HP OpenVMS Systems Documentation

This section describes tasks required before you configure Mobile IPv6.

Before you can use Mobile IPv6, you must configure your system as an IPv6 host node or a router. See Section 2.4 for more information.

You must verify that Mobile IPv6 support is enabled. You can verify this by issuing the following command:

$ sysconfig -q ipv6 mobileipv6_enabled

If the mobileipv6_enabled attribute is not set to 1, reconfigure it with the following command:

$ sysconfig -r ipv6 mobileipv6_enabled=1 mobileipv6_enabled: reconfigured

The system is now ready to function as a correspondent node. The correspondent node can also forward packets as a router. If you want your system to also function as a router, see Section 5.5.

5.5 Configuring Mobile IPv6

This section describes how to configure your IPv6 node both as a correspondent node and as a correspondent node that acts as an IPv6 router.

5.5.1 Configuring a Correspondent Node

After you verify that IPv6 mobile support is enabled, your system is ready to function as a correspondent node and to communicate with mobile nodes both through the home agent and, after the receiving a binding update from a mobile node, directly with the mobile node. No further configuration is necessary.

5.5.2 Configuring a Home Agent

Please see the HP TCP/IP Services for OpenVMS Release Notes for the latest information on configuring a mobile node as a home agent.

5.6 Monitoring the Mobile IPv6 Environment

To monitor the Mobile IPv6 environment, use the following:

• tcpdump command
• netstat command
• TCPIP$IP6RTRD log file

The tcpdump command captures, parses, and prints IPv6 packets. The binding update and acknowledgment options are contained in IPv6 Destination Option headers in IPv6 packets.

To see IPv6 packets, issue the tcpdump command as follows:

$ tcpdump -s 1500 -x ipv6

See the HP TCP/IP Services for OpenVMS Tuning and Troubleshooting manual for more information about using tcpdump .

5.6.2 Using netstat

The netstat -b command allows you to monitor current mobility bindings and their attributes. The following example shows the command output:

$ netstat -b

Mobile IPv6 Binding Cache

Home Address     Care-of Address    Flags     Refs  Sequence#   Lifetime
testhome         testcoa            A            1     1         43
  [1]               [2]             [3]          [4]        [5]        [6]

This example shows that:

1. The mobile node has a home address of testhome .
2. The mobile node is currently reachable at care-of address testcoa .
3. The mobile node has asked for the binding update to be acknowledged (A flag).
4. There is currently one reference on this binding data structure.
5. The sequence number is set to 1 in the binding update.
6. There are 43 seconds remaining on this binding's lifetime. When the lifetime expires, the entry is removed from the cache.

The netstat -bs command enables you to monitor mobility binding statistics. The following example shows the command output:

$ netstat -bs
Mobile IPv6:
       1 entry in binding cache
       1 add
       0 deletes
       0 changes
       0 frees
       3 lookups

5.6.3 TCPIP$IP6RTRD Log File

This chapter contains a diagnostic map to help you solve problems that might occur when you use an IPv6 network and network services. Use this chapter along with the appropriate HP documentation to solve problems that you encounter.

6.1 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, you may be referred to other TCP/IP Services for OpenVMS documentation for more information about problem-solving tools and utilities.

If you use other products along with the IPv6 networking software described in this manual, you may need to consult the documentation associated with those products for additional information.

6.2 Getting Started

Before you start problem solving, ensure that communications hardware is ready for use. Verify the following:

• The system's physical connections are properly installed. See the documentation for your system and communications hardware device.
• Event logging is enabled to monitor network events. See the system administration manual for information about starting event logging and for descriptions of event messages.

Also check the product release notes for up-to-date information on known problems.

