draft-ietf-ngtrans-isatap-07.txt   draft-ietf-ngtrans-isatap-08.txt 
NGTRANS Working Group F. Templin NGTRANS Working Group F. Templin
Internet-Draft Nokia Internet-Draft Nokia
Expires: June 13, 2003 T. Gleeson Expires: June 19, 2003 T. Gleeson
Cisco Systems K.K. Cisco Systems K.K.
M. Talwar M. Talwar
D. Thaler D. Thaler
Microsoft Corporation Microsoft Corporation
December 13, 2002 December 19, 2002
Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
draft-ietf-ngtrans-isatap-07.txt draft-ietf-ngtrans-isatap-08.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at http:// The list of current Internet-Drafts can be accessed at http://
www.ietf.org/ietf/1id-abstracts.txt. www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
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This Internet-Draft will expire on June 13, 2003. This Internet-Draft will expire on June 19, 2003.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract Abstract
This document specifies an Intra-Site Automatic Tunnel Addressing This document specifies an Intra-Site Automatic Tunnel Addressing
Protocol (ISATAP) that connects IPv6 hosts and routers within IPv4 Protocol (ISATAP) that connects IPv6 hosts and routers within IPv4
sites. ISATAP is a transition mechanism that treats the site's IPv4 sites. ISATAP is a transition mechanism that treats the site's IPv4
infrastructure as a Non-Broadcast Multiple Access (NBMA) link layer infrastructure as a Non-Broadcast Multiple Access (NBMA) link layer
for IPv6 with no requirement for IPv4 multicast. ISATAP enables for IPv6 with no requirement for IPv4 multicast. ISATAP enables
intra-site automatic IPv6-in-IPv4 tunneling whether globally assigned intra-site automatic IPv6-in-IPv4 tunneling whether globally assigned
or private IPv4 addresses are used. or private IPv4 addresses are used.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Applicability Statement . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Transmission of IPv6 Packets on ISATAP Links . . . . . . . . 4
4.1 ISATAP Interface Identifier Construction . . . . . . . . . . 4
4.2 Stateless Autoconfiguration and Link-Local Addresses . . . . 5
4.3 ISATAP Link/Interface Configuration . . . . . . . . . . . . 5
4.4 Sending Rules and Address Mapping . . . . . . . . . . . . . 6
4.5 Validity Checks for Received Packets . . . . . . . . . . . . 6
4.6 Tunnel MTU and Fragmentation . . . . . . . . . . . . . . . . 6
5. Neighbor Discovery for ISATAP Links . . . . . . . . . . . . 9
5.1 Address Resolution . . . . . . . . . . . . . . . . . . . . . 9
5.2 Router and Prefix Discovery . . . . . . . . . . . . . . . . 10
5.2.1 Conceptual Data Structures . . . . . . . . . . . . . . . . . 10
5.2.2 Validity Checks for Router Advertisements . . . . . . . . . 11
5.2.3 Router Specification . . . . . . . . . . . . . . . . . . . . 12
5.2.4 Host Specification . . . . . . . . . . . . . . . . . . . . . 12
6. ISATAP Deployment Considerations . . . . . . . . . . . . . . 13
6.1 Host And Router Deployment Considerations . . . . . . . . . 13
6.2 Site Administration Considerations . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . 14
8. Security considerations . . . . . . . . . . . . . . . . . . 14
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
Normative References . . . . . . . . . . . . . . . . . . . . 16
Informative References . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 17
A. Major Changes . . . . . . . . . . . . . . . . . . . . . . . 18
B. Rationale for Interface Identifier Construction Rules . . . 21
C. INTELLECTUAL PROPERTY . . . . . . . . . . . . . . . . . . . 22
Intellectual Property and Copyright Statements . . . . . . . 23
1. Introduction 1. Introduction
This document presents a simple approach that enables incremental This document presents a simple approach that enables incremental
deployment of IPv6 [1] within IPv4-based [2] sites in a manner that deployment of IPv6 [1] within IPv4-based [2] sites in a manner that
is compatible with inter-domain transition mechanisms, e.g., RFC 3056 is compatible with inter-domain transition mechanisms, e.g., RFC 3056
(6to4) [17]. We refer to this approach as the Intra-Site Automatic (6to4) [19]. We refer to this approach as the Intra-Site Automatic
Tunnel Addressing Protocol, or ISATAP (pronounced: "ice-a-tap"). Tunnel Addressing Protocol, or ISATAP (pronounced: "ice-a-tap").
