John, unfortunately the intermediate version you referenced
didn't yet include changes for the new consensus we reached on
the MIPv6 list. Below you will find the current summarized
situation:
All nodes MUST (no requirements!)
All nodes SHOULD be able to participate in Route Optimization
All nodes MAY be a mobile node
All routers MAY be a home agent
Here's the text:
8.1. General Requirements for All IPv6 Nodes
Any IPv6 node may at any time be a correspondent node of a mobile
node, either sending a packet to a mobile node or receiving a packet
from a mobile node. There are no Mobile IPv6 specific requirements
for such nodes, and standard IPv6 techniques are sufficient.
8.2. Requirements for IPv6 Nodes that Support Route Optimisation
Nodes that implement route optimization are a subset of all IPv6
nodes on the Internet. The ability of a correspondent node to
participate in route optimization is essential for the efficient
operation of the IPv6 Internet, beneficial for robustness and
reduction of jitter and latency, and necessary to avoid congestion
in the home network. The following requirements apply to all
correspondent nodes that support route optimization:
- The node MUST be able validate a Home Address option using an
existing Binding Cache entry, as described in Section 9.2.2.
- The node MUST be able to participate in a return routability
procedure (Section 9.3).
- The node MUST be able to process Binding Update messages
(Section 9.4).
- The node MUST be able to return a Binding Acknowledgement
(Section 6.1.8).
- The node MUST be able to maintain a Binding Cache of the
bindings received in accepted Binding Updates, as described in
Sections 9.1 and 9.5.
- The node MUST be able to insert a Routing Header type 2 into
packets to be sent to a mobile node, as described in Section 9.6.
- Unless the correspondent node is also acting as a mobile node, it
MUST ignore Type 2 Routing Headers and drop all packets that it
has received with such headers.
- The node SHOULD be able to interpret ICMP messages as described
in Section 9.7.
8.3. Requirements for All IPv6 Routers
All IPv6 routers, even those not serving as a home agent for
Mobile IPv6, have an effect on how well mobile nodes can communicate:
- Every IPv6 router SHOULD be able to send an Advertisement
Interval option (Section 7.3) in each of its Router
Advertisements [12], to aid movement detection by mobile nodes
(as in Section 11.5.1). The use of this option in Router
Advertisements MUST be configurable.
- Every IPv6 router SHOULD be able to support sending unsolicited
multicast Router Advertisements at the faster rate described in
Section 7.5. The use of this faster rate MUST be configurable.
- Each router SHOULD include at least one prefix with the Router
Address (R) bit set and with its full IP address in its Router
Advertisements (as described in Section 7.2).
- Filtering routers SHOULD support different rules for Type 0 and
Type 2 Routing Headers (see Section 6.4) so that filtering of
source routed packets (Type 0) will not necessarily limit MIPv6
traffic which is delivered via Type 2 Routing Headers.
8.4. Requirements for IPv6 Home Agents
In order for a mobile node to operate correctly while away from home,
at least one IPv6 router on the mobile node's home link must function
as a home agent for the mobile node. The following additional
requirements apply to all IPv6 routers that serve as a home agent:
- Every home agent MUST be able to maintain an entry in its Binding
Cache for each mobile node for which it is serving as the home
agent (Sections 10.1 and 10.3).
- Every home agent MUST be able to intercept packets (using
proxy Neighbor Discovery [12]) addressed to a mobile node for
which it is currently serving as the home agent, on that mobile
node's home link, while the mobile node is away from home
(Section 10.5).
- Every home agent MUST be able to encapsulate [15] such
intercepted packets in order to tunnel them to the primary
care-of address for the mobile node indicated in its binding in
the home agent's Binding Cache (Section 10.6).
- Every home agent MUST support decapsulating [15] reverse tunneled
packets sent to it from a mobile node's home address. Every home
agent MUST also check that the source address in the tunneled
packets corresponds to the currently registered location of the
mobile node (Section 10.7).
- Every home agent MUST be able to return a Binding Acknowledgement
in response to a Binding Update received with the Acknowledge (A)
bit set (Section 10.3).
- Every home agent MUST maintain a separate Home Agents List for
each link on which it is serving as a home agent, as described in
Section 4.5.
- Every home agent MUST be able to accept packets addressed to
the Mobile IPv6 Home-Agents anycast address for the subnet
on which it is serving as a home agent [16], and MUST be
able to participate in dynamic home agent address discovery
(Section 10.10).
- Every home agent SHOULD support a configuration mechanism to
allow a system administrator to manually set the value to be sent
by this home agent in the Home Agent Preference field of the Home
Agent Information Option in Router Advertisements that it sends
(Section 7.4).
- Every home agent SHOULD support sending ICMP Mobile Prefix
Advertisements (Section 6.8), and SHOULD respond to Mobile Prefix
Solicitations (Section 6.7). This behavior MUST be configurable,
so that home agents can be configured to avoid sending such
Prefix Advertisements according to the needs of the network
administration in the home domain.
- Every home agent MUST support IPsec ESP for protection of packets
belonging to the return routability procedure (Section 10.8).
8.5. Requirements for IPv6 Mobile Nodes
Finally, the following requirements apply to all IPv6 nodes capable
of functioning as mobile nodes:
- The node MUST be able to perform IPv6 encapsulation and
decapsulation [15].
- The node MUST support the return routability procedure
(Section 5.2.5).
- The node MUST be able to send Binding Updates, as specified in
Sections 11.7.1 and 11.7.2.
- The node MUST be able to receive and process Binding
Acknowledgements, as specified in Section 11.7.3.
- The node MUST maintain a Binding Update List (Section 11.1).
- The node MUST support receiving a Binding Refresh Request
(Section 6.1.2), by responding with a Binding Update.
- The node MUST support sending packets containing a Home Address
option (Section 11.3.1).
- The node MUST support receiving Mobile Prefix Advertisements
(Section 11.4.3) and reconfiguring its home address based on the
prefix information contained therein.
- The node SHOULD support use of the dynamic home agent address
discovery mechanism, as described in Section 11.4.1.
- The node MUST be able to process Type 2 Routing Header as defined
in Sections 6.4 and 11.3.3.
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