Bandwidth management

Bandwidth management mechanisms and techniques

Bandwidth management mechanisms may be used to further engineer performance and includes:

• Traffic shaping (rate limiting):
  • Token bucket
  • Leaky bucket
  • TCP rate control - artificially adjusting TCP window size as well as controlling the rate of ACKs being returned to the sender
• Scheduling algorithms:
  • Weighted fair queuing (WFQ)
  • Class based weighted fair queuing
  • Weighted round robin (WRR)
  • Deficit weighted round robin (DWRR)
  • Hierarchical Fair Service Curve (HFSC)
• Congestion avoidance:

  • RED, WRED - Lessens the possibility of port queue buffer tail-drops and this lowers the likelihood of TCP global synchronization

  • Policing (marking/dropping the packet in excess of the committed traffic rate and burst size)

  • Explicit congestion notification

  • Buffer tuning - allows you to modify the way a router allocates buffers from its available memory, and helps prevent packet drops during a temporary burst of traffic.

• Bandwidth reservation protocols / algorithms
  • Resource reservation protocol (RSVP) - is the means by which applications communicate their requirements to the network in an efficient and robust manner.
  • Constraint-based Routing Label Distribution Protocol (CR-LDP)
  • Top-nodes algorithm
• Traffic classification - categorising traffic according to some policy in order that the above techniques can be applied to each class of traffic differently

Link performance

Issues which may limit the performance of a given link include:

• TCP determines the capacity of a connection by flooding it until packets start being dropped (slow start)
• Queueing in routers results in higher latency and jitter as the network approaches (and occasionally exceeds) capacity
• TCP global synchronization when the network reaches capacity results in waste of bandwidth
• Burstiness of web traffic requires spare bandwidth to rapidly accommodate the bursty traffic
• Lack of widespread support for explicit congestion notification and quality of service management on the Internet
• Internet service providers typically retain control over queue management and quality of service at their end of the link
• Window Shaping allows higher end products to reduce traffic flows, which reduce queue depth and allow more users to share more bandwidth fairly

Tools and techniques

• Packet sniffer is a program or a device that eavesdrops on the network traffic by grabbing information traveling over a network
• Network traffic measurement

References

• "Deploying IP and MPLS QoS for Multiservice Networks: Theory and Practice" by John Evans, Clarence Filsfils (Morgan Kaufmann, 2007, )

References

1. https://www.internetsociety.org/wp-content/uploads/2017/08/BWroundtable_report-1.0.pdf Internet Society on Bandwidth Management
2. "Bits Per Second".
3. [[rfc:2475#section-2.3.3.3. IETF RFC 2475]] "An Architecture for Differentiated Services" section 2.3.3.3 - Internet standard definition of "Shaper"
4. AppNeta. "Rate Limiting Detection: Bandwidth and Latency".
5. "TCP Rate Control".
6. (2008). "TCP Friendly Rate Control (TFRC): Protocol Specification".
7. (1998). "Latency-rate servers: A general model for analysis of traffic scheduling algorithms". [[IEEE/ACM Transactions on Networking]].
8. "Buffer Tuning".
9. Sonia Fahmy. (2000). "Handbook of Emerging Communications Technologies: The Next Decade". CRC Press.
10. "Sniffers Basics and Detection".