Paul Tingey

Carrier Grade Linux version 4.0 specification is released

Last week saw Carrier Grade Linux take a further step forward with the release of the latest version of the specification. The CGL 4.0 document, released on 26th February 2007, is the result of work by individuals in many organizations and heralds a new level of collaboration between all those involved in the Carrier Grade equipment business.

CGL 4.0 is the first version of the Carrier Grade Linux specification to be released by the Linux Foundation, a recently created group formed by the merger of the Open Source Development Labs (OSDL) and the Free Standards Group.

Improved alignment between the requirements of the telecoms equipment providers and the contents of the CGL Specification itself has been made possible through the work of the SCOPE Alliance. This consortium of equipment providers (such as Motorola, Alcatel/Lucent, Nokia, Huawei and others) has created a profile to outline those features of a carrier grade system which are most important for them and their customers to act as a kind of guidance system to keep the CGL specification in line with end user requirements.

The CGL profile created by SCOPE defines a total of approximately 250 individual requirements or features divided into seven groups; Availability, Clustering, Serviceability, Performance, Standards, Hardware and Security. Each of the individual requirements is assigned one of three priority levels; Mandatory, Desired and Roadmap. Obviously those requirements defined as Mandatory are seen as necessary to a successful Carrier Grade Linux system and, as such, must be present in any CGL 4.0 registered distribution.

Prior to CGL 4.0 there was no formalized registration process for Linux distributions claiming compliance. However, CGL 4.0 introduces a formal registration process and requires that any compliant distribution must meet all of the 135 Mandatory requirements.

The next step in the evolution of CGL will see the specification aligned with the Linux Standards Base (LSB) with the aim of increasing compatibility between CGL compliant and mainline distributions such that applications will run on either type of Linux in exactly the same way.

The CGL specification has been through a number of iterations (the first version was released in 2002) but the collaboration between standards groups, Linux vendors and equipment providers which is such a feature of the development of the CGL 4.0 specification marks a particularly important milestone in the story of Carrier Grade Linux. Cooperation between interested parties of this kind is likely to reinforce the position of CGL as the operating system of choice for telecom systems in the future.

Is Carrier Grade Linux finding new friends?

While browsing the web recently I was interested to find an article (Carrier Grade Linux moves beyond telecoms into data centers, virtualization) featuring an interview with Bill Weinberg of the OSDL. In the article Weinberg outlines his view that Carrier Grade Linux has matured to a point where it's pushing out from it's traditional heartland of management blades and shelf controllers in telecoms infrastructure equipment. CGL is now finding new uses in new markets (for example Aerospace and Medical equipment) as well as new uses in its traditional market of telecoms equipment (such as managed nodes rather than management blades).

So why all this interest in Carrier Grade Linux?

In a word; reliability. Whilst many Linux based devices may not necessarily require high-availability, high reliability is now a ubiquitous requirement. CGL includes features such as health monitoring, live patching and remote management which are particularly attractive when reliability is crucial (even if high-availability features such as application fail-over, storage mirroring and hot-swap are simply not required).

Weinberg also suggests a potential marriage between CGL and virtualization technology in devices such as media gateways. The idea is that server virtualization could be used to run multiple instances of CGL on a single physical server (or server blade) with an application load balanced across the entire set of instances. This configuration provides for a more flexible approach to system design in a dynamic environment since server resources can be scaled to match the application workload.

However, I believe we should not expect this marriage of technologies to happen too soon. Whereas the CGL requirements documentation (and CGL registered distros) have reached relative maturity, virtualization in the baseline Linux kernel, on the other hand, is still in its relatively early development stages.

But the end goal is clear; an architecture framework which offers both reliability and flexibility. Could these twin benefits be enough to ensure that virtualized systems running Carrier Grade Linux will be commonplace across a number of market sectors in the years to come?