ISATAP allows dual-stack nodes that do not share a common link with ISATAP allows dual-stack nodes that do not share a common link with
an IPv6 router to automatically tunnel packets to the IPv6 next-hop an IPv6 router to automatically tunnel packets to the IPv6 next-hop
address through IPv4, i.e., the site's IPv4 infrastructure is treated address through IPv4, i.e., the site's IPv4 infrastructure is treated
as an NBMA link layer. as an NBMA link layer.
This document specifies details for the transmission of IPv6 packets This document specifies details for the transmission of IPv6 packets
over ISATAP links (i.e., automatic IPv6-in-IPv4 tunneling), including over ISATAP links (i.e., automatic IPv6-in-IPv4 tunneling), including
a new EUI-64 based interface identifier format [3][4][5] that embeds a new EUI-64 based interface identifier format [3][4][5] that embeds
an IPv4 address. This format supports configuration of global, an IPv4 address. This format supports configuration of global,
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multicast) multicast)
o supports both stateless address autoconfiguration and manual o supports both stateless address autoconfiguration and manual
configuration configuration
o supports networks that use non-globally unique IPv4 addresses o supports networks that use non-globally unique IPv4 addresses
(e.g., when private address allocations [8] are used), but does (e.g., when private address allocations [8] are used), but does
not allow the virtual ISATAP link to span a Network Address not allow the virtual ISATAP link to span a Network Address
Translator [9] Translator [9]
o compatible with other NGTRANS mechanisms (e.g., 6to4 [17]) o compatible with other NGTRANS mechanisms (e.g., 6to4 [19])
3. Terminology 3. Terminology
The terminology of RFC 2460 [1] applies to this document. The The terminology of RFC 2460 [1] applies to this document. The
following additional terms are defined: following additional terms are defined:
link: link:
same definition as [6][7]. same definition as [6][7].
underlying link: underlying link:
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List (see Section 5.2.1), i.e., previous hop is an on-link ISATAP List (see Section 5.2.1), i.e., previous hop is an on-link ISATAP
router router
Packets that do not satisfy at least one of the above checks are Packets that do not satisfy at least one of the above checks are
silently discarded. silently discarded.
4.6 Tunnel MTU and Fragmentation 4.6 Tunnel MTU and Fragmentation
ISATAP interfaces implement automatic tunnels that may be configured ISATAP interfaces implement automatic tunnels that may be configured
over multiple underlying links with diverse MTUs. The ISATAP over multiple underlying links with diverse MTUs. The ISATAP
interface MTU (ISATAP_MTU) SHOULD be no larger than the largest MTU interface MTU (ISATAP_MTU) SHOULD be set to the largest MTU of all
of all underlying links (LINK_MTU), minus 20 bytes for IPv4 underlying links (LINK_MTU) minus 120 bytes for possible link-layer
encapsulation. encapsulations (see note 1). The minimum value (ISATAP_MINMTU) MUST
be at least 1280 bytes [1], but SHOULD be set to 1380 bytes (see note
The minimum value (ISATAP_MINMTU) MUST be at least 1280 bytes [1], 2).
but SHOULD be set to 1380 bytes (see note 1). The maximum value used
for ISATAP_MTU SHOULD be 4140 bytes (see note 2). The maximum
receive unit (ISATAP_MRU) MUST be at least 4400 bytes.
IPv6 path MTU discovery [12] is required for IPv6 interfaces that IPv6 path MTU discovery [14] is required for IPv6 interfaces that
send packets larger than 1280 bytes. The following considerations send packets larger than 1280 bytes. The following considerations
for ISATAP interfaces are noted: for ISATAP interfaces are noted:
o ISATAP encapsulators and decapsulators are IPv6 neighbors since o ISATAP encapsulators and decapsulators are IPv6 neighbors since
they share a common link layer, i.e., the ISATAP link they share a common link layer, i.e., the ISATAP link
o ISATAP neighbors may be separated by multiple IPv4 hops requiring o ISATAP neighbors may be separated by multiple IPv4 hops requiring
IPv4 path MTU discovery [13] to establish per-neighbor MTUs IPv4 path MTU discovery [15] to establish per-neighbor MTUs
(NBR_MTU) (NBR_MTU)
o NBR_MTU information is stored as link-layer (IPv4) information o NBR_MTU information is stored as link-layer (IPv4) information
(e.g., in the IPv4 path MTU discovery cache), thus it may not be (e.g., in the IPv4 path MTU discovery cache), thus it may not be
visible to upper layers in all implementations visible to upper layers in all implementations
o NBR_MTU information may not always be available for each neighbor o NBR_MTU information may not always be available for each neighbor
due to finite storage limitations due to finite storage limitations
o IPv4 path MTU discovery delivers ICMPv4 "fragmentation needed" o IPv4 path MTU discovery delivers ICMPv4 "fragmentation needed"
messages, but these cannot be translated into ICMPv6 "packet too messages, but these do not provide enough state for translation
big" messages. Thus, encapsulated packets MUST be sent with the into ICMPv6 "packet too big" messages (see: RFC 792 [12] and RFC
DF flag in the IPv4 header NOT set unless additional state is 1812 [13], section 4.3.2.3).
