Internet DRAFT - draft-arifumi-ipv6-sas-policy-dist
draft-arifumi-ipv6-sas-policy-dist
IPv6 Working Group A. Matsumoto
Internet-Draft NTT
Expires: August 1, 2005 T. Fujisaki
H. Matsuoka
J. Kato
January 31, 2005
Source Address Selection Policy Distribution for Multihoming
draft-arifumi-ipv6-sas-policy-dist-00.txt
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document describes a method for the distribution of source
address selection policy from ISPs to gateway routers for consumers
and from the gateways to end nodes. This method is particularly
effective when a consumer site has multiple address blocks. Every
end node is guided by the policy in selecting an appropriate source
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address for each destination address and every gateway is guided by
the policy in forwarding packets to appropriate next-hop ISPs. This
makes it possible for an end node to set a connection up without
being concerned about failures of transfer due to ingress filtering
by the ISPs, for ISP operators to manage consumers' behavior and
networking policy, and for consumers to be provided with networks
that are almost automatically robust and reliable.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Ingress Filtering Problem . . . . . . . . . . . . . . . . 3
2.2 Closed Network Problem . . . . . . . . . . . . . . . . . . 4
3. Concepts of Our Proposal . . . . . . . . . . . . . . . . . . . 5
4. Proposal Overview For Each Case . . . . . . . . . . . . . . . 7
4.1 Case 1: Multihome Site with Global-Closed Mixed
Connectivity . . . . . . . . . . . . . . . . . . . . . . . 7
4.1.1 Description of Each Element . . . . . . . . . . . . . 7
4.1.2 Discussion . . . . . . . . . . . . . . . . . . . . . . 10
4.2 Case 2: Host with Multiple Addresses and Connectivity
to Two Global Networks . . . . . . . . . . . . . . . . . . 11
4.2.1 Description of Each Element . . . . . . . . . . . . . 11
4.2.2 Discussion . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Case 3: A Host Directly Connected to Multiple ISPs . . . . 13
5. Who merges conflicting policies and how ? . . . . . . . . . . 14
6. Failure Recovery . . . . . . . . . . . . . . . . . . . . . . . 14
6.1 Stop advertising . . . . . . . . . . . . . . . . . . . . . 14
6.2 Address Revocation . . . . . . . . . . . . . . . . . . . . 15
6.3 Policy Modification . . . . . . . . . . . . . . . . . . . 15
7. Solution Comparison . . . . . . . . . . . . . . . . . . . . . 15
7.1 Site Local Address . . . . . . . . . . . . . . . . . . . . 15
7.2 Router Selection . . . . . . . . . . . . . . . . . . . . . 16
7.3 Routing Protocol Based Policy Distribution . . . . . . . . 16
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. Revision History . . . . . . . . . . . . . . . . . . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1 Normative References . . . . . . . . . . . . . . . . . . . . 17
12.2 Informative References . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . 19
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1. Introduction
An IPv6 multihoming site has multiple nodes, each of which is
assigned multiple IPv6 addresses by up-stream ISPs. When there are
multiple up-stream ISPs, the means of selection of the ISP for an
outgoing packet is currently based on the destination address. In
general, however, each packet should have a source address that has
been allocated by the selected up-stream ISP. This is because the
routers of ISPs may be configured to perform ingress filtering with
the aim of blocking packets that have strange source addresses.
In this document, we clarify the problems of source address
selection, list up solutions for them, and propose our solution,
which is a technique that is used both to distribute policy
information for source address selection at end nodes and to
establish a method for the forwarding of packets by routers. This
enables the control of incoming traffic from customer sites by ISPs,
the selection of appropriate source addresses by end nodes, and the
selection of outgoing ISPs in a way that is almost certain to produce
successful connection setup.
