What are the SoftLayer corporate IPv6 netblocks?
The following are the IPv6 netblocks used on the SoftLayer management network, and should be allowed to connect to your server.
Dallas - 2607:F0D0:1000:0000:/48
Seattle - 2607:F0D0:2000:0000:/48
Washington, DC - 2607:F0D0:3000:0000:/48