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Ten frame-relay design do's and don'ts

By David Rohde
Network World, 9/1/97

1. Don't fall in love with your port speed. Many ports are oversubscribed; bursting all the way to the port speed may become more difficult.

2. Do/ reassess your committed information rate (CIR). Bump it higher if needed to guarantee throughput. To save money, consider asymmetrical permanent virtual circuits with lower CIRs in the direction away from most of the traffic flow.

3. Don't needlessly activate ISDN backup circuits. Monitor software triggers that open and close backup lines without necessarily sending data.

4. Do/ set router buffers based on CIR rather than port speed. Let nontime-sensitive file transfer traffic take longer if necessary rather than risk dropped packets.

5. Don't let dial-up access get out of hand. Watch for dramatic increases in 800-number usage into remote access servers; remind administrators and employees that dial-up access isn't "free.".

6. Do consider moving smaller branch offices directly onto the network to slash remote access fees. Compare dedicated-access charges vs. dial-up tolls.

7. Don't use performance measurement tools that average out traffic over an hour, day or week. Obtain software or a monitoring service that measures and reports traffic over 5- or 15-minute intervals.

8. Do consider moving intraLATA toll and local voice traffic onto the long-distance carrier's network via services such as AT&T Digital Link, to help justify dedicated-access circuits. If confident in your local carrier's data services, consider reversing the process when it obtains long-distance authority.

9. Don't automatically turn over network management to the carrier. Rigorous service level agreements combined with performance measurement tools may be more cost-effective.

10. Do watch for repeated "flattop" peaks in traffic at a consistent speed at or just above the CIR but below the port speed. Discuss with your carrier whether traffic buffered in its switch is leading to increased latency and sluggish bursts.