Internet DRAFT - draft-sarikaya-dhc-6man-dhcpv6-sadr

draft-sarikaya-dhc-6man-dhcpv6-sadr







Network Working Group                                        B. Sarikaya
Internet-Draft                                                Huawei USA
Intended status: Standards Track                             May 8, 2015
Expires: November 9, 2015


          DHCPv6 Solution for Source Address Dependent Routing
                 draft-sarikaya-dhc-6man-dhcpv6-sadr-01

Abstract

   This document describes DHCPv6 solution for provisioning DHCPv6
   client nodes for the next hop, IPv6 route prefixes and source
   address/prefixes the next hop supports.  Using these options, an
   operator can configure multi-homed nodes where other means of source
   address dependent route configuration may be impractical.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 9, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  DHCPv6 Based Solution . . . . . . . . . . . . . . . . . . . .   3
     2.1.  SADR route configuration  . . . . . . . . . . . . . . . .   4
     2.2.  Configuring on-link routes  . . . . . . . . . . . . . . .   4
     2.3.  Deleting obsolete routes  . . . . . . . . . . . . . . . .   4
     2.4.  Applicability to routers  . . . . . . . . . . . . . . . .   5
     2.5.  Updating Routing Information  . . . . . . . . . . . . . .   5
   3.  DHCPv6 SADR Route Options . . . . . . . . . . . . . . . . . .   6
     3.1.  Route Prefix Option Format  . . . . . . . . . . . . . . .   6
     3.2.  Next Hop Option Format  . . . . . . . . . . . . . . . . .   8
     3.3.  Source Address/Prefix Option Format . . . . . . . . . . .   9
   4.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . . . .  10
   5.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The Neighbor Discovery (ND) protocol [RFC4861] provides a mechanism
   for hosts to discover one or more default routers on a directly
   connected network segment.  Extensions to the Router Advertisement
   (RA) protocol defined in [RFC4191] allow hosts to discover the
   preferences for multiple default routers on a given link, as well as
   any specific routes advertised by these routers.  This provides
   network administrators with a new set of tools to handle multi-homed
   host topologies and influence the route selection by the host.

   In source address dependent routing, both Router Advertisement option
   defined in [I-D.sarikaya-6man-sadr-ra] and DHCPv6 options defined in
   this document can be used, e.g. in networks that deployed DHCPv6
   [RFC3315].

   DHCPv6 source address dependent routing SADR Route Options defined in
   this document can be used to configure fixed and mobile nodes in



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   multi-homed scenarios with route information and next hop address.
   Different scenarios exist such as the node is simultaneously
   connected to multiple access network of e.g.  WiFi and LTE.  The node
   may also be connected to more than one gateway.  Such connectivity
   may be realized by means of dedicated physical or logical links that
   may also be shared with other users nodes such as in residential
   access networks.

   A document defining topologies and in general providing an overview
   of the issue of source address dependent routing (SADR) is presented
   in [I-D.sarikaya-6man-sadr-overview].

   The solution presented in this document is part of the network
   configuration information.  A consistent set of network configuration
   is defined as Provisioning Domain (PvD) [I-D.ietf-mif-mpvd-arch].
   PvDs or so-called explicit PvDs may include information related to
   more than one interfaces as is the case in this document.  It is
   important to note that the node has a trust relationship with the
   PvD, in such a case, it is called trusted PvD.  The trust is
   established using authorization and authentication between the node
   that is using the PvD configuration and the source that provided that
   configuration.  In this document, we assume that DHCP server can
   provide trusted PvDs to the hosts.

   It should be noted that the next hop option and its suboptions (route
   prefix and source prefix) defined in this document are included in
   the PVD Container option defined in [I-D.ietf-mif-mpvd-dhcp-support].

2.  DHCPv6 Based Solution

   A DHCPv6 based solution allows an operator an on demand and node
   specific means of configuring SADR routing information.  Such a
   solution also fits into network environments where the operator
   prefers to manage Residential Gateway (RG) configuration information
   from a centralized DHCP server.  [RFC7157] provides additional
   background to the need for a DHCPv6 solution to the problem.