You should be familiar with the following terms:

• On-link node
  An on-link node is attached to the same subnetwork as your system. This subnetwork can be a LAN or an IPv6-over-IPv4 configured tunnel. There are no IPv6 routers between your system and the on-link node.
  For a configured tunnel, the on-link node is the node at the destination end of the tunnel.
• Off-link node
  An off-link node is not attached to the same subnetwork as your system. There is at least one IPv6 router between your system and the off-link node.

This section describes the most basic causes of IPv6 network problems. Before investigating further, make sure you perform the following checks:

1. Make sure the system is on and has completed all startup procedures.
   Check the power to your system. See the system management manual for your system's startup procedure and any problem solving information.
2. Verify IPv6 installation.
   To verify that the IPv6 components are installed, enter the following command:

   $ TCPIP SHOW VER/ALL

   
   TCP/IP Services files should be listed. If the components are not listed, install TCP/IP Services for OpenVMS by using the PCSI command. See the HP TCP/IP Services for OpenVMS Installation and Configuration manual for information about installing the product.
3. Verify IPv6 configuration.
   To verify that IPv6 is configured, enter the following command:

   $ DIR SYS$MANAGER:TCPIP$INET6_CONFIG.DAT

   
   See Section 2.4 for information about setting up and configuring an IPv6 host or router.
4. Verify that IPv6 is started.
   To verify that IPv6 is started, enter the following commands:

   $ SHOW LOGICAL TCPIP$IPV6_STARTED $ ping ::1

   
   If the "host is unreachable" message appears, enable IPv6 by entering the following command:

   $ @SYS$STARTUP:TCPIP$STARTUP

   
   This creates the IPv6 interfaces, brings them up, and starts the IPv6 processes.
   See Section 6.4 for a description of IPv6 host problems; see Section 6.5 for a description of IPv6 router problems.

This section describes possible problems with IPv6 hosts and procedures for solving them.

6.4.1 IPv6 Process Is Not Started

Verify that the TCPIP$ND6HOST process is running by issuing the following command:

$ SHOW SYSTEM /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.

6.4.2 Host Is Unknown

If a remote host is not known, the following message may appear in application log files:

unknown host

Perform the following steps:

1. Check whether the user is specifying a valid host name to reach the remote host.
2. Check whether the remote host is in another domain and whether the user specified the fully qualified domain name.
3. If the remote host is in a domain that you control and your site implements a BIND server, make sure the zone file contains an entry for the remote host. If you do not implement a BIND server, you can add the host to the local host database by editing the file TCPIP$ETC:TCPIP$IPNODES.DAT.
4. If the remote host does not reside in a domain under your control and you are using a BIND server to search the BIND database for name-to-address translation, make sure the resolver is pointing to a valid BIND server. See the HP TCP/IP Services for OpenVMS Management guide for additional information about setting up your BIND environment.

If an on-link node is not reachable, one of the following messages may appear in an application log file:

no route to host
network is unreachable
connection timed out

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:

