draft-ietf-ngtrans-isatap-06.txt   draft-ietf-ngtrans-isatap-07.txt 
NGTRANS Working Group F. Templin NGTRANS Working Group F. Templin
INTERNET-DRAFT Nokia Internet-Draft Nokia
T. Gleeson Expires: June 13, 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
Expires 31 April 2003 31 October 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-06.txt
Status of this Memo Status of this Memo
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Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract Abstract
This document specifies the Intra-Site Automatic Tunnel Addressing This document specifies an Intra-Site Automatic Tunnel Addressing
Protocol (ISATAP) that connects IPv6 hosts and routers (nodes) within Protocol (ISATAP) that connects IPv6 hosts and routers within IPv4
IPv4 sites. ISATAP is a transition mechanism that enables incremental sites. ISATAP is a transition mechanism that treats the site's IPv4
deployment of IPv6 by treating the site's IPv4 infrastructure as a infrastructure as a Non-Broadcast Multiple Access (NBMA) link layer
Non-Broadcast Multiple Access (NBMA) link layer for IPv6. ISATAP for IPv6 with no requirement for IPv4 multicast. ISATAP enables
mechanisms use an IPv6 interface identifier format that embeds an intra-site automatic IPv6-in-IPv4 tunneling whether globally assigned
IPv4 address - this enables automatic IPv6-in-IPv4 tunneling within a or private IPv4 addresses are used.
site, whether the site uses globally assigned or private IPv4
addresses. The new interface identifier format can be used with both
local and global unicast IPv6 prefixes - this enables IPv6 routing
both locally and globally. ISATAP mechanisms introduce no impact on
routing table size and require no special IPv4 services (e.g., IPv4
multicast).
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 within IPv4-based sites in a manner that is com- deployment of IPv6 [1] within IPv4-based [2] sites in a manner that
patible with inter-domain transition mechanisms, e.g., [6TO4]. We is compatible with inter-domain transition mechanisms, e.g., RFC 3056
refer to this approach as the Intra-Site Automatic Tunnel Addressing (6to4) [17]. We refer to this approach as the Intra-Site Automatic
Protocol, or ISATAP (pronounced: "ice-a-tap"). ISATAP allows dual- Tunnel Addressing Protocol, or ISATAP (pronounced: "ice-a-tap").
stack nodes that do not share a common link with an IPv6 router to ISATAP allows dual-stack nodes that do not share a common link with
automatically tunnel packets to the IPv6 next-hop address through an IPv6 router to automatically tunnel packets to the IPv6 next-hop
IPv4, i.e., the site's IPv4 infrastructure is treated as an NBMA link address through IPv4, i.e., the site's IPv4 infrastructure is treated
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 [EUI64] based interface identifier [ADDR][AGGR] format a new EUI-64 based interface identifier format [3][4][5] that embeds
that embeds an IPv4 address. This format supports configuration of an IPv4 address. This format supports configuration of global,
global, site-local and link-local addresses as specified in [AUTO] as site-local and link-local addresses as specified in RFC 2462 [6] as
well as simple link-layer address mapping. Simple validity checks for well as simple link-layer address mapping. Simple validity checks
received packets are given. Also specified in this document is the for received packets are given. Also specified in this document is
operation of IPv6 Neighbor Discovery for ISATAP, as permitted for the operation of IPv6 Neighbor Discovery for ISATAP, as permitted for
NBMA links by [DISC]. The document finally presents deployment and NBMA links by RFC 2461 [7]. The document finally presents deployment
security considerations for ISATAP. and security considerations for ISATAP.
2. Applicability Statement 2. Applicability Statement
ISATAP provides the following features: ISATAP provides the following features:
- treats site's IPv4 infrastructure as an NBMA link layer using o treats site's IPv4 infrastructure as an NBMA link layer using
automatic IPv6-in-IPv4 tunneling (i.e., no configured tunnel state) automatic IPv6-in-IPv4 tunneling (i.e., no configured tunnel
state)
- enables incremental deployment of IPv6 hosts within IPv4 sites with o enables incremental deployment of IPv6 hosts within IPv4 sites
no aggregation scaling issues at border gateways with no aggregation scaling issues at border gateways
- requires no special IPv4 services within the site (e.g., multicast) o requires no special IPv4 services within the site (e.g.,
multicast)
- supports both stateless address autoconfiguration and manual o supports both stateless address autoconfiguration and manual
configuration configuration
- supports networks that use non-globally unique IPv4 addresses (e.g., o supports networks that use non-globally unique IPv4 addresses
when private address allocations [PRIVATE] are used), but does not (e.g., when private address allocations [8] are used), but does
allow the virtual ISATAP link to span a Network Address not allow the virtual ISATAP link to span a Network Address
Translator [NAT] Translator [9]
- compatible with other NGTRANS mechanisms (e.g., [6TO4])
o compatible with other NGTRANS mechanisms (e.g., 6to4 [17])
3. Terminology 3. Terminology
The terminology of [IPv6] applies to this document. The following The terminology of RFC 2460 [1] applies to this document. The
additional terms are defined: following additional terms are defined:
link: link:
same definition as [AUTO][DISC]. same definition as [6][7].
underlying link: underlying link:
a link layer that supports IPv4 (for ISATAP), and MAY also support a link layer that supports IPv4 (for ISATAP), and MAY also support
IPv6 natively. IPv6 natively.
ISATAP link: ISATAP link:
one or more underlying links used for IPv4 tunneling. The IPv4 one or more underlying links used for tunneling. The IPv4 network
network layer addresses of the underlying links are used as layer addresses of the underlying links are used as link-layer
link-layer addresses on the ISATAP link. addresses on the ISATAP link.
ISATAP interface: ISATAP interface:
a node's attachment to an ISATAP link. a node's attachment to an ISATAP link.
ISATAP prefix: ISATAP prefix:
a prefix used to configure an address on the ISATAP interface. This a prefix used to configure an address on the ISATAP interface.
prefix is administratively assigned to the ISATAP link and MUST NOT This prefix is administratively assigned to the ISATAP link and
be duplicated on native IPv6 links. MUST NOT be duplicated on native IPv6 links.
ISATAP address: ISATAP address:
an IPv6 address with an ISATAP prefix and an ISATAP format interface an IPv6 address with an ISATAP prefix and an ISATAP format
identifier constructed as specified in section 4. interface identifier constructed as specified in section 4.
ISATAP router: ISATAP router:
an IPv6 node that has an ISATAP interface over which it forwards an IPv6 node that has an ISATAP interface over which it forwards
packets not explicitly addressed to itself. packets not explicitly addressed to itself.
