| IPv6 Network - Ping and Traceroute | | Print | |
IPv6 Network - Ping and Traceroute
Time-tested network debugging tools ping and traceroute are of course also available for IPv6. However, on most systems, there is no integrated IPv4/IPv6 ping or traceroute, so pinging and tracerouting in IPv6 must be done with separate commands: ping6 and traceroute6. Under Windows, traceroute is “tracert” and the IPv6 version is “tracert6.” The regular tracert also supports IPv6, and tracert6 is now deprecated under Windows though. On all systems, ping6 and traceroute6 are command line utilities. Under Windows, start a command prompt by choosing Start ➤ All Programs ➤ Accessories ➤ Command Prompt, and under MacOS, use the Terminal application in Applications ➤ Utilities. Listing 2-5 shows output from the traceroute6 command under FreeBSD.
Listing 2-5. traceroute6 on FreeBSD
% traceroute6 www.ipv6forum.com
traceroute6 to www.ipv6forum.com (2001:630:d0:131:a00:20ff:feb5:ef1e) from
2001:db8:31:2:201:2ff:fe29:2640, 30 hops max, 12 byte packets
1 46.ge-0-2-0.xr1.pbw.xs4all.net 0.984 ms 0.967 ms 0.798 ms
2 2001:db8:0:106::2 0.959 ms 0.93 ms 1.04 ms
3 0.ge-1-3-0.xr1.tc2.xs4all.net 1.35 ms 1.199 ms 1.125 ms
4 eth10-0-0.xr1.ams1.gblx.net 3.345 ms 1.299 ms 1.637 ms
5 2001:798:2014:20dd::5 19.015 ms 16.712 ms 17.752 ms
6 de.nl1.nl.geant.net 24.046 ms 23.325 ms 22.973 ms
7 nl.uk1.uk.geant.net 33.594 ms 31.715 ms 30.407 ms
8 janet-gw.uk1.uk.geant.net 29.726 ms 31.023 ms 28.623 ms
9 po3-0.lond-scr3.ja.net 28.85 ms 33.616 ms 28.204 ms
10 po6-0.lond-scr.ja.net 28.483 ms 28.863 ms 28.46 ms
11 po0-0.london-bar1.ja.net 29.143 ms 29.582 ms 28.813 ms
12 fe0-1-0.ulcc.ipv6.ja.net 24.845 ms 24.751 ms 24.918 ms
13 fa1-0.rtr1.ipv6.ja.net 24.844 ms 24.966 ms 24.565 ms
14 po2-0.rtr2.ipv6.ja.net 24.841 ms 24.639 ms 26.232 ms
15 zaphod.6core.ecs.soton.ac.uk 33.2 ms 32.621 ms 35.53 ms
16 2001:630:d0:131:a00:20ff:feb5:ef1e 32.953 ms 31.756 ms 30.08 ms
Unlike its IPv4 counterpart, traceroute6 as implemented in FreeBSD, MacOS, and Linux doesn’t by default show both hostnames and addresses for each hop, as the lines get too long that way. Instead, the command shows a hostname if one is available, and an address otherwise. With the -l option, traceroute6 shows both hostnames and addresses, and as usual, the -n option shows only addresses. Even more than with IPv4, it’s common that traceroute6 probes don’t receive an answer because the destination host or a router in the middle is rate limiting the number of ICMP messages it is prepared to return. Older IPv6 implementations tend to limit the number of ICMP messages they send to one per second; newer implementations often have a limit of one per 100 or 200 milliseconds. When traceroute6 doesn’t receive an answer, itprints an asterisk to the screen instead of a time in milliseconds.
The ping6 command is mostly very similar to the IPv4 ping. Listing 2-6 shows the output of the Windows XP ping6 command.
Listing 2-6. The Windows XP ping6 Command
C:\>ping6 www.hitachi.co.jp
Pinging www.hitachi.co.jp [2001:240:400::101]
from 2001:db8:1dde:1:59eb:57:32ff:b6f4 with 32 bytes of data:
Reply from 2001:240:400::101: bytes=32 time=395ms
Reply from 2001:240:400::101: bytes=32 time=396ms
Reply from 2001:240:400::101: bytes=32 time=398ms
Reply from 2001:240:400::101: bytes=32 time=397ms
Ping statistics for 2001:240:400::101:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 395ms, Maximum = 398ms, Average = 396ms
The system will show the available options for traceroute6 (or tracert6) and ping6 commands by typing the command without any arguments. Under Linux, FreeBSD, and MacOS, more detailed information is available in the man pages; to access it, type man ping6 or man traceroute6.
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