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To monitor your network, use the following UNIX style management tools:
See Appendix B for more information about both IPv6 extensions to the management utilities and IPv6 processes.
The following sections describe each topic.
4.1 Testing Access to Internet Network Hosts with the ping Command
The ping command accepts an IPv4 address, IPv6 address, or node name on the command line. The following sample command specifies an IPv6 address:
$ ping -c 2 5F00:2100:108C:4000:8C40:800:2B2D:2B2 PING (5F00:2100:108C:4000:8C40:800:2B2D:2B2): 56 data bytes 64 bytes from 5F00:2100:108C:4000:8C40:800:2B2D:2B2: icmp6_seq=0 hlim=58 time=17 ms 64 bytes from 5F00:2100:108C:4000:8C40:800:2B2D:2B2: icmp6_seq=1 hlim=58 time=17 ms ----5F00:2100:108C:4000:8C40:800:2B2D:2B2 PING Statistics---- 2 packets transmitted, 2 packets received, 0% packet loss round-trip (ms) min/avg/max = 17/17/17 ms |
The ping command accepts a -V4 or -V6 flag to send an IPv4 ECHO_REQUEST to a node with an IPv4 address, or to send an IPv6 ECHO_REQUEST to a node with an IPv6 address, respectively. If you do not specify either flag, the ping command sends an appropriate ECHO_REQUEST based on the address family being used.
You can also use the -I flag to force the use of a specific interface. For example:
$ ping -"I" "WE0" FE80::800:2B2D:2B2 |
You can display network statistics for sockets, interfaces, and routing tables. The netstat command accepts either the -f inet or -f inet6 flag to limit the data displayed to either IPv4 or IPv6, respectively. For example, the netstat -f inet6 -rn command displays only IPv6 routing table entries, whereas the default displays both IPv4 and IPv6 entries.
The netstat -s commmand displays statistics for all protocols including IPv6 and ICMPv6.
$ netstat -s |
UNIX flags are case sensitive. When using an uppercase flag you must enclose it with quotes to get the expected behavior. OpenVMS interface names are case sensitive. The name of the interface must be enclosed with quotes. |
The traceroute command used with the host argument prints the route that packets take to both IPv4 and IPv6 hosts.
In the following examples, the backslash (\) and the continuation of output onto a second line is for display purposes only. In actual output, the information appears on a single line.
$ traceroute -n host1-v6 traceroute to host1-v6.corp.com (3ffe:1200:4110:3:a00:2bff:feb4:89c5), \ 30 hops max, 24 byte packets 1 fe80::a00:2bff:fe2a:1ed3 130.86 ms 119.141 ms 119.14 ms 2 3ffe:1200:4110:1:a00:2bff:fe2d:2b2 126.014 ms 117.308 ms 116.33 ms 3 3ffe:1200:4110:3:a00:2bff:feb4:89c5 122.195 ms 135.882 ms 119.263 ms $ traceroute 3ffe:1200:4110:3:a00:2bff:feb4:89c5 traceroute to 3ffe:1200:4110:3:a00:2bff:feb4:89c5 \ (3ffe:1200:4110:3:a00:2bff:feb4:89c5), 30 hops max, 24 byte packets 1 fe80::a00:2bff:fe2a:1ed3 (fe80::a00:2bff:fe2a:1ed3) 123.046 ms \ 114.258 ms 117.188 ms 2 host2-v6.corp.com (3ffe:1200:4110:1:a00:2bff:fe2d:2b2) 115.234 ms \ 117.188 ms 116.287 ms 3 host1-v6.corp.com (3ffe:1200:4110:3:a00:2bff:feb4:89c5) 120.241 ms \ 113.398 ms 120.24 ms |
When the route has an IPv6 over IPv4 tunnel, traceroute views this as a single hop. It prints only the IPv6 addresses of the nodes at each end of a tunnel, and none of the intermediate IPv4 routers between the tunnel source and destination. If a traceroute command over a tunnel interface fails, run the command again and specify the tunnel's IPv4 destination address.
The following command shows a trace across the 6bone network to destination tw4.es.net . Note that the intermediate routers appear to drop every other message. The probable reason for this is that the routers rate-limit IPv6 ICMP error messages to one per second. Rate-limiting ICMP error messages is valid behavior.
In the following examples, the backslash (\) and the continuation of output onto a second line is for display purposes only. In actual output, the information appears on a single line.
$ traceroute tw4.es.net traceroute to tw4.es.net (3ffe:780:40:1:a00:2bff:febc:e96c), 30 hops max, 24 byte packets 1 gw1.ipv6.pa-x.dec.com (3ffe:1280:1000:1::f842:1428) 83.985 ms * 83.000 ms 2 3ffe:700:20:1::21 (3ffe:700:20:1::21) 108.399 ms * 112.305 ms 3 3ffe:780:40:1:a00:2bff:febc:e96c(3ffe:780:40:1:a00:2bff:febc:e96c) \ 124.023 ms 134.766 ms 116.211 ms |
The following example shows a trace to destination yogi-gbl using 2000-byte messages. It also shows the effect of path MTU discovery on traceroute results.
