Our Main Metric is Ping

• “Universally available”, easy to understand

  • no software for clients to install

• Low network impact

• Provides loss, response time, reachability, unpredictability

• select hosts carefully, concerns over routers, loaded hosts etc. (provide guidelines)

• does provide useful measures

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We have other tools (e.g. traceping, server response measurements) but will not talk about here, since either not ready, or there are no plans to distribute, or they are not for the WAN.

Some sites block ping (e.g. LANL scared of Ping O’ Death), but we choose clients so usually not a problem

Network impact is ~ 6bytes/sec per client monitored, plus ~ 0.06 bytes/sec per client for gathering data.Recommend sites identify hos to be pinged by providing and alias ping.site.domain

We would liketo recommend that sites identify the host be pinged by providing a DNS alias of the form ping.site.domain