MN-3-3-1-1-003 - Use Neighbor Unreachability Detection (Target Address=global)
Host
|
R CN0
| |
-----+-------+--------+---------------- LinkZ
|
R2 NUTY
| |
-----+-------+-----------------+------- LinkY
|
R1 NUTX
| |
-----+-------+-----------------+------- LinkX
|
HA0 Node0 NUT0
| | |
----------------------+---------------+---------+------- 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:a0a0 |
|
| Node0(Link0) |
3ffe:501:ffff:100:200:ff:fe00:a3a3 |
|
| R1(LinkX) |
3ffe:501:ffff:102:200:ff:fe00:a4a4 |
|
| R2(LinkY) |
3ffe:501:ffff:103:200:ff:fe00:a6a6 |
|
| CN0(LinkZ) |
3ffe:501:ffff:104:200:ff:fe00:a8a8 |
|
1. Selection Option
- none.
2. Position of Mobile Node
- none.
HA0 NUT0 R1 R2 CN0
| | | | |
| ----> | | | | 1.Router Advertisement
| | | | |
| NUTX | | |
| | | | |
| | <---- | | | 2.Router Advertisement
| | | | |
| <---- | | | | 3.Neighbor Solicitations(NUD) (*1)
| | | | | 4.(no reply)
| | | | |
1. Send Router Advertisement. (HA0 -> HA0_allnode_multi)
# The Router Address (R) bit is ON.
2. Send Router Advertisement. (R1 -> R1_allnode_multi)
3. Receive Neighbor Solicitations(NUD). (NUT0 -> HA0)
4. (no reply)
# Wait during a maximum of 3 seconds(RFC2461).
(*1) PASS: HA0 receives Neighbor Solicitation(NUD).
Then, check whether this packet fills all of the following.
- The target address is set to HA0 global address of Router Advertisement[1].
(draft-ietf-mobileip-ipv6-24.txt)
11.5.1 Movement Detection
(snip)
Mobile nodes can use the information in received Router
Advertisements to detect L3 handovers. In doing so the mobile node
needs to consider the following issues:
o There might be multiple routers on the same link, thus hearing a
new router does not necessarily constitute an L3 handover.
o When there are multiple routers on the same link they might
advertise different prefixes. Thus even hearing a new router with
a new prefix might not be a reliable indication of an L3 handover.
o The link-local addresses of routers are not globally unique, hence
after completing an L3 handover the mobile node might continue to
receive Router Advertisements with the same link-local source
address. This might be common if routers use the same link-local
address on multiple interfaces. This issue can be avoided when
routers use the Router Address (R) bit, since that provides a
global address of the router.
In addition, the mobile node should consider the following events as
indications that an L3 handover may have occurred. Upon receiving
such indications, the mobile node needs to perform Router Discovery
to discover routers and prefixes on the new link, as described in
Section 6.3.7 of RFC 2461 [12].
o If Router Advertisements that the mobile node receives include an
Advertisement Interval option, the mobile node may use its
Advertisement Interval field as an indication of the frequency
with which it should expect to continue to receive future
Advertisements from that router. This field specifies the minimum
rate (the maximum amount of time between successive
Advertisements) that the mobile node should expect. If this
amount of time elapses without the mobile node receiving any
Advertisement from this router, the mobile node can be sure that
at least one Advertisement sent by the router has been lost. The
mobile node can then implement its own policy to determine how
many lost Advertisements from its current default router
constitute an L3 handover indication.
o Neighbor Unreachability Detection determines that the default
router is no longer reachable.
o With some types of networks, notification that an L2 handover has
occurred might be obtained from lower layer protocols or device
driver software within the mobile node. While further details
around handling L2 indications as movement hints is an item for
further study, at the time of writing this specification the
following is considered reasonable: