|Summary:||netfront MTU drops to 1500 after domain migration|
|Product:||Red Hat Enterprise Linux 6||Reporter:||Paolo Bonzini <pbonzini>|
|Component:||kernel||Assignee:||Paolo Bonzini <pbonzini>|
|Status:||CLOSED ERRATA||QA Contact:||Virtualization Bugs <virt-bugs>|
|Version:||6.3||CC:||drjones, jzheng, leiwang, lersek, mrezanin, pasik, pbonzini, qguan, qwan, xen-maint, yuzhang|
|Fixed In Version:||kernel-2.6.32-206.el6||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2011-12-06 14:06:39 UTC||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Bug Depends On:||697021, 720347|
Description Paolo Bonzini 2011-08-26 11:18:47 UTC
+++ This bug was initially created as a clone of Bug #733416 +++ Xen drops the MTU of a guest's netfront interface to 1500 after migration. For now I'm attaching the bug to kernel-xen, but I am still not really sure whether this is the right component. Test info for QE: - connect two machines with a crossover cable so that eth0 is the crossover cable and eth1 is the public network - configure Xen so that you'll be able to migrate between the machines (shared storage, relocation server, etc.) - configure the cross link on one machine like # Intel Corporation 82574L Gigabit Network Connection DEVICE=eth0 HWADDR=00:21:5E:6E:F0:29 ONBOOT=yes HOTPLUG=no IPADDR=169.254.100.200 NETMASK=255.255.0.0 NETWORK=169.254.0.0 MTU=9000 and similarly on the other machine - on both machines, ensure the Xen bridge connects the right devices, for example by changing the network-script line in /etc/xen/xend-config.sxp to this: (network-script 'network-bridge netdev=eth0 bridge=xenbr0') - on both machines, ensure the Xen bridge has its MTU set to 9000, for example by adding this (huge hack) to /etc/init.d/xend at the end of function await_daemons_up sleep 5 ip link set mtu 9000 dev vif0.1 ip link set mtu 9000 dev peth0 ip link set mtu 9000 dev xenbr0 - install a guest in one of the machines. ensure the guest has also a static IP configuration in the same subnet, and also has MTU=9000 in its /etc/sysconfig/network-scripts/ifcfg-eth0. Also, ensure that the guest is using xenbr0 and not virbr0. - run ifconfig around "xm create" ifconfig > before xm create test1 # wait a few seconds ifconfig | diff before - The diff should show that the new vif interface has MTU=9000. Similarly, "ifconfig" in the guest should show MTU=9000. - ensure that you can ping the guest from both hosts. - migrate the guest from one host to the other. before migrating, run ifconfig > before on the guest and *destination* host and after migration run ifconfig | diff before - For both the guest and the destination host, the diff should show that the virtual network interface (vifN.0 on the host, eth0 on the guest) has MTU=9000. - ensure that you can ping the guest from both hosts --- Additional comment from email@example.com on 2011-08-26 04:49:40 EDT --- This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
Comment 1 Paolo Bonzini 2011-08-29 12:18:44 UTC
Created attachment 520373 [details] forward port of the RHEL5 patch Upstream did the same using the hw_features field (and ndo_fix_features/ndo_set_features; see commits fb50793 and later) that is not in RHEL6, so I'm instead forward porting the RHEL5 changes.
Comment 2 RHEL Product and Program Management 2011-08-29 14:10:39 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
Comment 3 Paolo Bonzini 2011-08-31 08:38:34 UTC
> - on both machines, ensure the Xen bridge has its MTU set to 9000, for example > by adding this (huge hack) to /etc/init.d/xend at the end of function > await_daemons_up > > sleep 5 > ip link set mtu 9000 dev vif0.1 > ip link set mtu 9000 dev peth0 > ip link set mtu 9000 dev xenbr0 This is not necessary if you have the patch for bug 733417.
Comment 4 Aristeu Rozanski 2011-10-05 15:14:46 UTC
Patch(es) available on kernel-2.6.32-206.el6
Comment 7 Qixiang Wan 2011-10-09 07:26:33 UTC
Verified with RHEL6.2-20111005.1 (kernel-2.6.32-206.el6, both 32 and 64 bit PV guests), host is kernel-xen-2.6.18-274.5.1.el5.x86_64 + xen-3.0.3-132.el5_7.1.x86_64 which has the fixes for bug 738389, bug 738608 and bug 738610. Test setup as bug 738608 comment 6. After migrate guest from source to destination, the MTU of vif in guest can keep the value of 9000. Change bug to VERIFIED.
Comment 8 errata-xmlrpc 2011-12-06 14:06:39 UTC
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2011-1530.html