Carrier Ethernet switch chip for wireless small cells

• 6-port low power 12 Gigabit Carrier Ethernet switch chip 
• Used for intra and inter-board comms, and back-hauling 
• Supports MPLS and MPLS-TP

 "Multi-carrier OA&M performance monitoring allows you to manage your network for your users through another carrier’s network”

Uday Mudoi, Vitesse Semiconductor

Vitesse Semiconductor has launched an Ethernet switch chip for Long Term Evolution (LTE) small cells.

Small cells are being adopted by mobile operators as a complement to their existing macrocells to boost signal coverage and network capacity. The small cells include microcells and picocells as well as femtocells for the enterprise.

The Serval Lite chip, the VSC7416, from Vitesse will be used to aggregate and switch traffic and will reside at the interface between the access and the pre-aggregation segments of the mobile network.

According to Uday Mudoi, director of product marketing at Vitesse, two units make up a carrier’s small cell: the base station and the back-hauling. The base station itself comprises baseband and general purpose processing. “What we are seeing on a base station – whether it is a macro or a small cell – is the use of multi-core processors, and you may need more than one such device on the baseband card,” says Mudoi. The Serval Lite IC can be used as an interface between the baseband and general purpose processors, and to other hardware on the card. 

The basestation features baseband (BB) and general purpose processing (GPP) cards. Source: Vitesse

The backhaul unit also features the Serval Lite IC. “The backhaul is more interesting from a switch perspective,” says Mudoi. The switch takes traffic from the base stations and places it on the outgoing interface, typically a microwave or fibre link, says Mudoi.

The switch also supports Carrier Ethernet for the traffic back-hauling. Such features include hierarchical quality of service (QoS), performance monitoring and operations, administration and management (OA&M).  "Multi-carrier OA&M performance monitoring allows you to manage your network for your users through another carrier’s network,” says Mudoi.

Switch characteristics

The Serval Lite is implemented using a 65nm CMOS process. The IC has six ports: four at 1 Gigabit Ethernet (GbE) and two that run at 1GbE or 2.5GbE. There is also a choice of NPI and PCI Express interfaces to connect to processors.

The chip has a full line rate switching capacity of 12 Gigabit. “It is a standard switching device, from any port to any port, that is standards compliant,” says Mudoi.

The switch supports the IEEE1588v2 timing protocol needed to synchronise between cell sites. The device also supports MPLS (Multiprotocol Label Switching) and MPLS-TP (Multiprotocol Label Switching Transport Profile).

“The 1588 timing issue is more complex when you are dealing with small cells,” says Mudoi. The back-hauling happens over millimeter wave or microwave links which adds extra timing constraints. This requires additional hardware to support the timing standard.

The device has been designed to achieve a low power consumption of typically 1.5W with the maximum being 3W. Vitesse has stripped out a T1/E1 processor used for back-hauling, with the chip supporting Ethernet only.  The device also adheres to the IEEE 802.3az (Energy Efficient Ethernet), powering down the ports when inactive.

The switch features a single core 416 MHz MIPS processor used for overall management of the small cell. Samples of the VSC7416 are now available.