THE INTERACTIVE NETWORK DESIGN MANUAL

Building a Frame Relay Network

Writing a Network Specification

If you've followed the procedure so far, writing the network specification should be easy. Provide prospective vendors* with a topology map, your list of applications and expected bandwidth requirements. This information will be a critical part of the Request for Proposal (RFP) process.

Other components that you'll want to consider in your network specification:

• Expected levels of service. If you expect the network to be available 99.8 percent of the time, put it in the specification. If you're running real-time services, be sure to place latency requirements in the spec and avoid oversubscribing ports.
  
• Low or 0 CIR links. If you don't need real time response, your interactive applications are not mission critical, and your end nodes use good Layer 4 protocols such as TCP/IP and IPX/SPX, let vendors specify '0 CIR' links. This can dramatically reduce ongoing costs.
  
• Usage based billing for links that are lightly used and traffic is tightly controlled.
  
• Future growth. If you expect to bring up new sites and applications soon, include them in the specification. Once you've got a successful WAN in place, it's likely that you'll be under pressure to expand it, and rapidly.
  
• High capacity options. Frame relay is available at speeds higher than T1. Just as with the jump from 56 Kbps to T1, you'll need new access circuits if you want to take advantage of these higher speeds.
  
• High availability options. Standby PVCs, ISDN failover and other availability features may be required for the level of availability that you need.
  
• Dialup access to your frame relay network. If you want users to dial into points-of-presence (POPs) managed by the carrier, provide a list of locations, technologies (such as analog or ISDN), connection speed and projected usage.
  
• Disaster planning and recovery. Incorporate your current disaster plan in the frame relay network specification. If you already have a plan for an off-site data center, network connectivity to it will be almost certainly needed before, during or after it is activated.
  
• Internet service options. Most carriers will provide PVCs to the Internet using their own service or by delivering your traffic to an ISP. Security options including firewalling may be available. Because you will use existing access circuits, this is often less expensive than running a physical circuit to an ISP. However, be sure you understand how your traffic will be routed to the ISP. If your packets have to cross the country to go next door, the additional latency may make this undesirable.
  

Note: Some carriers will not offer every option listed above.

* A partial list of frame relay service providers:

Ameritech
AT&T
Bell Atlantic
Bellsouth
BT Concert Communications
Cable and Wireless
CompuServe
GTE
Infonet Services Corp
Intermedia Communications
LCI International
LDDS Worldcom:
MCI
MFS
Nynex
Pacific Bell
SITA Group
Southwestern Bell
Sprint
Unispan
U S West