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3.2 Detailed Parameters
1. Bandwidth between PIDs: 100MBps (bidirection).
2. Size of block: 256 KB.
3. Number of seeds: 1
4. Upstream access link capacity of a seed: 5 MBps.
5. Upstream access link capacity of peers: uniform distribution between 550
KBps to 1000 KBps.
6. Downstream access link capacity of peers: twice the upstream capacity.
Tabl e 1. network topology
Network Region Aggregation level Nodes Links
Abilene
US
PoP
11
28
We use PoP-leveltopologies of Abilene.Table 1 the detailed parameters of Abilene.
Notice that the capacity of each link in Abilene is 10 Gbps on both directions.
3.3 Neighbor Selection Policy
P4P and Improved-P4P improve the neighbor selection policy with the interac-
tion of the ISP and the P2P application. For a peer,
1. Neighbor selection within PID: appTracker select a certain number of neigh-
bors within peer i 's PID; the ratio of this number to the number of peer i 's
neighbors should be limited below a certain percentage.
2. Neighbor selection between PIDs: Suppose that the link price between PID
i and PID j is p ij .Foreach i
1
p ij
= j ,if p ij
=0, w ij =
, else we can set w ij
to be a very large value.
w ij
i = j w ij
W ij =
(14)
For peers in PID i , after finishing neighbor selection within PID, they will se-
lect a certain percentage of neighbors from other PIDs according to W ij .Forro-
bustness, concave function f ( x ) can be introduced to enlarge the relative weight
of W ij . In this paper, we apply f ( x )= x .
3.4 Performance Metrics
We consider the following performance metrics:
1. Completion time: It includes statistics of time that all peers need to finish
downloading and the time that each single peer needs to finish downloading.
2. P2P bottleneck trac: It is the total P2P trac on a link that achieves the
maximum link utilization.
3. Interdomain trac: It is the totalP2P trac on links between ASes; this
metric is used only in interdomain settings.
 
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