   In terms of the high level operation of the solution defined in this
   draft, a DHCPv6 client interested in obtaining SADR routing
   information requests the route options using the DHCPv6 Option
   Request Option (ORO) sent to a server.  A Server, when configured to
   do so, provides the requested route information as part of a nested
   options structure covering; the next-hop address; the destination
   prefix; the route metric; source prefixes that the next hop router
   supports.






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2.1.  SADR route configuration

   A non-trustworthy network may be available at the same time as a
   trustworthy network, with the risk of bad consequences if the host
   gets confused between the two.  These are basically the two models
   for hosts with multiple interfaces, both of which are valid, but
   which are incompatible with each other.  In the first model, an
   interface is connected to something like a corporate network, over a
   Virtual Private Network (VPN).  This connection is trusted because it
   has been authenticated.  SADR routes obtained over such a connection
   can probably be trusted, and indeed it may be important to use those
   routes.  This is because in the VPN case, you may also be connected
   to a network that's offered you a default route, and you could be
   attacked over that connection if you attempt to connect to resources
   on the enterprise network over it.

   On the other, non-trustworthy network scenario, none of the networks
   to which the host is connected are meaningfully more or less
   trustworthy.  In this scenario, the untrustworthy network may hand
   out SADR routes to other hosts, e.g. those in the VPN going through
   some malicious nodes.  This will have bad consequences because the
   host's traffic intended for the corporate VPN may be hijacked by the
   intermediate nodes.

   DHCPv6 options described in this document can be used to install SADR
   routes.  However, the use of such a technique makes sense only in the
   former case above, i.e. trusted network.  So the host MUST have an
   authenticated connection to the network it connects so that DHCPv6
   route options can be trusted before establishing routes.

2.2.  Configuring on-link routes

   Server may also configure on-link routes, i.e. routes that are
   available directly over the link, not via routers.  To specify on-
   link routes, server MAY include RT_PREFIX option directly in
   Advertise and Reply messages.

2.3.  Deleting obsolete routes

   There are two mechanisms that allow removing a route.  Each defined
   route has a route lifetime.  If specific route is not refreshed and
   its timer reaches 0, client MUST remove corresponding entry from
   routing table.

   In cases where faster route removal is needed, server SHOULD return
   RT_PREFIX option with route lifetime set to 0.  Client that receives
   RT_PREFIX with route lifetime set to 0 MUST remove specified route
   immediately, even if its previous lifetime did not expire yet.



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2.4.  Applicability to routers

   SADR routing configuration over DHCPv6 defined in this document may
   be used by both hosts and routers.

   One of the envisaged usages for this solution is residential gateways
   (RG) or Customer Premises Equipment (CPE).  Those devices very often
   perform routing.  It may be useful to configure routing on such
   devices over DHCPv6.  One example of such use may be a class of
   premium users that are allowed to use dedicated router that is not
   available to regular users.

2.5.  Updating Routing Information

   Network configuration occassionally changes, due to failure of
   existing hardware, migration to newer equipment or many other
   reasons.  Therefore there a way to inform clients that SADR routing
   information have changed is required.

   There are several ways to inform clients about new SADR routing
   information.  Every client SHOULD periodically refresh its
   configuration, according to Information Refresh Time Option, so
   server may send updated information the next time client refreshes
   its information.  New routes may be configured at that time.  As
   every route has associated lifetime and source address/prefixes,
   client is required to remove its routes when this timer expires.
   This method is particularly useful, when migrating to new router is
   undergoing, but old router is still available.

   Server MAY also announce SADR routes via soon to be removed router
   with lifetimes set to 0.  This will cause the client to remove its
   SADR routes, despite the fact that previously received lifetime may
   not yet expire.

