ISDN,which stands for Integrated Services Digital Network, is a system of digital phone connections, which has been available for over a decade.This system allows data to be transmitted simultaneously across the world using (1) digital connectivity.With ISDN,voice and data are carried by bearer channels occupying a bandwith of (2) (bits per second).Some switches limit B channels to capacity of 56 Kbps.A data channel (3) handles signaling at 16Kbps or 64Kbps,depending on (4) .Note that,in ISDN terminology,”k” means (5),and not 1024(2^10) as in many computer applications;therefore,a 64Kbps channel carries data at a rate of 64000bps. A new set of standard prefixes has recently been created to handle this. Under this scheme,”K”(Kilo) means 1000(10^3),”M” (Mega) means 1000000(10^6),and soon ,and “Ki”(Kibi) means 1024 (2^10),”Mi” (Mebi) means 1048576(2^20).and soon。 (1). A.Multi-ends B.circle C.indirect D.end-to-end' y0 l. O6 r/ Q) q3 w0 \
(2). A.34 Kbps B. 84 Kbps C. 64 Kbps D. 54 Kbps
8 B9 c! P+ G @ (3). A.D channel B.A channel C.B channel D.C channel
3 ~: ?$ j" h m1 [1 F (4). A.the method B.the number C.the service type D.the user type
9 l- k. S3 w( @- H. j0 ~ (5). A.100000(10^5) B.1000(10^3) C.10000(10^4) D.100(10^2). ?8 k9 S( U# }4 L: I2 i3 z, ]/ r6 M
答案:! p9 q3 N; r% U) |
1:D,2:C,3:A,4:C,5:B |