Bandwidth management

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: • 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 == See also ==