   Aforementioned methods are useful, when there is no urgent need to
   update SADR routing information.  Bound by timer set by value of
   Information Refresh Time Option, clients may use outdated SADR
   routing information until next scheduled renewal.  Depending on
   configured value this delay may be not acceptable in some cases.  In
   such scenarios, administrators are advised to use RECONFIGURE
   mechanism, defined in [RFC3315].  Server transmits RECONFIRGURE
   message to each client, thus forcing it to immediately start renewal
   process.








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3.  DHCPv6 SADR Route Options

   A DHCPv6 client interested in obtaining source address dependent
   routing information includes the NEXT_HOP, RT_PREFIX and SOURCE_AP
   options as part of its Option Request Option (ORO) in messages
   directed to a server (as allowed by [RFC3315], i.e. Solicit, Request,
   Renew, Rebind or Information-request messages).  A Server, when
   configured to do so, provides the requested route information using
   zero, one or more NEXT_HOP options in messages sent in response
   (Advertise, and Reply).  So as to allow the route options to be both
   extensible, as well as conveying detailed info for routes, use is
   made of a nested options structure.  Server sends one or more
   NEXT_HOP options that specify the IPv6 next hop addresses.  Each
   NEXT_HOP option conveys in turn zero, one or more RT_PREFIX options
   that represents the IPv6 destination prefixes reachable via the given
   next hop.  Server includes RT_PREFIX directly in message to indicate
   that given prefix is available directly on-link.  Server MAY send a
   single NEXT_HOP without any RT_PREFIX suboptions or with RT_PREFIX
   that contains ::/0 to indicate available default route.  Server sends
   one or more SOURCE_AP options that specify the IPv6 source address/
   prefixes that this next hop supports.  This is to inform the host to
   use the correct source addresses when sending packets to destinations
   via this next hop so that the packets do not get ingress filtered.
   The Formats of the NEXT_HOP, RT_PREFIX and SOURCE_AP options are
   defined in the following sub-sections.

3.1.  Route Prefix Option Format

   The Route Prefix Option is used to convey information about a single
   prefix that represents the destination network.  The Route Prefix
   Option is used as a sub-option in the previously defined Next Hop
   Option.  It may also be sent directly in message to indicate that
   route is available directly on-link.


















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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       OPTION_RT_PREFIX        |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Route lifetime                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Prefix-Length |    Metric     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                            Prefix                             |
   |                          (up to 16 octets)                    |
   |                                                               |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 1: Route Prefix Option Format

   option-code:  OPTION_RT_PREFIX (TBD2).

   option-len:  Length of the Route Prefix option including all its sub-
             options.

   Route lifetime  32-bit unsigned integer.  Specifies lifetime of the
             route information, expressed in seconds (relative to the
             time the packet is sent).  There are 2 special values
             defined. 0 means that route is no longer valid and must be
             removed by clients.  A value of all one bits (0xffffffff)
             represents infinity.  means infinity.

   Prefix Length:  8-bit unsigned integer.  The length in bits of the IP
             Prefix.  The value ranges from 0 to 128.  This field
             represents the number of valid leading bits in the prefix.

   Resvd:    Reserved field.  Server MUST set this value to zero and
             client MUST ignore its content.

   Metric:   Route Metric. 8-bit signed integer.  The Route Metric
             indicates whether to prefer the next hop associated with
             this prefix over others, when multiple identical prefixes
             (for different next hops) have been received.

   Prefix:   a variable size field that specifies Rule IPv6 prefix.
             Length of the field is defined by prefix6-len field and is
             rounded up to the nearest octet boundary (if case when
             Prefix Length is not divisible by 8).  In such case
             additional padding bits must be zeroed.




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   Values for metric field have meaning based on the value, i.e. higher
   value indicates higher preference.

3.2.  Next Hop Option Format

   Each IPv6 route consists of an IPv6 next hop address, an IPv6
   destination prefix (a.k.a. the destination subnet), and a host
   preference value for the route.  Elements of such route (e.g.  Next
   hops and prefixes associated with them) are conveyed in NEXT_HOP
   option that contains RT_PREFIX suboptions.

