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How backplane technology is rising to the challenge of growing data traffic

Data usage across all parts of the communications network is growing rapidly, particularly in the mobile segment, where smart devices are driving exponential bandwidth growth.

According to a forecast from Cisco Systems, mobile data will grow by a factor of 10 over the next five years – a compound annual growth rate of 61%. This translates to additional capacity demands in most areas of the network. As a result, operators will either need to increase the capacity of their equipment or add more equipment, or both.

The network and server infrastructure for mobile and fixed line services requires many line rate functions. These include security, deep packet inspection (DPI), packet classification and load balancing. Line rate DPI enables advanced policy management and gives service providers full control of network resources for individual users and user groups. As network capacity increases, these line rates must also scale from 10 and 40Gbit/s today to hundreds of Gbit/s in the future.

Operators are looking for a platform architecture that will help address the need for scaling, whilst providing flexibility, '5 nines' availability and an open multivendor ecosystem. Having been deployed in most major networks and with a strong multivendor ecosystem, ATCA is a solid choice.

Platform architecture

ATCA is a standardised, but flexible, platform for telecom and computing applications. Developed in 2002, ATCA is used by many leading telecom equipment makers and is deployed in most telecom networks.

A broad range of blade and system options is available. ATCA platforms offer up to 16 slots for any mix of CPU, DSP, storage and I/O payload blades, together with up to four switch blades. Each blade can also have a rear transition module to support additional storage or I/O capacity. This isolates the major I/O from the compute blades, easing cabling and maintenance.

Such platforms integrate dual power supplies, dual shelf management modules and multiple fan trays. The ATCA shelf manager controls the modules and blades in the platform, supporting automatic switchover from active to backup switch blades, power supplies, cooling trays and shelf managers as needed. This approach allows ATCA systems to meet the requirements of Network Equipment Building Standard for telecom and other high availability applications.

ATCA platforms have a passive backplane that supports Base and Fabric Interfaces. The Base Interface is a pair of 1Gbit Ethernet channels connected from each payload blade to a pair of centralised switch/hub slots. This dual star configuration supports active and standby switch blades. In telecom systems, the Base Interface is typically used for control plane functions.

The Fabric Interface is the high speed interconnect and is typically used for data plane functions. This interface can be implemented as a mesh or a star configuration (see fig 1).

Most current ATCA platforms support the dual star configuration. In a 14 slot shelf, this enables 12 payload slots and 1+1 redundancy, with one active and one standby switch blade. The main system ingress/egress ports are usually connected directly into the active switch.

The 2+2 dual-dual star doubles the system switching and ingress/egress bandwidth with two active switch blades and two standby switch blades. The number of payload blades is reduced by two in order to accommodate the additional switch blades.

A more efficient implementation with four switch blades can be achieved with Artesyn's 3+1 QuadStar configuration. This has three active switch blades supporting three times the bandwidth of a standard dual star system. The fourth switch blade is on standby in case one of the three active blades fails.

Each Fabric Interface channel consists of four bidirectional differential pairs (lanes) combined to provide 10GbE or 40GbE bandwidth. For the best results, 40Gbit/s ATCA platforms need to have 10Gbit/s KR lanes and IEEE40GbaseKR4 switching.

Scaling ATCA to 4Tbit/s

An ATCA system with 40GBaseKR4 switching and dual star Fabric Interface will support 40Gbit/s to each payload blade. In a 14 slot system this provides a bandwidth of 480Gbit/s. However, ATCA can be scaled to support up to 4Tbit/s.

The first step is a QuadStar implementation with 40G fabric interfaces, which yields a non redundant aggregate bandwidth of 1.6Tbit/s. Further scaling requires 100G fabric interfaces. When implemented in a QuadStar topology, these interfaces bring an aggregate bandwidth of 4Tbit/s.

In the same way that the ATCA fabric interface has scaled from 1GbE to 10GbE and 40GbE, future switches and payload blades will support 100GbE fabric interfaces, with 25Gbit/s on each lane. This approach requires silicon switches that support up to 16 100GbE connections, a new connector and standards for implementing 25Gbit/s lanes on ATCA.

The 3+1 QuadStar Fabric configuration with 40GBaseKR4 switching supports 120Gbit/s per blade, or 160Gbit/s with four active switch blades and no redundancy, equating to 1.6Tbit/s aggregate bandwidth. This configuration can be implemented using current technology backplanes, switch devices and payload blades with support for four fabric interfaces.

Working with industry leaders, Artesyn has pioneered the technology to enable 100Gbit/s backplane links within ATCA. This means Artesyn's chassis and backplane supports 300Gbit/s interfaces with redundancy to each payload blade. In a 14 slot system, this provides an aggregate data bandwidth of 3Tbit/s, or 4Tbit/s with no redundancy.

Artesyn has pioneered the availability of multiple 100G fabric interfaces in ATCA in its Centellis platform. The Centellis 8000 series is the first high availability telecom platform that incorporates 100Gbit/s QuadStar backplane technology. It can be deployed in applications such as security, DPI, packet classification and load balancing in physical and virtual networks supporting SDN and NFV.

The Centellis 8x000 series platform supports multiple backplane, switch and payload blade configurations (see Table 1).

Configuration 1 shows a 1+1 dual star configuration with up to 12 payload blades and two 40Gbit/s switch blades – one active, one standby. Each payload blade has a 40Gbit/s link to the active switch blade, supporting an aggregate bandwidth of 480Gbit/s.

Configuration 2 is a 2+2 dual-dual system with two active 40Gbit/s switch blades and two standby switch blades. This will support up to 10 payload blades with 80Gbit/s from each payload blade split across the two active switch blades. Aggregate bandwidth is 800Gbit/s.

Configuration 3 is a 3+1 Quadstar configuration, with three active and one standby 40Gbit/s switch blades. Here, the payload blades have four 40Gbit/s links; three to the active switch blades and one to the standby. The bandwidth per payload blade is 120Gbit/s, with an aggregate bandwidth of 1.2Tbit/s.

Configuration 4 is a 3+1 Quadstar arrangement with 100Gbit/s switch blades and payload blades with 100Gbit/s fabric interfaces. The bandwidth per blade is 300Gbit/s and the aggregate bandwidth is 3Tbit/s.

Conclusion

ATCA is a flexible platform for telecom and other high availability applications. The continued development of more advanced backplanes and higher speed switching, together with power and cooling up to 600W per slot, is increasing ATCA system capacity by a factor greater than 10, more than matching the growth in network traffic.

Doug Sandy, Chief Technology Officer, and Todd Wynia, Vice President for Communication Products, are with Artesyn Embedded Technologies.

Author
Doug Sandy and Todd Wynia

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