Monday, June 17, 2024

Cisco (Quietly) Adds to Linux Kernel

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Without much fanfare or self-congratulations, networking giant Cisco Systems has become one of the top contributors to the Linux kernel and an active contributor to the broader open source community.

It’s a message that Cisco (NASDAQ: CSCO) isn’t boasting about yet, but was willing to discuss with Cisco is the world’s largest networking vendor and a technology juggernaut that is seeing the value in using and contributing to open source.

For example, Cisco is one of the top contributors to Linux, according to a recent Linux Foundation study.

While Cisco uses and produces proprietary software and hardware, the firm is actively participating in open source development efforts on a number of fronts. Cisco’s open source participation ramp up comes as it expands its product lines like the Nexus, which benefit from Cisco’s Linux efforts.

“The benefits of open source are really clear to all the executives I work with that report all the way up to [CEO] John Chambers,” Cisco engineer Roland Dreier told “There is no question that open source is a key part of a modern engineering organization. As budgets get tighter, I think that open source will be one of the last things we would retreat from, since we see such huge benefits from the participation that we have now.”

Dreier is one of Cisco’s most prolific contributors to the Linux kernel and is one of the maintainers of the RDMA (remote direct memory access) (define) sub system of the kernel.

Dreier explained that RDMA is a relatively new technology that is intended to improve latency and performance of network adapter throughput. RDMA is a technology that is in the mainstream Linux kernel and is a key part of Red Hat’s recent Real Time Linux MRG 1.1 release.

Cisco itself is benefiting from the RDMA technology in Linux with the Cisco RAB (RDMA Accelerated Buffer) that brings Infiniband’s low levels of latency to Ethernet on the Nexus 5000 switch line.

Though Cisco is a leading contributor to RDMA in Linux, Dreier was quick to point out that the Linux RDMA effort is a broad collaborative effort that includes the contributions of over 180 individuals and over 30 different organizations.

Cisco’s Linux Distribution

According to Dreier, the RDMA stack on Linux represents the bulk of Cisco’s direct a contributions to upstream Linux kernel at the moment, but that doesn’t mean Cisco isn’t doing more with Linux.

Cisco uses Linux in a number of its networking products, including the new AXP (Application eXtension Platform), a Linux server on a blade that can be plugged into a Cisco ISR router. At the time the AXP was released, Cisco said that it was using its own hardened Linux to power the AXP. But that doesn’t mean Cisco has its own Linux distribution goals.

“We tend to emphasize having a good relationship with the distribution providers,” Michael Enescu, CTO of Open Source Initiatives at Cisco told “We have both Red Hat and MontaVista as supplier to us. Occasionally there are pieces of a distro that we need to treat differently.”

In those cases where Cisco has a need to do something different, Enescu noted Cisco will sometimes start with a stock Linux kernel and will build from there. In general, the goal is to work with existing distributions in order to be more efficient.

“The initial condition is that we don’t want to burn cycles on engineering and development to build from a stock kernel up,” Enescu said. “We start with a distribution and we have a very good relationship with Red Hat and MontaVista.”

Though Cisco does customize its own Linux for some uses, Cisco is not about to enter the Linux distribution business itself. “We’re definitely not in that business and we don’t want to compete with them,” Enescu commented.

Enescu also noted that Cisco is a member of the Linux Foundation and is actively benefiting from it. One of the efforts that Cisco is involved in is the Carrier Grade Linux (CGL) initiative where Cisco is helping to define requirements. Dreier noted that as a customer of MontaVista Linux, Cisco is helping to fund development to meet CGL requirements.

MontaVista Linux spokesperson Dean Misenhimer declined to comment to about Cisco’s status as a MontaVista customer.

While Cisco is influencing the direction of Linux development, Enescu pointed out that Cisco is not looking for special treatment.

“We take a lot of time when dealing with MontaVista and the people in the Linux community explaining that we don’t want any special modification or secret sauce just for Cisco,” Enescu said. “We want to participate in the usual way that people contribute to open source. The value for us is to have the contributions be generally accepted and not a one off thing that only benefits Cisco.”

This article was first published on

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