   The Next Hop Option defines the IPv6 address of the next hop, usually
   corresponding to a specific next-hop router.  For each next hop
   address there can be zero, one or more prefixes reachable via that
   next hop.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        OPTION_NEXT_HOP        |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                    IPv6 Next Hop Address                      |
   |                       (16 octets)                             |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                        NEXT_HOP sub-options                   |
   .                                                               .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 2: IPv6 Next Hop Option Format

   option-code:  OPTION_NEXT_HOP (TBD1).

   option-len:  16 + Length of NEXT_HOP options field.

   IPv6 Next Hop Address:  16 octet long field that specified IPv6
             address of the next hop.

   NEXT_HOP options:  Options associated with this Next Hop. This
             includes, but is not limited to, zero, one or more
             RT_PREFIX options that specify prefixes reachable through
             the given next hop.

   NEXT_HOP options:  Options associated with this Next Hop. This
             includes, but is not limited to, zero, one or more



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             SOURCE_AP and RT_PREFIX options that specify prefixes
             reachable through the given next hop.

3.3.  Source Address/Prefix Option Format

   Each IPv6 route consists of an IPv6 next hop address, an IPv6
   destination prefix (a.k.a. the destination subnet), and a host
   preference value for the route.  Elements of such route (e.g.  Next
   hops and prefixes associated with them) are conveyed in NEXT_HOP
   option that contains RT_PREFIX suboptions.

   The Source Address/Prefix Option defines the source IPv6 prefix/
   address that are assigned from the prefixes that belong to this next
   hop.  This option MUST be used by the host to avoid ingress
   filtering.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        OPTION_SOURCE_AP        |          option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Prefix-Length |  Reserved     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |              IPv6 Source Address/Prefix                       |
   |                          (up to 16 octets)                    |
   |                                                               |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 3: IPv6 Source Address/Prefix Option Format

   option-code:  OPTION_SOURCE_AP (TBD1).

   option-len:  16 + Length of SOURCE_AP options field.

   Prefix Length:  8-bit unsigned integer.  The length in bits of the IP
             Prefix.  The value ranges from 0 to 128.  This field
             represents the number of valid leading bits in the prefix.
             In case of source address this field is set to 132.

   Resvd:    Reserved field.  Server MUST set this value to zero and
             client MUST ignore its content.

   IPv6 Source Address/Prefix:  16 octet long field that specified IPv6
             source address or source prefix.





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4.  DHCPv6 Server Behavior

   When configured to do so, a DHCPv6 server shall provide the NEXT_HOP
   and RT_PREFIX Options in ADVERTISE and REPLY messages sent to a
   client that requested the route option.  Each Next Hop Option sent by
   the server must convey at least one Route Prefix Option.

   Server includes NEXT_HOP option with possible RT_PREFIX suboptions to
   designate that specific routes are available via routers.  Server
   includes RT_PREFIX options in Next Hop sub-options directly in
   Advertise and Reply messages to inform that specific routes are
   available directly on-link.

   If there is more than one route available via specific next hop,
   server MUST send only one NEXT_HOP for that next hop, which contains
   multiple RT_PREFIX options.  Server MUST NOT send more than one
   identical (i.e. with equal next hop address field) NEXT_HOP option.

   When configured to do so, a DHCPv6 server shall send one or more
   NEXT_HOP options that contain one or more source address/prefixes
   Figure 3 included in the Next Hop sub-options field.  Each Next Hop
   Address may be associated with zero, one or more Source Prefix that
   represent the source addresses that are assigned from the prefixes
   that belong to this next hop.  The Next Hop sub-options field MAY
   contain Route Prefix options that represent the IPv6 destination
   prefixes reachable via the given next hop as defined in Figure 2.
   When configured to do so, a DHCPv6 server shall send NEXT_HOP option
   with Route Prefix option and Source Prefix in the message in the Next
   Hop sub-options field to indicate that given prefix is available
   directly on-link and that any source addresses derived from the
   source prefix will not be subject to ingress filtering on these
   routes supported by these next hops.