maintained in the encapsulator (see note 3)
Traditional packetization and network (IPv6) layer implementations
view ISATAP interfaces as ordinary IPv6 interfaces with a single MTU
(ISATAP_MTU). Such implementations forward only those IPv6 packets
of size ISATAP_MTU or smaller to the ISATAP interface. All other
packets are dropped, and an IPv6 ICMP "packet too big" message with
MTU = ISATAP_MTU is returned.
Modified packetization and network (IPv6) layer implementations MAY
look into the ISATAP link layer for per-neighbor MTU information.
When available, this information supersedes ISATAP_MTU in determining
whether to forward the packet or return an ICMPv6 "packet too big"
(see above).
For IPv6 packets forwarded to the ISATAP interface, all IPv6 sees the ISATAP interface as an ordinary IPv6 interface with a
implementations employ the following algorithm at the link layer to fixed MTU (ISATAP_MTU), i.e., only those IPv6 packets of size
determine when to perform IPv6-in-IPv4 encapsulation and when to ISATAP_MTU or smaller are accepted. All other packets are dropped,
return an IPv6 ICMP "packet too big" message: and an IPv6 ICMP "packet too big" message with MTU = ISATAP_MTU is
returned. ISATAP interfaces SHOULD implement the following
link-layer algorithm to determine when to perform IPv6-in-IPv4
encapsulation and when to return an ICMPv6 "packet too big" message:
Determine per-neighbor LINK_MTU; NBR_MTU, e.g., by consulting IPv4 Determine per-neighbor LINK_MTU; NBR_MTU, e.g., by consulting IPv4
forwarding table and/or IPv4 path MTU discovery cache, then: forwarding table and/or IPv4 path MTU discovery cache, then:
if NBR_MTU information exists if NBR_MTU information exists
if packet is larger than NBR_MTU - 20 and packet if packet is larger than NBR_MTU - 120 and packet
is larger than ISATAP_MINMTU is larger than ISATAP_MINMTU
Send IPv6 ICMP "packet too big" with Send IPv6 ICMP "packet too big" with
MTU = MAX(NBR_MTU - 20, ISATAP_MINMTU) MTU = MAX(NBR_MTU - 120, ISATAP_MINMTU)
Drop packet Drop packet
else else
Encapsulate but do not set the Don't Fragment if packet is larger than ISATAP_MINMTU
Encapsulate and set the Don't Fragment
flag in the IPv4 header flag in the IPv4 header
else
Encapsulate but do not set the Don't
Fragment flag in the IPv4 header
endif
endif endif
else else
if packet is larger than LINK_MTU - 20 and packet is if packet is larger than LINK_MTU - 120 and packet is
larger than ISATAP_MINMTU larger than ISATAP_MINMTU
Send IPv6 ICMP "packet too big" with Send IPv6 ICMP "packet too big" with
MTU = ISATAP_MINMTU MTU = ISATAP_MINMTU
Drop packet Drop packet
else else
if IPv6 neighbor is an IPv4 neighbor on the if IPv6 neighbor is also an IPv4 neighbor on
underlying link, or packet is less than the underlying link, or packet is less than
or == ISATAP_MINMTU</t> or == ISATAP_MINMTU
Encapsulate but do not set the Don't Encapsulate but do not set the Don't
Fragment flag in the IPv4 hdr Fragment flag in the IPv4 header
else else
send ICMPv6 "packet too big" with send ICMPv6 "packet too big" with
MTU = ISATAP_MINMTU MTU = ISATAP_MINMTU
Drop packet Drop packet
endif endif
endif endif
endif endif
Figure 2 Figure 2
NOTES: Encapsulators MAY maintain per-neighbor MTU (NBR_MTU) values by
periodically probing the IPv4 path, e.g., by sending packets larger
1. Nearly all IPv4 routers can forward 1500 byte packets without than ISATAP_MINMTU with the DF bit set in the IPv4 header. Large
fragmentation. However, sub-IPv4 layer encapsulation (e.g., for data packets and/or Neighbor Solicitation (NS) packets with padding
VPNs) may occur on some paths. Commonly-deployed VPNs use an MTU bytes added (up to a total length of ISATAP_MTU) may be used for this
of 1400 bytes, thus 1380 bytes SHOULD be used as ISATAP_MINMTU. purpose. (NS packets are preferred, since successful delivery
results in a positive acknowledgement from the decapsulator.)
