Red Hat Bugzilla – Bug 497451
vif0.0 not set correctly when ifcfg-eth0 has MTU value
Last modified: 2010-11-09 08:24:04 EST
Description of problem: When MTU value is defined in ifcfg-eth0 in Dom0 and xen kernel + associated startup scripts are used, the same MTU is propergated to peth0, xenbr0 and eth0 but not vif0.0. This leads to terrible network performance. Setting MTU to the same value as the previously mentioned devices solves this issue. Version-Release number of selected component (if applicable): 5.3 How reproducible: Every time. Steps to Reproduce: 1. Configure MTU=9000 in /etc/sysconfig/network-scripts/ifcfg-eth0 in Dom0 2. Reboot 3. Attempt large data transfer over, say, SMB Actual results: Dire network performance. Getting 2MB/s rather that 40MB/s. As an aside, agitates issues with network under Vista, cause it to become unresponsive and require Disable/enable of network interface Expected results: Similar throughput to none Xen environment Additional info: Can be resolved by setting MTU manual on vif0.0 Testing has not yet been done for DomUs.
Retesting shows that MTU is not propagated to any other device than eth0 and performance is not degrading. What scripts do you use?? Can you give us xend-config.sxp for this case or retest it with rhel 5.5?
I do not have the environment to test this further.
As we are not able to reproduce the problem and reproduce does not have the enviroment to test, we close this as WORKSFORME. If you ever encounter this problem, feel free to reopen the bz providing the setup of enviroment you reproduced the problem - ifcfg script file, ifconfig output.