When it comes to Ethernet, it’s a rather joyful and nostalgic walk on the Layer-2 memory lane.  This most recent walk has been triggered by a few good articles I read this week:

• Cisco’s Data Center Blog on Converged Enhanced Ethernet (CEE) versus Data Center Ethernet (DCE)
• Network World article on 100 Gigabit and Terabit Ethernet
• Network World slide show on the Evolution of Ethernet

Rise of Ethernet as the king of network connectivity, wired and wireless, has been simply fascinating.  Not necessarily the best technology, its price-performance, ease of use and flexibility to adopt better traits of others have helped Ethernet get ahead and stay ahead of its Layer-2 compatriots, whether it be FDDI, ATM, Frame Relay or Infiniband (hey Fibre channel – watch out, Ethernet is coming to town).  A clear case of pragmatism winning over perfection!  Perhaps the only native Ethernet characteristic that has remained constant is its frame format…

As Ethernet has evolved, the industry has ended up using different modifiers to differentiate Ethernet from its prior avatars, using terms such as shared Ethernet, fast Ethernet, switched Ethernet, carrier/metro Ethernet…  These prefix modifiers certainly provide a precise functional description but lack the temporal sense of the way Ethernet has evolved.  This post is a curious attempt to chronologically categorize advances in Ethernet using a numerical suffix modifier – in the same spirit as the widely used Web 2.0 categorization.

According to the following, it seems that we are in the era of Ethernet 4.0:

• Ethernet 1.0 (Classic era, pre-1990): shared or classic Ethernet as one of many Layer-2 technologies, proposed by Bob Metcalfe at Xerox PARC in 1973 and standardized by the IEEE in 1985. All users on the network share the total bandwidth, and collisions are avoided based on the CSMA/CD algorithm (Carrier Sense Multiple Access with Collision Detection). Interface speed: up to 10Mb/s.
• Ethernet 2.0 (LAN era, 1990 – 2000): This was the “coming out” era for Ethernet, where it became the LAN technology of choice with functionalities such as bridged (switched) Ethernet, spanning tree protocol, VLAN, link aggregation, class of service, Wireless LAN (WLAN), power over Ethernet (PoE)… Ethernet, along with its Layer-3 counterpart Internet Protocol (IP), enabled convergence of parallel data, voice and video networks into one multi-service Ethernet/IP network for data/voice/video.  Interface speeds: 100Mb/s and 1Gb/s.
• Ethernet 3.0 (MAN era, 2000 – 2007): A major win for Ethernet as it began to penetrate service provider networks for metro Ethernet services using technologies such as Q-in-Q, Mac-in-Mac and virtual private LAN service (VPLS).  Interface speed: 10Gb/s.
• Ethernet 4.0 (Cloud era, 2008 – ?): Ethernet is adopting concepts from IP, Infiniband and Fibre Channel protocols for powering next-generation virtualized, workload agile data centers and modern cloud environments.  These advanced characteristics consist of reliability, lower latency, multi-pathing and unified I/O (including Fibre Channel over Ethernet, or FCoE), and are being standardized in IEEE and IETF (see here).  Like its 2.0 predecessor, Ethernet 4.0 has the opportunity to collapse parallel networks of data (Ethernet), storage (Fibre Channel) and cluster computing (Infiniband) into a single unified Ethernet/IP cloud network.  Interface speeds: 40Gb/s and 100Gb/s (estimated 2010).

Interestingly, enhanced functionality of Layer-2 Ethernet as well as Ethernomics (10X interface speed increase for 3X price) have been the catalyst for most network equipment churns thus far.  MPLS and IPv6 are perhaps the only celebrated enhancements that come to mind at Layers 3 and 4 (IP and TCP/UDP) to which network refresh can be attributed in limited customer segments and/or geographics (service providers, federal/defense, Asia).

Though not a concern any time soon, Ethernet should continue its watchful eye on other popular connectivity protocols, such as Bluetooth and USB.  Like Ethernet, both these protocols are easy to use, very cost effective and widely deployed on personal computers, mobile phones, PDAs and electronic gadgets of all types.

What will Ethernet be up to in 5.0?  400 Gigabit and Terabit Ethernet?  TCP-less data centers (via RDMA over Ethernet)?  Massively scalable processor/memory area networks (through disaggregation of servers into mega islands of CPUs and memory communicating over Ethernet interconnect)?

After a long pause, the new world of networking is getting interesting again!

PG.

Update (5/21/09): Bob Klessig – who initiated me to the world of Metro Ethernet – indicated that “another key factor to the success of Ethernet is the addressing.  MAC addresses are administered in an open way which allowed easy market entry for vendors and a high probability of uniqueness for each manufactured device.  The similar nature of IP address administration is why IP was successful and why ATM failed.”

Will we run out of MAC addresses some day?  IETF solved the similar IPv4 addressing concerns with IPv6.  Perhaps IEEE 802 would need to deal with MAC address issue during the Ethernet 5.0 timeframe…