2. TCP adapts to an overestimated MSS by reducing the segment size When probing, implementations SHOULD maintain state for translating
based on IPv6 "packet too big" messages ([12], section 5.4), thus ICMPv4 "fragmentation needed" messages into ICMPv6 "packet too big"
setting ISATAP_MTU to the largest MTU of all underlying links messages for at least the round-trip time (RTT) between the
would optimize performance for asymmetric paths. encapsulator and decapsulator (see note 3). Implementations SHOULD
repeat the polling process within REACHABLE_TIME ([7], section 10) to
SCTP ([14], section 7.3) and other packetization layers ([12], detect link MTU restrictions.
section 5.5), perform upper-layer fragmentation based on IPv6
"packet too big" messages, which may result in unacceptable loss
when the initial MTU estimate is too large.
4140 is the RECOMMENDED maximum value for ISATAP_MTU, since: NOTES:
* 4140 bytes makes efficient use of common larger-than- ethernet 1. ISATAP requires 20 bytes for link-layer (IPv4) encapsulation.
MTUs in the internet (e.g., FDDI) However, sub-IPv4 layer encapsulation (e.g., for VPNs) may occur
on some paths. Commonly-deployed VPNs on Ethernet use an MTU of
1400 bytes, thus 100 bytes (1500 minums 1400) are reserverd for
sub-IPv4 layer encapsulation.
* Locally-generated ICMPv6 "packet too big" messages are likely 2. Nearly all IPv4 routers can forward 1500 byte packets without
to advertise an MTU of 1380, resulting in at most three fragmentation. Thus, 1380 bytes (1500 minus 100 minus 20) is
fragments and limiting loss probability RECOMMENDED as ISATAP_MINMTU.
3. Implementations MAY cache recently-sent IPv6 packets to provide 3. ICMPv4 "fragmentation needed" messages can be injected by
state for translating ICMPv4 "fragmentation needed" messages into malicious nodes, but this same problem exists in IPv4. Using
ICMPv6 "packet too big" messages. Such implementations MAY set Neighbor Solicitation messages for probing and receiving a
the DF flag in the IPv4 header in the above algorithm for packets positive acknowledgement from a trusted decapsulator MAY help
that will be retained in the cache at least as long as the encapsulators recognize spoofed ICMPv4 "fragmentation needed"
round-trip time (RTT) between the encapsulator and decapsulator. messages.
5. Neighbor Discovery for ISATAP Links 5. Neighbor Discovery for ISATAP Links
Section 3.2 of RFC 2461 [7] provides the following guidelines for Section 3.2 of RFC 2461 [7] provides the following guidelines for
non-broadcast multiple access (NBMA) link support: non-broadcast multiple access (NBMA) link support:
"Redirect, Neighbor Unreachability Detection and next-hop "Redirect, Neighbor Unreachability Detection and next-hop
determination should be implemented as described in this document. determination should be implemented as described in this document.
Address resolution and the mechanism for delivering Router Address resolution and the mechanism for delivering Router
Solicitations and Advertisements on NBMA links is not specified in Solicitations and Advertisements on NBMA links is not specified in
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A Potential Router List (PRL) is associated with every ISATAP link. A Potential Router List (PRL) is associated with every ISATAP link.
