我的托管服务提供商向我提供了以下信息：
子网：2a02:f99:0:64::/64
网关：2a02:f99:0:64::1
所以我这样做了（是的，eth3是正确的界面）
ip addr add 2a02:f99:0:64::2/64 dev eth3
ip -6 route add ::/0 via 2a02:f99:0:64::1 dev eth3
但
$ ip -6 neigh show
2a02:f99:0:64::1 dev eth3 FAILED
$ ping6 google.com
PING google.com(ams16s30-in-x0e.1e100.net) 56 data bytes
From 2a02:f99:0:64::2 icmp_seq=1 Destination unreachable: Address unreachable
...
我也试过
ip -6 route del ::/0 via 2a02:f99:0:64::1 dev eth3
ip -6 route add ::/0 via fe80::1 dev eth3
但这并没有改变任何事情，仍然无法 ping 进或 ping 出。
我哪里做错了？如何让 IPv6 运行？
更新 2017-07-07：
托管服务提供商坚称基础设施良好。
另一台可以访问同一子网的机器可以绑定地址并通过我认为的路由器通告（RA）建立 IPv6 连接，因为只有fe80::20a:8bff:fe98:3400网关有效而提供商指定的网关地址无效。
然而，这篇文章中提到的机器仍然没有找到任何邻居。启用 RA 似乎也没有任何效果。
在两台机器的交叉连接（在其辅助 NIC 上）上运行 IPv6 立即起作用，因此 IPv6 基本上应该对它们两台机器都可用（所有粘贴都来自有问题的机器）：
PING fe80::62eb:69ff:fed2:a122%eth2(fe80::62eb:69ff:fed2:a122) 56 data bytes
64 bytes from fe80::62eb:69ff:fed2:a122: icmp_seq=1 ttl=64 time=0.224 ms
64 bytes from fe80::62eb:69ff:fed2:a122: icmp_seq=2 ttl=64 time=0.171 ms
--- fe80::62eb:69ff:fed2:a122%eth2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
PING fd00:32::3(fd00:32::3) 56 data bytes
64 bytes from fd00:32::3: icmp_seq=1 ttl=64 time=0.286 ms
64 bytes from fd00:32::3: icmp_seq=2 ttl=64 time=0.168 ms
--- fd00:32::3 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
IP 配置如下：
2: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc htb state UP qlen 1000
link/ether f0:1f:af:df:c8:7b brd ff:ff:ff:ff:ff:ff
inet 85.XX.XX.186/30 brd 85.XX.XX.187 scope global eth3
inet6 2a02:f99:0:64::2/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::f21f:afff:fedf:c87b/64 scope link
valid_lft forever preferred_lft forever
2a02:f99:0:64::/64 dev eth3 proto kernel metric 256
fd00:32::/32 dev eth2 proto kernel metric 256
fe80::/64 dev eth2 proto kernel metric 256
fe80::/64 dev eth3-ifb proto kernel metric 256
fe80::/64 dev eth3 proto kernel metric 256
default via 2a02:f99:0:64::1 dev eth3 metric 1024
邻居发现仅找到接口的链路本地地址：
PING ff02::1%eth3(ff02::1) 56 data bytes
64 bytes from fe80::f21f:afff:fedf:c87b: icmp_seq=1 ttl=64 time=0.055 ms
64 bytes from fe80::f21f:afff:fedf:c87b: icmp_seq=2 ttl=64 time=0.076 ms
64 bytes from fe80::f21f:afff:fedf:c87b: icmp_seq=3 ttl=64 time=0.060 ms
--- ff02::1%eth3 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1998ms
尝试 ping 网关也会导致：
PING 2a02:f99:0:64::1(2a02:f99:0:64::1) from 2a02:f99:0:64::2 eth3: 56 data bytes
From 2a02:f99:0:64::2 icmp_seq=1 Destination unreachable: Address unreachable
From 2a02:f99:0:64::2 icmp_seq=2 Destination unreachable: Address unreachable
From 2a02:f99:0:64::2 icmp_seq=3 Destination unreachable: Address unreachable
--- 2a02:f99:0:64::1 ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3999ms
以下是sysctl -A | grep ipv6结果（我也没有发现什么错误）：
