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AL1022
Advance Information
Two-Port Gigabit Ethernet Switch
Product Description
The AL1022 is a two-port Gigabit Ethernet switch chip. The device is a part of the Allayer RoX-II
switch chip set family. It is intended as a gigabit uplink for Fast Ethernet switches. In addition, a
low-cost Gigabit Ethernet switch solution up to eight-ports can be designed by using four AL1022s.
Figure 1
System Block Diagram
Supports two Gigabit Ethernet ports
Integrated MAC and PCS functions
Interface to industry standard SERDES
and GMII
Supports 802.1p with four priority queues
Supports both port-based VLAN and
802.1q VLAN
RMON and SNMP support with external
(MIB) device
Built-in 1K address table expandable up to
32K MAC addresses
On-chip table supports 64 multicast group
entries for IP multicast application
IGMP frames trapping and filtering
Designed to utilize low-cost SGRAM
Flexible prioritized queueing for multimedia
and data traffic
Layer 3/4 switching with AL3000 on RoX-II
Full-duplex mode operation
RoX-II expansion link supports 6.4 Gbit/s
throughput
Scalable design
Supports port aggregation/trunking
Secure mode traffic filtering
Broadcast storm control
Port monitoring support
IEEE 802.3x flow control
0.25 micron, 2.5V CMOS technology
Packaged in 456-pin BGA
High Speed
Switch Fabric
Switch
Controller
Address
Control
Address
Table
Buffer
Manager
EEPROM
Interface
Expansion
Buffer
Management
Information
PCS/PMA
Gigabit MAC
PCS/PMA
Gigabit MAC
AL1022 Advance Information
2/2000
Reference Only / Allayer Confidential
2
AL1022 Overview
The RoX-II provides a 6.4 Gbit/s interface which can support up to four switch chips. Various
system configurations can be achieved using the RoX-II family of components. The
RoX-II bus enables the design engineer to implement a wide range of Fast Ethernet and Gigabit
Ethernet switch configurations, ranging from an eight-port Gigabit Ethernet switch (using the
AL1022) to a 24-port 100 Mbit/s switch with two-Gigabit Ethernet ports (using the AL126 and
the AL1022).
The AL1022 supports two full-duplex Gigabit Ethernet ports. Data received from the MAC
interface is stored in the external memory buffer. During transmission, the data is obtained from
the buffer memory and routed to the destination port. The AL1022 utilizes cost effective SGRAM
to provide up to 16 Mbit of buffer memory.
The RoX-II interface also supports an external management device, the AL300A. SNMP and
RMON are supported through this external management device. When the management option is
enabled, network statistics for each port is gathered and sent across the RoX-II bus. The AL300A
on the bus will collect and store the data for the network management agent. Access to the statistic
counters is provided via the CPU interface of the MIB device. The RoX-II interface also supports
Layer 3 and Layer 4 external switching provided by the AL3000 device.
All ports support multiple MAC addresses. The switch-chip supports 1K MAC internal addresses
that are expandable to 32K with external memory. MAC addresses are shared among the two
ports.
The device also provides 64 IP multicast group addresses for IP multicast applications. The
AL1022 can perform IGMP, ARP, and GARP frame trapping, and forward them to the CPU. The
CPU thus can participate in these protocols and determine which ports should participate in the
multicast session.
The switch is initialized and configured by an external EEPROM. For an unmanaged switch
design, there is no need for a CPU. A parallel interface can be utilized to reprogram the EEPROM
for field reconfiguration.
The device also supports port-based and tagged VLAN (IEEE 802.3ac/802.1q VLAN) for
workgroup and segment switching applications.
The AL1022 supports the IEEE 802.3x flow control protocol.
Other features include port monitoring broadcast storm filtering to reduce broadcast traffic
through the switch.
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