A S I C C O R E
The Gigabit Ethernet Media Access Controller (GMAC) ASIC core is a macro designed to increase the
network's bandwidth between routers, switches, hubs, and servers and is expected to be deployed in
desktop systems in the near future.
The GMAC is compliant with the IEEE 802.3z Gigabit Ethernet Protocol and IEEE 802.3x Full-Duplex
Flow Control Protocol. The GMAC includes a MAC control sublayer, transmit/receive MAC sublayer
function, and PCS sublayer that supports 8b/10b exchange mode or GMII mode. It also provides auto-
negotiation and GMII management, a host interface, and clock and reset functions. Optional modules
include transmit/receive FIFOs with flow control, statistics collection, and station address filtering logic.
G I G A B I T E T H E R N E T M E D I A A C C E S S C O N T R O L L E R
B L O C K D I A G R A M
32
32
MCS
MAC Control
Sublayer
MAC
Sublayer
PCS
Sublayer
GMAC CORE
GMAC
System
Host
Gigabit
MAC
Control
32
1.
TFIFO*
Gigabit
Transmit
FIFO
2.
STAT*
Gigabit
Statistics
Collection
3.
SAL*
Gigabit
Address
Filtering
TFUN
Gigabit
Transmit
Function
32
32
32
32
32
10
TEXCH
Gigabit
Transmit
Exchange
10
ANX
Gigabit
Auto-
Negotiation
REXCH
Gigabit
Receive
Exchange
MIIM
GMII
Management
RFUN
Gigabit
Receive
Function
SERDES/
PHY
RFIFO*
Gigabit
Receive
FIFO
GMAC2HOST
Gigabit Host Interface
*
Optional module
CLKRST
Clocks and Resets
98YL-0225C (12/98)
The new Gigabit implementation of Ethernet increases the bandwidth of a network by a factor of ten. Typical GMAC
system applications are in the area of routing switches, switching hubs, full-duplex buffered repeaters, and network
interface cards (NIC).
F E A T U R E S
T Y P I C A L S Y S T E M A P P L I C A T I O N E X A M P L E
1998 NEC Electronics Inc. NEC is either a trademark or a registered trademark of NEC Corporation in the United States and/or other countries. All other trademarks are the property of their respective owners. No part
of this document may be copied or reproduced in any form or by any means without the prior written consent of NEC Electronics Inc. (NECEL). The information in this document is subject to change without notice. ALL
DEVICES SOLD BY NECEL ARE COVERED BY THE PROVISIONS APPEARING IN NECEL TERMS AND CONDITIONS OF SALES ONLY, INCLUDING THE LIMITATION OF LIABILITY, WARRANTY, AND PATENT
PROVISIONS. NECEL makes no warranty, express, statutory, implied, or by description, regarding information set forth herein or regarding the freedom of the described devices from patent infringement. NECEL assumes
no responsibility for any errors that may appear in this document. NECEL makes no commitments to update or to keep current information contained in this document. The devices listed in this document are not suitable
for use in applications such as, but not limited to, aircraft control systems, aerospace equipment, submarine cables, nuclear reactor control systems, and life-support systems. "Standard" quality grade devices are rec-
ommended for computers, office equipment, communication equipment, test and measurement equipment, machine tools, industrial robots, audio and visual equipment, and other consumer products. For automotive and
transportation equipment, traffic control systems, and anti-disaster and anti-crime systems, it is recommended that the customer contact the responsible NECEL salesperson to determine the reliability requirements for
any such application and any cost adder. NECEL does not recommend or approve use of any of its products in life-support devices or systems or in any application where failure could result in injury or death. If customers
wish to use NECEL devices in applications not intended by NECEL, customers must contact the responsible NECEL salespeople to determine NECEL's willingness to support a given application.
Document # A14028EU1V0PB00
For literature, call 1-800-366-9782 7 a.m. to 6 p.m. Pacific time
or fax your request to 1-800-729-9288
or visit our Web site at www.necel.com
MMF
Fiber Optic
SERDES
GMAC
FIFO
MMF
Fiber Optic
SERDES
GMAC
FIFO
MMF
Fiber Optic
SERDES
GMAC
FIFO
Gigabit
Uplink
ATM, FDDI
BACKPLANE
98YL-0226C (12/98)
Legacy
Downlink
10/100
Ethernet
Forwarding
Control
Station address filtering: promiscuous mode,
broadcast, unicast, and fast 64-bit table look-
up for multicast frames
Synchronous dual-port SRAM-based
transmit/receive FIFO (IEEE 802.3x compliant)
RX FIFO: frame pipeline up to 10 (max.);
16 KB frame storage; pause frame request
TX FIFO: frame pipeline up to 5 (max.);
8 KB frame storage
Offered at soft macro
Test chip based on NEC 3.3V gate-array,
0.35-m ASIC process technologies under
evaluation
Customer's requests for mapping to NEC
3.3V cell-based 0.35-m (CB-C9vx) or
0.25-m (CB-C10) process technologies
Gigabit Ethernet MAC with IEEE 802.3z compliance
Transmit function: full duplex, Gulliver, CRC
enable, frame padding, delay CRC check
Receive function: full duplex, Gulliver and VLAN
tag detect (IEEE 802.1Q), delay CRC check
IEEE 802.3x flow control
MAC control sublayer: pause control frame;
receive and flow control frame transmit
PCS sublayer: 8b/10b mode, GMII mode,
auto-negotiation with auto sensing, GMII management
Full-scale host-interface for internal register accesses
and controls, plus easy clock and reset control
Register-based statistics collect module:
EtherStats, RMON, specific frame count, byte count,
CRC or length error based on transmit and receive
status vectors generated on a per-packet basis
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