Hi,
Disclaimer, I do not have in depth knowledge of vmware, so please excuse the wrong wording, misconception, and ignorance in the post below.
The current topology is as follows:
Each esxi 4.1 update 3 host (DL380 G8) is connect to both layer 2 switch.
on each host, the vswitch has the two NICs configured as active/active, with the default NIC teaming method (route based on the originating virtual port ID).
Everything else is default.
The switches are connected via a trunk link (not stacked)
I have two Windows Server 2008 R2 VMs in the same subnet and have enabled ipv6 on them (default setting)
When the two VMs are on the same physical host, ping -6 destination_ipv6_address works (I just use the link local address)
When the two VMs are on different host, ping fails with "destination unreachable" message, which usually means neighbor discovery process fails (analogous to arp in ipv4 where source VM can't get the destination vm's mac address)
When the two VMs are on the same physical host, packet capture shows that neighbor solicitation message is sent over an ipv6 multicast address
When they are not on the same physical hosts, packet capture on the destination VM shows that the destination VM never gets the ipv6 multicast packet.
I then connect two DL380 G8 in a similar way to the switches, and install windows server 2008 R2 directly without virtualisation on them, and ping -6 works perfectly.
My questions are:
- Am I missing a configuration somewhere to allow ipv6 multicast to work? Or even to remove any "logic" and just treat it as a broadcast?
On network switches, you can do this by turning off IGMP which will then treat multicast as broadcast packets.
Though I can't find a similar setting under esxi anywhere.
- I saw an "enable ipv6" option on esxi, but i assume this is only useful if the host itself wants to participate in ipv6 and therefore not applicable to my particular case?
The only similar issue I found from searching is on the link below, which suggest hardcoding the neighbor table on the VMs, which is not ideal.
I can confirm though, hard coding the neighbor table on both VMs work. So problem seems to lie on how esxi vswitches handle ipv6 multicast traffic
Ideas, insights are greatly appreciated
Ed
Accepted Solutions
- Am I missing a configuration somewhere to allow ipv6 multicast to work? Or even to remove any "logic" and just treat it as a broadcast?
On network switches, you can do this by turning off IGMP which will then treat multicast as broadcast packets.
Though I can't find a similar setting under esxi anywhere.
No, it should work out of the box. The vSwitch makes forwarding decisions based on the layer 2 addresses and shouldn't care about the protocols above.
Can both your VMs communicate via IPv4/layer2-broadcasts when spread across hosts?
I've tested this myself on ESXi 5.1 U1 with two Windows 2008 R2 VMs with the vmxnet3 vNIC, and ICMPv6 Neighbor Discovery for link-local IPv6s works fine on the same host as well as across hosts.
The destination IPv6 of the solicitation message is the usual solicited-node address of the destination, and the layer 2 destination MAC is derived from it and in the IPv6 multicast MAC range prefix 33:33:
- I saw an "enable ipv6" option on esxi, but i assume this is only useful if the host itself wants to participate in ipv6 and therefore not applicable to my particular case?
Correct, that is only for the host management network itself and not related to VM traffic.