The PRL provides a trust basis for router validation (see security The PRL provides a trust basis for router validation (see security
considerations). Each entry in the PRL has an IPv4 address and an considerations). Each entry in the PRL has an IPv4 address and an
associated timer. The IPv4 address represents a router's ISATAP associated timer. The IPv4 address represents a router's ISATAP
interface (likely to be an "advertising interface"), and is used to interface (likely to be an "advertising interface"), and is used to
construct the ISATAP link-local address for that interface. The construct the ISATAP link-local address for that interface. The
following sections specify the process for initializing the PRL: following sections specify the process for initializing the PRL:
When a node enables an ISATAP link, it first discovers a DNS (RFC When a node enables an ISATAP link, it first discovers a DNS (RFC
1035 [20]) fully-qualified domain name for the site's ISATAP service. 1035 [22]) fully-qualified domain name for the site's ISATAP service.
The domain name MAY be established by a DHCPv4 [15] option for ISATAP The domain name MAY be established by a DHCPv4 [17] option for ISATAP
(option code TBD, see IANA Considerations), by manual configuration, (option code TBD, see IANA Considerations), by manual configuration,
or by an unspecified alternative method. The DHCPv4 option for or by an unspecified alternative method. The DHCPv4 option for
ISATAP is implemented exactly as in RFC 3361 [16] with the following ISATAP is implemented exactly as in RFC 3361 [18] with the following
noted exceptions: noted exceptions:
o the DHCP option code for ISATAP (TBD) is used o the DHCP option code for ISATAP (TBD) is used
o the encoding byte MUST be 0, i.e.; only FQDNs are accepted o the encoding byte MUST be 0, i.e.; only FQDNs are accepted
o if multiple domain names occur, only the first is used o if multiple domain names occur, only the first is used
Next, the node initializes the link's PRL with IPv4 addresses Next, the node initializes the link's PRL with IPv4 addresses
associated with the domain name discovered above. IPv4 addresses are associated with the domain name discovered above. IPv4 addresses are
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interfaces (normally as address records in the site's name interfaces (normally as address records in the site's name
service). Administrators may also advertise the domain name in a service). Administrators may also advertise the domain name in a
DHCPv4 option for ISATAP. DHCPv4 option for ISATAP.
2. There are no mandatory rules for the selection of a domain name, 2. There are no mandatory rules for the selection of a domain name,
but administrators are encouraged to use the convention but administrators are encouraged to use the convention
"isatap.domainname" (e.g., isatap.example.com). "isatap.domainname" (e.g., isatap.example.com).
3. After initialization, nodes periodically re-initialize the PRL 3. After initialization, nodes periodically re-initialize the PRL
(after ResolveInterval). When DNS is used, nodes MUST follow the (after ResolveInterval). When DNS is used, nodes MUST follow the
cache invalidation procedures in [20] when the DNS time-to-live cache invalidation procedures in [22] when the DNS time-to-live
expires. expires.
5.2.2 Validity Checks for Router Advertisements 5.2.2 Validity Checks for Router Advertisements
A node MUST silently discard any Router Advertisement messages it A node MUST silently discard any Router Advertisement messages it
receives that do not satisfy both the validity checks in ([7], receives that do not satisfy both the validity checks in ([7],
section 6.1.2) and the following additional validity check for section 6.1.2) and the following additional validity check for
ISATAP: ISATAP:
o the network-layer (IPv6) source address is an ISATAP address and o the network-layer (IPv6) source address is an ISATAP address and
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o ISATAP nodes periodically refresh the entries on the PRL, o ISATAP nodes periodically refresh the entries on the PRL,
typically by querying the DNS. Responsible site administration typically by querying the DNS. Responsible site administration
can reduce the control traffic. At a minimum, administrators can reduce the control traffic. At a minimum, administrators
SHOULD ensure that the site's address records for ISATAP router SHOULD ensure that the site's address records for ISATAP router
interfaces are well maintained. interfaces are well maintained.
7. IANA Considerations 7. IANA Considerations
A DHCPv4 option assignment for ISATAP is requested, as outlined in A DHCPv4 option assignment for ISATAP is requested, as outlined in
the procedures found in RFC 2939 [21], section 3. the procedures found in RFC 2939 [23], section 3.
Appendix B proposes a specification for managing the IEEE OUI Appendix B proposes a specification for managing the IEEE OUI
assigned to IANA for EUI-64 interface identifier construction. This assigned to IANA for EUI-64 interface identifier construction. This
specification is made freely available to IANA for any purpose they specification is made freely available to IANA for any purpose they
may find useful. may find useful.
8. Security considerations 8. Security considerations
Site administrators are advised that, in addition to possible attacks Site administrators are advised that, in addition to possible attacks
against IPv6, security attacks against IPv4 MUST also be considered. against IPv6, security attacks against IPv4 MUST also be considered.
