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20 ways to assure you're not framed by frame relay.

If looking at frame relay (FR), consider these questions:

1. How does the network handle congestion? When a node accumulates a "rush" of frames, response time could be slowed, frames could be dropped and overall performance will suffer. Perhaps the overall network configuration needs to be redesigned to more efficiently handle high-traffic periods. See if you can design flow control features, such as those in SDLC and BSC, into the network.

2. How does your terminal gear handle congestion? Make sure the equipment will respond to Forward and Backward Explicit Congestion Notification (FECN/BECN) bits received from the network. Make sure the response to these bits is suitable for your network (e.g. LAN/WAN) activities. Can your equipment lower the threshold in which discard eligibility (DE) bits are transmitted into the network?

3. Is FR equipment-compatible? Even though Vendor A claims its equipment supports existing FR standards, it might not be totally compatible with products from Vendor B. Make sure compatibility (between vendors and carriers) is assured by each vendor.

4. Are interexchange carrier FR networks compatible? At present a network-to-network interface similar to X.75 has not been defined for FR. If your network has nodes in numerous cities, it is possible the same FR carrier may not be available in all cities.

5. Is error-checking but no error-correction acceptable? Traditional packet switching retransmits packets if errors are detected; FR does not.

6. How will you handle lost frames? At least two options are possible: software in your network access equipment or a resident feature in the carrier's FR network. Check availability, prices.

7. What happens if network synchronization is lost? Depending on where your network's clocking source exists, determine what the carrier/vendor will do to ensure clocking is maintained.

8. Will your network management system handle FR?

9. Are you picking the right applications for FR service? Frame relay is supposed to be ideal for LAN-to-WAN communications. It is supposed to handle "bursty" network traffic more efficiently than traditional packet switching. Are your traffic requirements suitable for FR?

10. Have you accurately predicted your real traffic volumes? FR can handle periodic bursty traffic occurrences, but could break down in extremely bursty situations. Maybe you don't need FR.

11. Do you understand FR pricing structures? At present, pricing represents a major gray area for most telecomm and network professionals. Some carriers price on a flat rate basis; others are usage-sensitive. Develop a common denominator, e.g., kiloframes, so that services can be compared.

12. How motivated is your IXC to sell FR? Since FR is designed to replace private lines, a carrier like Sprint, with a very small body of private lines, is highly motivated. A recent ad for Sprints's FR service states as the reasons for getting their service, "One, you need it. Two, it'll drive AT&T nuts." AT&T is naturally interested in protecting that important revenue base of private lines, but also cannot be perceived as behind the times. So it has to respond to market pressure. The question for you is: How can I get the best deal for my company?

13. How does your carrier address the committed information rate (CIR) issue? Carriers have different rules for permitting users to send traffic bursts in excess of their CIR (the maximum amount of traffic guaranteed to be handled by the carrier in time period).

14. How do carriers handle transport of local management interface (LMI) data across network boundaries? Users may not be able to verify status of all network devices from a central NM point.

15. How will FR service billing be handled? If a common billing scheme is not developed by carriers, users will have to deal with different billing formats.

16. What kind of network disaster recovery plans are provided by carriers?

17. How will LECs support FR, especially in a disaster situation? Using FR can reduce the number of access lines required to implement a network. That also increases the risk associated with access line disruptions. Remember that telcos, RBOCs and leading independents in particular, are keen on SMDS.

18. How secure is the FR service being offered? It is a connection-oriented service, so security concerns are generally no different than for traditional networks (e.g., dial-up voice). However, for connection-less networks such as LANs and SMDS, security becomes a critical issue.

19. Can FR support planned network changes, i.e., as part of a company's five-year network plan? Many of the industry's pundits see FR as having a five-year lifespan before being superseded by cell relay, SMDS and other services. While nobody really knows what will happen over the next five years, one thing is certain: if you install FR now, you will probably have to live with it for several years beyond your five-year plan (assuming you have one).

20. What happens if your FR carrier changes nodal systems? Suppose your carrier's FR service is implemented on StrataCom's IPX mux. But the carrier is investigating other platforms on which it could offer FR service--such as AT&T's BNS-2000 switch which is a bout a year away from introduction. What will happen when the carrier switches out StrataCom and installs AT&T or some other equipment? What changes will you have to make it your operation?
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Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Communications Management
Author:Kirvan, Paul
Publication:Communications News
Article Type:Column
Date:Apr 1, 1992
Words:879
Previous Article:Focus efforts on disaster avoidance not on recovery.
Next Article:How frame relay stacks up against packet switching.
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