Multiplex communications – Diagnostic testing
Reexamination Certificate
2002-08-19
2004-10-26
Jung, Min (Department: 2663)
Multiplex communications
Diagnostic testing
C370S445000, C345S215000
Reexamination Certificate
active
06810017
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of computer networks. In particular, the present invention relates to a system, computer program product and method for analyzing handshake protocols for the physical link layer of a computer network.
BACKGROUND OF THE INVENTION
Network protocol analyzers are widely used to monitor computer network performance and assist users in analyzing the causes of network slowdowns or outages. Protocol analyzers assist in explaining possible causes for network problems, collect expert analysis data automatically, learn network configurations continuously, show breakdown of network protocol activity automatically, display network errors, frame size, and station statistics, enable creation and generation of management reports, consolidate information from remote sites at a central location, point out problems proactively by communicating alarms to a central location, and display multiple windows concurrently allowing a service person to view prioritized alarms, global statistics, traffic statistics, and expert analysis information from one or several servers simultaneously. An exemplary protocol analyzer is the Sniffer Pro 3.0 currently available from Network Associates, Inc, described in the user's manuals for the Sniffer Pro 3.0® and Sniff master® for Windows, the contents of which are hereby incorporated by reference. Protocol analyzers are described in various white papers, available at Network Associate's website, http://www.nai.com, and specifically at the webpage http://www.nai.com/asp
13
set/buy
13
try/try/whitepapers.asp, hereby incorporated by reference as of the filing date of this application.
FIG. 1
is a diagram of an exemplary enterprise network
100
, comprising a plurality of local area networks
104
,
106
,
108
and
110
. Local area networks
104
,
106
and
110
are connected via routers
132
and
134
. Local area network
108
is a remote network coupled to the remaining network through the Internet
112
and gateway devices
114
and
116
. The network
100
includes a protocol analysis server
140
, and protocol analysis agent computers
148
,
150
and
152
, to provide monitoring and troubleshooting information for the entire network
100
. Protocol analysis software, such as the Sniffer Pro 3.0, loads onto protocol analysis server
140
and may also comprise remote agents that are loaded onto the protocol analysis agent computers
148
,
150
, and
152
. The protocol analysis software compiles and displays information on network activity from the data-collecting protocol analysis agent computers
148
,
150
, and
152
.
For many network topologies, including Gigabit Ethernet, communication requires establishing a point-to-point link—that is, the link at the physical layer. To establish this link, the two devices attempting to communicate go through a training and negotiation process until an agreement is reached on parameters for communication. If no agreement is reached within some reasonable period (on the order of several seconds), or an error condition occurs, the attempt to establish a link has failed.
An example of this process for Gigabit Ethernet is shown in FIG.
2
. At time t
0
, node
1
initiates the training and negotiation process by sending information in the form of an “auto-negotiation ordered set” to node
2
. The auto-negotiation ordered set is the physical link layer handshake protocol control packet used for Gigabit Ethernet. An auto-negotiation ordered set includes of several copies of an auto-negotiation configuration register value, reg
13
value, transmitted with alternating headers. The two alternating headers are /C1/ and /C2/, consist of two ten-bit codes, and signify that what follows is an auto-negotiation configuration register value. The register value is conveyed by two 10-bit codes, which are converted to two eight-bit words corresponding to hexadecimal characters. The register value consists thus consists of one sixteen bit word. The individual bits in the sixteen-bit word have meanings defined by the protocol standard, indicating the various capabilities of the sending node. The receiving node responds at time t
1
with its own auto-negotiation configuration register value, indicating its own capabilities, along with an acknowledgment.
The two nodes continue to modify their requirements, as reflected in the auto-negotiation configuration register value, until an agreement is reached. When a node receives an acceptable auto-negotiation configuration register value from the other node, the node transmits an “IDLE” signal. When both nodes transmit “IDLE” signals an agreement has been reached and frames may be sent. Details of the auto-negotiation process, the ten-bit to eight-bit conversion, and the register values for Gigabit Ethernet are described in the IEEE 802.3z standard, the contents of which are hereby incorporated by reference into the present application.
Prior art protocol analyzers are directed primarily to gathering and analyzing information relating to data transmission—that is, the frames of data exchanged by the various devices attached to the network. Efforts to establish the physical layer link are not traditionally visible to users. As shown in
FIG. 3
, the protocol analyzer does not begin capture
303
or analysis
304
until after a link is established
302
. Until the link is established
302
, no frames of data can be exchanged. For relatively low-speed communication protocols, establishing a link is usually not problematic, because the technology for low-speed links is mature.
However, for some high-speed topologies such as Gigabit Ethernet, many network failures occur during attempts to establish a link. For example, one device may have communication requirements that are incompatible with another device, or a device may not modify its requirements appropriately in order to reach an agreement. Most prior art protocol analyzers fail to capture any information on the training and negotiation process, requiring the use of one or more logic analyzers to capture the information as digital waveforms, and extensive effort to decode the information. That is, the physical link layer handshake protocol control packets are not captured by these prior art protocol analyzers. Furthermore, those prior art protocol analyzers that do capture the physical link layer handshake protocol control packet provide no merged information and no decoding or analysis, requiring a time-consuming process to troubleshoot the link failure. For example, as shown in
FIG. 4
, Version 2.5 of Network Associate's Sniffer Pro® protocol analyzer captures the auto-negotiation ordered sets
401
for each of the two channels between the two devices—one channel transmitting in each direction—and displays the raw binary and converted hexadecimal auto-negotiation ordered sets for each channel on a separate page
405
, without merging the information for the two channels onto a single, time-ordered display. The auto-negotiation ordered sets for each channel are kept in the order in which they were sent
402
on separate displays for each channel. No decoding or analysis is provided for the auto-negotiation ordered sets—only for the frame data.
FIGS. 5
a
-
5
i
are screen displays for Sniffer Pro v.2.5 corresponding to the process shown in FIG.
4
.
FIG. 5
a
is a screen display of the main menu, before the training and negotiation process is initiated. Neither channel is up, and the capture buffers are both empty.
FIG. 5
b
is the help menu describing the various display capabilities.
FIGS. 5
c
-
5
e
show the sequentially-ordered auto-negotiation ordered sets
405
for channel
1
, corresponding to node
1
. The auto-negotiation register values and frame information are provided in hexadecimal in the first two columns, and decoding for the frame information and the idle signals is provided in the third column. The time stamps appear in the far right column.
The first auto-negotiation ordered set appears on
FIG. 5
c
at timestamp 01:998:509:424, in units of sec
Leong Pak-Tak Patrick
Won King L.
Hamaty Christopher J.
Jung Min
Networks Associates Technology Inc.
Silicon Valley IP Group PC
Zilka Kevin J.
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