3Com 3CR990SVR97, 3CR990-TX-97, 3CR990-TX-95 manual Load Balancing, Self-Healing Drivers, Failover

18CHAPTER 1: INTRODUCTION

Load Balancing

Load balancing maximizes bandwidth at the server through the use of multiple parallel resilient server links (RSLs) that share the network load.

An RSL consists of two or more NICs that form a virtual NIC. Each virtual NIC has multiple physical NICs bound to it, forming a group. Each NIC in a group uses the same protocols and frame types. One NIC is designated the primary NIC and the others secondary NICs.

Figure 2 Types of Load Balancing Arrangements

Transmit-onlyBidirectional

Server

Primary Secondaries Primary Secondaries

Switch

Clients

Self-Healing Drivers

Self-healing drivers (SHDs) are automatically installed with the NIC software, and work together with RSLs to maintain the network connection. An SHD monitors the NIC continuously for error conditions and makes corrections. These corrections can include resetting the NIC, rebuilding software data structures, temporarily disabling features, or transferring all network traffic to secondary NICs (termed a failover event). An SHD can also continuously monitor the status of the physical NICs in a virtual NIC group before and after failover. Errors and actions are reported to the system console and to the system log file. Error threshold values can be configured at any time.

Failover

In addition to load balancing, RSLs provide failover fault tolerance between a server and a switch—if one NIC in a group fails, the others assume the network load of the