net.ipv6.neigh.default.mcast_solicit = 3
net.ipv6.neigh.default.ucast_solicit = 3
net.ipv6.neigh.default.app_solicit = 0
net.ipv6.neigh.default.delay_first_probe_time = 5
net.ipv6.neigh.default.gc_stale_time = 60
net.ipv6.neigh.default.unres_qlen = 3
net.ipv6.neigh.default.proxy_qlen = 64
net.ipv6.neigh.default.anycast_delay = 100
net.ipv6.neigh.default.proxy_delay = 80
net.ipv6.neigh.default.locktime = 0
net.ipv6.neigh.default.retrans_time_ms = 1000
net.ipv6.neigh.default.base_reachable_time_ms = 30000
net.ipv6.neigh.default.gc_interval = 30
net.ipv6.neigh.default.gc_thresh1 = 128
net.ipv6.neigh.default.gc_thresh2 = 512
net.ipv6.neigh.default.gc_thresh3 = 1024
net.ipv6.neigh.lo.mcast_solicit = 3
net.ipv6.neigh.lo.ucast_solicit = 3
net.ipv6.neigh.lo.app_solicit = 0
net.ipv6.neigh.lo.delay_first_probe_time = 5
net.ipv6.neigh.lo.gc_stale_time = 60
net.ipv6.neigh.lo.unres_qlen = 3
net.ipv6.neigh.lo.proxy_qlen = 64
net.ipv6.neigh.lo.anycast_delay = 100
net.ipv6.neigh.lo.proxy_delay = 80
net.ipv6.neigh.lo.locktime = 0
net.ipv6.neigh.lo.retrans_time_ms = 1000
net.ipv6.neigh.lo.base_reachable_time_ms = 30000
net.ipv6.neigh.eth3.mcast_solicit = 3
net.ipv6.neigh.eth3.ucast_solicit = 3
net.ipv6.neigh.eth3.app_solicit = 0
net.ipv6.neigh.eth3.delay_first_probe_time = 5
net.ipv6.neigh.eth3.gc_stale_time = 60
net.ipv6.neigh.eth3.unres_qlen = 3
net.ipv6.neigh.eth3.proxy_qlen = 64
net.ipv6.neigh.eth3.anycast_delay = 100
net.ipv6.neigh.eth3.proxy_delay = 80
net.ipv6.neigh.eth3.locktime = 0
net.ipv6.neigh.eth3.retrans_time_ms = 1000
net.ipv6.neigh.eth3.base_reachable_time_ms = 30000
net.ipv6.neigh.eth2.mcast_solicit = 3
net.ipv6.neigh.eth2.ucast_solicit = 3
net.ipv6.neigh.eth2.app_solicit = 0
net.ipv6.neigh.eth2.delay_first_probe_time = 5
net.ipv6.neigh.eth2.gc_stale_time = 60
net.ipv6.neigh.eth2.unres_qlen = 3
net.ipv6.neigh.eth2.proxy_qlen = 64
net.ipv6.neigh.eth2.anycast_delay = 100
net.ipv6.neigh.eth2.proxy_delay = 80
net.ipv6.neigh.eth2.locktime = 0
net.ipv6.neigh.eth2.retrans_time_ms = 1000
net.ipv6.neigh.eth2.base_reachable_time_ms = 30000
net.ipv6.neigh.eth3-ifb.mcast_solicit = 3
net.ipv6.neigh.eth3-ifb.ucast_solicit = 3
net.ipv6.neigh.eth3-ifb.app_solicit = 0
net.ipv6.neigh.eth3-ifb.delay_first_probe_time = 5
net.ipv6.neigh.eth3-ifb.gc_stale_time = 60
net.ipv6.neigh.eth3-ifb.unres_qlen = 3
net.ipv6.neigh.eth3-ifb.proxy_qlen = 64
net.ipv6.neigh.eth3-ifb.anycast_delay = 100
net.ipv6.neigh.eth3-ifb.proxy_delay = 80
net.ipv6.neigh.eth3-ifb.locktime = 0
net.ipv6.neigh.eth3-ifb.retrans_time_ms = 1000
net.ipv6.neigh.eth3-ifb.base_reachable_time_ms = 30000
net.ipv6.xfrm6_gc_thresh = 2048
net.ipv6.conf.all.forwarding = 0
net.ipv6.conf.all.hop_limit = 64
net.ipv6.conf.all.mtu = 1280
net.ipv6.conf.all.accept_ra = 1
