Primer: A new generation of programmable ASICs

Programmable application-specific integrated circuits allow the data plane of switches to support new technologies, like software-defined networking.

Application-specific integrated circuits (ASICs) used in networking are customized network silicon designed for a particular purpose. Traditionally, ASICs were closed platforms with fixed, integrated software. If a vendor needed to introduce new network protocol support, it needed to build new ASICs. But a new generation of programmable ASICs are emerging that could add flexibility and investment protection for networks.

Only a subset of networking vendors even work with ASICs because developing custom silicon requires an enormous financial investment and a minimum two-year R&D commitment. Many vendors rely on merchant silicon from chip manufacturers like Broadcom, Intel-Fulcrum and Marvell. But vendors like Juniper Networks Inc. and Cisco Systems Inc. build ASICs because they offer much faster performance than pure software technology delivered on top of merchant silicon.

Now Cisco and Juniper are introducing programmable ASICs that can support new protocols without a platform refresh, which could allow them to apply that programmability to support software-defined networking (SDN) and continue to evolve to support new protocols as they emerge.

Which vendors are offering switches with programmable ASICs?

Not many networking vendors beyond Juniper Networks and Cisco can afford to develop custom silicon solutions.Juniper, for example, spent hundreds of millions of dollars developing programmable ASICs during a three-year period.

"But having custom silicon provides a real advantage, because merchant silicon vendors have always trailed the capabilities of custom chips by at least three years," explained Dhritiman Dasgupta, Juniper's senior director of product marketing.

It certainly looks like there may be some real substance to programmable ASICs in core switches.

Juniper's programmable Trio ASIC, originally developed for routing, has been repurposed for its latest campus and data center core switch offering, the EX9200. The Trio ASIC enables the data plane of EX9200 to be upgraded with software to support new network protocols, which can be used to deploy SDN services.

"The term programmable implies programmability without any performance impact," Dasgupta said. While software can be used to forward packets, do routing, switching or security, "ASICs are 100 to 1,000 times faster than a pure silicon solution."

Cisco is also introducing its own programmable ASICs in switches. "The Cisco Unified Access Data Plane (UADP) ASIC converges processing of wired and wireless traffic into a single data plane and is used in the Cisco Catalyst 3850 Unified Access Switch and the Cisco 5760 Unified Access WLAN Controller," said Lauren Cooney, senior director, software strategy and planning at Cisco.

Cisco's UADP ASIC features a programmable data plane, so it too can be used to deploy SDN services.

"This will be an interesting story to watch as it unfolds, because few vendors are keeping proprietary ASICs programs alive -- aside from Juniper and Cisco," noted Brad Casemore, research director for datacenter networks at IDC. "We'll have to wait and see exactly where these vendors target ASICs. Core switches make a lot of sense, but, as always, the customers will decide."

Why use programmable ASICs?

Programmable ASICs can also be a "location agnostic" investment. Programmable silicon isn't custom-made just for the data center -- it can be run in the data center, campus, in a service provider environment or in a metro Ethernet environment. As new data plane requirements emerge for each of these network types, a programmable ASIC can adapt to support them.

But programmable ASICs aren't for every enterprise -- not everyone needs the level of capability and flexibility custom silicon provides. Consider it a "gourmet platform," Dasgupta said.

Be aware that not all "programmable" network silicon is created equal. Some vendors are taking merchant silicon integrated circuits or homegrown silicon that isn't fully programmable and claiming to be able to program new protocols and do encapsulation. "Well, yes, they can, but not at line rate," Dasgupta cautioned. "Be sure to ask."

Vendors claim that programmable ASICs can help support network functions virtualization. "If a server is receiving traffic or sending traffic to multiple networks, the core switch in a data center needs to send packets out to an MPLS network, an IP network, and it needs to send packets to a PCI or compliance network with a high degree of security and encryption," Dasgupta explained.

For example, Juniper's EX9200 with programmable silicon is designed to handle, aggregate and virtualize the functions normally handled by three separate switches and routers. In other words, the switch is positioned to be able to handle all future SDN protocols.

Role for programmable ASICs in a SDN context?

Programmable ASICs can allow vendors to reprogram the data plane in their core switches and add new SDN protocols as they evolve, so enterprises should be able to avoid dreaded rip-and-replace scenarios.

Programmable ASICs in core switches should be able to evolve as vendors find new ways for overlay networks to interoperate with the physical network, according to Casemore.

"SDN coupled with ASICs allows for an end-to-end offering that allows customers, partners and developers to use application programming interfaces [APIs] to build applications and services that control the network, including the ASICs themselves," Cooney said.

It's still too early to tell whether this is a positioning exercise, according to Casemore, but it certainly looks like there may be some real substance to programmable ASICs in core switches. Merchant silicon manufacturers could introduce their own programmable chips, too. "Expect Broadcom and Intel to also have compelling stories to tell regarding the capabilities of their chips in terms of protocol support and a general availability to support next-generation networks," he added.

This was first published in April 2013

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