Box" of 1985 was more of a dedicated router, having purpose-built hardware and software, and the "Fuzzball" was more of a core router, since it was in that role for the NSFNet, even though it ran on more generic hardware than the "Blue Box".

It should also be noted that these were very early examples, and pre-date the competitive push among companies like Cisco to make truly high-speed routers. Naturally, these later routers continued to use purpose-built OS software, but added ASIC and custom peripheral hardware to speed packet processing. Of course, Cisco Systems was a leader in this regard, and their device lineage clearly goes back to the Stanford "Blue Box".

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I'm not clear what you mean by "core router," nor on what kind of protocols and purposes you want the selection limited to. Providing more details about the implicit taxonomy of routers that you're using would help.

For a start, there are two rather different types of entities that use what might be termed "core" routers: public network service providers (who connect networks among disparate organisations), and "enterprises," who are connecting many internal networks within a single organisation or a group of related organisations.

An example of the former are ISPs and telephone companies. From that point of view, a "core router" might be (if we restrict ourselves to computerised switching) something like an AT&T 4ESS tandem switch; these were used to build the core of the AT&T network from the mid-70s onward. (Note that these used packet switching of the packet-based control protocols, even though they used circuit switching for the actual voice connections themselves.) Or, if you're going to restrict yourself to packet routing between clients, large public network X.25 routers might qualify.

An example of the latter are large companies, usually with multiple sites. For the earlier uses where the network was divided into "core" and "edge" routers, they would more often than not be using protocols other than IP: IP didn't really become popular until the early '90s at best, and didn't entirely wipe out its competitors (such as the ISO OSI stack) until the late '90s.

Restricting things to "Internet" doesn't really help, since we still see a split in router functionality between the two types of organisations (ISPs and enterprises) and even there whether a router is seen as a "core" router depends at least somewhat on your viewpoint. An ISP is going to use high-capacity routers that support BGP in order to connect with other ISPs, but from the ISP point of view these might be seen as "edge" routers since they're at the interface between that ISP and others, rather than at the core of the ISP's own network. But a client of that ISP might see all of that ISP's and other ISP's routers used for that purpose as "core" routers since they are part of the "Internet core," rather than routers they directly connect to.

And, of course, organisations of the '80s and early '90s that have large internal networks, even if IP based, would have their own "core" routers even though they were often not connecting to the Internet.

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