ISATAP host: ISATAP host:
any node that has an ISATAP interface and is not an ISATAP router. any node that has an ISATAP interface and is not an ISATAP router.
4. Transmission of IPv6 Packets on ISATAP Links 4. Transmission of IPv6 Packets on ISATAP Links
ISATAP links transmit IPv6 packets via automatic tunneling using the ISATAP links transmit IPv6 packets via automatic tunnels using the
site's IPv4 infrastructure as an NBMA link layer. Automatic tunneling site's IPv4 infrastructure as an NBMA link layer. IPv4 ICMP errors
for ISATAP uses the same encapsulation, hop limit, IPv4 header con- and ARP failures may be processed as link error notifications, as
struction, and decapsualtion specifications in [MECH, 3], i.e., IPv6 allowed by RFC 2461 [7]. The common tunneling mechanisms specified
packets are automatically encapsulated in IPv4 using 'ip-protocol-41' in Section 3 of RFC 2893 [10] are used, with the following noted
as the payload type number. The specifications in [MECH, 3.2, 3.4] do specific considerations for ISATAP links and automatic tunnels:
not apply for ISATAP; instead:
- The default link MTU SHOULD be set to the minimum IPv6 MTU of
1280 bytes [IPV6], unless specific configuration information
is available. The Don't Fragment bit SHOULD NOT be set in the
encapsulating IPv4 header.
- IPv4 ICMP errors and ARP failures may be processed as
link error notifications, as allowed by [DISC]
Specific considerations for ISATAP links are given below:
4.1. ISATAP Interface Identifier Construction 4.1 ISATAP Interface Identifier Construction
IPv6 unicast addresses [ADDR][AGGR] include a 64-bit interface iden- IPv6 unicast addresses [3][4] include a 64-bit interface identifier
tifier field in "modified EUI-64 format", based on the IEEE EUI-64 field in "modified EUI-64 format", based on the IEEE EUI-64 [5]
[EUI64] specification. (Modified EUI-64 format inverts the sense of specification. (Modified EUI-64 format inverts the sense of the 'u/
the 'u/l' bit from its specification in [EUI64], i.e., 'u/l' = 0 l' bit from its specification in [5], i.e., 'u/l' = 0 indicates
indicates local-use.) ISATAP interface identifiers are constructed by local-use.) ISATAP interface identifiers are constructed by
prepending the 32-bit string '00-00-5E-FE' with an IPv4 address (see prepending the 32-bit string '00-00-5E-FE' with an IPv4 address (see
the following section for examples). Appendix B includes text the following section for examples). Appendix B includes text
explaining the rationale for this construction rule. explaining the rationale for this construction rule.
4.2. Stateless Autoconfiguration and Link-Local Addresses 4.2 Stateless Autoconfiguration and Link-Local Addresses
ISATAP addresses are unicast addresses [ADDR,2.5] that use ISATAP ISATAP addresses are unicast addresses that use ISATAP format
format interface identifiers as follows: interface identifiers as follows:
| 64 bits | 32 bits | 32 bits | | 64 bits | 32 bits | 32 bits |
+------------------------------+---------------+----------------+ +------------------------------+---------------+----------------+
| link-local, site-local or | 0000:5EFE | IPv4 Address | | link-local, site-local or | 0000:5EFE | IPv4 Address |
| global unicast prefix | | of ISATAP link | | global unicast prefix | | of ISATAP link |
+------------------------------+---------------+----------------+ +------------------------------+---------------+----------------+
Figure 1
Link-local, site-local, and global ISATAP addresses can be created Link-local, site-local, and global ISATAP addresses can be created
exactly as specified in [ADDR], (e.g., by auto-configuration [AUTO] exactly as specified in [3], (e.g., by auto-configuration [6] or
or manual configuration). For example, the IPv6 address: manual configuration). For example, the IPv6 address:
3FFE:1A05:510:1111:0:5EFE:8CAD:8108 3FFE:1A05:510:1111:0:5EFE:8CAD:8108
has a prefix of '3FFE:1A05:510:1111::/64' and an ISATAP format inter- has a prefix of '3FFE:1A05:510:1111::/64' and an ISATAP format
face identifier with embedded IPv4 address: '140.173.129.8'. The interface identifier with embedded IPv4 address: '140.173.129.8'.
address is alternately written as: The address is alternately written as:
3FFE:1A05:510:1111:0:5EFE:140.173.129.8 3FFE:1A05:510:1111:0:5EFE:140.173.129.8
The link-local and site-local variants (respectively) are: The link-local and site-local variants (respectively) are:
FE80::0:5EFE:140.173.129.8 FE80::0:5EFE:140.173.129.8
FEC0::1111:0:5EFE:140.173.129.8 FEC0::1111:0:5EFE:140.173.129.8
4.3. ISATAP Link/Interface Configuration 4.3 ISATAP Link/Interface Configuration
A node configures an ISATAP link over one or more underlying IPv4 An ISATAP link consists of one or more underlying links that support
links, i.e., the ISATAP link MAY be configured over one or more link- IPv4 for tunneling within a site.
layer (IPv4) addresses. Each link-layer address 'V4ADDR_LINK' is used
to configure a link-local address 'FE80::0:5EFE:V4ADDR_LINK' on an
ISATAP interface. ISATAP interfaces MAY be assigned one per link-
layer address, or as a single interface for multiple link-layer
addresses.
In the former case, the address of each ISATAP interface SHOULD be ISATAP interfaces are configured over ISATAP links; each IPv4 address
added to the Potential Routers List (see section 5.2.1). In the lat- assigned to an underlying link is seen as a link-layer address for
ter case, the interface will accept ISATAP packets addressed to any ISATAP.
of the IPv4 link-layer addresses, but will choose one as its primary
address, used for sourcing packets. Only this address need be repre-
sented in the Potential Routers List.
4.4. Sending Rules and Address Mapping At least one link-layer address per each ISATAP router interface
SHOULD be added to the Potential Routers List (see Section 5.2.1).
4.4 Sending Rules and Address Mapping
The IPv6 next-hop address for packets sent on an ISATAP link MUST be The IPv6 next-hop address for packets sent on an ISATAP link MUST be
an ISATAP address. Packets that do not satisfy this constraint MUST an ISATAP address. Packets that do not satisfy this constraint MUST
be discarded and an ICMP destination unreachable indication with code be discarded and an ICMPv6 destination unreachable indication with
3 (Address Unreachable) [ICMPv6] MUST be returned. No other sending code 3 (Address Unreachable) [11] MUST be returned. No other sending
rules are necessary. rules are necessary.
