Arista Unveils Single-Tier Ethernet Switches update from November 2013

In the network market, versatility is suddenly in vogue as Arista Networks joins Juniper Networks in releasing products that can be deployed as either leaf or spine switches in Gigabit Ethernet network fabric architectures.

Arista was one of the earliest champions of simple two-tier designs and products that supported Layer 2 MLAG and Layer 3 ECMP architectures back in 2008. Earlier this year, it introduced a new generation of modular spine switch, the 7500E. Now, Arista is launching two platforms in a new 7000X series that bridges the performance gap between the 7500E and 7X50 leaf switches: the 7250X and 7300X, both of which use the same EOS operating system and software features as the rest of its lineup.

Arista calls the new devices "spline" switches, meaning they can be deployed in a single-tier network of up to 2,000 servers as spine switches with the 7X50 series or as leaf devices in larger networks where the 7500E would act as the spine device. The company estimates such collapsed topologies, which provide non-blocking local connections, cut operating and capital asset costs by 40% and power usage by 25% per port.

As is typical of Arista, the new X series hardware pushes the price/performance envelope, mixing merchant silicon -- in this case, Broadcom's Trident II -- a modular, programmable Linux-based OS, and high-port density. The smaller, 7250X products are 2U boxes in either 64x40 Gigabit Ethernet (GbE) or 256x10 GbE ports, feature a 5 Tbps backplane, and offer 2 microsecond port-to-port latency while drawing less than 3.5W per 10 GbE port.

Unlike the fixed configuration 7250X series, the 7300X uses the familiar backplane/line card design and is available in 4-, 8-, or 16-slot (supporting a like number of line cards) chassis sizes. Maxed out, the 16-slot 7316 model supports up to 512 40 GbE ports (four times that for 10 GbE) from a 40 Tbps switch backplane in a 21U footprint. All the network specs scale down to the 4-slot 7304 model, although the power supply and fan overhead take a toll: At 8U, it's 2U per slot versus the 1.3 per slot of the 16-slot model.

A nice feature of both new X-series products is reversible fans, meaning they work regardless of your hot aisle/cold aisle deployment configuration -- server rack with rear-facing network ports or network rack with front-facing.

Both products also use a unified forwarding table -- a feature also available in recent Extreme Networks' line cards -- which uses a single cache ternary content addressable memory for L2 MAC entries, L3 host route lookup and LPM route table. Thus, depending on the network topology and application needs, the table can dynamically reconfigure up to 288K MAC entries, 144K LPM routes or a mix of -- for example -- 128K MAC addresses and 128K host routes. The switches also introduce Arista's new duplex fiber 40 GbE optics, the LRL4 QSFP, which uses just a pair of single-mode fiber per 40 GbE connection versus the 8 fiber bundles used by SR4 optics, while extending the maximum cable distance from 400m to 1000m.

Much like Apple uses a common OS across a spectrum of mobile devices, Arista maintains a consistent EOS revision and feature set across switch platforms, thus the new hardware inherits a mature and robust software platform. Using a standard Linux kernel and modular state database that's accessible via an extensible API using familiar JSON syntax, EOS provides much of the programmability network admins look for in software-defined networking and OpenFlow without introducing a new network architecture and control protocol.

[Read about Juniper Networks' new MetaFabric architecture in "Juniper Launches New Fabric Architecture, Switch Line."]

For example, the new smart system upgrade feature allows switches to gradually shut down, install new software and reboot without disturbing applications. It does this by taking a snapshot of existing network state and redirecting flows to other devices in the switch fabric if possible. If that's not possible, it puts physical or virtual hosts into maintenance mode. It also restores network state after the upgrade and validates consistency against the original snapshot.

In essence, the smart system upgrade automates a lot manual network reconfiguration and consequently eliminates errors and admin workload. Its network telemetry application provides real-time visibility into network congestion, buffer management and industry-standard sFlow support for traffic analysis, while network tracers can monitor switch health, link status and latency, VM visibility and movement, and even MapReduce workloads in a Hadoop cluster.

The 7250X products are scheduled to ship in December, while the 7300 series is planned for Q1 of 2014. The 64x40 7250X product runs about $96K ($1500 per 40 GbE port), and the 7300X series is expected to start at $500 per 10 GbE port.