On Mon, Jun 11, 2012 at 10:29 PM, Timothy Oefelein <[email protected]> wrote: > > Hello Everybody, > > I've had a server in the pool for a long time now (at least four or five > years). I recently added two more and noted the option of joining this > mailing list. Thought it was dead until the discussion from today. My > servers: > > higgins.chrtf.org - 3.0mbit/s link (bonded T-1s from AT&T) > athena.arpage.org - 6.0mbit/s DS, 1.0mbit/s US (ADSL from Frontier) > tttime.arpage.org - 10.0mbit/s link (fiber connection from Time Warner > Cable) > > Anyhow, two NTP related questions: > > 1) What kind of accuracy/precision loss occurs when you run ntpd on an > asymmetrical connection (e.g., DSL). I've read that ntpd makes the > assumption that your connection is symmetrical when calcuating the effects > of network latency. One of my servers is on an ADSL connection, hence the > question.
I can't speak with any authority, but I thought the main issue was asymmetric *routing*, when your path for inbound and outbound traffic is different. (And that's pretty standard.) I think the problem you're likely to see will be if you start to saturate either side of the link and packets get queued. > 2) Do any of you use the limit and/or kod options in your config? I've > noted some really obnoxious clients (bursts of 20+ queries at a time, every > minute or so) hitting my servers in the past and wondered if any of the > other pool admins take proactive steps against such clients. I don't do anything outside of the default ntpd config, personally. I used to monitor stats pretty closely and identified a ton of obnoxious behavior similar to what you describe. Ultimately, the net bandwidth consumed is still low enough that it's just not worthwhile for me to do anything. (I also figure that the type of people who so badly misconfigure NTP as to flood me with queries are unlikely to notice that I've blocked them at the firewall.) I understand that some people have seen a much greater deal of abuse, though, so others may have a decidedly different opinion here. -- Matt _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