The procedure for mapping unicast addresses into link-layer addresses The procedure for mapping unicast addresses into link-layer addresses
is to simply treat the last four octets of the ISATAP address as an is to simply treat the last four octets of the ISATAP address as an
IPv4 address (in network byte order). No multicast address mappings IPv4 address (in network byte order). No multicast address mappings
are specified. are specified.
4.5. Validity Checks for Received Packets 4.5 Validity Checks for Received Packets
Packets received on ISATAP interfaces MUST satisfy at least one Packets received on ISATAP interfaces MUST satisfy at least one
(i.e., one or both) of the following validity checks: (i.e., one or both) of the following validity checks:
- the network-layer (IPv6) source address has a prefix configured on o the network-layer (IPv6) source address has a prefix configured on
the ISATAP interface and an ISATAP-format interface identifier that the ISATAP interface and an ISATAP-format interface identifier
embeds the link-layer (IPv4) source address, i.e., source is on-link that embeds the link-layer (IPv4) source address, i.e., source is
on-link
- the link-layer (IPv4) source address is an "active" member of o the link-layer (IPv4) source address is in the Potential Routers
the Potential Routers List (see section 5.2), i.e., previous List (see Section 5.2.1), i.e., previous hop is an on-link ISATAP
hop is an on-link ISATAP router actively being used by the node 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
ISATAP interfaces implement automatic tunnels that may be configured
over multiple underlying links with diverse MTUs. The ISATAP
interface MTU (ISATAP_MTU) SHOULD be no larger than the largest MTU
of all underlying links (LINK_MTU), minus 20 bytes for IPv4
encapsulation.
The minimum value (ISATAP_MINMTU) MUST be at least 1280 bytes [1],
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
send packets larger than 1280 bytes. The following considerations
for ISATAP interfaces are noted:
o ISATAP encapsulators and decapsulators are IPv6 neighbors since
they share a common link layer, i.e., the ISATAP link
o ISATAP neighbors may be separated by multiple IPv4 hops requiring
IPv4 path MTU discovery [13] to establish per-neighbor MTUs
(NBR_MTU)
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
visible to upper layers in all implementations
o NBR_MTU information may not always be available for each neighbor
due to finite storage limitations
o IPv4 path MTU discovery delivers ICMPv4 "fragmentation needed"
messages, but these cannot be translated into ICMPv6 "packet too
big" messages. Thus, encapsulated packets MUST be sent with the
DF flag in the IPv4 header NOT set unless additional state is
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
implementations employ the following algorithm at the link layer to
determine when to perform IPv6-in-IPv4 encapsulation and when to
return an IPv6 ICMP "packet too big" message:
Determine per-neighbor LINK_MTU; NBR_MTU, e.g., by consulting IPv4
forwarding table and/or IPv4 path MTU discovery cache, then:
if NBR_MTU information exists
if packet is larger than NBR_MTU - 20 and packet
is larger than ISATAP_MINMTU
Send IPv6 ICMP "packet too big" with
MTU = MAX(NBR_MTU - 20, ISATAP_MINMTU)
Drop packet
else
Encapsulate but do not set the Don't Fragment
flag in the IPv4 header
endif
else
if packet is larger than LINK_MTU - 20 and packet is
larger than ISATAP_MINMTU
Send IPv6 ICMP "packet too big" with
MTU = ISATAP_MINMTU
Drop packet
else
if IPv6 neighbor is an IPv4 neighbor on the
underlying link, or packet is less than
or == ISATAP_MINMTU</t>
Encapsulate but do not set the Don't
Fragment flag in the IPv4 hdr
else
send ICMPv6 "packet too big" with
MTU = ISATAP_MINMTU
Drop packet
endif
endif
endif
Figure 2
NOTES:
1. Nearly all IPv4 routers can forward 1500 byte packets without
fragmentation. However, sub-IPv4 layer encapsulation (e.g., for
VPNs) may occur on some paths. Commonly-deployed VPNs use an MTU
of 1400 bytes, thus 1380 bytes SHOULD be used as ISATAP_MINMTU.
2. TCP adapts to an overestimated MSS by reducing the segment size
based on IPv6 "packet too big" messages ([12], section 5.4), thus
setting ISATAP_MTU to the largest MTU of all underlying links
would optimize performance for asymmetric paths.
SCTP ([14], section 7.3) and other packetization layers ([12],
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:
* 4140 bytes makes efficient use of common larger-than- ethernet
MTUs in the internet (e.g., FDDI)
* Locally-generated ICMPv6 "packet too big" messages are likely
to advertise an MTU of 1380, resulting in at most three
fragments and limiting loss probability
3. Implementations MAY cache recently-sent IPv6 packets to provide
state for translating ICMPv4 "fragmentation needed" messages into
ICMPv6 "packet too big" messages. Such implementations MAY set
the DF flag in the IPv4 header in the above algorithm for packets
that will be retained in the cache at least as long as the
round-trip time (RTT) between the encapsulator and decapsulator.
5. Neighbor Discovery for ISATAP Links 5. Neighbor Discovery for ISATAP Links
Section 3.2 of [DISC] ("Supported Link Types") provides the following Section 3.2 of RFC 2461 [7] provides the following guidelines for
guidelines for non-broadcast multiple access (NBMA) link support: non-broadcast multiple access (NBMA) link support:
"Redirect, Neighbor Unreachability Detection and next-hop determi- "Redirect, Neighbor Unreachability Detection and next-hop
nation should be implemented as described in this document. Address determination should be implemented as described in this document.
resolution and the mechanism for delivering Router Solicitations Address resolution and the mechanism for delivering Router
and Advertisements on NBMA links is not specified in this docu- Solicitations and Advertisements on NBMA links is not specified in
ment." this document."
ISATAP links SHOULD implement Redirect, Neighbor Unreachability ISATAP links SHOULD implement Redirect, Neighbor Unreachability
Detection, and next-hop determination exactly as specified in [DISC]. Detection, and next-hop determination exactly as specified in [7].
Address resolution and the mechanisms for delivering Router Solicita- Address resolution and the mechanisms for delivering Router
tions and Advertisements for ISATAP links are not specified by Solicitations and Advertisements for ISATAP links are not specified
[DISC]; instead, they are specified in this document. (Note that by [7]; instead, they are specified in this document. (Note that
these mechanisms MAY potentially apply to other types of NBMA links these mechanisms MAY potentially apply to other types of NBMA links
in the future.) in the future.)
5.1. Address Resolution 5.1 Address Resolution
Protocol addresses (IPv6) in ISATAP are resolved to link-layer Protocol addresses (IPv6) in ISATAP are resolved to link-layer
addresses (IPv4) by a static computation, i.e., the last four octets addresses (IPv4) by a static computation, i.e., the last four octets
are treated as an IPv4 address. are treated as an IPv4 address.
