In the last few days I've noticed network connectivity issues from multiple virtual machines (fedora, centos, winxp) running on a fedora 12 host. What seemed odd was that I could ping by host name, showing that both the basic network functionality as well as DNS was working. What was failing was browser access to any site outside my own subnet.
I'm reasonably sure the issue is the MTU setting for my host bridge (br0) interface. It currently shows:
# ifconfig br0 [...] UP BROADCAST RUNNING PROMISC MULTICAST MTU:576 Metric:1 [...]
I would have expected MTU:1500. In fact most of the examples I've found show other people with br0 having MTU=1500.
My short term workaround has been to manually set MTU to 576 in each of my VMs. This works, but I'm wondering:
1) Have others seen this? 2) Is there any way to manually increase MTU for the bridge interface?
WRT #2, I tried:
ifconfig br0 mtu 1500
and get this error:
SIOCSIFMTU: Invalid argument
I also tried adding MTU=1500 to ifcfg-br0. No joy.
Any ideas?
Thanks,
Joe