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To reduce the network impact and reduce the initial rough estimate time, we also break the landmarks into two tiers. Tier0 landmarks are used to identify the region for the target. Then tier1 hosts for that region can be used to more exactly locate the target. Tier0 hosts are chosen as being at the edges of the region, being well connected, highly reliable and quick to respond. We currently only define tier0 hosts for North America and Europe. In other regions all the landmarks are regarded as tier0. There are about 8 tier0 hosts for North America and 4 for Europe. This reduces the number of landmarks to make measurements from with a tier0 request since there are over 100 landmarks in either North America or Europe.When sending the query to reflector we can characterize it in to three tiers 0,1 and 2. These tiers would be matched with sites.xml nodes and relevant tiering information would be extracted from tag name "tier".
Responses
The responses appear as:
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