$ traceroute yogi-gbl 2000 traceroute to yogi-gbl (fec0:10:60:0:200:f8ff:fe40:d8e6), 30 hops max, 2024 byte packets 1 a30rtr-gbl (fec0:10:30:0:200:f8ff:fe45:cfb2) 5.859 ms 3.906 ms 3.907 ms 2 fec0:10:20:0:a00:2bff:feb0:972d (fec0:10:20:0:a00:2bff:feb0:972d) \ 4.882 ms 3.906 ms 3.906 ms 3 * fec0:10:40:1::a0a:283c (fec0:10:40:1::a0a:283c) 6.836 ms 6.836 ms 4 yogi-gbl (fec0:10:60:0:200:f8ff:fe40:d8e6) 8.789 ms 8.789 ms 7.812 ms |
Hops 1 and 2 occur across Ethernet links that have a link MTU of 1500 bytes. Hop 3 occurs across a configured tunnel with an MTU of 1280 bytes.
The 1500-byte message fragments were transmitted without error until
they hit the tunnel. The first fragment across hop 3 triggered a
"message too big" error, which in turn caused the sender to
record a reduced Path MTU for
yogi-gbl
. The sender sent all subsequent messages with smaller fragments. The
traceroute
display shows that the first probe to the tunnel was dropped but that
all others succeeded.
4.4 IPv6 Process Log Files
The TCPIP$ND6HOSTD and TCPIP$IP6RTRD processes log informational and severe events in the TCPIP$ND6HOSTD.LOG and TCPIP$IP6RTRD.LOG files, which are located in the SYS$MANAGER directory.
Currently logging is always enabled.
This chapter contains a diagnostic map to help you solve problems that
might occur when you use the IPv6 network and network services. Use
this chapter along with the appropriate Compaq documentation to solve
as many problems as possible.
5.1 Using the Diagnostic Suggestions
IPv6 network and network service problems can occur for a number of reasons. This chapter should help you isolate the problem.
After you isolate the problem, the section refers you to other sections for instructions on how to use the various problem-solving tools and utilities.
You may experience problems that are not documented in this manual when
you use the IPv6 network software with other products. See the getting
started documentation for the other products for additional information.
5.2 Getting Started
Before you start problem solving, ensure that communications hardware is ready for use. Verify the following:
Also check the product release notes for up-to-date information on known problems.
You should be familiar with the following terms:
This section describes the most basic causes of IPv6 network problems. Before investigating further, make sure you perform the following checks:
$ TCPIP SHO VER/ALL |
$ DIR SYS$MANAGER:TCPIP$INET6_CONFIG.DAT |
$ SHO LOG TCPIP$IPv6_STARTED $ ping ::1 |
$ @SYS$STARTUP:TCPIP$STARTUP |
This section describes possible problems with IPv6 hosts and procedures
for solving them.
5.4.1 IPv6 Process Is Not Started
Verify that the TCPIP$ND6HOST process is running by issuing the following command:
$ SHO SYS /PROCESS=TCPIP$ND6HOST |
If the process is not running, enable IPv6 with the following command:
$ @SYS$STARTUP:TCPIP$STARTUP.COM |
This creates the IPv6 interfaces, brings them up, and starts the
TCPIP$ND6HOST process.
5.4.2 Host Is Unknown
If a remote host is not known, the following message appears:
unknown host |
Perform the following steps:
If an on-link node is not reachable, one of the following messages appears:
host is unreachable network is unreachable timeout |
Verify that an on-link node or router (if one exists) is reachable by using the ping command. If the command fails or if packets are frequently dropped, perform the following steps:
If an off-link node is not reachable, one of the following message appears:
host is unreachable network is unreachable timeout |
Verify that an off-link node is reachable by issuing the ping command.
If there is 100% packet loss, perform the following steps:
$ ping -"I" interface ff02::2 |
Frequently dropped packets might indicate either network congestion or an intermittent routing problem. To determine the cause, do the following:
If someone reports a problem reaching your node from another node, perform the following steps:
If a remote node is not configured to accept a connection from your application, the following message might appear:
connection refused |
Verify that TCP/IP Services has been correctly configured on the remote node to accept connections.
Contact the administrator for the remote node and ask whether the
correct socket-based service definitions are defined in the
TCPIP$SERVICES.DAT file. Check whether the service has IPv6 enabled.
5.4.7 Connection Terminates
If the connection terminates abnormally or a network application appears to hang, perform the following steps:
This section describes problems with IPv6 routers.
5.5.1 IPv6 Process Is Not Running
Verify that the TCPIP$IP6RTRD process is running by issuing the following command:
$ SHO SYS /PROCESS=TCPIP$IP6RTRD |
If the process is not running, start IPv6 with the following command:
$ @SYS$STARTUP:TCPIP$STARTUP.COM |
This creates the IPv6 interfaces, brings them up, and starts the
TCPIP$IP6RTRD process.
5.5.2 Host Is Unknown
If a remote host is not known, the following message appears:
unknown host |
Perform the following steps:
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