SendingDHAAD - MN sends ICMP HAAD request
Host
SendingDHAAD.seq [-tooloption ...] -pkt MN_Common.def
-tooloption: v6eval tool option
| R TN | | --------+-------+--------------- LinkZ
| R2 NUT2 | | --------+---------------+------- LinkY
| | HA2 R1 NUT1 | | | --------+-------+-------+------- LinkX
| | NUT0 HA1 HA0 | | | Link0 --------+-----------+-----------+-----------------------
Link0 3ffe:501:ffff:100::/64 home link LinkX 3ffe:501:ffff:102::/64 LinkY 3ffe:501:ffff:103::/64 LinkZ 3ffe:501:ffff:104::/64 HA0(Link0) 3ffe:501:ffff:100:200:ff:fe00:a1a1/64 HA1(Link0) 3ffe:501:ffff:100:200:ff:fe00:a2a2/64 HA2(LinkX) 3ffe:501:ffff:102:200:ff:fe00:a3a3 R1(LinkX) 3ffe:501:ffff:102:200:ff:fe00:a4a4 R2(LinkY) 3ffe:501:ffff:103:200:ff:fe00:a5a5 TN(LinkZ) 3ffe:501:ffff:104:200:ff:fe00:a6a6
11.3.2.1. MN sends ICMP HAAD message
NUT1 R1 HA0 | | | | <---- | | RA | | | | ------------> | Home Agent Address Discovery Request (*1) | <------------ | Home Agent Address Discovery Reply | | |
(*1) PASS: TN receives HAAD Request
draft-ietf-mobileip-ipv6-20.txt
Sometimes, when the mobile node needs to send a Binding Update to its home agent to register its new primary care-of address, as described in Section 11.7.1, the mobile node may not know the address of any router on its home link that can serve as a home agent for it. For example, some nodes on its home link may have been reconfigured while the mobile node has been away from home, such that the router that was operating as the mobile node's home agent has been replaced by a different router serving this role.
In this case, the mobile node MAY attempt to discover the address of a suitable home agent on its home link. To do so, the mobile node sends an ICMP Home Agent Address Discovery Request message to the Mobile IPv6 Home-Agents anycast address [16] for its home subnet prefix. As described in Section 10.5, the home agent on its home link that receives this Request message will return an ICMP Home Agent Address Discovery Reply message, giving the global unicast IP addresses for the home agents operating on the home link