Fujitsu looks to Layer 3 switches for speed, backup

By Jim Duffy
Network World, 7/6/98

Richardson, Texas - Expanding operations and a desire to boost network performance and distribute routing functions prompted Fujitsu Network Communications, Inc. to install a switched Layer 3 network.

The maker of telecommunications equipment is adding new buildings to its campus research-and-development network here, and in doing so will have more users and offices to interconnect. So Fujitsu is replacing a Bay Networks, Inc. Backbone Concentrator Node (BCN) router at the center of its network with redundant CoreBuilder 3500 Layer 3 switches from 3Com Corp.

Fujitsu's BCN router is now providing WAN access for the Fujitsu campus.

Dept. of redundancy dept.
The main focus of Fujitsu's new campus environment is redundancy. Each of the wiring closets in the four buildings features dual-homed 3Com CoreBuilder 3500 switches and SuperStack II Switch 1100 workgroup switches for redundancy.
[Topography]

"We had one router that was the core of our network, and everything went through that core," said Lance Shinall, Fujitsu project manager and senior manager of information technology. "I was looking to disperse that and get something else in the core while we were putting in our new building."

Fujitsu installed a redundant Fast Ethernet network, comprised of 20 CoreBuilder 3500s in the network core, in building equipment rooms and in wiring closets. The company also installed 48 SuperStack II Switch 1100s on building floors.

The network was implemented in two months for less than $500,000, Shinall said. It supports CAD/CAM applications used to develop ATM, Synch-ronous Optical Network (SONET) and network management products. SAP R/3 and e-mail applications are also running on the network.

Eight hundred Fujitsu staffers currently use the new network, but the company will add 1,000 more over the next few years. Currently the most mission-critical applications on the network are e-mail and SAP R/3, Shinall said.

The company chose to go with Layer 3 switching to control traffic flow and avoid latency. Previously, the company connected Bay System 5000 hubs in each building wiring closet to the BCN router in the core. But as more buildings were added to the campus net, Fujitsu decided to experiment with the latest in routing and switching technology rather than buy more BCNs, company officials said.

The BCN slowed transmissions by 1 to 5 msec, Fujitsu officials said. The Layer 3 switches forward packets at wire speed, which they said eliminates latency. Also, Layer 3 forwarding at the edges of the Fujitsu network helps control traffic flow. The switches do this by handling routing locally, which helps contain broadcast traffic. Previously, all traffic had to go through the BCN router in the core of the network. But the CoreBuilder 3500s in the wiring closets learn the routes from Address Resolution Protocol (ARP) tables instead of performing IP lookups on each packet. ARP "snooping" can also be done at wire speed, which makes it practical to employ Layer 3 routing at the edge, Fujitsu officials said.

Another factor in selecting Layer 3 switches was capacity. Even with up to 5 msec of latency, Fujitsu was satisfied with the BCN's performance; but the company had filled up every BCN port.

"Even with all of our 100M bit/sec links we did not see a performance problem," Shinall said. "However, we were maxed out on slots. We couldn't put anymore in; we used every port."