Linux under the Ping6__linux

Yesterday tried a bit of Linux and Windows under the IPv6 Ping, found that can not ping link-local address, baffled, and then online Google, and finally found the reason.

IPV6 address under Windows XP:

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

Note that the%6 represents the interface number.

IPV6 address under Linux:

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

Ping a Linux machine under Windows:

C:/>ping FE80::21C:A0FF:FEC5:16CD

Destination Net unreachable.
Destination Net unreachable.
Destination Net unreachable.

Need to use an address with an interface ID:

C:/>ping fe80::21c:a0ff:fec5:16cd%6

Pinging fe80::21c:a0ff:fec5:16cd%6 with bytes of data:

Reply from Fe80::21c:a0ff:fec5:16cd%6:time<1ms
Reply from Fe80::21c:a0ff:fec5:16cd%6:time<1ms
Reply from Fe80::21c:a0ff:fec5:16cd%6:time<1ms
Reply 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 trips times in Milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

On Linux machines:

[Root@test ~]$ ping6 fe80::21a:a5ff:fec1:1060
Connect:invalid argument

An article on the Internet mentions this problem:

https://bugzilla.redhat.com/show_bug.cgi?id=136852

The point are that link-local adress can ' t being used in this way. You ' d
Better set a different global IPv6 adress to eth0 or specify device
Used for ping-ping6-i eth0 FE80:: ...

That is, the interface name must be with:

[Heym@jupiter ~]$ ping6-i eth0 fe80::21a:a5ff:fec1:1060
PING fe80::21a:a5ff:fec1:1060 (fe80::21a:a5ff:fec1:1060) from FE80::21C:A0FF:FEC5:16CD eth0:56 data bytes
Bytes from fe80::21a:a5ff:fec1:1060:icmp_seq=0 ttl=64 time=4.23 ms
Bytes from Fe80::21a:a5ff:fec1:1060:icmp_seq=1 ttl=64 time=0.366 ms
Bytes from fe80::21a:a5ff:fec1:1060:icmp_seq=2 ttl=64 time=0.369 ms

Analysis:

Because the link-local address is in the form of: fe80::a:b:c:d format, without any subnet information, such as indicating the route. So if there are multiple link-local addresses on a machine with multiple network adapters, you must specify which interface to go out from, otherwise the system does not know which link is the address of the path.