Red Hat Bugzilla – Bug 473110
RHEL 5.3: allow tun/tap support larger MTU sizes
Last modified: 2009-01-20 14:58:52 EST
Currently, the tun/tap driver doesn't support setting it's MTU size to more than 1500 bytes:
$> ip link set vnet0 mtu 9000
SIOCSIFMTU: Invalid argument
In order to gain the performance improvement resulting from less packet overhead, it's quite common for customers to configure their network so that the entire path between two nodes support jumbo frames (i.e. frame size of 9000 bytes).
Since tun/tap doesn't support this, it's impossible to obtain this benefit with KVM/virtio guests.
The patch to implement this support is quite trivial and has been upstream since 2.6.24.
Created attachment 324770 [details]
You can download this test kernel from http://people.redhat.com/dzickus/el5
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
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