imers, 418 373-374 ISSU. See In-Service Software Hops, sky wave, 267-268 INTELSAT VI communication Upgrades Horizontal Radiation Pattern satellites, 303-304 IVL. See Independent VLAN (HRP), 232-233, 252 Intercoded pictures, 72 Learning Index LDP. See Label Distribution Local Management Interface, Jitter, 26-27 Protocol 368-369 accumulation, 47, 50-51 LDPC. See Low-Density Parity Locations for optical amplifiers, data transmission, 49-51 Check codes 155-156 specifications, 51-52 LEAF. See Large Effective Area Long birefringent fibers, 191-192 video transport over Internet, Fiber Loop antennas, 236-237 Leased lines and SDH/SONET Loop-free domains, 409 Joint Photographic Experts networks, 363-364 Losses Group (JPEG) standard, LEDs. See Light Emitting Diodes antenna resistance, 280 61-62 Left-hand circular polarization, multimode fibers, 120-121 optical fibers, 115-118 Legacy packet-switched data video transmissions, 81-83 Kerr effect, 197 overlay networks Lossless and lossy compression, Keys, encryption, 103 ATM, 370-373 5, 57-58 Knife edge diffraction, 238-240, Frame Relay services, 368-369 Low-Density Parity Check ISDN, 373-374 (LDPC) codes, 101 local exchanges, 367-368 Low-frequency ground waves, PSTN, 367 radio wave propagation, Label Distribution Protocol SDH/SONET, 363-364 263-265 (LDP), 387-389 tail circuits, 366-367 Low-order VCAT, 350-351 Label mapping messages, WANs, 364-366 Lowest Usable Frequency (LUF), 388-389 WAN services overview, Label stacks, 382-383, 387 361-363 LPF (Linear Predictive Filter), 6 Label Switch Paths (LSPs), 377 X.25 services, 369 LSPs. See Label Switch Paths control mode, 389 Length of multimode fibers, 125 LSRs. See Label Switch Routers tunnels, 383, 395 Lenz's law, 236 LTE. See Line Terminating VPN paths, 400-401 LEs. See Local Exchanges Equipment Label Switch Routers (LSRs), 382, LF frequency, 275 Ludwig's third definition, 279 384-386, 397-400 LFSRs. See Linear Feedback Shift LUF. See Lowest Usable Frequency Label-switching principles, Registers 378-379 Liberal label retention, 3