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In real-time multiplayer games that use UDP for the actual game (CS:S, UT, etc.), how is network latency (ping) measured? More specifically, how do you find out how long ago a UDP packet was sent?

Sorry if this is a dumb question, but I'm very new to network programming.

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  • \$\begingroup\$ Update: on the Quake 3 Networking Model page (web.archive.org/web/20110718080312/http://trac.bookofhook.com/…), there's a mention of unreliable acks. Would this be a good approach — send out a bunch of unreliable UDP packets, noting their sequence number, and then record (halve?) the round-trip time when an ack for a packet returns? \$\endgroup\$ – Archagon Feb 27 '12 at 18:50
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Just send some 'ping', write timestamp of that packet/session, wait for 'pong' response and get timestamp 'now' and divide the difference by two.

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  • \$\begingroup\$ Thank you! In retrospect, this seems really obvious, but I'm really new to all this. :) \$\endgroup\$ – Archagon Feb 27 '12 at 19:00

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