On 3/5/08 9:05 PM, "Sto Rage©" netbacker@gmail.com wrote:
Quick question to all the networking gurus on this list. Is there a performance impact if the filer and the clients have different MTU sizes defined. Also is there a way to check this. Our filers all have jumbo frame MTU set to 9000, but for some reason our solaris admin chose to set them on his side to 9194. ifstat on the filer interfaces don't show any errors/discards or retransmits. Example:
Yes, there's definitely a performance impact. Essentially, if one packet's 9100 and one's 9000, you've got 100 that's going to have to be split back into another packet. Your filer will give a response saying "MTU size is too big", please break it into chunks. I'm not sure if this only happens once / session, or per-packet, but if it happens per-packet it's a lot of extra overhead. Even if it's not, that extra 100 needs to go into a new packet, so you're getting overhead of splitting it into chunks and then overhead of re-assembling it on the destination.
Essentially... Yes. :) you want them all to match.