Combining virtual local area networks and load balancing...

Details Combining virtual local area networks and load balancing... Combining virtual local area networks and load balancing...

1999-03-18

2003-07-08

Rao, Seema S. (Department: 2666)

Multiplex communications

Fault recovery

C370S218000, C370S230000, C370S242000, C709S238000

Reexamination Certificate

active

06590861

ABSTRACT:

TECHNICAL FIELD
The present invention relates to the field of computer system networks. In particular, the present invention pertains to a software-based module for augmenting a server computer system to perform network interface card load balancing and fault tolerance.
BACKGROUND ART
Computer systems linked to each other in a network are commonly used in businesses and other organizations. Computer system networks (“networks”) provide a number of benefits for the user, such as increased productivity, flexibility, and convenience as well as resource sharing and allocation.
Networks are configured in different ways depending on implementation-specific details such as the hardware used and the physical location of the equipment, and also depending on the particular objectives of the network. In general, networks include one or more server computer systems, each communicatively coupled to numerous client computer systems.
One common type of network configuration includes a number of virtual local area networks (VLANs). VLANs provide numerous advantages, a primary advantage being that the client computer systems associated with a particular server computer system do not need to all be in the same physical location.
In contemporary networks, server computer systems are typically coupled to the network using more than one network interface card (NIC). Multiple NICs increase the total available bandwidth capacity for transmitting and sending data packets. Multiple NICs also provide resiliency and redundancy if one of the NICs fails. In the case of a failure of a NIC, one of the other NICs is used to handle the traffic previously handled by the failed NIC, thereby increasing overall system reliability. Therefore, the client computer systems in communication with the server computer system through a particular NIC are not cut off from the server should that NIC fail.
Accordingly, it is necessary to be able to detect when a NIC fails and, when a failed NIC is detected, to switch to a functioning NIC (this is referred to as fault tolerance). Also, it is desirable to balance the traffic over each NIC so that one NIC doesn't handle too much traffic and become a bottleneck (this is referred to as load balancing). Furthermore, it is desirable that the fault tolerance and load balancing schemes support a computer system network comprised of multiple VLANs.
Prior Art
FIG. 1
is an illustration of exemplary network
50
including two VLANs. In network
50
, client computer system
140
(e.g., a workstation) is in one VLAN, and client computer systems
141
,
142
and
143
are in a second VLAN. Both VLANs are serviced by server computer system
160
. A data packet sent by server computer system
160
contains address information that is used to identify the particular client computer system(s) to which the data packet is to be sent. In addition, the data packet is tagged with a VLAN identifier that identifies the destination VLAN. The methods for addressing a data packet in a network comprising multiple VLANs are well known in the art; one method is defined by the IEEE 802.1Q standard.
Switches
150
and
151
are able to read the VLAN identifier and the other address information contained in the data packet and direct the data packet accordingly. Thus, switch
150
reads the VLAN identifier and will direct the data packet to client computer system
140
if appropriate. Otherwise, the data packet proceeds to switch
151
, which directs the data packet to the proper client computer system (e.g., client computer systems
141
,
142
or
143
) depending on the address information contained in the data packet.
One prior art technique for fault tolerance and load balancing utilizes a switch-dependent protocol implemented using server computer system
160
and switches
150
and
151
. This prior art technique also requires NICs that are specifically designed for compatibility with switches
150
and
151
and the protocol being used. This prior art technique is problematic because it requires the use of a specific protocol with a specific type of hardware (e.g., a specific type of NIC compatible with a specific type of switch). Thus, this prior art technique is not suitable for different types of hardware (e.g., NICs and switches) and protocols. In particular, the prior art is not suitable for legacy hardware already present in a network.
Another drawback to this type of prior art technique is that the switch must be designed with the capability to implement the fault tolerance and load balancing schemes. Thus, the complexity and the cost of the switch are substantially increased. Even so, the capabilities of the switch are relatively limited, and so the schemes for providing fault tolerance and load balancing are also limited. In addition, the cost of implementing this type of prior art technique is increased by the need to replace or upgrade legacy devices.
Accordingly, a need exists for a system and method that integrate fault tolerance and load balancing in a multiple VLAN environment wherein the system and method are not limited by the capabilities of a switch. A need also exists for a system and method that satisfy the above need, are switch-independent, and can be used with legacy hardware (e.g., switches and NICs). A need further exists for a system and method that satisfy the above needs and can be used with the protocols used by the server computer system.
DISCLOSURE OF THE INVENTION
The present invention provides a system and method that integrate fault tolerance and load balancing in a multiple VLAN environment wherein the system and method are not limited by the capabilities of a switch. The present invention also provides a system and method that satisfy the above need, are switch-independent, and can be used with legacy hardware (e.g., switches and NICs). In addition, the present invention provides a system and method that satisfy the above needs and can be used with the protocols used by the server computer system.
Specifically, in one embodiment, the present invention pertains to a software module implemented on the server computer system and used to send and receive data packets over a network of computer systems using a plurality of network interface cards (NICs) coupled to the server computer system. An outgoing data packet is addressed using a first media access control (MAC) address, wherein the first MAC address is a virtual MAC address representing the plurality of NICs. A NIC is selected from the plurality of NICs using a load balancing scheme. The functionality of the selected NIC is verified using a fault tolerance scheme. The first MAC address in the outgoing data packet is replaced with a second MAC address, wherein the second MAC address represents the selected NIC. The outgoing data packet is then transmitted using the selected NIC. For an incoming data packet received at one of the plurality of NICs, the existing MAC address in the incoming data packet is replaced with the first MAC address.
In the present embodiment, the present invention is utilized with a network of computer systems comprising a plurality of virtual local area networks (VLANs) compliant with the IEEE 802.1Q standard.
Other embodiments of the present invention include one or more of the following additional features: class of service, wherein a priority is assigned to each of the data packets, compatibility with GARP (generic attributes registration protocol) multicast registration protocol (GMRP), compatibility with GARP VLAN registration protocol (GVRP), and compatibility with Fast Internet Protocol (FIP). The present embodiment of the present invention is implemented in the server computer system as a module, and therefore snap-in modules can be used to update and enhance the present embodiment with other features.
The present invention provides a high performance system and method that support multiple VLANs and elegantly combine a load balance scheme and a fault tolerance scheme into a software element implemented on a server computer system.
These and other objects and advantages of the

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