net.ipv6.conf.all.accept_redirects = 1
net.ipv6.conf.all.autoconf = 1
net.ipv6.conf.all.dad_transmits = 1
net.ipv6.conf.all.router_solicitations = 3
net.ipv6.conf.all.router_solicitation_interval = 4
net.ipv6.conf.all.router_solicitation_delay = 1
net.ipv6.conf.all.force_mld_version = 0
net.ipv6.conf.all.use_tempaddr = 0
net.ipv6.conf.all.temp_valid_lft = 604800
net.ipv6.conf.all.temp_prefered_lft = 86400
net.ipv6.conf.all.regen_max_retry = 3
net.ipv6.conf.all.max_desync_factor = 600
net.ipv6.conf.all.max_addresses = 16
net.ipv6.conf.all.accept_ra_defrtr = 1
net.ipv6.conf.all.accept_ra_pinfo = 1
net.ipv6.conf.all.accept_ra_rtr_pref = 1
net.ipv6.conf.all.router_probe_interval = 60
net.ipv6.conf.all.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.all.proxy_ndp = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv6.conf.all.optimistic_dad = 0
net.ipv6.conf.all.mc_forwarding = 0
net.ipv6.conf.all.disable_ipv6 = 0
net.ipv6.conf.all.accept_dad = 1
net.ipv6.conf.all.force_tllao = 0
net.ipv6.conf.default.forwarding = 0
net.ipv6.conf.default.hop_limit = 64
net.ipv6.conf.default.mtu = 1280
net.ipv6.conf.default.accept_ra = 1
net.ipv6.conf.default.accept_redirects = 1
net.ipv6.conf.default.autoconf = 1
net.ipv6.conf.default.dad_transmits = 1
net.ipv6.conf.default.router_solicitations = 3
net.ipv6.conf.default.router_solicitation_interval = 4
net.ipv6.conf.default.router_solicitation_delay = 1
net.ipv6.conf.default.force_mld_version = 0
net.ipv6.conf.default.use_tempaddr = 0
net.ipv6.conf.default.temp_valid_lft = 604800
net.ipv6.conf.default.temp_prefered_lft = 86400
net.ipv6.conf.default.regen_max_retry = 3
net.ipv6.conf.default.max_desync_factor = 600
net.ipv6.conf.default.max_addresses = 16
net.ipv6.conf.default.accept_ra_defrtr = 1
net.ipv6.conf.default.accept_ra_pinfo = 1
net.ipv6.conf.default.accept_ra_rtr_pref = 1
net.ipv6.conf.default.router_probe_interval = 60
net.ipv6.conf.default.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.default.proxy_ndp = 0
net.ipv6.conf.default.accept_source_route = 0
net.ipv6.conf.default.optimistic_dad = 0
net.ipv6.conf.default.mc_forwarding = 0
net.ipv6.conf.default.disable_ipv6 = 0
net.ipv6.conf.default.accept_dad = 1
net.ipv6.conf.default.force_tllao = 0
net.ipv6.conf.lo.forwarding = 0
net.ipv6.conf.lo.hop_limit = 64
net.ipv6.conf.lo.mtu = 16436
net.ipv6.conf.lo.accept_ra = 1
net.ipv6.conf.lo.accept_redirects = 1
net.ipv6.conf.lo.autoconf = 1
net.ipv6.conf.lo.dad_transmits = 1
net.ipv6.conf.lo.router_solicitations = 3
net.ipv6.conf.lo.router_solicitation_interval = 4
net.ipv6.conf.lo.router_solicitation_delay = 1
net.ipv6.conf.lo.force_mld_version = 0
net.ipv6.conf.lo.use_tempaddr = -1
net.ipv6.conf.lo.temp_valid_lft = 604800
net.ipv6.conf.lo.temp_prefered_lft = 86400
net.ipv6.conf.lo.regen_max_retry = 3