2. Problem Statement
2.1 Ingress Filtering Problem
==================
| Internet |
==================
| |
2001:db8::/32 | | 3ffe:1800::/32
+----+-+ +-+----+
| ISP1 | | ISP2 |
+----+-+ +-+----+
| |
2001:db8:a::/48 | | 3ffe:1800:a::/48
++-------++
| Gateway |
+----+----+
| 2001:db8:a:1::/64
| 3ffe:1800:a:1::/64
------+---+----------
|
+-+----+ 2001:db8:a:1:EUI64
| Host | 3ffe:1800:a:1:EUI64
+------+
[Fig. 1]
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When a relatively small site, we call it "consumer network", is
attached to two up-stream ISPs, each ISP delegates network address
block, which is usually /48, and a host has multiple IPv6 addresses.
When the source address of an outgoing packet isn't the one that is
delegated by a transit ISP, the packet will be very probably dropped
by ISP's ingress filter. Ingress filtering is getting popular and
popular among ISPs in order to mitigate the damage of DoS attacks.
One possible solution for this problem is to adopt source address
based routing at consumer site's gateway, but this new way of routing
is not widely deployed yet.
2.2 Closed Network Problem
You can see a second typical source address selection problem in a
multihome site with global-closed mixed connectivity like the figure
below. In this case, Host-A is in a multihomed network and has two
IPv6 addresses delegated from each of up-stream ISPs. Note that ISP2
is closed network and doesn't have connectivity to the Internet.
+--------+
| Host-C | 3ffe:503:c:1:EUI64
+-----+--+
|
============== +--------+
| Internet | | Host-B | 3ffe:1800::EUI64
============== +--------+
| |
2001:db8::/32 | | 3ffe:1800::/32
+----+-+ +-+---++
| ISP1 | | ISP2 | (Closed Network / VPN tunnel)
+----+-+ +-+----+
| |
2001:db8:a::/48 | | 3ffe:1800:a::/48
++-------++
| Gateway |
+----+----+
| 2001:db8:a:1::/64
| 3ffe:1800:a:1::/64
------+---+----------
|
+--+-----+ 2001:db8:a:1:EUI64
| Host-A | 3ffe:1800:a:1:EUI64
+--------+
[Fig. 2]
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This network environment isn't so uncommon as you might perhaps think
of it. The access-line to the ISP2 might be actually a VPN tunnel
over ISP1 and the Internet.
When Host-A starts connection to Host-B in ISP2, the source address
of a sending packet will be the one delegated from ISP2, that is
3ffe:1800:a:1:EUI64, because of rule 8 (longest matching prefix) in
RFC 3484 [RFC3484].
Host-C is located somewhere in the Internet and has an IPv6 address
3ffe:503:c:1:EUI64. When Host-A sends a packet to Host-C, longest
matching algorithm chooses 3ffe:1800:a:1:EUI64 for the source
address. In this case, the packet goes through ISP1 and may be
filtered by ISP1's ingress filter. Even if the packet isn't filtered
by ISP1 fortunately, a return packet from Host-C won't possibly reach
at Host-A, because the return packet is destined for
3ffe:1800:a:1:EUI64, which is closed from the Internet.
In this case, source address based routing alone described in the
previous section doesn't solve the problem. What is important is
that each host chooses a correct source address for a given
destination address as far as NAT doesn't exist in IPv6 world.
3. Concepts of Our Proposal
In this document, we propose a method by which an ISP can distribute
source address selection policies to each end node at a customer
site. The policy information is particularly helpful to hosts in
which multihoming is used, since an end node can use the destination
address to select a source address that leads to a high probability
of successful setup for the connection.
An up-stream ISP is expected to use DHCPv6 Prefix Options [RFC3633]
to delegate a certain portion of the IPv6 address space to its
subscribers. We propose a DHCPv6 new option, which contains a per-
delegating-prefix address-selection policy. By making use of this
option, an ISP can inform its customers of an address block that can
be reached through the ISP and of a corresponding source address of
packets, that is, a source address that must be used to reach the
given block. This is simply achieved through delegation of the
delegated source-address prefix and policy by the ISP.
