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bab
Asked: 2012-02-24 14:12:51 +0800 CST

VMware ESX 5.0 blocking DHCPv6 solicitations in vSwitches?

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We have a network on which we're setting up a test IPv6 deployment. Here's the layout:

Win2008R2 DHCP VM and Debian Squeeze radvd VM -> vSphere 5.0 vSwitch -(Trunk)-> Catalyst 2960G -(Trunk)-> Catalyst 2960G -> Win7 Laptop

SLAAC works fine, but as soon as I turn off autonomous mode for the prefix, I can see that DHCPv6 is not working properly (the client doesn't get any of the scope options from the Win 2008R2 DHCP Server). Running Wireshark on the client shows that DHCPv6 solicitations are being sent, as expected. Running Wireshark on the DHCP server shows that the packets aren't making it across the network.

My question: I know that DHCPv6 is multicast-based. Could the Catalysts or vSwitches be eating these solicitations? If so - how do I rectify that?

dhcp vmware-esx ipv6 multicast

1 Answers

  1. My guess would be the VM. The IPv6 multicast traffic gets sent out as ethernet multicast so it gets flooded to all ports on the segment. Have you tried sniffing the wire at the trunk cable that connects into the vSphere switch?

    http://en.wikipedia.org/wiki/Multicast_address#Ethernet

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