`ping6 google.com' works out of the box, then as soon as I run `sudo ip -6 addr add 2600:3c00::f/64 dev eth0', it stops working (100% packet loss). If I remove the address with `sudo ip -6 addr del 2600:3c00::f/64 dev eth0', it starts working again.

(after adding second ip)

ip -6 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2600:3c00::f/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 2600:3c00::f03c:91ff:fe89:57a/64 scope global dynamic 
       valid_lft 2591987sec preferred_lft 604787sec
    inet6 fe80::f03c:91ff:fe89:57a/64 scope link 
       valid_lft forever preferred_lft forever

Appears to be the same after adding IP

ip -6 route show
2600:3c00::/64 dev eth0  proto kernel  metric 256  expires 2591976sec
fe80::/64 dev eth0  proto kernel  metric 256 
default via fe80::1 dev eth0  proto ra  metric 1024  expires 66sec

sudo ip6tables-save
# Generated by ip6tables-save v1.4.21 on Sun Dec 14 19:21:08 2014
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [29:2816]
:POSTROUTING ACCEPT [29:2816]
COMMIT
# Completed on Sun Dec 14 19:21:08 2014
# Generated by ip6tables-save v1.4.21 on Sun Dec 14 19:21:08 2014
*security
:INPUT ACCEPT [143:13344]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [159:14432]
COMMIT
# Completed on Sun Dec 14 19:21:08 2014
# Generated by ip6tables-save v1.4.21 on Sun Dec 14 19:21:08 2014
*raw
:PREROUTING ACCEPT [145:13456]
:OUTPUT ACCEPT [159:14432]
COMMIT
# Completed on Sun Dec 14 19:21:08 2014
# Generated by ip6tables-save v1.4.21 on Sun Dec 14 19:21:08 2014
*mangle
:PREROUTING ACCEPT [145:13456]
:INPUT ACCEPT [143:13344]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [159:14432]
:POSTROUTING ACCEPT [159:14432]
COMMIT
# Completed on Sun Dec 14 19:21:08 2014
# Generated by ip6tables-save v1.4.21 on Sun Dec 14 19:21:08 2014
*filter
:INPUT ACCEPT [39:3776]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [159:14432]
-A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 134 -m hl --hl-eq 255 -j ACCEPT
-A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 135 -m hl --hl-eq 255 -j ACCEPT
-A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 136 -m hl --hl-eq 255 -j ACCEPT
-A INPUT -p ipv6-icmp -m icmp6 --icmpv6-type 137 -m hl --hl-eq 255 -j ACCEPT
COMMIT
# Completed on Sun Dec 14 19:21:08 2014

Does "2600:3c00::f/64" actually belong to you?

That seems highly unlikely; I'd recommend confirming what IPv6 ranges your Linode has in the Remote Access tab.

- Les

Hm. According to this calculator: http://www.tunnelsup.com/subnet-calculator I should have 2600:3C00:0000:0000:0000:0000:0000:0000 - 2600:3C00:0000:0000:FFFF:FFFF:FFFF:FFFF, which 2600:3c00::f/64 belongs to.

Unless I'm doing something horribly incorrect.

EDIT: according to the Linode Manager, I have 2600:3c00::f03c:91ff:fe89:057a / 64

That's the subnet you belong to, not that you have the entire subnet addressable to you.

-Chris

These may be useful:

https://www.linode.com/docs/networking/ ... ress-pools

https://www.linode.com/docs/networking/ ... ipv6-pools

-Chris

https://www.linode.com/docs/networking/ ... networking mentions something along the lines of Public IP Pools showing in the remote access tab of the Linode manager, which certainly is not the case. It also says that the default pool size is /64, which I interpret as the last 16 hex digits of the IP being fully addressable to me. Since it appears to not be displaying my pool, I GUESS that it is 2600:3c00:0000:0000::/64.

They show up after you open a ticket and request a pool from us

-Chris

Well, that should be shown more prominently in the ipv6 documentation (at the top)

It does say that; it's the first sentence of the section on additional IPv6 addresses:

Aware. It's just a basic requirement of the guide to have an ipv6 block, which is apparently not default.

I'd like to second this "make it clearer in the guide" suggestion. I thought the pool assigned to my linode was the default that I had. The wording in the guide is "You can request additional IPv6 addresses at any time by opening a support ticket." I inferred that by "additional" it meant more than your initial /64, which is why the guide listed the various options. It would be nice to change it to, "All linodes initially only have one IPv6 address, but you can request additional IPv6 addresses at any time by opening a support ticket."

And putting a similar note at the top of the guide wouldn't hurt, either.