Many security considerations in RFC 2529 [18], section 9 apply also Many security considerations in RFC 2529 [20], section 9 apply also
to ISATAP. to ISATAP.
Responsible IPv4 site security management is strongly encouraged. In Responsible IPv4 site security management is strongly encouraged. In
particular, border gateways SHOULD implement filtering to detect particular, border gateways SHOULD implement filtering to detect
spoofed IPv4 source addresses at a minimum; ip-protocol-41 filtering spoofed IPv4 source addresses at a minimum; ip-protocol-41 filtering
SHOULD also be implemented. SHOULD also be implemented.
If IPv4 source address filtering is not correctly implemented, the If IPv4 source address filtering is not correctly implemented, the
ISATAP validity checks will not be effective in preventing IPv6 ISATAP validity checks will not be effective in preventing IPv6
source address spoofing. source address spoofing.
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Advertisements they receive from on-link routers, as indicated by a Advertisements they receive from on-link routers, as indicated by a
value of 255 in the IPv6 'hop-limit' field. Since this field is not value of 255 in the IPv6 'hop-limit' field. Since this field is not
decremented when ip-protocol-41 packets traverse multiple IPv4 hops decremented when ip-protocol-41 packets traverse multiple IPv4 hops
([10], section 3), ISATAP links require a different trust model. In ([10], section 3), ISATAP links require a different trust model. In
particular, ONLY those Router Advertisements received from a member particular, ONLY those Router Advertisements received from a member
of the Potential Routers List are trusted; all others are silently of the Potential Routers List are trusted; all others are silently
discarded. This trust model is predicated on IPv4 source address discarded. This trust model is predicated on IPv4 source address
filtering, as described above. filtering, as described above.
The ISATAP address format does not support privacy extensions for The ISATAP address format does not support privacy extensions for
stateless address autoconfiguration [19]. However, since the ISATAP stateless address autoconfiguration [21]. However, since the ISATAP
interface identifier is derived from the node's IPv4 address, ISATAP interface identifier is derived from the node's IPv4 address, ISATAP
addresses do not have the same level of privacy concerns as IPv6 addresses do not have the same level of privacy concerns as IPv6
addresses that use an interface identifier derived from the MAC addresses that use an interface identifier derived from the MAC
address. (This issue is the same for NAT'd addresses.) address. (This issue is the same for NAT'd addresses.)
9. Acknowledgements 9. Acknowledgements
Some of the ideas presented in this draft were derived from work at Some of the ideas presented in this draft were derived from work at
SRI with internal funds and contractual support. Government sponsors SRI with internal funds and contractual support. Government sponsors
who supported the work include Monica Farah-Stapleton and Russell who supported the work include Monica Farah-Stapleton and Russell
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The following peer reviewers are acknowledged for taking the time to The following peer reviewers are acknowledged for taking the time to
review a pre-release of this document and provide input: Jim Bound, review a pre-release of this document and provide input: Jim Bound,
Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader, Ole Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader, Ole
Troan, Vlad Yasevich. Troan, Vlad Yasevich.
The authors acknowledge members of the NGTRANS community who have The authors acknowledge members of the NGTRANS community who have
made significant contributions to this effort, including Rich Draves, made significant contributions to this effort, including Rich Draves,
Alain Durand, Nathan Lutchansky, Karen Nielsen, Art Shelest, Margaret Alain Durand, Nathan Lutchansky, Karen Nielsen, Art Shelest, Margaret
Wasserman, and Brian Zill. Wasserman, and Brian Zill.
The authors also wish to acknowledge the work of Quang Nguyen [22] The authors also wish to acknowledge the work of Quang Nguyen [24]
under the guidance of Dr. Lixia Zhang that proposed very similar under the guidance of Dr. Lixia Zhang that proposed very similar
ideas to those that appear in this document. This work was first ideas to those that appear in this document. This work was first
brought to the authors' attention on September 20, 2002. brought to the authors' attention on September 20, 2002.
Normative References Normative References
[1] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) [1] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
Specification", RFC 2460, December 1998. Specification", RFC 2460, December 1998.
[2] Postel, J., "Internet Protocol", STD 5, RFC 791, September [2] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981. 1981.
[3] Hinden, R. and S. Deering, "IP Version 6 Addressing [3] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998. Architecture", RFC 2373, July 1998.
