1 / 27

Telecom Systems Dr. George Scheets: Cybercrime Exploration

Dive into the world of underground enterprises and the Stuxnet incident in telecom systems. Learn about switch capacities, WAN connectivity, LAN carriers, and internet performance in this comprehensive study.

syshe
Download Presentation

Telecom Systems Dr. George Scheets: Cybercrime Exploration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ECEN5553 Telecom SystemsDr. George ScheetsWeek 6Read [11a] "Cybercrime: Dissecting the State of Underground Enterprise"[11b] "The Real Story of Stuxnet"Exam #1 27 September (Local) No later than 3 October (Remote DL)Outline Lecture 22, 9 October (Local) No later than 16 October (Remote)

  2. OutlinesReceiveddue 9 October (Local)By 16 October (Remote) 30 %

  3. Internet (Inside the Cloud) • Infinite Buffers • "OK" so long as Average Offered Input Rate < Output Line Speed Internet Router 100 Mbps Trunk ?? 1.54 Mbps Connections P(Access Line is Active) = 10% How many access lines can this switch support? 100 Mbps/154 Kbps = 649 (theoretically)

  4. Internet (Inside the Cloud) • Negligible Buffers • OK so long as Instantaneous Offered Input Rate < Output Line Speed Internet Router 100 Mbps Trunk ?? 1.54 Mbps Connections P(Access Line is Active) = 10% How many access lines can this switch support? With 404 users, 99.99% sure Input Rate < Line Speed

  5. Bounds on Packet Switch Carrying Capacity 100 Mbps Trunk, 1.54 Mbps Inputs with 154 Kbps average loads Lower Upper90% 553 64999% 485 64999.9% 439 64999.99% 404 649 Instantaneous Input < Line Speed Where switch could operate Where switch probably operates

  6. WAN Connectivity Options • Leased Line • Cross Connects are byte aware • Circuit Switched • Resources dedicated to customer use for duration of connection • Connection Set-Up Procedure • Coordinates byte time slot assignments between switches • Bytes are assigned at 1/8000th second intervals (TDM) • Switch then repetitively moves input bytes to designated output byte time slots • Pricing a function of connection size & distance

  7. LAN LAN Carrier Leased Line Network PC Trunks Byte Aware Leased Line Cross-Connect Corporate customers might attach via Edge Router & Leased Lines. WS

  8. Leased Lines (Inside the Cloud) • OK so long as Sum of Input Line Speeds < Output Line Speeds Leased Line Cross-Connect 100 Mbps Trunk ?? 1.54 Mbps Connections P(Access Line is Active) = 10% How many access lines can this switch support? 64

  9. 3 2 1 3 3 2 2 1 1 3 2 1 Leased Lines (TDM) • TDM time slots are moved from input to output • TDM switch is not "packet aware" • Time slots are allocated whether or not there is any traffic on them Leased Line Cross-Connect

  10. Circuit Switched connections waste bandwidth for bursty traffic. traffic NYC to OKC 1.54 Mbps Line Speed 146 Kbps Average time Idle Time >> Active Time

  11. Given 100 Mbps of Bandwidth... • 64 1.54 Mbps Circuit SwitchedTDM Customers with 154 Kbps average load & 100% availability • 404 - 649 1.54 Mbps Packet SwitchedStatMux Customers with 154 Kbps average load & 99.99% availability 64 x 154 Kbps = 9.856 Mbps 404 x 154 Kbps = 62.22 Mbps More Bursty Data Traffic can be moved with the Packet Switched StatMux network.

  12. Switched Network Carrying Capacities Carrying Capacity Packet Switch StatMux Circuit Switch TDM 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Load

  13. Network Cost... • Can be spread over 64 Leased Line customers • Can be spread over 404 Internet customers • The Internet Is a Packet Switched StatMux network Largely hauling bursty data traffic Effectively hauling bursty data traffic Inexpensive (compared to a Leased Line)

  14. Internet Performance This type of plot valid for all real world full duplex statistically multiplexed switches: Ethernet, Internet, Frame Relay Number of dropped packets Average Delay for delivered packets 0% 100% Trunk Offered Load

  15. Internet Performance Effect of priorities Average Delay for low priority packets Average Delay for all delivered packets Average Delay for high priority packets 0% 100% Trunk Offered Load

  16. Internet Performance Effect of priorities Number of low priority drops Number of dropped packets Number of high priority drops 0% 100% Trunk Offered Load

  17. Internet Backbone Engineering • Option A)Deploy ‘best effort’ RoutersRapidly Deploy Trunk BandwidthKeep Trunks Lightly Loaded • Delays will be small • Dropped packets will be few • Quality fine for all traffic

  18. Backbone Engineering: Option A Number of dropped packets Average Delay for delivered packets 0% 100% Keep Trunks Lightly Loaded

  19. Internet Backbone Engineering • Option B)Deploy more complex QoS enabled Routers Deploy fewer, more heavily loaded Trunks Give preferential treatment to interactive Voice/Video • Option A seems to be preferred today

  20. Backbone Engineering: Option BHigh Priority delay at 50% Load = Delay for all traffic at 20% Load Average Delay for low priority packets Average Delay for all delivered packets Average Delay for high priority packets 0% 70% Heavier Trunk Load

  21. Frame Relay • ANSI Standard covering OSI Layer 2 • Accessed by Routers • Derived from X.25 Protocol Dumps almost all error checking Requires fiber on the long haul • Uses Virtual Circuits (VC’s) VC differs from Datagram Long Term Connection Requires Carrier intervention to change

  22. Frame Relay • 1st Commercial Deployment 1990 • WilTel → Worldcom→ bankrupt → Verizon • Cheaper alternative to Leased Lines • Faster alternative to X.25 • Internet a small network in 1990 • Academia • Military • Some commercial traffic • See CUCKOO'S EGG to get a flavor

  23. Frame Relay • 7 Application • 6 Presentation • 5 Session TCP • 4 Transport TCP • 3 NetworkIP • 2 Data Link Frame Relay • 1 Physical

  24. Wide Area Connectivity Options • Frame Relay Network • Switches are frame aware • Virtual Circuit is assigned trunk BW via StatMux • BW required based more so on average input rates • Routing through system determined in advance • Pricing a function of Port Speed, CIR, and maybe distance

  25. Frame Relay • Committed Information Rate (CIR) Is a Quality of Service Guarantee "Guaranteed" minimum Bandwidth Should be set > average traffic during appropriate peak period • Port Connection Speed a.k.a. Port Speed or Burst Speed Bandwidth you can burst to provided network capacity exists. Set = Bit Rate of Access Line

  26. Frame Relay Packet Format 3 20 20 up to 8,146 3 FR Header FR Trailer IP TCP Data + Padding Header includes 10 bit Data Link Connection Identifier (DLCI) - Locally Unique (FR ports)Trailer includes 2 byte CRC Sequence that only checks Header I/O decisions based on FR address & look-up table.

More Related