Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network access regulating
Reexamination Certificate
2000-02-17
2004-04-20
Cardone, Jason D. (Department: 2142)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network access regulating
C709S223000, C709S246000, C370S389000
Reexamination Certificate
active
06725264
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of data communications networks. More particularly, the present invention relates to an apparatus and method for redirecting network management messages in a cluster of network devices.
2. Background
Two types of data communication networks known to those skilled in the art are Local Area Networks (“LANs”) and Wide Area Networks (“WAN”). Network devices are used to transmit information across networks, which may include various combinations of LANs and WANs. Without limitation, such network devices may include switches, bridges, and routers. “Switching” refers to a technology in which a network device (known as a switch) connects two or more LAN segments. A switch transmits frames of data from one segment to their destinations on the same or other segments. When a switch in an Ethernet LAN begins to operate, it examines the Media Access Control (“MAC”) address embedded in the frames that flow through it to build a table of known sources. If the switch determines that the destination of a frame is on the same segment as the source of the frame, it drops, or filters, the frame because there is no need to transmit it. If the switch determines that the destination is on another segment, it transmits the frame onto the destination segment only. Finally, using a technique known as flooding, if the destination segment is unknown, the switch transmits the frame on all segments except the source segment.
Because a switch maintains a table of the source MAC addresses received on every port, it “learns” to which port a station is attached every time the station transmits. Then, each packet that arrives for that station is forwarded only to the correct port, eliminating the waste of bandwidth on the other ports. Since station addresses are relearned every time a station transmits, if stations are relocated the switch will reconfigure its forwarding table immediately upon receiving a transmission from the stations.
An Ethernet LAN switch improves bandwidth by separating collision domains and selectively forwarding traffic to the appropriate segments.
FIG. 1
illustrates the topology of a typical Ethernet network
100
in which a LAN switch
110
has been installed. As shown in
FIG. 1
, LAN switch
110
has five ports:
120
,
130
,
140
,
150
, and
160
. The first port
120
is connected to LAN segment
125
. The second port
130
is connected to LAN segment
135
. The third port
140
is connected to LAN segment
145
. The fourth port
150
is connected to LAN segment
155
. The fifth port
160
is connected to LAN segment
165
. The Ethernet network
100
also includes a plurality of servers
170
-A-
170
-C and a plurality of clients
180
-A-
180
-K, each of which is attached to one of the LAN segments
125
,
135
,
145
,
155
, or
165
. If server
170
-A on port
120
needs to transmit to client
180
-D on port
130
, the LAN switch
110
forwards Ethernet frames from port
120
to port
130
, thus sparing ports
140
,
150
, and
160
from frames destined for client
180
-D. If server
170
-C needs to send data to client
180
-J at the same time that server
170
-A sends data to client
170
-D, it can do so because the LAN switch can forward frames from port
140
to port
150
at the same time it is forwarding frames from port
120
to port
130
. If server
170
-A on port
120
needs to send data to client
180
-C, which is also connected to port
120
, the LAN switch
110
does not need to forward any frames.
Thus, performance improves in LANs in which LAN switches are installed because the LAN switch creates isolated collision domains. By spreading users over several collision domains, collisions are avoided and performance improves. In addition, many LAN switch installations dedicate certain ports to a single users, giving those users an effective bandwidth of 10 Mbps when using traditional Ethernet. As a LAN grows, either due to additional users or network devices, additional switches must often be added to the LAN and connected together to provide more ports and new network segments.
As LAN and WAN topologies become more complex, network management tools become critically important. As is known to those skilled in the art, the Simple Network Management Protocol (“SNMP”) is one currently popular example of a network management tool. SNMP is a simple request/response protocol that communicates management information between two types of SNMP software entities: SNMP applications (also called SNMP managers) and SNMP agents.
SNMP applications are typically executed in a network management station, and issue queries to gather information about the status, configuration, and performance of external network devices (called network elements in SNMP terminology). The CiscoWorks™ software package, available from Cisco Systems, Inc. of San Jose, Calif., is an example of a network management station, and a LAN switch is an example of a network element that can be managed using SNMP. Relevant details of the SNMP protocol will be discussed in subsequent sections of this document.
Traditionally, network device installation includes inserting the device into the network and assigning it an Internet Protocol (“IP”) address, which is typically a 32-bit number :assigned to hosts that want to participate in a TCP/IP Internet. Newer versions of the IP protocol may use more bits for the IP address. The IP address of a network device is a unique address that specifies the logical location of a host or client on the Internet.
Once a network device has been assigned an IP address, a network administrator can enter the device's IP address into a network management station to access the network device and to configure it from anywhere in the Internet using a protocol such as SNMP. However, currently, each network device to be configured and managed must have its own IP address, which must be registered with a domain name service (“DNS”). Assigning an IP address to each and every network device is undesirable, because registering IP addresses with a DNS is both costly and cumbersome.
In order to implement a paradigm where several different devices can be managed and configured as a single network entity (called a “cluster”), what is needed is a way to allow all the device in a cluster to share a single IP address for the purposes of network management. Accordingly, it would be convenient for a network administrator to be able to assign a single IP address to one network device in a cluster, and then to be able to configure and manage all of the network devices in the cluster using this single IP address. Unfortunately, no current mechanism exists to enable this activity. The present invention provides an apparatus and method which permits an entire cluster of network devices to share a single IP address for the purposes of network management, and to provide a commander device which redirects network management data requests and responses (such as SNMP messages) to and from other devices in the cluster. These and other features and advantages of the present invention will be presented in more detail in the following specification of the invention and in the associated figures.
SUMMARY OF THE INVENTION
A group of network devices, such as Ethernet switches, are logically configured as a single cluster, with one commander device and one or more member devices. Each device in the cluster is capable of supporting a network management protocol and contains its own management information base. Each device in the cluster is identified by a unique identifier such as;a unique community string in the case of a Simple Management Network Protocol (“SNMP”) implementation. Each device in the cluster may also be uniquely identified by a Media Access Control (“MAC”) address if so desired in a particular implementation. However, only the cluster commander is required to have an IP address. The cluster commander redirects and translates network management messages from one or more management consoles destined for member
Cardone Jason D.
Ritchie David B.
Thelen Reid & Priest LLP
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