n problem. Frame Relay Speeds Frame Relay was designed initially to start from 64 Kbps up to 1.544 Mbps in North America. Speeds of 2.048 Mbps were approved in the rest of the world. This speed is based on the use of' T1 or E1 for the access link as spec- ified for GPRS from ETSI. The Frame Relay network can be mapped to carry traffic from a larger location to multiple smaller locations, each oper- ating at a different speed. Figure 9-13 shows the multiple flows from a sin- gle location on a high-speed circuit operating at 1.5 to 2.0 Mbps. Figure 9-13 Multiple sites served by a single high- speed connection. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PCUSN-to-SGSN Interface (Gb) PCUSN-to-SGSN Interface (Gb) A small company came along and introduced speeds of 50 Mbps. This company, Cascade Communications, broke all the barriers. Cascade wanted the network to be robust, not limited to old data rates. Cascade was later acquired by Ascend Communications, and then Ascend was acquired by Lucent Technologies. When designing a Frame Relay service, the speed of access is important both prior to and after installation. The customer must be aware of the need for and select a specified delivery rate. The speed can be assigned from both an access and a pricing perspective through various ways. For small loca- tions, such as branch offices with little predictable traffic, the customer might consider the lowest possible access speed. The Frame Relay suppliers offer speeds that are flat rate, usage-sensitive, and flat-rate/usage-sensitive combined. The flat-rate service offers the speed of service at a fixed rate of speed, whereas the usage-based service might not include flat-rate service, but might have a pay-as-you-go rate for all usage. The combined service is a mix of both offerings. The customer selects a certain committed informa- tion rate (CIR