ISATAP nodes SHOULD perform Neighbor Unreachability Detection (NUD) ISATAP hosts SHOULD enhance the static address resolution computation
as specified in [DISC, 7.3], and MUST send solicited neighbor adver- with a unicast Neighbor Solicitation(NS)/Neighbor Advertisement(NA)
tisements as specified in [DISC, 7.2.4]. exchange to ensure IPv6 level reachability of the neighbor and also
SHOULD perform Neighbor Unreachability Detection (NUD) as specified
in (RFC 2461 [7], section 7.3). ISATAP routers MAY implement the
enhanced address resolution and NUD, but this might not scale in all
environments. All ISATAP nodes MUST send solicited neighbor
advertisements ([7], section 7.2.4).
The link-layer address option used in [DISC] is not needed. Link- Link-layer address options ([7], section 4.6.1) for this
layer address options SHOULD NOT be sent in any Neighbor Discovery specification MUST have Length = 1 and a six-octet interface
packets, and MUST be silently ignored in any received Neighbor Dis- identifier consisting of two zero octets followed by a four-octet
covery packets. IPv4 address. Options of this form SHOULD NOT be sent in NS/NA
messages and MUST be silently ignored in received NS/NA messages.
5.2. Router and Prefix Discovery 5.2 Router and Prefix Discovery
Since the site's IPv4 infrastructure is treated as an NBMA link Since the site's IPv4 infrastructure is treated as an NBMA link
layer, unsolicited Router Advertisements do not provide sufficient layer, unsolicited Router Advertisements do not provide sufficient
means for router discovery on ISATAP links. Thus, alternate mecha- means for router discovery on ISATAP links. Thus, alternate
nisms are required and specified below: mechanisms are required and specified below:
5.2.1. Conceptual Data Structures 5.2.1 Conceptual Data Structures
ISATAP nodes use the conceptual data structures Prefix List and ISATAP nodes use the conceptual data structures Prefix List and
Default Router List exactly as specified in [DISC,5.1]. ISATAP links Default Router List exactly as in ([7], section 5.1). ISATAP links
add a new conceptual data structure "Potential Router List" and the add a new conceptual data structure "Potential Router List" and the
following new configuration variable: following new configuration variable:
ResolveInterval Time between name service resolutions. ResolveInterval
Default and suggested minimum: 1hr Time between name service resolutions. Default and suggested
minimum: 1hr
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 context for router discovery and a trust basis for The PRL provides a trust basis for router validation (see security
router validation (see security considerations). Each entry in the considerations). Each entry in the PRL has an IPv4 address and an
PRL has an IPv4 address and an associated timer used for polling. The associated timer. The IPv4 address represents a router's ISATAP
IPv4 address represents a router's ISATAP interface (likely to be an interface (likely to be an "advertising interface"), and is used to
"advertising interface"), and is used to construct the ISATAP link- construct the ISATAP link-local address for that interface. The
local address for that interface. following sections specify the process for initializing the PRL:
When a node enables an ISATAP link, it initializes the Potential When a node enables an ISATAP link, it first discovers a DNS (RFC
Router List (PRL) for that link. Unless other information is avail- 1035 [20]) fully-qualified domain name for the site's ISATAP service.
able (e.g., manual address configuration, a vendor-specific DHCP The domain name MAY be established by a DHCPv4 [15] option for ISATAP
option, etc.) the following method (similar to the [SIP, 1.4.2] pro- (option code TBD, see IANA Considerations), by manual configuration,
cedure) SHOULD be used: or by an unspecified alternative method. The DHCPv4 option for
ISATAP is implemented exactly as in RFC 3361 [16] with the following
noted exceptions:
1. The site administrator maintains address records for ISATAP o the DHCP option code for ISATAP (TBD) is used
router interfaces, and makes these available in the site's
name service. Nodes attempt to find one or more addresses
for the PRL by querying the name service.
2. There are no mandatory rules on the selection of domain name o the encoding byte MUST be 0, i.e.; only FQDNs are accepted
to be used within a site for this purpose, but administrators
are encouraged to use the "isatap.domainname" convention
(e.g., isatap.example.com), as specified in [RFC2219]. Nodes
can construct this domain name by prepending the label "isatap"
to their parent domain name, which is established by other
means. Nodes then query this domain name for address records
(e.g., DNS 'A' resource records), and initialize the PRL with
the IPv4 addresses in the replies.
3. After initialization, nodes periodically repeat the above o if multiple domain names occur, only the first is used
procedure ResolveInterval to update the PRL with any IPv4
addresses added/deleted since the previous iteration. When
DNS is used, nodes MUST follow the procedures in [RFC1035]
regarding cache invalidation when the DNS time-to-live expires.
5.2.2. Validation of Router Advertisement Messages Next, the node initializes the link's PRL with IPv4 addresses
associated with the domain name discovered above. IPv4 addresses are
discovered through manual config or by querying the name service to
resolving the domain name into address records (e.g., DNS 'A'
resource records) containing IPv4 addresses. Unspecified alternative
methods may also be used.
A node MUST silently discard any received Router Advertisement mes- Notes:
sages that do not satisfy the validity checks in [DISC,6.1.2] as well
as the following additional validity check for ISATAP:
- the network-layer (IPv6) source address is derived from 1. Site administrators maintain a domain name for the ISATAP service
an IPv4 address in the PRL and a list of IPv4 addresses representing ISATAP router
interfaces (normally as address records in the site's name
service). Administrators may also advertise the domain name in a
DHCPv4 option for ISATAP.
5.2.3. Router Specification 2. There are no mandatory rules for the selection of a domain name,
but administrators are encouraged to use the convention
"isatap.domainname" (e.g., isatap.example.com).
Advertising ISATAP interfaces of routers behave the same as advertis- 3. After initialization, nodes periodically re-initialize the PRL
ing interfaces described in [DISC,6.2]. However, periodic unsolicited (after ResolveInterval). When DNS is used, nodes MUST follow the
multicast Router Advertisements are not required, thus the "interval cache invalidation procedures in [20] when the DNS time-to-live
timer" associated with advertising interfaces is not used for that expires.
purpose.
5.2.2 Validity Checks for Router Advertisements
A node MUST silently discard any Router Advertisement messages it
receives that do not satisfy both the validity checks in ([7],
section 6.1.2) and the following additional validity check for
ISATAP:
o the network-layer (IPv6) source address is an ISATAP address and
embeds an IPv4 address from the PRL
5.2.3 Router Specification
Advertising ISATAP interfaces of routers behave the same as
advertising interfaces described in ([7], section 6.2). However,
periodic unsolicited multicast Router Advertisements are not
required, thus the "interval timer" associated with advertising
interfaces is not used for that purpose.
