Dual NICs for niftier networking
Ray Geroski
Published: 23 Jul 2002 08:32 BST
For one thing, they represent bottlenecks that can slow the transmission and processing of data across the network. For another, they represent points of failure. If a NIC fails, it could potentially sever an important connection.
One way to lessen the potential for these problems is to install two or more NICs in network servers. Using multiple NICs offers these key benefits:
- Load balancing
- Failover
- Improved throughput
You can also install dual NICs to separate private networks from public networks to improve security. The question is, how do you make it work?
In our Technical Q&A section, member D Chen asked what software was necessary to install dual NICs to make them work together. Chen was interested in software that would work with 3Com NICs.
"I know Compaq has a utility," he wrote, "but that doesn't work with the 3Com cards."
Here's a look at some of the available solutions.
Options
One possible option to explore, which member Sean Flynn recommended, was IP Metrics' NIC Express, a software utility that enables network load balancing in Windows NT, 2000, and Linux. A 30-day trial of NIC Express is available for download, and if you decide to purchase it, the price is $395 per copy.
According to IP Metrics, NIC Express can detect faults on the network and reroute traffic as needed, eliminate bottlenecks by distributing traffic among multiple adapters, and work with any hardware in any network environment.
Flynn also feels it's a good idea to buy cards that come with their own software for accomplishing these tasks, and recommended Adaptec's ANA-62022.
Many solutions of this kind are hardware specific. Intel, for example, offers a teaming utility for its Pro 100 Intelligent Server adapter to support load balancing and fault tolerance across multiple NICs.
Another similar hardware-specific solution is Cisco Fast EtherChannel, which provides fault tolerance and load balancing between switches, routers, and servers. Fast EtherChannel also offers incremental bandwidth scalability between different network groups. Cisco users can take advantage of the feature to improve performance and reliability.
Windows 2000 Advanced Server Windows 2000 Advanced Server users have it a little easier. Win2K Advanced Server includes a Network Load Balance (NLB) service that can be activated for the NICs installed in the server. Since Windows is the most prevalent NOS, this would appear to be a good solution for most networks because it's hardware independent. The catch, of course, is that you must have Win2K Advanced Server or above installed. But if you're already running Win2K Advanced Server, you don't have to spend extra money for the necessary utilities to take advantage of using multiple NICs. All you have to do is activate and configure the service, and you've got instant load balancing and failover.
Mike, an administrator at a company in the Southeast who is using the NLB service in Win2K Advanced Server, said that the primary benefit of the setup was improved performance. The Microsoft solution, he said, is good for front-end application servers. "Load balancing Web servers would be one application of the solution."
Another important benefit of the system is failover. With NLB, the failure of a NIC will not block traffic to and from a server. "If anything causes the primary to fail, the backup takes over. The most common [occurrence] may be when someone accidentally pulls a cable."
To improve the performance of a key application used at his company, Mike installed dual NICs in each of the servers hosting the application and configured NLB so that the servers share the workload. As requests for the application come in, NLB distributes the tasks across the servers and NICs to provide the best availability and response time. The dual-NIC setup improves throughput across the servers and provides an additional failover measure.
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