Guerra Ro Ca Richard%20Nixon 自然之道 Guerra Ro Ca Richard%20Nixon

Xiaofei Liao,

Basic:

Goal：

(1) improve global resource utilization and distribute traffic to all physical links evenly;
(2) assign resources based on their locality and delay;
(3) guarantee streaming service quality by using the nearest peers, even when such peers might belong to different overlays; and
(4) balance the load among the group members.

Metrics:

Problem:

still suffer from long delay and unplanned interruptions, especially when a large number of peers join the network simultaneously.

challenges:

(1) how to find paths with low delays, including source-to-end delay and startup delay, in a global P2P network;
(2) how to maintain the service continuity and stability (decreasing the impact of interruption caused by peers leaving);
(3) how to determine the frequency of optimization operations; and
(4) how to reduce the control overhead caused by the algorithm.

Component：

explores appropriate paths, builds backup links, and cuts off paths with low QoS for each end peer.

Peer join or leave the topology

LastDelay, which is the minimal of all source-to-end delays from the current node to the streaming source on different paths.
Peers join or leave the topology according to LastDelay.
Generally, each peer maintains one active streaming path set and one backup streaming path set.
When the number of backup streaming paths is less than a threshold, the inter-overlay optimization algorithm is called to find appropriate streaming paths in the global P2P network with the help of the mesh-based overlay.
a probing message named ProbM
There are mainly two tasks for the inter-overlay optimization manager, including backup streaming path set management(reverse tracing) and active streaming path set management.
When one active streaming path is cut off due to its poor QoS or peer’s leaving, a new streaming path is selected from the backup set.

Fetch algorithm:

The playback deadline for each segment and the heterogeneous streaming bandwidth from partners.

topologies

two types of topologies, physical topology and logical P2P topology.
AnySee requires each peer maintain an INCD, from which each peer can have a position, named GID in the global network. The GID value of an end host is a 128-bits integer encoded by the 4-layer geometrical information corresponding to ISPs, cities, campuses, and buildings,
height is always less than 7 even with a thousand peers included in one tree

Buffer size

a small buffer space is enough, and indeed a small buffer often means a shorter startup delay.
threshold DS is set to 25 seconds
the necessary buffer size of AnySee is only 40 seconds, while Coolstreaming needs a 120-second buffer.
layer-aware buffer management: Each peer computes its appropriate buffer space size according to the layer number.

Delay

xx is the average disconnection times of one connection. T’ is the total transporting delay, ta denotes the total link delay,
source-to-end delay is always less than 200 ms. the startup delay of most peers is less than 20s. the startup delay of Coolstreaming is around 60 seconds.

Problem

too many users are leaving the overlay is the signal that the overlay is under heavy burden and needs to be optimized.
“optimization index”, ADL= leaving percentage100 / average delay

Refer

Guerra Ro Ca Richard%20Nixon