Voice Network Signaling (cont)

SS7 Practice questions 1)The signaling of SS7 features _____ signaling. a) in-band b) Out of band 2) SS7 ______ multifrequency tones for signaling. a) uses b) does not use

SS7 Questions 3) Associated signaling ___ for signaling to network elements to which there is no direct trunk connection. a) allows b) does not allow 4) Signal switching points (SSPs) ___ of the SS7 network a) are the packet switches b) are not the packet switches

SS7 Questions 5) What is the difference between ISUP and TUP? 6) What are some phone services enabled by SS7, not available previously? 7) How does SS7 conserve bandwidth in the switched network?

SS7 Questions (cont) 8) STPs and SCPs are not customarily deployed in pairs True or False 9) SCPs are always deployed in pairs True or False 10) “A” Links connect an STP and either an SSP or and SCP True or False

SS7 Questions (cont) 11) An ACM indicates that an Initial Address Message (IAM) has reached the called subscriber’s switch and that the subscriber is not busy. True or False 12) An Initial Address Message (IAM) indicates that a call has reached its proper destination. True or False

SS7 Questions (cont) 13) When a called subscriber picks up the phone, his or her switch sends an answer message (ANM) to indicate that the trunks should be connected in both directions. True or False 14) An REL is a message that indicates that switches at both ends have released the trunk. True or False

SS7 Questions (cont) 15) All 800 numbers are assigned to a subscriber line themselves. True or False 16) Dialing an 800 number causes the switch to suspend a call and query a database for further instructions. True or False

SS7 Questions (cont) 17) Links which connect non-mated STP pairs in different networks may be referred to as ______. a. B links b. D links c. B/D links d. any of the above.

SS7 Questions (cont) 18) MTP management messages and ISUP call set-up messages are addressed to: a. separate applications b. a signal connection control port c. B links d. a node as a whole 19) The SCCP supports ______ a. routing to subsystems b. global title translation c. load sharing among SCPs. d. all of the above and other functionality

SS7 Questions (cont) 20) Signaling units are broken up into units of how many bits? a. 8, b. 16, c. 32, d ) How many types of signal units are defined? a. 1, b. 2, c. 3, d. 4 22) Signal units are transmitted over a link a. whenever messages need to be sent. b. continuously

SS7 Questions (cont) 23. Signal units are transmitted on a signaling link a. in both directions at once b. in one direction at a time 24. What does a checksum verify? a. that the SU has passed through the network unscathed. b. the number of octets in the unit.

SS7 Questions (cont) 25) How many MSUs can a node send before it requires an acknowledgement? a) 128, b) ) How many fields of information are contained within the service information octet? a) 8, b) 4, c) 3, d) 1 27) Do FISUs have an information payload? a) Yes, b) No

Cable TV Networks Adapted from notes of Shivkuma at Rochester Institute of Technology (RIT)

Cable Technology Coaxial cable RF distribution networks. Attributes: –Broadcast oriented -- low-band reverse channels –Mainly one-way video channels –Reasonably secure network (private conduit to home) –Free from free-space interferences (Not RF based) –Good signal capacity (over 1 GHz) and flexibility (Coax has high BW)

Cable Attributes (cont) Multiple signaling channels Significant attenuation that increases proportional to frequency (active) RF amplification (every 1000 ft) Freq responses of deployed amps and filters limit practical usage of frequencies < 1 GHz

Cable Building Blocks

Video Channel Characteristics NTSC Analog Video –~ 6 MHz for a single channel –Analog signal, noise sensitive –Uses Vestigal Side Band modulation (VSB) Digital Video Channels –4 Mbps is great quality –Use MPEG2 or variant –Allows more dense channel packing Requires digital cable box (or TV) for decoding –Recall from Shannon example, 6MHz channel Supports about 80 Mbps (with 43dB SNR) Digital video more spectrally efficient

Cable Spectrum: Up to 750 Mhz “Digital services” above 550 MHz

Overall CATV Spectrum Note: “Reverse Path” between 5-40MHz Analog channels up to 550 MHz

Cable Technology & Architecture Head End –The “heart” of the CATV operation –Each carrier: Baseband analog or digital modulation –Carriers multiplexed w/ freq-selective filters allows simultaneous info transfer in both directions –Channels are combined from multiple sources Local Access channels National Networks Data

Tree and Branch Architecture Well-suited for one-way broadcast video transmission (same signals to every customer) Accumulates noise & distortions (amplifiers) Affects plant reliability and received signal quality Limits on the number of amplifiers cascaded Limits on bandwidth in operation (few 100s of MHz): below cable potential… Makes delivery of “switched” services (separate stream for each customer) difficult

Frequencies 5-42 MHz is the “reverse path” spectrum –Used to send information back up the CATV network. –Signals from set-top, cable-modem, etc. –How much digital bandwidth is this when divided over 20,000 subscribers??? Note difference between layer 1 and layer 2 –Layer 1 (Physical) is a tree and branch architecture –Layer 2 (Datalink) looks like hub and spoke architecture

Tree-and-Branch Architecture

Fiber Optics For Cable Networks Key: Leave the laser ON and intensity- modulate with the analog signal Such analog modulated lasers are very different from their digital counterparts –Low internal noise and high linearity in the range Receiver: simple photo-detector -> back to RF spectrum

HFC Networks Fiber pushing deeper into Coax Infrastructure –Coax plant serves smaller range (segmentation), but overall HFC reach dramatically increased –Also, it allows the economical support of remote, smaller clusters of homes –Each part could also provide different services to area (micro-market segmentation) –Assign different portions of HFC spectrum to diff uses: many virtual networks: sustained investments possible

Hybrid Fiber Coax (HFC) Networks

CATV Architecture with HFC

Multiple Services over HFC

Future Potential of HFC Broadband Due to smaller loops, the region from 900MHz – 1 GHz can be used for data. –Reduced noise in this region => increased bit rate (200 Mbps) per segment… Future: fiber moves closer, smaller coax- segments, reduced homes per coax run (60 homes), use of frequencies above 1 Ghz using new electronics –Latest DOCSIS 2.0 spec: 256 QAM (=> 8 bits/Hz) or S-CDMA on cable for more robust transmissions

Cable Regulation Very different from telephony: not common-carrier –Able to control content AND the conduit! –Grew by providing an alternative (and extension) to broadcast TV and had initial growth troubles –Did not have to offer service on a non-discriminatory basis (unlike common carriers) –Asserted first-amendment rights to maintain control over content –Not required to provide access to their distribution system to other providers (some portion of capacity required to be offered to unaffiliated players: eg: CNN) –But they reserve rights to appropriately bundle these channels

Cable regulation (cont) Limited regulation: basic tier is rate-regulated by local authorities till 1999 based upon FCC rules Cable networks limited in horizontal expansion, and from vertically integrating w/ CNN etc Cable service is multi-faceted and varied from area to area => regulation formulation more complicated Over-builders (satellite providers) got access to independent content providers: otherwise regulation achieved little for cable

Cable regulation (cont) Local authorities get revenue from cable regulation HFC dominates franchise regulation talks, but cable providers are not obligated to provide broadband access..