net.ipv6.conf.lo.max_desync_factor = 600
net.ipv6.conf.lo.max_addresses = 16
net.ipv6.conf.lo.accept_ra_defrtr = 1
net.ipv6.conf.lo.accept_ra_pinfo = 1
net.ipv6.conf.lo.accept_ra_rtr_pref = 1
net.ipv6.conf.lo.router_probe_interval = 60
net.ipv6.conf.lo.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.lo.proxy_ndp = 0
net.ipv6.conf.lo.accept_source_route = 0
net.ipv6.conf.lo.optimistic_dad = 0
net.ipv6.conf.lo.mc_forwarding = 0
net.ipv6.conf.lo.disable_ipv6 = 0
net.ipv6.conf.lo.accept_dad = -1
net.ipv6.conf.lo.force_tllao = 0
net.ipv6.conf.eth3.forwarding = 0
net.ipv6.conf.eth3.hop_limit = 64
net.ipv6.conf.eth3.mtu = 1500
net.ipv6.conf.eth3.accept_ra = 1
net.ipv6.conf.eth3.accept_redirects = 1
net.ipv6.conf.eth3.autoconf = 0
net.ipv6.conf.eth3.dad_transmits = 1
net.ipv6.conf.eth3.router_solicitations = 3
net.ipv6.conf.eth3.router_solicitation_interval = 4
net.ipv6.conf.eth3.router_solicitation_delay = 1
net.ipv6.conf.eth3.force_mld_version = 0
net.ipv6.conf.eth3.use_tempaddr = 1
net.ipv6.conf.eth3.temp_valid_lft = 604800
net.ipv6.conf.eth3.temp_prefered_lft = 86400
net.ipv6.conf.eth3.regen_max_retry = 3
net.ipv6.conf.eth3.max_desync_factor = 600
net.ipv6.conf.eth3.max_addresses = 16
net.ipv6.conf.eth3.accept_ra_defrtr = 1
net.ipv6.conf.eth3.accept_ra_pinfo = 1
net.ipv6.conf.eth3.accept_ra_rtr_pref = 1
net.ipv6.conf.eth3.router_probe_interval = 60
net.ipv6.conf.eth3.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.eth3.proxy_ndp = 0
net.ipv6.conf.eth3.accept_source_route = 0
net.ipv6.conf.eth3.optimistic_dad = 0
net.ipv6.conf.eth3.mc_forwarding = 0
net.ipv6.conf.eth3.disable_ipv6 = 0
net.ipv6.conf.eth3.accept_dad = 1
net.ipv6.conf.eth3.force_tllao = 0
net.ipv6.conf.eth2.forwarding = 0
net.ipv6.conf.eth2.hop_limit = 64
net.ipv6.conf.eth2.mtu = 1500
net.ipv6.conf.eth2.accept_ra = 1
net.ipv6.conf.eth2.accept_redirects = 1
net.ipv6.conf.eth2.autoconf = 1
net.ipv6.conf.eth2.dad_transmits = 1
net.ipv6.conf.eth2.router_solicitations = 3
net.ipv6.conf.eth2.router_solicitation_interval = 4
net.ipv6.conf.eth2.router_solicitation_delay = 1
net.ipv6.conf.eth2.force_mld_version = 0
net.ipv6.conf.eth2.use_tempaddr = 0
net.ipv6.conf.eth2.temp_valid_lft = 604800
net.ipv6.conf.eth2.temp_prefered_lft = 86400
net.ipv6.conf.eth2.regen_max_retry = 3
net.ipv6.conf.eth2.max_desync_factor = 600
net.ipv6.conf.eth2.max_addresses = 16
net.ipv6.conf.eth2.accept_ra_defrtr = 1
net.ipv6.conf.eth2.accept_ra_pinfo = 1
net.ipv6.conf.eth2.accept_ra_rtr_pref = 1
net.ipv6.conf.eth2.router_probe_interval = 60
net.ipv6.conf.eth2.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.eth2.proxy_ndp = 0
net.ipv6.conf.eth2.accept_source_route = 0
net.ipv6.conf.eth2.optimistic_dad = 0
net.ipv6.conf.eth2.mc_forwarding = 0
