Issue

After update of host packages (yum update), we have troubles sending status to SIP proxy in VMs. This did not happen on older kernel.

The communication diagram is as follows:

• HOST 1 hosts VM1.
  • VM1 communicates using eth1/eth1.5.
  • This interface is a bridge to brVOIP46 interface on HOST 1.
  • brVoIP46 is a bond over eth3 and eth4.

               HOST1                                  GUEST (VM1)
  eth3/4 ->  bondVOIP46 -> brVOIP46 | ------------- | eth1
                                                      eth1.5 (VLAN)
                                                      eth1.6 (VLAN)

• HOST 2 hosts VM2.

  • VM2 communicates using eth1/eth1.5.
  • This interface is a bridge to brVOIP46 interface on HOST 2.
  • brVoIP46 is a bond over eth4 and eth5.

• HOST 1 eth3,eth4 and HOST 2 eth4,eth5 are connected to a pair of L2/L3 switch.

Scenario 1
Host kernel:
kernel-2.6.32-431.el6.x86_64

VM kernel:
kernel-2.6.32-431.11.2.el6.x86_64

sip_proxy_mon works fine and heartbeat packages are received by VMs.

Scenario 2
After "yum update" on Host:

Host kernel:
kernel-2.6.32-431.11.2.el6.x86_64

VM kernel:
kernel-2.6.32-431.11.2.el6.x86_64

Communication from with heartheat from VM 1 to VM 2 does not work and VM 2 claims VM 1 application "DEAD":

TCP connections over IPv6 from a VM 1 running on a host with new kernel to another VM 2 running with old kernel are not stable, a connection is established (SYN, ACK/SYN, ACK) but data packets are retransmitted due to missing an acknowledgement, it seems data packets are dropped due to a wrong TCP checksum. Connections in an opposite direction are OK.