When an ISATAP router receives a valid Router Solicitation on an When an ISATAP router receives a valid Router Solicitation on an
advertising ISATAP interface, it replies with a unicast Router Adver- advertising ISATAP interface, it replies with a unicast Router
tisement to the address of the node which sent the Router Solicita- Advertisement to the address of the node which sent the Router
tion. The source address of the Router Advertisement is a link-local Solicitation. The source address of the Router Advertisement is a
unicast address associated with the interface. This MAY be the same link-local unicast address associated with the interface. This MAY
as the destination address of the Router Solicitation. ISATAP routers be the same as the destination address of the Router Solicitation.
MAY engage in the polling process described under Host Specification ISATAP routers MAY engage in the solicitation process described under
below (e.g. if Router Advertisement consistency verification Host Specification below, e.g., if Router Advertisement consistency
[DISC,6.2.7] is desired), but this is not required. verification ([7], section 6.2.7) is desired.
5.2.4. Host Specification 5.2.4 Host Specification
Hosts periodically poll one or more entries in the PRL ("PRL(i)") by All entries in the PRL are assumed to represent active ISATAP routers
sending unicast Router Solicitation messages using the IPv4 address within the site, i.e., the PRL provides trust basis only; not
("V4ADDR_PRL(i)") and associated timer in the entry. Hosts add the reachability detection. Hosts periodically solicit information from
following variable to support the polling process: one or more entries in the PRL ("PRL(i)") by sending unicast Router
Solicitation messages using the IPv4 address ("V4ADDR_PRL(i)") and
associated timer in the entry. Hosts add the following variable to
support the solicitation process:
MinRouterSolicitInterval MinRouterSolicitInterval
Minimum time between sending Router Solicitations Minimum time between sending Router Solicitations to any router.
to any router. Default and suggested minimum: 15min Default and suggested minimum: 15min
When a PRL(i) is selected for polling, the host sets its associated When a PRL(i) is selected, the host sets its associated timer to
timer to MinRouterSolicitInterval and initiates polling following a MinRouterSolicitInterval and initiates solicitation following a short
short delay as for initial solicitations [ND,6.3.7]), and when the delay as in ([7], section 6.3.7). The solicitation process repeats
associated timer expires. when the associated timer expires.
Polling consists of sending Router Solicitations to the ISATAP link- Solicitation consists of sending Router Solicitations to the ISATAP
local address constructed from the entry's IPv4 address, i.e., they link-local address constructed from the entry's IPv4 address, i.e.,
are sent to 'FE80::0:5EFE:V4ADDR_PRL(i)' instead of 'All-Routers mul- they are sent to 'FE80::0:5EFE:V4ADDR_PRL(i)' instead of 'All-Routers
ticast'. They are otherwise sent in the same manner described in multicast'. They are otherwise sent exactly as in ([7], section
[DISC,6.3.7]. 6.3.7).
When the host receives a valid Router Advertisement (i.e., one that Hosts process received Router Advertisements exactly as in ([7],
satisfies the validity checks in sections 4.5 and 5.2.2) it is pro- section 6.3.4). Hosts additionally reset the timer associated with
cesses in the same manner described in [DISC,6.3.4]. The host addi- the V4ADDR_PRL(i) embedded in the network-layer source address in
tionally resets the timer associated with the V4ADDR_PRL(i) embedded each received Router Advertisement. The timer is reset to either 0.5
in the network-layer source address in the Router Advertisement. The * (the minimum value in the router lifetime or valid lifetime of any
timer is reset to either 0.5 * (the minimum value in the router life- on-link prefixes advertised) or MinRouterSolicitInterval; whichever
time or valid lifetime of any on-link prefixes advertised) or Min- is longer.
RouterSolicitInterval; whichever is longer.
([7], section 6.3.4) includes the following specification:
"To limit the storage needed for the Default Router List, a host
MAY choose not to store all of the router addresses discovered via
advertisements. However, a host MUST retain at least two
addresses and SHOULD retain more."
The router solicitation process for ISATAP nodes is analogous to
choosing which router addresses to store as in the above text.
ISATAP nodes may wish to consider the control traffic overhead of
this process when choosing how many routers to solict. The manner of
choosing particular routers in the PRL for solicitation is outside
the scope of this specification.
6. ISATAP Deployment Considerations 6. ISATAP Deployment Considerations
6.1. Host And Router Deployment Considerations 6.1 Host And Router Deployment Considerations
For hosts, if an underlying link supports both IPv4 (over which ISA- For hosts, if an underlying link supports both IPv4 (over which
TAP is implemented) and also supports IPv6 natively, then ISATAP MAY ISATAP is implemented) and also supports IPv6 natively, then ISATAP
be enabled if the native IPv6 layer does not receive Router Adver- MAY be enabled if the native IPv6 layer does not receive Router
tisements (i.e., does not have connection with an IPv6 router). After Advertisements (i.e., does not have connection with an IPv6 router).
a non-link-local address has been configured and a default router After a non-link-local address has been configured and a default
acquired on the native link, the host SHOULD discontinue the 'Router router acquired on the native link, the host SHOULD discontinue the
Polling Process' process specified in section 5.2.4 and allow exist- router solicitation process described in the host specification and
ing ISATAP address configurations to expire as specified in allow existing ISATAP address configurations to expire as specified
[DISC,5.3][AUTO,5.5.4]. Any ISATAP addresses added to the DNS for in ([7], section 5.3) and ([6], section 5.5.4). Any ISATAP addresses
this host should also be removed. In this way, ISATAP use will gradu- added to the DNS for this host should also be removed. In this way,
ally diminish as IPv6 routers are widely deployed throughout the ISATAP use will gradually diminish as IPv6 routers are widely
site. deployed throughout the site.
Routers MAY configure an interface to simultaneously support both Routers MAY configure an interface to simultaneously support both
native IPv6, and also ISATAP (over IPv4). Routing will operate as native IPv6, and also ISATAP (over IPv4). Routing will operate as
usual between these two domains. Note that the prefixes used on the usual between these two domains. Note that the prefixes used on the
ISATAP and native IPv6 interfaces will be distinct. The IPv4 ISATAP and native IPv6 interfaces will be distinct. The IPv4
address(es) configured on a router's ISATAP interface(s) SHOULD be address(es) configured on a router's ISATAP interface(s) SHOULD be
added (either automatically or manually) to the site's address added (either automatically or manually) to the site's address
records for ISATAP router interfaces (see section 5.2.1). records for ISATAP router interfaces.
