Red Hat Bugzilla – Bug 474645
network scripts don't set interface MTU when bridging is enabled
Last modified: 2008-12-04 13:58:07 EST
Description of problem:
When an interface is configured to be attached to a bridge, the MTU= line on ifcfg-ethX is ignored by the network setup scripts.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
# cat ifcfg-eth0
# Broadcom Corporation NetXtreme BCM5752 Gigabit Ethernet PCI Express
# cat ifcfg-br0
# ifup eth0
# ifup br0
Determining IP information for br0... done.
# ip link show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:19:b9:45:c2:ca brd ff:ff:ff:ff:ff:ff
eth0 MTU kept as 1500.
eth0 MTU to be set as specified on ifcfg-eth0.
Bridging configuration is common on virtualization setups, and increasing the MTU on network interfaces that support that is a recommended way of improving network performance. Being able to configure the MTU of interfaces attached to bridges is important on those cases.
Two patches from the upstream Fedora initscripts fix this issue (but they involve bonding also, so a simpler fix is possible for mtu/bridging setup only).
*** This bug has been marked as a duplicate of bug 463014 ***