   When configured to do so, a DHCPv6 server shall send one or more
   NEXT_HOP option that specify the IPv6 next hop addresses and source
   address.  Each Next Hop Address option may be associated with zero,
   one or more Source Address/Prefix that represent the source address/
   prefixes that are assigned from the prefixes that belong to this next
   hop.  The Next Hop sub-options field shall contain Source Address
   Figure 3 and Route Prefix options Figure 1 that represent the IPv6
   destination prefixes reachable via the given next hop.  DHCPv6 server
   shall include Next Hop Address with Source Address and Route Prefix
   option in Next Hop sub-options field in the message to indicate that
   given prefix is available directly on-link and that the source
   address will not be subject to ingress filtering.  For the Source
   Address, Source Address/Prefix option Figure 3 is used with prefix
   length set to 128.




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   Each Next Hop Address may be associated with zero, one or more Source
   Prefix that represent the source addresses that are assigned from the
   prefixes that belong to this next hop.  The option MAY contain Route
   Prefix options that represent the IPv6 destination prefixes reachable
   via the given next hop.  DHCP server shall include Next Hop Address
   with Route Prefix option in Next Hop sub-option field defined in
   Figure 2 in the message to indicate that given prefix is available
   directly on-link.  To indicate that any source addresses derived from
   the source prefix will not be subject to ingress filtering on these
   routes supported by these next hops DHCPv6 server shall send two
   options, Next Hop option with Route Prefix option in Next Hop options
   field and a Source Prefix option defined in Figure 3.

   Servers SHOULD NOT send NEXT_HOP, RT_PREFIX or SOURCE_AP to clients
   that did not explicitly requested it, using the ORO.

   Servers MUST NOT send NEXT_HOP, RT_PREFIX or SOURCE_AP in messages
   other than ADVERTISE or REPLY.

   Servers MAY also include Status Code Option, defined in Section 22.13
   of the [RFC3315] to indicate the status of the operation.

   Servers MUST include the Status Code Option, if the requested routing
   configuration was not successful and SHOULD use status codes as
   defined in [RFC3315] and [RFC3633].

   The maximum number of routing information in one DHCPv6 message
   depend on the maximum DHCPv6 message size defined in [RFC3315]

5.  DHCPv6 Client Behavior

   A DHCPv6 client compliant with this specification MUST request the
   NEXT_HOP, RT_PREFIX and SOURCE_AP Options in an Option Request Option
   (ORO) in the following messages: Solicit, Request, Renew, Rebind, and
   Information-Request.  The messages are to be sent as and when
   specified by [RFC3315].

   When processing a received SADR Route Options a client MUST
   substitute a received 0::0 value in the Next Hop Option with the
   source IPv6 address of the received DHCPv6 message.  It MUST also
   associate a received Link Local next hop addresses with the interface
   on which the client received the DHCPv6 message containing the route
   option.  Such a substitution and/or association is useful in cases
   where the DHCPv6 server operator does not directly know the IPv6
   next-hop address, other than knowing it is that of a DHCPv6 relay
   agent on the client LAN segment.  DHCPv6 Packets relayed to the
   client are sourced by the relay using this relay's IPv6 address,
   which could be a link local address.



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   The Client SHOULD refresh assigned SADR route information
   periodically.  The generic DHCPv6 Information Refresh Time Option, as
   specified in [RFC4242], can be used when it is desired for the client
   to periodically refresh of route information.

   The routes conveyed by the SADR Route Option should be considered as
   complimentary to any other static route learning and maintenance
   mechanism used by, or on the client with one modification: The client
   MUST flush DHCPv6 installed SADR routes following a link flap event
   on the DHCPv6 client interface over which the routes were installed.
   This requirement is necessary to automate the flushing of routes for
   clients that may move to a different network.

