Lippis Report 201: What Comes After Zero Latency Switching?

During mid-September 2012, Arista Networks and Cisco Systems launched what both claimed to be the industry’s lowest latency switches aimed at big data, cloud, Web 2.0 and high frequency trading markets. Both products are Top of Rack (ToR), 10 and 40GbE switches. Arista’s is based upon merchant silicon, while Cisco utilized custom ASIC. Arista’s 7150 Series claims 10 and 40GbE, 350 nanoseconds Layer 2 or 3 forwarding, VXLAN support and what it calls “flexible forwarding.” Cisco’s Nexus 3548 claims 10GbE, 250ns to 190ns Layer 2 or 3 forwarding, and Cisco Algorithm Boost or Algo Boost technology. At 10GbE speeds, a bit is 1/10 of a nanosecond long, so Arista’s 7150 and Cisco’s 3548 switches delay is 3500 and 2500 or 1900 bits, respectively. That is, these products offer processing delays equal to the time it takes a few thousands of bits to traverse a simple metallic or optical wire at 10Gbs! In this Lippis Report, we review Arista’s and Cisco’s new ToR switches and answer the question: what comes after zero latency switching?

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Arista’s 7150 Series

The Arista 7150 Series offers up to 64 wire-speed 1/10 GbE ports or 16 40GbE ports, VXLAN tunnels at wire-speed, supporting workload mobility between physical and virtual machines. Its 40GbE port-to-port latency is 350 ns for Layer 2/3 forwarding, according to Arista. The 7150 Series offers wire speed Network Address Translation (NAT) that eliminates 100s of microseconds of forwarding delay in High Performance Computing (HPC) and financial trading architectures and supports IEEE-1588 Precision Time Protocol (PTP), key for regulatory compliance.

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In addition to 1/10/40GbE and low latency, Arista has invested in a set of network technologies designed to deliver Software-Defined Networking functionality and network optimization. For example, Arista’s 7150 Series was designed with the Intel Ethernet Switch FM6000 silicon for flexible forwarding. A flexible forwarding path enables new packet formats to be parsed and forwarded with deterministic performance. Arista’s Latency Analyzer (LANZ+) functions provide application-level microburst detection, congestion monitoring and analysis essential to optimize big data and other performance-sensitive applications. Along with open EOS APIs, the 7150 Series offers monitoring, analysis and forensic capabilities for both coarse and fine-grained views of data flows and network activities, including stateless load balancing and network analyzer functionality. Its AgilePort capability allows four individual 10Gb ports to be combined into a single 40Gb ports for scale and simple network migrations to 40GbE.

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Arista has combined a flexible forwarding data path with its EOS (Extensible Operating System) to deliver industry leading low latency, low power consumption, high density and advanced SDN features in a compact 1U form-factor. The Arista 7150 Series switches are orderable now and shipping in CQ4 2012, with a list price starting at $12,995.

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Cisco’s Nexus 3548

Cisco’s Nexus 3548 is a 48 10GbE port ToR Layer 2/3 switch that forwards at line rate, according to Cisco. Cisco states that the Nexus 3548’s latency is 250 ns to 190 ns, and it can deliver stock market data to financial trading servers in as little as 50 ns, thanks to its warp switch port analyzer (SPAN) feature. It also provides active buffer monitoring for proactive monitoring and congestion alerts as well as line rate Network Address Translation (NAT) without latency penalty. It too supports IEEE-1588 Precision Time Protocol (PTP) with Pulse per Second output time synchronization to better achieve regulatory compliance. There is an intelligent traffic mirroring (ERSPAN) for better performance analysis and runs its proven NX-OS Networking Software.

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In addition to the Nexus 3548’s hardware and embedded features, Cisco launched what’s called “Cisco Algorithm Boost” or “Algo Boost” technology that provides a direct link between the Nexus 3548 and trading or big data algorithms. Algo Boost is a based upon a set of pending patents that offer a means to increase speed or reduce latency for faster trade processing, network visibility, active buffer monitoring, NAT and time synchronization. The Nexus 3548 is the first Cisco switch to sport Algo Boost.

Cisco Nexus 3548 Switch

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Cisco Algorithm Boost

The Algo Boost silicon executes multiple functions in parallel, significantly reducing latency, and delivers a switch that could move packets from one port to another in less than 250 ns. This is less than a third of the latency of its current generation Nexus 3000, and about half of what we have measured at iSimCity during our data center switch industry tests. Cisco claims that this latency comes without compromise, running line rate and holding true for Layer 2 and Layer 3, unicast and multicast, for all packet sizes, with any feature enabled, even with NAT. We have not tested the Nexus 3548 and cannot confirm these claims.

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To bring the latency down below 250 ns, Cisco engineers came up with another innovative solution that is storing different types of data in the same table. This allows the switch to do multiple functions with a single lookup operation, resulting in an additional 20% reduction in port-to-port latency, according to Cisco. This is what’s called “warp mode.” The Nexus 3548 running in warp mode offers latencies as low as 190 ns for small- to medium-sized Layer 2 and 3 deployments, according to Cisco. The Nexus 3548 switch also facilitates efficient delivery of stock market data to financial trading servers in as little as 50 ns with the warp SPAN feature, again according to Cisco.

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As the networking industry innovates to remove latency from switches down to the point where switch-processing latency equals transit latency from ingress to egress, look for innovation to shift away from hardware toward software. Cisco’s Aglo Boost and Arista’s Latency Analyzer (LANZ+) offer a glimpse of what’s to come. Networking vendors will offer communication or protocol links between trading, big data, et al, algorithms and a switch’s internal status. For example, LANZ+ and Aglo Boost give customers a view into how much latency is being introduced by microbursts; Cisco Algo Boost analytical framework includes active buffer monitoring that provides

The Arista 7150 Series

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granular data and pro-active notifications on switch congestion directly to financial or big data algorithms. Compared to software-driven techniques that take periodic snapshots of the packet buffer, Algo Boost utilizes hardware to provide millisecond-level polling to form histograms, charting buffer usage over time. This empowers trading firms and exchanges to rapidly evolve their infrastructures to turn market volatility into opportunity. In short, the opportunity to link network and analytical algorithms through software-defined networking may very well be the next major innovation cycle in our industry.

2 Debates over Lippis Report 201: What Comes After Zero Latency Switching?

  1. Ranga Rao said:

    Shouldn’t the switch latencies add up to 3500 and 2500 bits long, respectively, and not 35 and 25?

  2. Nick Lippis said:

    Hello Ranga, yes you are correct. Thank you for the fact check and the research note has been corrected. The update doesn’t change the main concept of the note, however.

    All the best,

    Nick