Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network monitoring
Reexamination Certificate
1997-08-18
2001-05-15
Meky, Moustafa M. (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network monitoring
C709S203000, C709S200000, C709S200000, C709S246000, C370S241000, C370S340000, C370S238000, C324S076490, C324S322000, C324S534000, C324S710000, C326S030000, 36, 36
Reexamination Certificate
active
06233613
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to the field of local area networks (LANs) using the Ethernet communication protocol (e.g., the IEEE 802.3 Standard). Specifically, the present invention relates to a probe design for monitoring information transmitted over a point to point communication link of a fast Ethernet LAN.
2. Related Art
Networked communication systems (“networks”) are very popular mechanisms for allowing multiple computer and peripheral systems to communicate with each other. Local area networks (LANs) are one type of networked communication system and one type of LAN is the Ethernet communication standard (IEEE 802.3). One Ethernet LAN standard, 10 BaseT, communicates at a rate of 10 Megabits per second while another Ethernet LAN standard, 100 BaseT, communicates at a rate of 100 Megabits per second.
There are many well known reasons for which the traffic over a LAN is monitored and monitoring typically uses probes and monitoring equipment.
FIG. 1A
illustrates a prior art Ethernet LAN system
10
using the 10 BaseT communication standard in which traffic is monitored. In system
10
, several communication nodes (e.g., computer systems)
12
-
18
are individually coupled through communication links to ports of a repeater hub (“repeater”)
20
. The repeater hub
20
repeats every communication it receives from a node to all other nodes that are coupled to the ports of the repeater
20
. Therefore, in order to monitor the traffic of the entire system
10
, a single probe
22
can be coupled to a port of the repeater
20
and it then receives all messages that are broadcast by any node
12
-
18
. Although the monitoring configuration of system
10
is relatively straight forward, its communication speed is relatively slow because the technology requires that all messages from one node be repeated (e.g., re-transmitted) by the repeater
20
to all communication nodes in system
10
thereby reducing the overall bandwidth of system
10
.
FIG. 1B
illustrates a point to point communication link
40
within a fast Ethernet LAN system that allows much faster communication rates compared to the 10 BaseT system
10
of FIG.
1
A. In fast Ethernet, e.g., of the 100 BaseT, 100 BaseT
2
, 100 BaseTX, or 1000BaseT communication standards, repeater hubs are replaced by equipment (e.g., switches, managed hubs, etc.) that establishes point to point communication links
46
between two communication nodes
42
and
44
. In this framework, a message sent from one node to the switched hub is not automatically repeated to all other nodes coupled to the switched hub, but is rather communicated only to a select number of other nodes, or, only communicated to a single other node, as shown in FIG.
1
B. In the system of
FIG. 1B
, it is not uncommon for one communication node
42
to have its own bi-directional communication link
46
with another communication node
44
. In fast Ethernet LAN systems, the only way to monitor the traffic over the system is to monitor the communication traffic over individual communication links
46
that the system forms between the various communication nodes of the LAN.
As shown in
FIG. 1C
, within fast Ethernet LAN systems, probe equipment
52
is inserted between prior art communication link
46
. This causes the communication link
46
(
FIG. 1B
) to be separated into two links
46
a
and
46
b
that individually link the probe
52
to node
42
and the probe
52
to node
44
, respectively. Once inserted between the communication link
46
, the probe
52
can gather any required traffic information with respect to the communication link between nodes
42
and
44
. However, probe
52
electrically interrupts the communication link
46
because it is inserted in series with the nodes
42
and
44
.
There are several disadvantages to the probe configuration shown in FIG.
1
C. The first disadvantage is that power down and power interruption protection circuitry must be placed within the probe equipment
52
because if a power interruption occurs, communication between links
46
a
and
46
b
will become broken. This power down and power interruption protection circuitry typically includes one or more relays that are used to bypass the monitoring circuitry within probe
52
if power should be interrupted or removed from the probe
52
. The relay circuit within probe
52
then restores the communication link
46
during periods of power interruption. However, this circuitry is very expensive and adds to the overall cost of the probe equipment
52
. Further, the power interruption prevention circuitry does not switch immediately after the power failure, but rather requires some latency period to restore the communication link
46
. During this latency period, the communication link
46
is broken which can cause data loss and/or initiate an auto-negotiation session between node
42
and node
44
. Both of these factors further delay communication over point to point communication link
46
. It would be advantageous to provide a probe that eliminates the need for power down and power interruption protection circuitry.
The second disadvantage to the probe equipment configuration of
FIG. 1C
is that the probe
52
must act as a repeater in repeating messages received from node
42
for node
44
and in repeating messages received from node
44
for node
42
because the probe
52
is inserted in series between node
44
and node
42
. The act of repeating these messages introduces unwanted latency in the communication between nodes
42
and
44
. It would be advantageous to provide a probe that eliminates the need to repeat messages between the linked nodes of a point to point communication link.
The third disadvantage to the probe equipment configuration of
FIG. 1C
originates due to auto-negotiation sessions between node
42
and node
44
. When probe equipment
52
is first placed between communication link
46
, the link
46
a
auto-negotiates between probe
52
and the node
42
. Simultaneously, link
46
b
auto-negotiates between probe
52
and the node
44
. Each auto-negotiation session is independent and can, unfortunately, result in an auto-negotiated speed of 10 Megabits for one node (e.g., node
42
) and 100 Megabits for the other node (e.g., node
44
). This is an impermissible result as the probe equipment
52
is not configured to allow split rate communication between its two different ends. Therefore, specialized software is included within the circuitry of probe
52
to: (1) detect when split rate communication is auto-negotiated; and (2) force the higher communication rate down to 10 Megabits. This specialized software is expensive and adds to the overall cost of the probe
52
. Further, the auto-negotiation sessions initiated by an inserted probe
52
and the specialized software (1) takes time to determine if split rate communication was auto-negotiated and also (2) takes time to alter the communication rate of one of the links (e.g., link
46
b
). Each of the above further introduces unwanted latency in the communication between nodes
42
and
44
. It would be advantageous to provide a probe that eliminates the need to auto-negotiate with each communication node of a monitored point to point communication link.
Accordingly, the present invention provides effective probe and monitoring equipment that can be used for monitoring traffic over a point to point communication link but eliminates the need for power down and power interruption protection circuitry. The present invention further provides a probe and monitoring equipment that can be used for monitoring traffic over a point to point communication link but eliminates the need to repeat messages between the linked nodes. Also, the present invention provides a probe and monitoring equipment that can be used for monitoring traffic over a point to point communication link but eliminates the need to auto-negotiate with each communication node of a monitored communication link. These and other advantages of the present invention not spe
Iddon Robin
Walker Douglas
3Com Corporation
Le Hieu C.
Meky Moustafa M.
Wagner , Murabito & Hao LLP
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