The gateway router of a customer's site receives the delegated prefix
and address-selection policy mentioned above from its up-stream ISPs.
The router in turn distributes this information to end nodes at the
site. Here, we propose an extension to the ND6 Router Advertisement
Message [RFC2461] and a DHCPv6 [RFC3315] new option to cover delivery
of address-selection policy to the end nodes. The address-selection
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policy delivered to an end node is stored in the form of a Policy
Table as defined in RFC 3484 [RFC3484].
Once the above series of processes is complete, an end node can
select an appropriate source address for a given destination address.
Routing of an outgoing packet to the corresponding up-stream ISP can
be implemented in several ways that avoids blocking of the packet by
ingress filtering. One way is a routing method guided by the source
address of the packet, which is sometimes called "policy routing".
Another method uses destination address based routing with the aid of
additional routing information.
This mechanism is particularly effective when a site subscribes to an
ISP or VPN service that provides connectivity to a certain closed
network as described in the previous section. This is because
selecting an appropriate source address for a given destination
address is crucial in such a network environment.
This approach gives end nodes an advance measure against connection
setup failure. At the same time, an ISP can control incoming traffic
from customers' sites, and the network managers of customers' sites
can reflect their networking policy to some extent by configuring
DHCPv6 or ND6 RA settings on routers. The last but not the least
significant feature to note here is that this sequence of passing,
processing, generation, and reflection of policy information can be
made almost totally automatic from the viewpoint of customers.
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4. Proposal Overview For Each Case
4.1 Case 1: Multihome Site with Global-Closed Mixed Connectivity
Fig. 3 shows a multihome site that subscribes to two ISPs. One ISP
provides global network connectivity and the other provides
connectivity to a closed network but not to the Internet. This site
has one border router, labeled Gateway here, and the router may be
connected to up-stream ISPs through a physical or logical link, say
PPPoE or an IPsec Tunnel.
==============
| Internet |
==============
|
2001:db8::/32 | 3ffe:1800::/32
+----+-+ +-+----+
| ISP1 | | ISP2 | (Closed Network / VPN tunnel )
+----+-+ +-+----+
| |
2001:db8:a::/48 | | 3ffe:1800:a::/48
(DHCP-PD') ++-------++ (DHCP-PD')
| Gateway |
+----+----+
| 2001:db8:a:1::/64
| 3ffe:1800:a:1::/64
| (RA'/DHCP')
------+---+----------
|
+-+----+ 2001:db8:a:1:EUI64
| Host | 3ffe:1800:a:1:EUI64
+------+
[Fig. 3]
4.1.1 Description of Each Element
i) ISP -> Gateway
This figure shows that ISP1 has been allocated 2001:db8::/32 and
ISP2 has been allocated 3ffe:1800::/32. Each ISP delegates part
of its address block, called the "provider aggregatable (PA)"
block, to this customer site. Here, ISP1 and ISP2 use DHCP-PD to
delegate 2001:db8:a::/48 and 3ffe:1800:a::/48, respectively.
In this document, we propose an extension to DHCP-PD, which is
actually a new DHCP option and called DHCP-PD' here. DHCP-PD'
gives DHCP servers (ISPs) functionality for delivering an address-
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selection policy in combination with a delegated prefix to a
client (gateway). In this example, ISP2 includes
Address Addr. Sel. Policy
3ffe:1800:a::/48 ---- 3ffe:1800::/32
in the PD and address-selection policy options sent to the client.
This means that the subscribers of ISP2 should use an address from
the delegated range, that is, 3ffe:1800:a::/48, when communicating
with 3ffe:1800::/32.
Selection of an appropriate source address is very important, and
this is particularly so when one of the subscribing networks is
closed as in this example. This is simply because a return packet
from the closed network can't possibly reach the session-
originating host if the return packet is destined for an address
beyond the range available to the closed ISP.
ISP1 also uses DHCP-PD', in this case to deliver its address-
selection policy to its customers. As ISP1 provides global
network connectivity, the PD and policy options will take the
following form.