1. If the node is attached to a LAN, check the data link counters by using the LANCP SHOW DEVICE device /COUNTERS command. Problems with the counters and their possible causes are as follows:
   • Zero blocks sent or received can indicate a network hardware failure or a wiring problem.
   • High collision rates can indicate an improperly wired network or a node that is sending excessive message traffic.
   • Data overrun and buffer unavailable errors indicate that your system is not configured properly.
2. If there is no problem with the data link counters, check the IPv6 and ICMPv6 counters with the netstat -p ipv6 and netstat -p ipv6-icmp commands, respectively. Problems with counters and their possible causes are:
   • Packets discarded because of errors or errors resulting from ICMP errors indicate that another node is generating invalid messages. Other counters show more specific information.
   • Allocation errors can indicate excessive message traffic, an improperly configured system, or a program that repeatedly allocates memory without freeing it.
3. Using the ifconfig -a command, verify that IPv6 network interfaces exist, are up, and have inet6 addresses. If the interfaces do not have inet6 addresses, check the startup file TCPIP$INET6_CONFIG.DAT. Run the TCPIP$IP6_SETUP utility to correct any errors.
   If your interface does not have a global or site-local address, contact your network administrator to verify that your local router is advertising a prefix on the link. If there is no local router, you can define a prefix by using the ifconfig command.
4. Contact the system manager for the adjacent on-link node. Verify that the on-link node is up and running, that it is configured correctly for IPv6, and that the address you are using is enabled on the node's interface.
5. If IPv4 is configured on both systems, issue the ping command to the on-link node's IPv4 address, If the commands succeeds, verify the IPv6 configuration on both systems. If the command fails, see the HP TCP/IP Services for OpenVMS Tuning and Troubleshooting manual for diagnostic procedures.
6. Issue the ping command to other nodes on the link to determine whether the failure is confined to one node or extends to multiple nodes. Partial connectivity might indicate a faulty network device or cable on the link.
7. If the link is a configured tunnel, do the following:
   1. Verify the tunnel source and destination addresses by using the ifconfig -a command. Contact the administrator for the tunnel destination node and verify that your source and destination addresses match the destination and source addresses on that node.
   2. Issue the ping command to the tunnel destination address. If the command fails, see the HP TCP/IP Services for OpenVMS Tuning and Troubleshooting guide for diagnostic procedures.

If an off-link node is not reachable, one of the following messages may appear in an application log files:

no route to host
network is unreachable
connection timed out

Verify that an off-link node is reachable by issuing the ping command.

If there is 100% packet loss, perform the following steps:

1. Verify connectivity between your system and an on-link router by using the ping command.
   If the command fails or shows frequently dropped packets, follow the steps in Section 6.4.3.
   If you do not know the address to a router, issue the following command:

   $ ping -"I" interface ff02::2

2. Verify that the interface over which you are sending messages has a global or site-local unicast address enabled by using the ifconfig -a command.
   If it does not, contact the router's administrator to verify that the router is advertising a prefix on the link.
   If the link is a configured tunnel and the router is not advertising an address prefix, manually define one for the tunnel by using the TCPIP$IP6_SETUP utility.
3. Contact the administrator for the remote system to verify that the system is up and running, that it is configured correctly for IPv6, and that the IPv6 address on its interface is the same as the address you are using.
   If the address is different, check your system's TCPIP$ETC:TCPIP$IPNODES.DAT file, or have the administrator for the remote system check the DNS entry.
4. Verify that there is a default route (with U and G flags set) to a router on the network by issuing the netstat -rf inet6 command. If there is no default route, contact the router administrator to check whether the router is advertising itself as a default router.
   Also, check other routers to see whether your messages are being directed on the wrong path.
5. Trace the path to the off-link node by using the traceroute command.

Frequently dropped packets might indicate either network congestion or an intermittent routing problem. To determine the cause, do the following:

1. Verify connectivity between your system and an on-link router by using the ping command.
2. Trace the path to the off-link node by using the traceroute command.

If someone reports a problem reaching your node from another node, perform the following steps:

1. Verify that their node is reachable by issuing the ping command.
   If the command fails, follow the steps in Section 6.4.3 for an on-link node or Section 6.4.4 for an off-link node.
2. If they are using a name from the DNS database, verify that the address for your node in the DNS database matches one of the addresses configured on your system's interfaces.
   Use the dig AAAA nodename command to retrieve the address from DNS and the ifconfig -a command to display addresses for your system.
3. If they are using an address defined in their local host file TCPIP$ETC:TCPIP$IPNODES.DAT, use the ifconfig -a command to compare that address with the addresses configured on your system's interfaces.

If a remote node is not configured to accept a connection from your application, the following message might appear in an application log file:

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.

