Burning NAC questions

Take a look at important questions surrounding Cisco, NAC implementation and NAC policies.

Should I deploy a NAC appliance in-line or out-of-band?

Neither answer is right for every case.

Ultimately for large deployments, out-of-band NAC that uses some form of edge enforcement such as access switches will be more practical because it scales better, Whiteley says. In-band NAC requires more and more devices as the rollout grows.

But for smaller networks or for targeted NAC enforcement, in-line NAC appliances can serve just as well, says Joel Snyder, a senior partner in Opus One and a member of the Network World Test Alliance. "In-band I think of more for the occasional guest access -- drop one of those boxes in between your guests and let it handle that load," Snyder said in a recent Network World online chat about NAC.

Out-of-band NAC relies on existing network mechanisms to enforce policies, such as 802.1X authentication, ARP and MAC tables and DHCP assignment. It gets its name from the fact that the NAC device does not sit directly in the flow of traffic - usually it hangs off a switch port - without any direct means to restrict traffic.

In-band NAC includes devices that traffic must pass through, usually placed between access-layer devices and distribution layer devices, although some can sit between distribution and core layers of networks. In some cases, vendors have incorporated NAC capabilities in access switches themselves.

There are many arguments in favor of both methods. Network World asked two vendors -- one selling inline gear, one selling out-of-band -- to come up with the best reasons for their positions.

Quick deployment without interrupting business use of the network, no single point of failure and lower risk of creating network latency are cited as advantages of out-of-band deployment by Grant Hartine, CTO of NAC vendor Mirage Networks.

He also says out-of-band NAC gear finds devices when they send ARP packets that may be missed by in-line devices, depending on their placement.

By contrast, in-band NAC provides better control of traffic and can monitor and restrict traffic after devices are admitted to networks if they violate usage policies, says Jeff Prince, CTO of NAC vendor ConSentry Networks. In-band deployment also supports enforcement of user-specific policy rules about what resources a person can access without creating extensive virtual LANs to address each case, he says.

"Out -of-band is what I like to call 'edge enforcement," Snyder says. "It scales, it handles the load and it doesn't depend on a single point to do enforcement. [In-line] is really where I think we want to go for big enterprise deployments.

"Of course, that doesn't mean that the in-band guys can't handle the load, but you really want to aim for edge enforcement if it fits, and go for in-band if it doesn't."

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Tim Greene

Network World
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Kurt Hegetschweiler

Brother PocketJet PJ-773 A4 Portable Thermal Printer

It’s perfect for mobile workers. Just take it out — it’s small enough to sit anywhere — turn it on, load a sheet of paper, and start printing.

Featured Content

Product Launch Showcase

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?