Address Addr-Sel. Policy
2001:db8:a::/48 --+-- 2001:db8::/32
+-- ::/0 (all address)
This means that ISP1 can provide connectivity to 2001:db8::/32 and
act as a transit point for any other address (::/0) in the
Internet as long as the source address is that delegated by ISP1,
namely 2001:db8:a::/48.
Of course, ::/0 includes 2001:db8::/32, so 2001:db8::/32 isn't
necessary information for down-stream users. Like this way,
however, by announcing more specific network block than ::/0 as a
policy to down-stream, it is more likely to be adopted by
down-stream nodes. This is because conflicting policies will be
probably discarded at end nodes and routers, as mentioned below in
4.2.1, and ::/0 is much more likely to conflict with other ISP's
policy than 2001:db8::/32. ISPs often provides additional
services, such as video streaming and homepage building tool, only
to their customers. This kind of access control is easily
implemented by announcing ISP's specific network block in their
address-selection policies.
With regard to backward compatibility, a normal DHCP-PD packet,
which does not carry address-selection policy information of the
above type, should be deemed to have ::/0 as its policy field.
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ii) Gateway -> Host
A gateway router receives address-delegation information and
address-selection policy from up-stream ISPs, in turn delivering
both to down-stream nodes. In this document, we propose DHCP new
option and an extension to RA (Router Advertisement Message). We
refer to these as DHCP' and RA', respectively. The gateway router
combines information given by multiple up-stream ISPs and
distributes the following information down-stream through DHCP' or
RA'.
Address Addr. Sel. Policy
1 2001:db8:a:1::/64 --+-- 2001:db8::/32
+-- ::/0
2 3ffe:1800:a:1::/64 ----- 3ffe:1800::/32
This is just the combination of the information from the two up-
stream elements in the previous section, except that each
advertising address prefix is 64 bits long.
iii) Host
When a host receives an RA' or DHCP' message from the site
gateway, it configures addresses for each receiving network
interface and reflects address-selection policy in its
RFC3484-based policy table.
In this example, we propose that the policy table should be
configured as follows, by making use of the Label field defined in
RFC3484, and the relation between address prefix and address-
selection policy should be kept in this table.
Prefix Pref. Label
2001:db8::/32 10 100
::/0 10 100
2001:db8:a:1::/64 10 100
3ffe:1800::/32 10 200
3ffe:1800:a:1::/64 10 200
When this host sends a packet to, for example, 3ffe:1800:a::100,
whose longest matching entry in this table is 3ffe:1800::/32, the
host chooses the address beginning with 3ffe:1800:a:1:: as the
source address. The source-address selection algorithm will
select the longest entry that is a candidate source-address range
and has the same label as the longest matching address for the
destination address. In the same way, the source address of a
packet destined for 2001:db8::/32 or 2002::/16 will be
2001:db8:a:1:EUI64.
Preference values are only used in the selection of destination
addresses. This document does not include an algorithm for
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determining preference values.
iv) Gateway
As well as delivering addresses and policy information to hosts
through RA' or DHCP', the gateway is in charge of forwarding
packets according to policy information distributed by up-stream
ISPs. One way of implementing such forwarding or routing, called
policy routing, is based on the source addresses of out-going
packets. Policy routing is illustrated in the table below.
Src. Next Hop
2001:db8:a:1::/64 ISP1
3ffe:1800:a:1::/64 ISP2
This kind of routing method, however, isn't so common for
consumer network routers. Even if this technique is implemented,
it may degrade packet forwarding performance seriously when it
doesn't have hardware acceleration support. One alternative for
policy routing is to use a routing protocol or some similar
protocols and give a consumer network gateway as much routing
information as the gateway can do destination address based
routing. In this example, the routing table of the gateway looks
like this.
Dst. Next Hop
2001:db8::/32 ISP1
::/0 ISP1
3ffe:1800::/32 ISP2
4.1.2 Discussion
The benefits of this scheme are very clear. Every end node can
determine which source address should be used and can send packets
without a risk of failure due to ingress filtering or the limited
reachability of a closed network.
