Electronic Design

Switcher, Router Cut Costs In Gigabit Ethernet Switch Design

The AL1022 and AL3000 chip set lets designers of gigabit Ethernet layer 3/4 switches reduce both chip count and cost. The AL1022 is a two-port gigabit Ethernet switch chip, while the AL3000 is a layer 3/4 routing engine that also offers network management.

Each device contains the company's 12.8-Gbit/s, 32-bit RoX-II interface, which gives engineers a way to scale designs by linking multiple chips. The interface also enables them to design a wide variety of switches by linking to other devices from the company.

The AL1022 supports quality of service (QoS), trunking, virtual LANs (VLANs), and internal addresses that are expandable up to 32 kbytes with external memory. Additionally, it contains support for multiple MAC addresses, while providing 64 IP multicast group addresses for IP multicast applications.

The AL3000 implements layer 3/4 routing algorithms in hardware. It includes a command interpreter, a search engine, a parser, a memory server, two memory interfaces, six DMA channels, the RoX-II bus, and a network manager. The network manager uses the RoX-II interface to collect network-management information from up to 32 ports. The device supplies all of the management-information-base (MIB) statistics required to support SNMP and RMON.

One typical application for the chip set would be the design of an 8-port gigabit Ethernet layer 3/4 switch. This can be put together with four AL1022 chips and a single AL3000 (see the figure). Another application would be the design of a 24+2 port workgroup switch with dual uplinks. Here, the AL1022 provides two ports of 1-Gbit/s uplink capacity that can be combined into a 2-Gbit/s link through the use of the trunking feature. Three AL126 Fast Ethernet switch devices with eight ports each, plus one AL300A management chip, can be connected to the AL1022 through the RoX-II expansion bus for a complete solution.

In 1000-unit quantities, the AL1022 is priced at $45, while the AL3000 goes for $50. Both chips come housed in a 456-pin BGA package.

Allayer Communications, 107 Bonaventura Dr., San Jose, CA 95134; (408) 570-0888; fax (408) 570-0880; Internet: www.allayer.com.

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