6.4.7 Connection Terminates

If the connection terminates abnormally or a network application appears to hang, perform the following steps:

1. Verify that there is network connectivity to the remote node by using the ping command immediately after the failure.
   If the ping command fails or shows a high rate of packet loss, follow the steps in either Section 6.4.3 for on-link nodes, or in Section 6.4.4 for off-link nodes.
2. If your application transfers a large amount of data over the network, verify whether large or fragmented messages are being handled correctly by using the ping -s 2000 nodename command.
   If the ping command fails, trace the path to the remote node with 1200-byte packets by using the traceroute nodename 1200 command. All IPv6 links should support message sizes of at least 1280 bytes. This command might show the location of the problem in the network.
3. Run the application with different client and server nodes located on different links in the network.

This section describes problems with IPv6 routers.

6.5.1 IPv6 Process Is Not Running

Verify that the TCPIP$IP6RTRD process is running by issuing the following command:

$ SHOW SYSTEM /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.

6.5.2 Host Is Unknown

If a remote host is not known, the following message may appear in an application log file:

unknown host

If you receive this message, perform these steps:

1. Check whether the user is specifying a valid host name to reach the remote host.
2. Check whether the remote host is in another domain and whether the user specified the fully qualified domain name.
3. If the remote host is in a domain that you control and if your site implements a BIND server, make sure the zone file contains an entry for the remote host. If you do not implement a BIND server, you can add the host to the local host database by editing the file TCPIP$ETC:TCPIP$IPNODES.DAT.
4. If the remote host does not reside in a domain under your control and you are using a BIND server to search the BIND database for name-to-address translation, make sure the resolver is pointing to a valid BIND server. See the HP TCP/IP Services for OpenVMS Management guide for additional information about setting up your BIND environment.

If an on-link node is not reachable, one of the following messages may appear in an application log file:

no route to host
network is unreachable
connection timed out

Verify that an on-link node or router is reachable by using the ping command. If the command fails or if packets are frequently dropped, complete the following steps:

1. If the node is attached to a LAN, check the data link counters by using the LANCP SHOW DEVICE device /COUNTERS command. Problems with the counters and their possible causes are as follows:
   • Zero blocks sent or received can indicate a network hardware failure or a wiring problem.
   • High collision rates can indicate an improperly wired network or a node that is sending excessive message traffic.
   • Data overrun and buffer unavailable errors indicate your system is not configured properly.
2. If the data link counters are okay, check the IPv6 and ICMPv6 counters with the netstat -p ipv6 and netstat -p ipv6-icmp commands, respectively. Problems with the counters and their possible causes are as follows:
   • Packets discarded because of errors, or errors resulting from ICMP errors, indicate that another node is generating invalid messages. Other counters show more specific information.
   • Allocation errors can indicate excessive message traffic, an improperly configured system, or a program that repeatedly allocates memory without freeing it.
3. Verify that IPv6 network interfaces exist, are up, and have inet6 addresses by using the ifconfig -a command. If they do not have inet6 addresses, check the configuration file TCPIP$INET6_CONFIG.DAT. Run the TCPIP$IP6_SETUP utility to correct any errors.
4. Contact the system administrator for the adjacent on-link node and verify that the on-link node is up and running, that it is configured correctly for IPv6, and that the address you are using is enabled on the node's interface.
5. If IPv4 is configured on both systems, issue the ping command to the on-link node's IPv4 address. If the command succeeds, verify the IPv6 configuration on both systems. If the command fails, see the HP TCP/IP Services for OpenVMS Tuning and Troubleshooting manual.
6. Issue the ping command to other nodes on the link to determine whether the failure is confined to one node or whether it extends to multiple nodes. Partial connectivity might indicate a faulty network device or cable on the link.
7. If the link is a configured tunnel, do the following:
   1. Verify the tunnel source and destination addresses by using the ifconfig -a command. Contact the administrator for the tunnel destination node and verify that your source and destination addresses match the destination and source addresses on that node.
   2. Issue the ping command to the tunnel destination address. If the command fails, see the HP TCP/IP Services for OpenVMS Tuning and Troubleshooting guide for diagnostic procedures.