What should be discussed from here is the need for and implementation
of policy enforcement to end nodes and the process of combining
multiple address-selection policies. It's so hard to combine two
policies automatically when a policy coming from an ISP conflicts
with another ISP's policy. We may also have to think about combining
or pruning algorithm to contain too much policy information in one
packet.
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4.2 Case 2: Host with Multiple Addresses and Connectivity to Two Global
Networks
==================
| Internet |
==================
| |
2001:db8::/32 | | 3ffe:1800::/32
+----+-+ +-+----+
| ISP1 | | ISP2 |
+----+-+ +-+----+
| |
2001:db8:a::/48 | | 3ffe:1800:a::/48
(DHCP-PD') ++-------++ (DHCP-PD')
| Gateway |
+----+----+
| 2001:db8:a:1::/64
| 3ffe:1800:a:1::/64
| (RA'/DHCP')
------+---+----------
|
+-+----+ 2001:db8:a:1:EUI64
| Host | 3ffe:1800:a:1:EUI64
+------+
[Fig. 4]
Fig. 4 shows a host with multiple addresses that subscribes to two
ISPs for connectivity to the Internet. The manner of address
delegation and allocation is as described in the previous example.
4.2.1 Description of Each Element
i) ISP -> Gateway
The difference between this and the previous example is that ISP2
provides global network connectivity, so the DHCP-PD' address-
selection policy option for ISP2 includes an additional entry.
Address Addr. Sel. Policy
3ffe:1800:a::/48 --+-- 3ffe:1800::/32
+-- ::/0
ii) Gateway -> Host
As both ISPs provide global network connectivity, the policy for
address-selection from the gateway router to the end nodes is of
the form shown below.
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Address Addr. Sel. Policy
1 2001:db8:a:1::/64 --+-- 2001:db8::/32
+-- ::/0
2 3ffe:1800:a:1::/64 --+-- 3ffe:1800::/32
+-- ::/0 (deleted)
Note that the gateway is notified of an address-selection policy
that includes prefix ::/0 by both ISPs. A policy table cannot
have multiple entries whose prefixes are the same and labels
aren't the same, which we call conflicting policies.
Though the next section includes further statements about merging
conflicting policies, there are basically two solutions for this
issue: to remove all the conflicting policies or to choose one.
Here, we continue the description of this example with the latter
solution, so the second entry above is removed here and not
forwarded down-stream.
iii) Host
Each end node will have the following address-selection policy
table.
Prefix. Pref. Label
2001:db8::/32 10 100
::0 10 100
2001:db8:a:1::/64 10 100
3ffe:1800::/32 10 200
3ffe:1800:a:1::/64 10 200
It doesn't have any conflicting entries anymore, owing to the
conflict removal at the gateway. Thus, end nodes can determine a
source address for any destination addresses without any trouble.
iv) Gateway
If you remove conflicting source address selection policies for
::/0 and choose one ::/0 policy, the gateway can do destination
address based routing. The routing table at the gateway looks
like this.
Dst. Next Hop
2001:db8::/32 ISP1
::/0 ISP1
3ffe:1800::/32 ISP2
Here, we assume that end nodes select an appropriate source
address for any destination addresses by the aid of distributed
source address selection policy. So, destination address based
routing suffices in this case.
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4.2.2 Discussion
One of the benefits of having an ISP provide address-selection policy
to its customers is that it can explicitly check incoming packets to
see if it is delegated their source addresses. Delivery of an
address-selection policy makes the following mechanisms possible.
- Since end nodes and routers in a multihoming site are given some
kind of routing information, they can select the route expected to
be optimal. In the above example, end nodes can communicate with
servers of the ISPs without any circumvention.
- Another possible usage of this framework is notification of
security policy. ISPs commonly apply IP-address-based filtering
to packets that attempt access to their services, such as POP,
SMTP and Web content, partly for security reasons and partly as a
value- added service for their customers.
