I recently had a conversation with industry analyst Nick Lippis about why SDN represents such a fundamental change in networking, one we have not seen in a long time. Nick likes to think about Networking Epochs and we related them to Computing Epochs, counting and matching three of each:
First Epoch: For networking, the First Epoch consisted of circuit switching, time-division multiplexing (TDM), early datacom “protocols” (not really) like Binary Synchronous Communication (BSC), and novel but proprietary layered architectures like IBM’s Systems Networking Architecture (SNA). In other words, the First Networking Epoch, which lasted roughly from 1955-1980, was about terminals and telephones, and the applications that had to know intimate details of links and terminals. On the computing side, this was the epoch of mainframes, the manufacturers of which wrote most of the applications, too.
- Anecdote: an early 1980s issue of the Sunday business section of the Durham Morning Herald noted the promotion of an IBM employee in nearby Research Triangle Park with this statement: “… promoted to Senior Engineer at IBM. He works on network management protocols for SNA networks, whatever those are.”
Second Epoch: The Second Networking Epoch, which lasted from approximately1980-2005, marked the entry of LANs and TCP/IP, in other words layered datacom architecture concentrated in layer 2 and layer 3. The layering did allow independent evolution of the different layer functions, but the applications still had to contend with network specifics. On the computing side, this was the beginning of the era of PCs and client-server, characterized by the democratization of computer application programs, peripherals, and even operating systems.
- Anecdote: While TCP/IP was quietly lurching along in the ARPANET, all the industry buzz was about Open Systems Interconnection, the famed OSI seven-layer reference model. Certain advocates of the proprietary network architectures, which themselves were layered, referred to OSI derisively as the “seven-layer itch”.
Third Epoch: Networking’s Third Epoch is the era we are living in today, the era of network programmability, and in particular SDN, which enables the democratization of network application programs and features. With SDN, the notion of layering in the forwarding plane in network switches disappears. Indeed the switches become protocol-ignorant, while layering remains meaningful in hosts and at transition points between networks with different control mechanisms. On the computing side, this is the era of mobility, virtualization, and the cloud, with applications finally freed from having to be aware of specific details of network plumbing, like IP addresses and ports.
|First||1955-1980||Circuits, TDM, BSC, SNA||Mainframes|
|Second||1980-2005||LANs, TCP/IP||PC, client-server|
|Third||2005-?||SDN||Mobile, virtual, cloud|
The previous epochs lasted around 25 years. Do you think the Third Epoch last from 2005-2030?