net.ipv6.conf.eth2.disable_ipv6 = 0
net.ipv6.conf.eth2.accept_dad = 1
net.ipv6.conf.eth2.force_tllao = 0
net.ipv6.conf.eth3-ifb.forwarding = 0
net.ipv6.conf.eth3-ifb.hop_limit = 64
net.ipv6.conf.eth3-ifb.mtu = 1500
net.ipv6.conf.eth3-ifb.accept_ra = 1
net.ipv6.conf.eth3-ifb.accept_redirects = 1
net.ipv6.conf.eth3-ifb.autoconf = 1
net.ipv6.conf.eth3-ifb.dad_transmits = 1
net.ipv6.conf.eth3-ifb.router_solicitations = 3
net.ipv6.conf.eth3-ifb.router_solicitation_interval = 4
net.ipv6.conf.eth3-ifb.router_solicitation_delay = 1
net.ipv6.conf.eth3-ifb.force_mld_version = 0
net.ipv6.conf.eth3-ifb.use_tempaddr = 0
net.ipv6.conf.eth3-ifb.temp_valid_lft = 604800
net.ipv6.conf.eth3-ifb.temp_prefered_lft = 86400
net.ipv6.conf.eth3-ifb.regen_max_retry = 3
net.ipv6.conf.eth3-ifb.max_desync_factor = 600
net.ipv6.conf.eth3-ifb.max_addresses = 16
net.ipv6.conf.eth3-ifb.accept_ra_defrtr = 1
net.ipv6.conf.eth3-ifb.accept_ra_pinfo = 1
net.ipv6.conf.eth3-ifb.accept_ra_rtr_pref = 1
net.ipv6.conf.eth3-ifb.router_probe_interval = 60
net.ipv6.conf.eth3-ifb.accept_ra_rt_info_max_plen = 0
net.ipv6.conf.eth3-ifb.proxy_ndp = 0
net.ipv6.conf.eth3-ifb.accept_source_route = 0
net.ipv6.conf.eth3-ifb.optimistic_dad = 0
net.ipv6.conf.eth3-ifb.mc_forwarding = 0
net.ipv6.conf.eth3-ifb.disable_ipv6 = 0
net.ipv6.conf.eth3-ifb.accept_dad = -1
net.ipv6.conf.eth3-ifb.force_tllao = 0
net.ipv6.ip6frag_high_thresh = 262144
net.ipv6.ip6frag_low_thresh = 196608
net.ipv6.ip6frag_time = 60
net.ipv6.route.gc_thresh = 1024
net.ipv6.route.max_size = 4096
net.ipv6.route.gc_min_interval = 0
net.ipv6.route.gc_timeout = 60
net.ipv6.route.gc_interval = 30
net.ipv6.route.gc_elasticity = 9
net.ipv6.route.mtu_expires = 600
net.ipv6.route.min_adv_mss = 1220
net.ipv6.route.gc_min_interval_ms = 500
net.ipv6.icmp.ratelimit = 1000
net.ipv6.bindv6only = 0
net.ipv6.ip6frag_secret_interval = 600
net.ipv6.mld_max_msf = 64
更新 2017-07-07 #2：
提供商称两台机器都连接到同一个交换机。这意味着这肯定是配置问题。
更新 2017-07-08：
我已经将内核从 3.4 升级到 3.16，并将 Intel igbNIC 驱动程序升级到其网站上的最新软件包。然而，毫无效果，观察到的行为根本没有改变。
答案1
根据提供商提供的引用信息，您输入的命令乍一看完全正确。这让我们对可能出现的问题有一些可能的猜测。
- 提供商向您提供了错误的信息。
- 正确使用的界面实际上不是，
eth3而是别的东西。 - 从您的机器到网关的路径上存在严重配置错误的防火墙。
- 通信不应该使用以太网上的 IPv6，而是应该使用其他协议，可能是以太网上的 PPP 上的 IPv6。
whois 查询将显示您使用的 IP 地址是分配给 RIPE 的一部分2a00::/12，但尚未分配给任何 ISP。所以我猜想提供商在您收到的信息中输入了错误的 IP 地址。
一些额外的注释可能会引起你的兴趣，也可能不感兴趣。你的路由命令可以缩写为：
ip -6 route add ::/0 via 2a02:f99:0:64::1
这里没有必要指定，dev eth3因为您已经有一条路线表明2a02:f99:0:64::1
我见过至少一家提供商使用fe80::1网关地址。鉴于提供商告诉您将其用作2a02:f99:0:64::1网关地址，它不应该起作用，但这仍然是找出问题所在明智的尝试。
您还可以通过查看数据包捕获来尝试找出正在发生的事情，例如输入：
tcpdump -ni eth3 ip6 -s0
您可以尝试使用以下命令查找该网段上的所有 IPv6 节点：
ping6 ff02::1%eth3
但我最好的建议是向提供商询问2a02:f99::/32未分配的正确信息。
答案2
经过与托管提供商一周的反复沟通（以及浪费了无数个小时尝试各种方法）后，结果发现这毕竟是提供商/基础设施的问题。
将服务器插入不同的路由器后，一切正常。
我想这里要吸取的教训是，当提供商告诉你这是一个机器配置问题时，他们并不总是正确的。