昨天分别试用了一下Linux下和Windows下的IPv6 Ping，，发现无法ping Link-local地址，百思不得其解，遂上网google一下，终于找到了原因。
Windows XP下的IPv6地址：
Ethernet adapter Test:
Connection-specific DNS Suffix . : IP Address. . . . . . . . . . . . : 192.168.39.137 Subnet Mask . . . . . . . . . . . : 255.255.255.0 IP Address. . . . . . . . . . . . : fe80::21a:a5ff:fec1:1060%6 Default Gateway . . . . . . . . . : 192.168.39.1 fe80::20f:e6ff:fed4:33da%6
注意其中%6表示接口编号。
Linux下的IPv6地址：
eth0 Link encap:Ethernet HWaddr 00:1C:A0:C5:16:CD inet addr:192.168.39.226 Bcast:192.168.39.255 Mask:255.255.255.0 inet6 addr: fe80::21c:a0ff:fec5:16cd/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:274560 errors:11 dropped:0 overruns:0 frame:11 TX packets:4651 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:25845320 (24.6 MiB) TX bytes:1234107 (1.1 MiB) Interrupt:16
在Windows下ping Linux机器：
C:/>ping fe80::21c:a0ff:fec5:16cd
Destination net unreachable.Destination net unreachable.Destination net unreachable.
需要使用带接口ID的地址：
C:/>ping fe80::21c:a0ff:fec5:16cd%6
Pinging fe80::21c:a0ff:fec5:16cd%6 with 32 bytes of data:
Reply from fe80::21c:a0ff:fec5:16cd%6: time<1msReply from fe80::21c:a0ff:fec5:16cd%6: time<1msReply from fe80::21c:a0ff:fec5:16cd%6: time<1msReply from fe80::21c:a0ff:fec5:16cd%6: time<1ms
Ping statistics for fe80::21c:a0ff:fec5:16cd%6: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms
Linux机器上：
[root@test ~]$ ping6 fe80::21a:a5ff:fec1:1060 connect: Invalid argument
网上一篇文章提到这个问题：
https://bugzilla.redhat.com/show_bug.cgi?id=136852
The point is that link-local adress can’t be used in this way. You’dbetter set a different global ipv6 adress to eth0 or specify deviceused for ping – ping6 -I eth0 fe80:: …
也就是必须带接口名：
[heym@jupiter ~]$ ping6 -I eth0 fe80::21a:a5ff:fec1:1060PING fe80::21a:a5ff:fec1:1060(fe80::21a:a5ff:fec1:1060) from fe80::21c:a0ff:fec5:16cd eth0: 56 data bytes64 bytes from fe80::21a:a5ff:fec1:1060: icmp_seq=0 ttl=64 time=4.23 ms64 bytes from fe80::21a:a5ff:fec1:1060: icmp_seq=1 ttl=64 time=0.366 ms64 bytes from fe80::21a:a5ff:fec1:1060: icmp_seq=2 ttl=64 time=0.369 ms
分析：
由于Link-Local地址的形式都是： FE80::a:b:c:d 格式，不带任何子网信息等指示路由。因此如果有多个网卡的机器上就有多个Link-Local地址，就必须指定从哪个接口出去，否则系统不知道是哪条链路上的地址。
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