Configuring Mobile IPv6 Home Agents

At least one router node on the Mobile Node’s home link must be a Home Agent to allow a Mobile Node to remain reachable while away from it is away the home link. As described in “The Router Advertisement Daemon: rtradvd”, the rtradvd determines if a system is Home Agent—not mip6mod.

The rtradvd and mip6mod must be running on Home Agents. The rtradvd configures mip6mod Mobile Node prefix lists and handles handling ICMPv6 messages, the only Mobile IPv6 message mip6mod does not handle. Generally there are no limits to the number of Home Agents you can configure on each home link. The rtradvd is not required on Correspondent Nodes.




	NOTE: Use the man rtradvd command to view the rtradvd (1M) manpage.

Use the following steps to configure an HP-UX IPv6 system as a Home Agent:

Start the interface using the following command:
ifconfig lan1 inet6 -private up
Configure the Home Agent IPv6 global address, for example:
ifconfig lan1:1 inet6 5009:55::230:6eff:fe04:a848 up
Use the mip6config tool to configure the parameters in the mip6mod configuration file. Refer to Chapter 4 “Creating Mobile IPv6 Kernel Module Configuration Files with the mip6config Tool” for more information.
Use the mip6admin tool to start and configure mip6mod with the configuration file. Refer to “Starting mip6mod: start” for more information.
Enable (turn on) the AdvHomeAgentFlag and AdvRouterAddress parameters in the rtradvd configuration file, /etc/rtradvd.conf by default. Enabling the AdvHomeAgentFlag parameter identifies the system as a Home Agent on the link. Enabling the AdvRouterAddress parameter sets the R flag in Router Advertisements and sets the Prefix field to include the sending router node’s address.
Start the rtradvd, for example: rtradvd -c [rtradvd.conf filename]

NOTE: To avoid the Home Agent from dropping Binding Acknowledgment messages while resolving the link layer address of the default router after receiving Binding Update messages, increase the ip6_nd_pending_queue_limit parameter (for example, setting the value to 100). The default setting for this parameter is 5.

Use the following command to set the ip6_nd_pending_queue_limit parameter:

ndd -set /dev/ip6 ip6_nd_pending_queue_limit 100

You can also set the ip6_nd_pending_queue_limit parameter in /etc/rc.config.d/nddconf. Use the following example, where [n] represents the number of entries in /etc/rc.config.d/nddconf:

TRANSPORT_NAME[n]=ip6
NDD_NAME[n]=ip6_nd_pending_queue_limit
NDD_VALUE[n]=100

Configuring Dynamic Home Agent Address Discovery

As described in configure in “Dynamic Home Agent Address Discovery” a Mobile Node only needs a home network prefix configured and it can dynamically find the address of a Home Agent on its home network when it needs to register its Care-of Address. To enable Dynamic Home Agent Address Discovery, you must configure a Mobile IPv6 anycast address on the Home Agent loop-back interface. Use the following steps to enable Dynamic Home Agent Address Discovery:




	NOTE: The following procedure explains how to temporarily enable (not at system boot-up) Dynamic Home Agent Address Discovery on Home Agents. Repeat the following procedure if a Home Agent using Dynamic Home Agent Address Discovery stops and restarts.

Use the mip6config tool to configure the parameters in the mip6mod configuration file on the Home Agent. Refer to Chapter 4 “Creating Mobile IPv6 Kernel Module Configuration Files with the mip6config Tool” for more information.
Use the mip6admin tool to start and configure mip6mod with the mip6mod configuration file. Refer to “Starting mip6mod: start” for more information.
Configure the Home Agent by following the procedure in “Configuring Mobile IPv6 Home Agents ”.
Turn off the private flag on the Home Agent, for example:
ifconfig lo0 inet6 -private up
Configure the Mobile IPv6 anycast address on the Home Agent loop-back interface, for example:
ifconfig lo0:1 inet6 5009:55::fdff:ffff:ffff:fffe up
If the network uses a 64-bit subnet prefix, the format of the Mobile IPv6 anycast address is:
subnet prefix + fdff:ffff:ffff:fffe
For example, if your subnet prefix is 5009:55::, the Mobile IPv6 anycast address is 5009:55::fdff:ffff:ffff:fffe
NOTE: Refer to IETF RFC 2526, Reserved IPv6 Subnet Anycast Addresses, at http://www.ietf.org for more information on anycast address formats.
Temporarily disable Duplicate Address Detection on the Home Agent to avoid disrupting other Home Agents on the link, for example:
ndd -set /dev/ip6 ip6_nd_dad_solicit_count 0
Create a Proxy Neighbor Discovery entry for the Home Agent’s Mobile IPv6 anycast address on the loop-back interface and map the entry to the lan1 MAC address, for example:
ndp -s lan1 5009:55::fdff:ffff:ffff:fffe 0:30:6e:4:a8:48 pub
Start Duplicate Address Detection on the Home Agent, for example:
ndd -set /dev/ip6 ip6_nd_dad_solicit_count 1

Configuring Mobile IPv6 Home Agents

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Configuring Dynamic Home Agent Address Discovery