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Frame Relay Congestion Control

Frame Relay Congestion Control. ENTC 345 Dr. Ana Goulart Assistant Professor. Announcements. Reading: Stallings Chapter 10 and 13 Lab #2 tomorrow (please take the Lab Manual) TA: Aninda@neo.tamu.edu Office hours: Mondays 5 to 8 pm (T 101) Hw # 2 due Friday. Review.

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Frame Relay Congestion Control

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  1. Frame Relay Congestion Control ENTC 345 Dr. Ana Goulart Assistant Professor

  2. Announcements • Reading: Stallings • Chapter 10 and 13 • Lab #2 tomorrow (please take the Lab Manual) • TA: Aninda@neo.tamu.edu • Office hours: Mondays 5 to 8 pm (T 101) • Hw # 2 due Friday

  3. Review • Problem on Packet Switching – we’ve underestimated the delays for PS

  4. Review • Problem on Packet Switching • Frame Relay • What is a DLCI? • Difference between X.25 and FR protocols? • Call control signaling: in-band or out-of-band? • Congestion control mechanisms

  5. Frame Relay Definition: a connection-oriented public packet-switched service offered by the phone company (defines only layer 2) Packet switching Network Virtual circuits (called Data Link Connections) Connection-oriented network

  6. Frame Relay Connection-oriented: a connection between the communicating parties is set up before the actual data transmission Two types of virtual circuits: - Permanent Virtual Circuit (PVC): permanent established VC for frequent data transfer between end points (no call setup) - Switched Virtual Circuit (SVC) : a new VC for every connection

  7. Protocol Architecture – Layer 2

  8. User Plane – LAPF frames Packet format 1 Flag Variable length Data 2 checksum 1 Flag 2 – 4 octets Address + Control Congestion notification Discard Eligibility

  9. Congestion Control

  10. FR Congestion Control • CIR – Committed Information Rate

  11. FR Congestion Control • Access Rate = physical data rate across the user-network interface ΣCIRi,j ≤ Access Rate j i Contract Parameters: • Committed Information Rate (CIR) • Committed Burst Size (Bc) • Excess Burst Size (Be)

  12. FR Congestion Control

  13. FR Congestion Control

  14. Opnet Models for Frame Relay • FR-enabled clients and servers for direct access to FR network • FR-capable routers with at least one interface supporting FR • FR switches for constructing the core of the FR network

  15. Opnet Models for Frame Relay (cont.) • FR clouds, providing an abstract way to specify the FR network core • FR-PVC-Config Object, to facilitate PVC configuration

  16. Opnet Models for Frame Relay FRAD = Frame Relay Access Device

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