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Thread ID: 115224	2011-01-08 06:46:00	MTU settings.	mzee (3324)	Press F1

Post ID	Timestamp	Content	User
1168125	2011-01-08 06:46:00	My ISP is Orcon. Windows default MTU is 1500. With this setting a ping test shows loss of data and fragmentation. At an MTU of 1462 there is no loss of data. Below this, total loss of data. Above this no change. I can not detect any change in performance with these settings. It all seems to be a waste of time! Latency and speed remain the same. "ping www.orcon.net.nz -f -l 1500"	mzee (3324)
1168126	2011-01-08 07:31:00	What's the problem you're trying to fix? 1500 Bytes is the standard MTU for ethernet; 1492 Bytes is the standard for ADSL. Unless you're having major issues, you should leave these settings alone. In most cases, the lower the MTU, the worse your connection will perform (due to packet fragmentation [also results in higher routing load] & a higher proportion of overhead to data). Setting too low an MTU can also cause problems with some types of connections; most notably VPN.	Erayd (23)
1168127	2011-01-08 10:02:00	The query is; Why does the ping test show data loss at all settings other than 1462 MTU? I have tried them all without any great change in speed or latency. An MTU of 1462+28=1490 + Auto seems to be the best for me.	mzee (3324)
1168128	2011-01-08 10:54:00	The query is; Why does the ping test show data loss at all settings other than 1462 MTU?Normally when ping-testing MTU, the DF (Don't Fragment) bit is set in the IP header. This means that if you send a packet larger than the smallest MTU in the link path, that packet will be dropped rather than fragmented to match the MTU. Packets smaller than 1462 should still be getting through though; if they're not, it means that either you're sending packets that are too large, or you're mucking with the MTU on a link type that doesn't allow it. I have tried them all without any great change in speed or latency.That statement makes no sense, MTU is a scalar value measured in bytes, and doesn't have a defined set of valid sizes. An MTU of 1462+28=1490 + Auto seems to be the best for me.Not quite sure what you're explaining there, MTU is a single value that is set on each end of an IP link. In most cases, both ends should match. The effective MTU of a route is the one of the link with the lowest MTU in the complete path. Which link endpoint[s] are you stating / setting those values for? Can you clarify the problem you're trying to solve? You still haven't actually told us what you're having trouble with.	Erayd (23)
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