6.2. Site Administration Considerations 6.2 Site Administration Considerations
The following considerations are noted for sites that deploy ISATAP: The following considerations are noted for sites that deploy ISATAP:
- ISATAP links are administratively defined by a set of router o ISATAP links are administratively defined by a set of router
interfaces, and set of nodes which have those interface addresses interfaces, and set of nodes which have those interface addresses
in their potential router lists. Thus, ISATAP links are defined by in their potential router lists. Thus, ISATAP links are defined
administrative (not physical) boundaries. by administrative (not physical) boundaries.
- ISATAP hosts and routers can be deployed in an ad-hoc and independent o ISATAP hosts and routers can be deployed in an ad-hoc and
fashion. In particular, ISATAP hosts can be deployed with little/no independent fashion. In particular, ISATAP hosts can be deployed
advanced knowledge of existing ISATAP routers, and ISATAP routers with little/no advanced knowledge of existing ISATAP routers, and
can deployed with no reconfiguration requirements for hosts. ISATAP routers can deployed with no reconfiguration requirements
for hosts.
- ISATAP nodes periodically send Router Solicitations to all entries o ISATAP nodes periodically send Router Solicitations (RS) to one or
in the Potential Router List. Worst-case control traffic is on the more members of the potential router list. When Router
order of (M x N), where 'M' is the number of routers in the Potential Advertisements (RAs) are received, the Router Lifetime value
Router List and 'N' is the total number of nodes on the ISATAP link. provides a timer for the next RS to be sent. Worst-case is for
The MinRouterSolicitInterval ([5.2.4]) bounds control traffic for small values of Router Lifetime which is bounded by
large numbers of nodes even in worst-case scenarios. MinRouterSolicitInterval.
- ISATAP nodes periodically refresh the entries on the PRL, typically o ISATAP nodes periodically refresh the entries on the PRL,
by polling the DNS. Responsible site administration can reduce the typically by querying the DNS. Responsible site administration
control traffic. At a minimum, administrators SHOULD ensure that can reduce the control traffic. At a minimum, administrators
the site's address records for ISATAP router interfaces (see SHOULD ensure that the site's address records for ISATAP router
section 5.2.1) are well maintained. interfaces are well maintained.
7. IANA considerations 7. IANA Considerations
Appendix B offers one possible specification for managing the IEEE A DHCPv4 option assignment for ISATAP is requested, as outlined in
OUI assigned to IANA for EUI-64 interface identifier construction. the procedures found in RFC 2939 [21], section 3.
This specification is made freely available to IANA for any purpose
they may find useful. Appendix B proposes a specification for managing the IEEE OUI
assigned to IANA for EUI-64 interface identifier construction. This
specification is made freely available to IANA for any purpose they
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 [6OVER4,9] apply also to ISATAP. Many security considerations in RFC 2529 [18], section 9 apply also
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
validity checks in section 4.7 will not be effective in preventing ISATAP validity checks will not be effective in preventing IPv6
IPv6 source address spoofing. source address spoofing.
If filtering for ip-protocol-41 is not correctly implemented, IPv6 If filtering for ip-protocol-41 is not correctly implemented, IPv6
source address spoofing is clearly possible, but this can be elimi- source address spoofing is clearly possible, but this can be
nated if both IPv4 source address filtering, and the validity checks eliminated if both IPv4 source address filtering, and the ISATAP
in section 4.7 are implemented. validity checks are implemented.
[DISC,6.1.2] implies that nodes trust Router Advertisements they (RFC 2461 [7]), section 6.1.2 implies that nodes trust Router
receive from on-link routers, as indicated by a value of 255 in the Advertisements they receive from on-link routers, as indicated by a
IPv6 'hop-limit' field. Since this field is not decremented when ip- value of 255 in the IPv6 'hop-limit' field. Since this field is not
protocol-41 packets traverse multiple IPv4 hops [MECH,3.3], ISATAP decremented when ip-protocol-41 packets traverse multiple IPv4 hops
links require a different trust model. In particular, ONLY those ([10], section 3), ISATAP links require a different trust model. In
Router Advertisements received from a member of the Potential Routers particular, ONLY those Router Advertisements received from a member
List are trusted; all others are silently discarded (see section of the Potential Routers List are trusted; all others are silently
5.2.2). This trust model is predicated on IPv4 source address filter- discarded. This trust model is predicated on IPv4 source address
ing, 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 [PRIVACY]. However, since the stateless address autoconfiguration [19]. However, since the ISATAP
ISATAP interface identifier is derived from the node's IPv4 address, interface identifier is derived from the node's IPv4 address, ISATAP
ISATAP addresses do not have the same level of privacy concerns as addresses do not have the same level of privacy concerns as IPv6
IPv6 addresses that use an interface identifier derived from the MAC addresses that use an interface identifier derived from the MAC
address. address. (This issue is the same for NAT'd addresses.)
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
Langan from U.S. Army CECOM ASEO, and Dr. Allen Moshfegh from U.S. Langan from U.S. Army CECOM ASEO, and Dr. Allen Moshfegh from U.S.
Office of Naval Research. Within SRI, Dr. Mike Frankel, J. Peter Mar- Office of Naval Research. Within SRI, Dr. Mike Frankel, J. Peter
cotullio, Lou Rodriguez, and Dr. Ambatipudi Sastry supported the work Marcotullio, Lou Rodriguez, and Dr. Ambatipudi Sastry supported the
and helped foster early interest. work and helped foster early interest.
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, Art Shelest, Margaret Wasserman, and Alain Durand, Nathan Lutchansky, Karen Nielsen, Art Shelest, Margaret
Brian Zill. Wasserman, and Brian Zill.
The authors wish to acknowledge the work of Quang Nguyen [VET] under
the guidance of Dr. Lixia Zhang that proposed very similar ideas to
those that appear in this document. This work was first brought to
the authors' attention on September 20, 2002.
Finally, the authors recognize that ideas similar to those in this The authors also wish to acknowledge the work of Quang Nguyen [22]
document may have already been presented by others and wish to under the guidance of Dr. Lixia Zhang that proposed very similar
acknowledge any other such contributions. ideas to those that appear in this document. This work was first
brought to the authors' attention on September 20, 2002.
Normative References Normative References
[ADDR] Hinden, R., and S. Deering, "IP Version 6 Addressing [1] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
Architecture", RFC 2373, July 1998. (Pending approval Specification", RFC 2460, December 1998.
of "addr-arch-v3").
[AGGR] Hinden., R, O'Dell, M., and Deering, S., "An IPv6 [2] Postel, J., "Internet Protocol", STD 5, RFC 791, September
Aggregatable Global Unicast Address Format", 1981.