4.3 Case 3: A Host Directly Connected to Multiple ISPs
==================
| Internet |
==================
| |
2001:db8::/32 | | 3ffe:1800::/32
| |
2001:db8:a::/48 | | 3ffe:1800:a::/48
(DHCP-PD') +----+-+ +-+----+ (DHCP-PD')
| GW1 | | GW2 |
+----+-+ +-+----+
2001:db8:a:1::/64 | | 3ffe:1800:a:1::/64
(RA'/DHCP') | | (RA'/DHCP')
-----+---+---+-----
|
2001:db8:a:1:EUI64 +--+---+ 3ffe:1800:a:1:EUI64
| Host |
+------+
[Fig. 5]
This example shows an end node directly connected to two ISPs, both
of which provide global network connectivity. This case also has
source address selection problem. Even if a host has enough
knowledge about up-stream network addresses and routes, a host in
this site cannot select an appropriate source address for a given
destination address, as we've mentioned in the problem statement
section.
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[I-D.ietf-ipv6-router-selection] defines another Neighbor Discovery
Router Advertisement option for distributing routing information. In
a case that a host has two network interfaces and is connected to
gateways on a separate link, routing information suffices for
choosing a correct source address. In a site like this, however, a
host should store relationships between routing information and
source address selection. So, in this kind of site, it seems to be
better to use both router-selection mechanism, for distributing
routing information, and our mechanism, for distributing source
address selection policy.
In case gateways are under your control, there is one alternative
approach. It is to redirect packets with a wrong source address at
gateways.
5. Who merges conflicting policies and how ?
Another discussion topic should be about merging method of
conflicting policies and who merges them. As far as an end node
cannot have or make use of multiple source address selection policy
entry for the same prefix, somebody has to merge them into one
policy. There may be three cases for this issue; the site exit
gateway does the merging job, end nodes do and both gateways and end
nodes do.
The management cost of a site might be relatively low, if you let a
gateway to decide which policy to choose, in that you have only to
configure the gateway.
In contrast, if you give end nodes all the information the gateway
received, you can let each end node to choose which source address
selection policy to apply and to select which access-line to use.
This means, at the same time, you have to configure each end node.
Even in such a site that a gateway removes policy conflicts, an end
node should be capable of receiving and manipulating conflicting
policies in case that an additional gateway gets into a local link.
6. Failure Recovery
When one of the links to up-stream ISPs has network trouble and the
consumer gateway detects it, the gateway can take the following
responses.
6.1 Stop advertising
"Stop advertising IPv6 address prefix of the ISP in trouble."
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If the address is assigned by Router Advertisement, this doesn't have
effects on source address selection immediately, because IPv6 address
has relatively long valid and preferred lifetime.
6.2 Address Revocation
"Revoke an address delegated by an ISP in trouble."
If IPv6 address is assigned to end nodes by DHCPv6, the gateway
(DHCPv6 Server) can revoke those addresses that is delegated by a
troubled ISP in a reasonably short time.
6.3 Policy Modification
"Distribute modified source address selection policy that prevents
end nodes from using a certain address."
By distributing, for example, the following source address selection
policy to end nodes, the gateway can control end hosts' address
selection quickly.
Prefix. Pref. Label
2001:db8::/32 10 100
::0 10 100
2001:db8:a:1::/64 10 100
3ffe:1800::/32 10 100
3ffe:1800:a:1::/64 10 200
In this case, this host doesn't use the address 3ffe:1800:a:1:EUI64,
except when it communicate with hosts on the same link.
You may argue that Router Advertisement is essentially a rather
static protocol and isn't suitable for this kind of dynamic
configuration modification. However, it seems also to be true that
these failure recovery methods are useful enough. We basically leave
this topic to an operational issue.
