Bandwidth management
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Bandwidth management is the process of measuring and controlling the communications (traffic, packets) on a network link, to avoid filling the link to capacity or overfilling the link,[1] which would result in network congestion and poor performance of the network. Bandwidth is described by bit rate and measured in units of bits per second (bit/s) or bytes per second (B/s).[2]
Bandwidth management mechanisms and techniques
Bandwidth management mechanisms may be used to further engineer performance and includes:
- Traffic shaping[3] (rate limiting):[4]
- 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[5][6]
- Scheduling algorithms:
- Congestion avoidance:[1]
- 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)[8]
- Explicit congestion notification
- Buffer tuning - [9] 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.[10]
- 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[11] is a program or a device that eavesdrops on the network traffic by grabbing information traveling over a network
- Network traffic measurement
See also
- Bandwidth cap
- Bandwidth management is a subset of network management and performance management
- Bandwidth management using NetFlow and IPFIX data
- Bandwidth throttling
- Customer service unit a device to balance the data rate on user's telecommunication equipment
- INASP runs bandwidth management training workshops and produces reports
- Network congestion avoidance lists some techniques for prevention and management of congestion on routers
- Network traffic measurement is a subset of network monitoring
- Traffic shaping and rate limiting are bandwidth management (traffic control) techniques
References
- ^ a b https://www.internetsociety.org/wp-content/uploads/2017/08/BWroundtable_report-1.0.pdf Internet Society on Bandwidth Management
- ^ "Bits Per Second". www.edrm.net. Retrieved 2020-07-23.
- ^ IETF RFC 2475 "An Architecture for Differentiated Services" section 2.3.3.3 - Internet standard definition of "Shaper"
- ^ AppNeta. "Rate Limiting Detection: Bandwidth and Latency". Appneta. Retrieved 2020-07-23.
- ^ "TCP Rate Control" (PDF).
- ^ Handley, Mark; Padhye, Jitendra; Floyd, Sally; Widmer, Joerg. "TCP Friendly Rate Control (TFRC): Protocol Specification". tools.ietf.org. Retrieved 2020-07-23.
- ^ Stiliadis, D.; Varma, A. (1998). "Latency-rate servers: A general model for analysis of traffic scheduling algorithms" (PDF). IEEE/ACM Transactions on Networking. 6 (5): 611. doi:10.1109/90.731196. S2CID 206475858. Archived from the original (PDF) on 2016-03-04. Retrieved 2020-07-23.
- ^ "Traffic Shaping and Policing" (PDF).[permanent dead link]
- ^ "Buffer Tuning" (PDF).
- ^ "Resource ReSerVation Protocol (RSVP)" (Document).
{{cite document}}: Cite document requires|publisher=(help); Unknown parameter|s2cid=ignored (help) - ^ "Sniffers Basics and Detection" (PDF).
- "Deploying IP and MPLS QoS for Multiservice Networks: Theory and Practice" by John Evans, Clarence Filsfils (Morgan Kaufmann, 2007, ISBN 0-12-370549-5)