RFC 2374, July 1998.
[AUTO] Thomson, S., and T. Narten, "IPv6 Stateless Address [3] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.
[4] Hinden, R. and S. Deering, "An IPv6 Aggregatable Global Unicast
Address Format", RFC 2374, July 1998.
[5] IEEE, "http://standards.ieee.org/regauth/oui/tutorials/
EUI64.html", March 1997.
[6] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998. Autoconfiguration", RFC 2462, December 1998.
[DISC] Narten, T., Nordmark, E., and W. Simpson, "Neighbor [7] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery
Discovery for IP Version 6 (IPv6)", RFC 2461, for IP Version 6 (IPv6)", RFC 2461, December 1998.
December 1998.
[EUI64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) [8] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G. and E.
Registration Authority", Lear, "Address Allocation for Private Internets", BCP 5, RFC
http://standards.ieee.org/regauth/oui/tutori- 1918, February 1996.
als/EUI64.html,
March 1997.
[ICMPv6] Conta, A. and S. Deering, "Internet Control Message [9] Egevang, K. and P. Francis, "The IP Network Address Translator
Protocol (ICMPv6) for the Internet Protocol Version 6 (NAT)", RFC 1631, May 1994.
(IPv6) Specification", RFC 2463, December 1998.
[IPV4] Postel, J., "Internet Protocol", RFC 791. [10] Gilligan, R. and E. Nordmark, "Transition Mechanisms for IPv6
Hosts and Routers", RFC 2893, August 2000.
[IPV6] Deering, S., and R. Hinden, "Internet Protocol, Version 6 [11] Conta, A. and S. Deering, "Internet Control Message Protocol
(IPv6) Specification", RFC 2460. (ICMPv6) for the Internet Protocol Version 6 (IPv6)
Specification", RFC 2463, December 1998.
[MECH] Gilligan, R., and E. Nordmark, "Transition Mechanisms for [12] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery for
IPv6 Hosts and Routers", RFC 2893, August 2000. IP version 6", RFC 1981, August 1996.
[NAT] Egevang, K., and P. Francis, "The IP Network Address [13] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
Translator (NAT)", RFC 1631, May 1994. November 1990.
[PRIVATE] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., [14] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer,
and E. Lear, "Address Allocation for Private Internets", H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
RFC 1918, February 1996. "Stream Control Transmission Protocol", RFC 2960, October 2000.
[SIP] Handley, M., Schulzrinne, H., Schooler, E., and [15] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
J. Rosenberg, "SIP: Session Initiation Protocol", March 1997.
RFC 2543, March 1999.
Informative References [16] Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCP-for-IPv4) Option for Session Initiation Protocol (SIP)
Servers", RFC 3361, August 2002.
[6OVER4] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 Informative References
Domains without Explicit Tunnels", RFC 2529.
[6TO4] Carpenter, B., and K. Moore, "Connection of IPv6 Domains [17] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via
via IPv4 Clouds", RFC 3056, February 2001. IPv4 Clouds", RFC 3056, February 2001.
[IANA] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, [18] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
USC/Information Sciences Institute, October 1994. Domains without Explicit Tunnels", RFC 2529, March 1999.
[PRIVACY] Narten, T., R. Draves, "Privacy Extensions for Stateless [19] Narten, T. and R. Draves, "Privacy Extensions for Stateless
Address Autoconfiguration in IPv6", RFC 3041, Address Autoconfiguration in IPv6", RFC 3041, January 2001.
January 2001.
[RFC1035] Mockapetris, P., "Domain Names - Implementation and [20] Mockapetris, P., "Domain names - implementation and
Specification", RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[RFC2219] Hamilton, M., and R. Wright, "Use of DNS Aliases for [21] Droms, R., "Procedures and IANA Guidelines for Definition of
Network Services", RFC 2219 (BCP), October 1997. New DHCP Options and Message Types", BCP 43, RFC 2939,
September 2000.
[VET] Nguyen, Quang, "Virtual Ethernet: A New Approach to [22] Nguyen, Q., "http://irl.cs.ucla.edu/vet/report.ps", spring
IPv6 Transition", http://irl.cs.ucla.edu/vet/report.ps, 1998.
MS Project Report, Spring 1998.
Authors Addresses Authors' Addresses
Fred L. Templin Fred L. Templin
Nokia Nokia
313 Fairchild Drive 313 Fairchild Drive
Mountain View, CA, USA Mountain View, CA 94110
Phone: (650)-625-2331 US
Email: ftemplin@iprg.nokia.com
Phone: +1 650 625 2331
EMail: ftemplin@iprg.nokia.com
Tim Gleeson Tim Gleeson
Cisco Systems K.K. Cisco Systems K.K.