7. Solution Comparison
7.1 Site Local Address
One alternative method for this approach is to use site-local address
for closed network ISP. The site-local address, however, is
deprecated and isn't recommended to use anymore. The newly proposed
site-local address, what we call Unique Local IPv6 Unicast Address
[I-D.ietf-ipv6-unique-local-addr], isn't appropriate for such kind of
use as this, because the address block size of it (/48) is too small
for ISPs to delegate a certain size of IPv6 address block to each
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customer.
7.2 Router Selection
Router Selection [I-D.ietf-ipv6-router-selection] internet-draft is a
proposal for introducing new options for Router Advertisement. As it
is mentioned in section 4.3, this is a solution especially for those
IPv6 nodes that has multiple network interfaces and assigned one IPv6
address for each network interface. Our proposal and this draft
surely has close relationship with each other, but our scope of
problem cannot be resolved only by this mechanism.
7.3 Routing Protocol Based Policy Distribution
Another alternative might be such a modified form of routing
protocol, so that it can store relationships of routes and source
address selection policy. However, it seems to be a big drawback
that consumer site gateway has to support a dynamic routing protocol.
This can bring a big impact on both consumer site gateways and a
provider edge routers.
8. Security Considerations
With regard to the possibility of traffic abduction through the
announcement of a bogus policy, this scheme seems to neither lower
nor raise the security level obtained by the existing base-protocols,
such as DHCP-PD, DHCP and RA. However, it does raise the possibility
of a new form of DoS attack on routers and hosts, in which large
numbers of address-selection policies are generated by different
source addresses. We will have to discuss this and take
precautionary measures in designing the protocol specification.
9. Revision History
The previous revision of this document is
"draft-arifumi-multi6-sas-policy-dist-00.txt".
[I-D.arifumi-multi6-sas-policy-dist] Here lists differences from it.
o Section 2,5,6,7,9 are added.
o We removed descriptions that show dependency on source address
base routing.
o 3rd case in section 4 is changed to one network interface host
from two.
o A little description about merging conflicting policies is added
to 2nd case in section 4.
10. IANA Considerations
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This document has no actions for IANA.
11. Acknowledgement
Many thanks to Iljitsch, Changming and Shin Miyagawa for detailed
feedbacks and discussions on this document. We really appreciate all
the members in our laboratory for their contributions.
12. References
12.1 Normative References
[I-D.ietf-ipv6-router-selection]
Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", draft-ietf-ipv6-router-selection-07
(work in progress), January 2005.
[I-D.ietf-ipv6-unique-local-addr]
Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", draft-ietf-ipv6-unique-local-addr-09 (work in
progress), January 2005.
[RFC2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461, December
1998.
[RFC2991] Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
Multicast Next-Hop Selection", RFC 2991, November 2000.
[RFC2992] Hopps, C., "Analysis of an Equal-Cost Multi-Path
Algorithm", RFC 2992, November 2000.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and
M. Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
12.2 Informative References
[I-D.arifumi-multi6-sas-policy-dist]
Matsumoto, A., "Source Address Selection Policy
Distribution for Multihoming",
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Internet-Draft SAS Policy Distribution January 2005
draft-arifumi-multi6-sas-policy-dist-00 (work in
progress), October 2004.
Authors' Addresses
Arifumi Matsumoto
NTT PFLab
Midori-Cho 3-9-11
Mitaka City, Tokyo Prefecture 180-8585
JP
Phone: +81 422 59 3334
EMail: arifumi@nttv6.net
Tomohiro Fujisaki
Midori-Cho 3-9-11
Mitaka City, Tokyo Prefecture 180-8585
JP
Phone: +81 422 59 7351
EMail: fujisaki@syce.net
Hirotaka Matsuoka
Midori-Cho 3-9-11
Mitaka City, Tokyo Prefecture 180-8585
JP
Phone: +81 422 59 4949
EMail: matsuoka@syce.net
Jun-ya Kato
Midori-Cho 3-9-11
Mitaka City, Tokyo Prefecture 180-8585
JP
Phone: +81 422 59 2939
EMail: kato@syce.net
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