   Client MUST confirm that routers announced over DHCPv6 are reachable,
   using one of methods suitable for specific network type.  The most
   common mechanism is Neighbor Unreachability Detection (NUD),
   specified in [RFC4861].  Client SHOULD use NUD to verify that
   received routers are reachable before adjusting its routing tables.
   Client MAY use other reachability verification mechanisms specific to
   used network technology.  To avoid potential long-lived routing black
   holes, client MAY periodically confirm that router is still
   reachable.

6.  IANA Considerations

   IANA is kindly requested to allocate DHCPv6 option code TBD1 to the
   OPTION_NEXT_HOP, TBD2 to OPTION_RT_PREFIX, TBD3 to OPTION_SOURCE_AP.
   All values should be added to the DHCPv6 option code space defined in
   Section 24.3 of [RFC3315].

7.  Security Considerations

   The overall security considerations discussed in [RFC3315] apply also
   to this document.  The Route option could be used by malicious
   parties to misdirect traffic sent by the client either as part of a
   denial of service or man-in-the-middle attack.  An alternative denial
   of service attack could also be realized by means of using the route
   option to overflowing any known memory limitations of the client, or
   to exceed the client's ability to handle the number of next hop
   addresses.

   Neither of the above considerations are new and specific to the
   proposed route option.  The mechanisms identified for securing DHCPv6
   as well as reasonable checks performed by client implementations are
   deemed sufficient in addressing these problems.






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   It is essential that clients verify that announced routers are indeed
   reachable, as specified in Section 5.  Failing to do so may create
   black hole routing problem.

   Reader is also encouraged to read DHCPv6 security considerations
   document [I-D.ietf-dhc-sedhcpv6].

8.  Acknowledgements

   TBD.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [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.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

9.2.  Informative References

   [I-D.ietf-dhc-sedhcpv6]
              Jiang, S., Shen, S., Zhang, D., and T. Jinmei, "Secure
              DHCPv6", draft-ietf-dhc-sedhcpv6-07 (work in progress),
              March 2015.

   [I-D.ietf-mif-mpvd-arch]
              Anipko, D., "Multiple Provisioning Domain Architecture",
              draft-ietf-mif-mpvd-arch-11 (work in progress), March
              2015.

   [I-D.ietf-mif-mpvd-dhcp-support]
              Krishnan, S., Korhonen, J., and S. Bhandari, "Support for
              multiple provisioning domains in DHCPv6", draft-ietf-mif-
              mpvd-dhcp-support-01 (work in progress), March 2015.

   [I-D.sarikaya-6man-sadr-overview]
              Sarikaya, B., "Source Address Dependent Routing and Source
              Address Selection for IPv6 Hosts", draft-sarikaya-6man-
              sadr-overview-06 (work in progress), March 2015.




Sarikaya                Expires November 9, 2015               [Page 13]

Internet-Draft                                                  May 2015


   [I-D.sarikaya-6man-sadr-ra]
              Sarikaya, B., "IPv6 RA Options for Source Address
              Dependent Routing", draft-sarikaya-6man-sadr-ra-02 (work
              in progress), May 2015.

   [RFC3442]  Lemon, T., Cheshire, S., and B. Volz, "The Classless
              Static Route Option for Dynamic Host Configuration
              Protocol (DHCP) version 4", RFC 3442, December 2002.

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, November 2005.

   [RFC4242]  Venaas, S., Chown, T., and B. Volz, "Information Refresh
              Time Option for Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 4242, November 2005.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC7084]  Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
              Requirements for IPv6 Customer Edge Routers", RFC 7084,
              November 2013.

   [RFC7157]  Troan, O., Miles, D., Matsushima, S., Okimoto, T., and D.
              Wing, "IPv6 Multihoming without Network Address
              Translation", RFC 7157, March 2014.

Author's Address

   Behcet Sarikaya
   Huawei USA
   5340 Legacy Dr.
   Plano, TX  75024
   United States

   Phone: +1 972-509-5599
   Email: sarikaya@ieee.org













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