Bandwidth management

Bandwidth management mechanisms and techniques

• Traffic shaping :
• *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
• * Class based weighted fair queuing
• * Weighted round robin
• * Deficit weighted round robin
• * Hierarchical Fair Service Curve
• Congestion avoidance:
• *RED, WRED - Lessens the possibility of port queue buffer tail-drops and this lowers the likelihood of TCP global synchronization
• * Policing
• * 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 - is the means by which applications communicate their requirements to the network in an efficient and robust manner.
• * Constraint-based Routing Label Distribution Protocol
• * 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

• TCP determines the capacity of a connection by flooding it until packets start being dropped
• Queueing in routers results in higher latency and jitter as the network approaches 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