Monday, October 01, 2007
NCL 2.0 beta and Xen
I found a good candidate for why the Novell Client for Linux 2.0-beta is so crappy in a Xen kernel. Take a look at this:
Frame 6 (4434 bytes on wire, 4434 bytes captured)
What the heck? What it should look like is this:
Frame 6 (1514 bytes on wire, 1514 bytes captured)
So I go to our network guys and ask, "Have we turned on jumbo frames anywhere?" No, we haven't. Anywhere. Which I pretty much knew, since we're not doing any iSCSI. So where the heck is that jumbo coming from? The only thing I can think of is that the sniffing layer I'm getting this at is above the layer that'd grab what actually hits the wire, and something between the sniffer and the wire is converting these jumbos to the normal 1514B ethernet MTU, and that's where my lag is coming from.
This is a case where I'd like to span a port and get a sniff of what actually hits the wire so I can compare.
Frame 6 (4434 bytes on wire, 4434 bytes captured)
What the heck? What it should look like is this:
Frame 6 (1514 bytes on wire, 1514 bytes captured)
So I go to our network guys and ask, "Have we turned on jumbo frames anywhere?" No, we haven't. Anywhere. Which I pretty much knew, since we're not doing any iSCSI. So where the heck is that jumbo coming from? The only thing I can think of is that the sniffing layer I'm getting this at is above the layer that'd grab what actually hits the wire, and something between the sniffer and the wire is converting these jumbos to the normal 1514B ethernet MTU, and that's where my lag is coming from.
This is a case where I'd like to span a port and get a sniff of what actually hits the wire so I can compare.
Labels: linux, novell, virtualization
<permalink> posted by riedesg : 10/01/2007 10:47:00 AM