[4] Hinden, R. and S. Deering, "An IPv6 Aggregatable Global Unicast [4] Hinden, R. and S. Deering, "An IPv6 Aggregatable Global Unicast
skipping to change at page 19, line 42 skipping to change at page 16, line 39
[9] Egevang, K. and P. Francis, "The IP Network Address Translator [9] Egevang, K. and P. Francis, "The IP Network Address Translator
(NAT)", RFC 1631, May 1994. (NAT)", RFC 1631, May 1994.
[10] Gilligan, R. and E. Nordmark, "Transition Mechanisms for IPv6 [10] Gilligan, R. and E. Nordmark, "Transition Mechanisms for IPv6
Hosts and Routers", RFC 2893, August 2000. Hosts and Routers", RFC 2893, August 2000.
[11] Conta, A. and S. Deering, "Internet Control Message Protocol [11] Conta, A. and S. Deering, "Internet Control Message Protocol
(ICMPv6) for the Internet Protocol Version 6 (IPv6) (ICMPv6) for the Internet Protocol Version 6 (IPv6)
Specification", RFC 2463, December 1998. Specification", RFC 2463, December 1998.
[12] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery for [12] Postel, J., "Internet Control Message Protocol", STD 5, RFC
792, September 1981.
[13] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812,
June 1995.
[14] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery for
IP version 6", RFC 1981, August 1996. IP version 6", RFC 1981, August 1996.
[13] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [15] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
November 1990. November 1990.
[14] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, [16] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer,
H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson, H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
"Stream Control Transmission Protocol", RFC 2960, October 2000. "Stream Control Transmission Protocol", RFC 2960, October 2000.
[15] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, [17] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997. March 1997.
[16] Schulzrinne, H., "Dynamic Host Configuration Protocol [18] Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCP-for-IPv4) Option for Session Initiation Protocol (SIP) (DHCP-for-IPv4) Option for Session Initiation Protocol (SIP)
Servers", RFC 3361, August 2002. Servers", RFC 3361, August 2002.
Informative References Informative References
[17] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via [19] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via
IPv4 Clouds", RFC 3056, February 2001. IPv4 Clouds", RFC 3056, February 2001.
[18] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 [20] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
Domains without Explicit Tunnels", RFC 2529, March 1999. Domains without Explicit Tunnels", RFC 2529, March 1999.
[19] Narten, T. and R. Draves, "Privacy Extensions for Stateless [21] Narten, T. and R. Draves, "Privacy Extensions for Stateless
Address Autoconfiguration in IPv6", RFC 3041, January 2001. Address Autoconfiguration in IPv6", RFC 3041, January 2001.
[20] Mockapetris, P., "Domain names - implementation and [22] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[21] Droms, R., "Procedures and IANA Guidelines for Definition of [23] Droms, R., "Procedures and IANA Guidelines for Definition of
New DHCP Options and Message Types", BCP 43, RFC 2939, New DHCP Options and Message Types", BCP 43, RFC 2939,
September 2000. September 2000.
[22] Nguyen, Q., "http://irl.cs.ucla.edu/vet/report.ps", spring [24] Nguyen, Q., "http://irl.cs.ucla.edu/vet/report.ps", spring
1998. 1998.
Authors' Addresses Authors' Addresses
Fred L. Templin Fred L. Templin
Nokia Nokia
313 Fairchild Drive 313 Fairchild Drive
Mountain View, CA 94110 Mountain View, CA 94110
US US
skipping to change at page 23, line 7 skipping to change at page 18, line 33
Microsoft Corporation Microsoft Corporation
One Microsoft Way One Microsoft Way
Redmond, WA 98052-6399 Redmond, WA 98052-6399
US US
Phone: +1 425 703 8835 Phone: +1 425 703 8835
EMail: dthaler@microsoft.com EMail: dthaler@microsoft.com
Appendix A. Major Changes Appendix A. Major Changes
changes from version 07 to version 08:
o updated MTU section
changes from version 06 to version 07: changes from version 06 to version 07:
o clarified address resolution, Neighbor Unreachability Detection o clarified address resolution, Neighbor Unreachability Detection
o specified MTU/MRU requirements o specified MTU/MRU requirements
changes from version 05 to version 06: changes from version 05 to version 06:
o Addressed operational issues identified in 05 based on discussion o Addressed operational issues identified in 05 based on discussion
between co-authors between co-authors
 End of changes. 

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