Shinjuku Mitsu Building Shinjuku Mitsu Building
2-1-1 Nishishinjuku, Shinjuku-ku 2-1-1 Nishishinjuku, Shinjuku-ku
Tokyo 163-0409, JAPAN Tokyo 163-0409
email: tgleeson@cisco.com Japan
EMail: tgleeson@cisco.com
Mohit Talwar Mohit Talwar
Microsoft Corporation Microsoft Corporation
One Microsoft Way One Microsoft Way
Redmond, WA 98052-6399 Redmond, WA> 98052-6399
US
Phone: +1 425 705 3131 Phone: +1 425 705 3131
EMail: mohitt@microsoft.com EMail: mohitt@microsoft.com
Dave Thaler Dave Thaler
Microsoft Corporation Microsoft Corporation
One Microsoft Way One Microsoft Way
Redmond, WA 98052-6399 Redmond, WA 98052-6399
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 06 to version 07:
o clarified address resolution, Neighbor Unreachability Detection
o specified MTU/MRU requirements
changes from version 05 to version 06: changes from version 05 to version 06:
- Addressed operational issues identified in 05 based on o Addressed operational issues identified in 05 based on discussion
discussion between co-authors between co-authors
- Clarified ambiguous text per comments from Hannu Flinck; o Clarified ambiguous text per comments from Hannu Flinck; Jason
Jason Goldschmidt Goldschmidt
changes from version 04 to version 05: changes from version 04 to version 05:
- Moved historical text in section 4.1 to Appendix B in o Moved historical text in section 4.1 to Appendix B in response to
response to comments from Pekka Savola comments from Pekka Savola
- Identified operational issues for anticipated deployment o Identified operational issues for anticipated deployment scenarios
scenarios
- Included SRI IPR statement and contact information o Included SRI IPR statement and contact information
- Included reference to Quang Nguyen work o Included reference to Quang Nguyen work
changes from version 03 to version 04: changes from version 03 to version 04:
- Re-wrote section on Potential Router List initialization to o Re-wrote section on Potential Router List initialization to
reference existing precedence in other documents reference existing precedence in other documents
- several minor wording changes based on feedback from the o several minor wording changes based on feedback from the community
community
changes from version 02 to version 03: changes from version 02 to version 03:
- Added contributing co-authors o Added contributing co-authors
- RSs are now sent to unicast addresses rather than all-routers-multicast o RSs are now sent to unicast addresses rather than
- Brought draft into better alignment with other IPv6 all-routers-multicast
o Brought draft into better alignment with other IPv6
standards-track documents standards-track documents
- Added applicability statement o Added applicability statement
changes from version 01 to version 02: changes from version 01 to version 02:
- Cleaned up text and tightened up terminology. Changed "IPv6 destination o Cleaned up text and tightened up terminology
address" to "IPv6 next-hop address" under "sending rules". Changed
definition of ISATAP prefix to include link and site-local. Changed o Changed "IPv6 destination address" to "IPv6 next-hop address"
language in sections 4 and 5 under "sending rules"
o Changed definition of ISATAP prefix to include link and site-local
o Changed language in sections 4 and 5
changes from version 00 to version 01: changes from version 00 to version 01:
- Revised draft to require different /64 prefixes for ISATAP o Revised draft to require different /64 prefixes for ISATAP
addresses and native IPv6 addresses. Thus, a node's ISATAP addresses and native IPv6 addresses. Thus, a node's ISATAP
interface is assigned a /64 prefix that is distinct from the interface is assigned a /64 prefix that is distinct from the
prefixes assigned to any other interfaces attached to the prefixes assigned to any other interfaces attached to the node -
node - be they physical or logical interfaces. This approach be they physical or logical interfaces. This approach eliminates
eliminates ISATAP-specific sending rules presented in earlier ISATAP-specific sending rules presented in earlier draft versions.
draft versions.
- Changed sense of 'u/l' bit in the ISATAP address interface o Changed sense of 'u/l' bit in the ISATAP address interface
identifier to indicate "local scope", since ISATAP interface identifier to indicate "local scope", since ISATAP interface
identifiers are unique only within the scope of the ISATAP identifiers are unique only within the scope of the ISATAP prefix.
prefix. (See section 4.) (See section 4.)
changes from personal draft to version 00: changes from personal draft to version 00:
- Title change to provide higher-level description of field of o Title change to provide higher-level description of field of use
use addressed by this draft. Removed other extraneous text. addressed by this draft. Removed other extraneous text.
- Major new section on automatic discovery of off-link IPv6 routers o Major new section on automatic discovery of off-link IPv6 routers
when IPv6-IPv4 compatibility addresses are used. when IPv6-IPv4 compatibility addresses are used.
APPENDIX B: Rationale for Interface Identifier Construction Rules Appendix B. Rationale for Interface Identifier Construction Rules
ISATAP specifies an [EUI64]-format address construction for the Orga- ISATAP specifies an EUI64-format address construction for the
nizationally-Unique Identifier (OUI) owned by the Internet Assigned Organizationally-Unique Identifier (OUI) owned by the Internet
Numbers Authority [IANA]. This format (given below) is used to con- Assigned Numbers Authority (IANA). This format (given below) is used
struct both native [EUI64] addresses for general use and modified to construct both native EUI64 addresses for general use and modified
EUI-64 format interface identifiers for use in IPv6 unicast EUI-64 format interface identifiers for use in IPv6 unicast
addresses: addresses:
|0 2|2 3|3 3|4 6| |0 2|2 3|3 3|4 6|
|0 3|4 1|2 9|0 3| |0 3|4 1|2 9|0 3|
+------------------------+--------+--------+------------------------+ +------------------------+--------+--------+------------------------+
| OUI ("00-00-5E"+u+g) | TYPE | TSE | TSD | | OUI ("00-00-5E"+u+g) | TYPE | TSE | TSD |
+------------------------+--------+--------+------------------------+ +------------------------+--------+--------+------------------------+
Where the fields are: Where the fields are:
skipping to change at page 16, line 35 skipping to change at page 25, line 44
0x00-0xFD RESERVED for future IANA use 0x00-0xFD RESERVED for future IANA use
0xFE (TSE, TSD) together contain an embedded IPv4 address 0xFE (TSE, TSD) together contain an embedded IPv4 address
0xFF TSD is interpreted based on TSE as follows: 0xFF TSD is interpreted based on TSE as follows:
TSE TSD Interpretation TSE TSD Interpretation
--- ------------------ --- ------------------
0x00-0xFD RESERVED for future IANA use 0x00-0xFD RESERVED for future IANA use
0xFE TSD contains 24-bit EUI-48 intf id 0xFE TSD contains 24-bit EUI-48 intf id
0xFF RESERVED by IEEE/RAC 0xFF RESERVED by IEEE/RAC
Figure 3
Thus, if TYPE=0xFE, TSE is an extension of TSD. If TYPE=0xFF, TSE is Thus, if TYPE=0xFE, TSE is an extension of TSD. If TYPE=0xFF, TSE is
an extension of TYPE. Other values for TYPE (hence, other interpreta- an extension of TYPE. Other values for TYPE (thus, other
tions of TSE, TSD) are reserved for future IANA use. interpretations of TSE, TSD) are reserved for future IANA use.
The above specification is compatible with all aspects of EUI64,
including support for encapsulating legacy EUI-48 interface
identifiers (e.g., an IANA EUI-48 format multicast address such as:
The above specification is compatible with all aspects of [EUI64],
including support for encapsulating legacy EUI-48 interface identi-
fiers (e.g., an IANA EUI-48 format multicast address such as:
'01-00-5E-01-02-03' is encapsulated as: '01-00-5E-FF-FE-01-02-03'). '01-00-5E-01-02-03' is encapsulated as: '01-00-5E-FF-FE-01-02-03').
But, the specification also provides a special TYPE (0xFE) to indi- But, the specification also provides a special TYPE (0xFE) to
cate an IPv4 address is embedded. Thus, when the first four octets of indicate an IPv4 address is embedded. Thus, when the first four
a [ADDR]-compatible IPv6 interface identifier are: '00-00-5E-FE' octets of an IPv6 interface identifier are: '00-00-5E-FE' (note: the
(note: the 'u/l' bit MUST be 0) the interface identifier is said to 'u/l' bit MUST be 0) the interface identifier is said to be in
be in "ISATAP format" and the next four octets embed an IPv4 address "ISATAP format" and the next four octets embed an IPv4 address
encoded in network byte order. encoded in network byte order.
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