Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1997-11-21
2003-01-07
Yao, Kwang Bin (Department: 2662)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S419000, C370S257000, C714S039000
Reexamination Certificate
active
06504851
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of computer networking, specifically to the field of local area networks using Ethernet, Token-Ring, or Asynchronous Transfer Mode protocols.
BACKGROUND OF THE INVENTION
The present invention is an adapter card for a workstation or personal computer for receiving any of the Ethernet, Token-Ring, or Asynchronous Transfer Mode (ATM) protocols, and automatically determining which protocol is presently active and the speed at which it is operating.
Historically, numerous protocols have evolved for local area networks (LANs). Three of the most popular protocols are Ethernet, Token-Ring, or Asynchronous Transfer Mode (ATM). The diversity of protocols has created a problem for manufacturers of electronic equipment, such as computers, file servers, hubs, printers, and like equipments that connect to LANS. The problem is how to build hardware to attach workstations to the local area networks that is compatible with a plurality of protocols. In recent years, the problem has been further complicated by the introduction of a second higher performing versions of the Ethernet, Token-Ring, or Asynchronous Transfer Mode protocols. Ethernet now operates at 10 MHz rates (called 10Base-T) and 100 MHz rates (called 100Base-TX), Token-Ring operates at either 4 or 16 MHz rates, and ATM operates at either 25 or 155 MHz rates.
One simple solution to the problem, which has been implemented in the prior art, is to manufacture a different pluggable card type to support each of the different network protocols and speeds. The user would buy the type of pluggable card required to interface with the network protocol that was available in his office or building. This is not an ideal solution, because the vendor requires more development funds and a larger inventory of parts, while the user buys an inflexible solution and also requires a larger inventory of parts. The industry has evolved to more flexible solutions using a single card type that has automatic detection of the protocol type and speed. This is possible, because a standardized connector has evolved which requires the protocols of interest to be standardized to the same physical connector called RJ-45.
FIG. 1
shows the RJ-45 contact assignments and how they differ for the protocols of interest.
In U.S. Pat. No. 5,574,722, “Protocol Independent Switch” by Slykhouse et al., Slykhouse teaches a method for automatically determining the network protocol, either Token-Ring or Ethernet, for a network hub or concentrator. Slykhouse uses the RJ-45 pin connections as shown in FIG.
1
and teaches hardware for listening for a frame on specific pins to differentiate between Token Ring or Ethernet. The present invention uses the RJ-45 pins to help in the automatic determination of the LAN protocol being used but, in addition, requires recognizing the media access control (MAC) layer protocol differences. The present invention requires a more complex mechanism for automatic protocol determination because of the additional ATM protocol and additional speed selections allowable for Ethernet and ATM. The present invention is not an obvious extension of Slykhouse's method but involves media speed/encoding detection hardware and active transmission of test frames which loopback to the sender and are non-intrusive in nature. This is vastly different than Slykhouse's passive listening method. The present invention also differs from Slykhouse in the field of application. Slykhouse provides a method for network protocol detection in the networking infrastructure device (hub or concentrator), while the present invention is for an adapter card in a workstation.
In U.S. Pat. No. 5,249,183, “Interfacing Unit for Local Area Networks” by Wong et al., Wong teaches a mechanism for an Ethernet adapter to provide attachment to a traditional Ethernet coaxial network or an Ethernet twisted pair (10Base-T) network. The adapter automatically selects the network that is active by first checking for activity on the 10Base-T network by sensing the presence of link integrity pulses. If the 10Base-T network is inactive, it then uses the coaxial network. The approach for detecting Ethernet activity (presence of link integrity pulses) is the same listening approach used in the present invention. Detection allows the adapter to select the appropriate Ethernet media to use. However, Wong applies only to selection of the appropriate physical media specifically for an Ethernet network, whereas the present invention applies to selection of the appropriate protocol used by the network, that of Token-Ring, Ethernet, or ATM.
Wong's method is passive, but the present invention involves media speed/encoding detection hardware and active transmission of test frames which loop back to the sender and are non-intrusive in nature.
In U.S. Pat. No. 5,142,528, “Protocol Selector and Protocol Selection Method” by Kobayashi et. al., Kobayashi teaches a mechanism for two stations which support multiple protocols to negotiate the protocol to be used. Generically, this is accomplished through the use of an independent communication port over which the protocol to be used by the primary communication port is negotiated. Kobayashi also teaches the specific case of negotiating B channel protocols over the D channel of an Integrated Services Digital Network (ISDN) link. This does not relate to the present invention in that no independent communication channel exists for determining or negotiating the protocol used by the primary channel. The present invention deals with determining the operational protocol of a LAN network in a non-disruptive manner and then attaching to the network. Negotiation of the operating protocol is not part of the process.
In U.S. Pat. No. 5,497,460, “System and Method for Determining Network Connectivity” by Bailey et al., Bailey teaches a mechanism for providing automated detection of the LAN protocol for a network interface card in a workstation that supports multiple protocols. The automated detection mechanism in the workstation detects the protocol utilized by the networking infrastructure device to which the workstation is attached. This is the same problem solved by the present invention. Bailey's method differs in that the process proposed by Bailey can be disruptive, and the present invention is non-disruptive. Bailey detects the protocol by sending a logical link control (“LLC”) frame—which is a potentially disruptive process. The present invention does not send any frames which may be disruptive during the protocol detection process. In addition, the transmission of LLC frames proposed by Bailey is applicable only to Ethernet and Token-Ring but not for ATM. The present invention provides detection for Ethernet, Token-Ring, and ATM.
In U.S. Pat. No. 5,442,629, Token Ring Speed Detector” by Geyer et al., Geyer teaches a method and apparatus for determining LAN speed for Token-Ring LANs by choosing between the two standard Token-Ring speeds: 4 MHz and 16 MHz. Geyer's method applies only to Token-Ring. Geyer's teachings are applicable to the present invention in that Geyer's method is used directly to supplement the present invention by determining at what speed the Token-Ring is operating after the present invention determines that the connected LAN is Token-Ring. Geyer differs from the present invention in that it does not provide automatic determination of the LAN type from amongst three candidates: Ethernet, Token-Ring, and ATM.
In U.S. Pat. No. 5,530,842, “Generic Backplane System Which Is Configurable to Serve Different Network Access Methods Simultaneously” by Abraham et al., Abraham teaches a mechanism for supporting multiple protocols over a generic backplane of a communications hub or concentrator. Separate modules, which are protocol and physical network specific, are still provided for attaching to the appropriate LAN network. Abraham's invention is specific to the implementation of a hub backplane which, in essence, is a proprietary LAN network. It does not speci
Abler Joseph Michael
Noel, Jr. Francis Edward
Tomek Lorrie A.
Cockburn Joscelyn G.
International Business Machines - Corporation
Nguyen Hanh
Yao Kwang Bin
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