Network Working Group F. Templin Internet-Draft Nokia Expires: August
4,15, 2004 T. Gleeson Cisco Systems K.K. M. Talwar D. Thaler Microsoft Corporation February 4,16, 2004 Internet/SiteIntra-Site Automatic Tunnel Addressing Protocol (ISATAP) draft-ietf-ngtrans-isatap-18.txtdraft-ietf-ngtrans-isatap-19.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 4,15, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract The Internet/SiteIntra-Site Automatic Tunnel Addressing Protocol (ISATAP) connects IPv6 hosts/routers over IPv4 networks. ISATAP views the IPv4 network as a link layer for IPv6 and views other nodes on the network as potential IPv6 hosts/routers. ISATAP supports automatic tunneling and a tunnel interface management abstraction similar to the Non- Broadcast, Multiple Access (NBMA) and ATM Permanent/Switched Virtual Circuit (PVC/SVC) models. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. ISATAP Conceptual Model . . . . . . . . . . . . . . . . . . . 45 5. Node Requirements . . . . . . . . . . . . . . . . . . . . . . 56 6. Addressing Requirements . . . . . . . . . . . . . . . . . . . 57 7. Configuration and Management Requirements . . . . . . . . . . 68 8. Automatic Tunneling . . . . . . . . . . . . . . . . . . . . . 1012 9. Neighbor Discovery for ISATAP Interfaces . . . . . . . . . . . 1517 10. Other Requirements for Control Plane Signaling . . . . . . . . 18 11.Security considerations . . . . . . . . . . . . . . . . . . . 18 12.20 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 13.20 12. IAB Considerations . . . . . . . . . . . . . . . . . . . . . . 19 14.20 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 2022 A. Major Changes . . . . . . . . . . . . . . . . . . . . . . . . 2123 B. Example ISATAP Driver API . . . . . . . . . . . . . . . . . . 21 C.The IPv6 Minimum MTU . . . . . . . . . . . . . . . . . . . . . 24 D.23 C. Modified EUI-64 Addresses in the IANA Ethernet Address Block . 24 E.D. Proposed ICMPv6 Code Field Types . . . . . . . . . . . . . . . 25 Normative References . . . . . . . . . . . . . . . . . . . . . 25 Informative References . . . . . . . . . . . . . . . . . . . . 27 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 2928 Intellectual Property and Copyright Statements . . . . . . . . 3029 1. Introduction This document specifies a simple mechanism called the Internet/SiteIntra-Site Automatic Tunnel Addressing Protocol (ISATAP) that connects IPv6 [RFC2460] hosts/routers over IPv4 [STD0005][STD5] networks. Dual-stack (IPv6/IPv4) nodes use ISATAP to automatically tunnel IPv6 packets in IPv4, i.e., ISATAP views the IPv4 network as a link layer for IPv6 and views other nodes on the network as potential IPv6 hosts/routers. ISATAP enables automatic tunneling whether global or private IPv4 addresses are used, and supports a tunnel interface management abstraction similar to the Non-Broadcast, Multiple Access (NBMA) [RFC2491] and ATM Permanent/Switched Virtual Circuit (PVC/SVC) [RFC2492] models. The main objectives of this document are to: 1) describe the ISATAP conceptual model, 2) specify addressing requirements, 3) discuss configuration and management requirements, 4) specify automatic tunneling using ISATAP, 5) specify operational aspects of IPv6 Neighbor Discovery, and 6) discuss IANA and Security considerations. This document surveys all IETF v6ops WG documents current up to February 4,16, 2004. 2. Requirements The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [BCP0014].[BCP14]. This document also makes use of internal conceptual variables to describe protocol behavior and external variables that an implementation must allow system administrators to change. The specific variable names, how their values change, and how their settings influence protocol behavior are provided to demonstrate protocol behavior. An implementation is not required to have them in the exact form described here, so long as its external behavior is consistent with that described in this document. 3. Terminology The terminology of [STD0003][RFC2460][RFC2461][RFC3582][STD3][RFC2460][RFC2461][RFC3582] applies to this document. The following additional terms are defined: ISATAP node: a node that implements the specifications in this document. ISATAP daemon: an ISATAP node's server application that uses an ISATAP driverAPI for control plane signaling and tunnel interface configuration/management. ISATAP driver: an ISATAP node's network drivermodule that provides an API for control plane signaling and tunnel interface configuration/ management.configuration/management. Also provides an engine for tunneleda packet encapsulation, decapsulationencapsulation/decapsulation engine, and forwarding.an embedded gateway function (see: [STD3], section 126.96.36.199). logical interface: an IPv6 address or a configured tunnel interface associated with an ISATAP interface.interface (see: [STD3], section 188.8.131.52). ISATAP interface: an ISATAP node's point-to-multipoint IPv6interface for automatic IPv6-in-IPv4 tunneling. Providesthat provides a control plane interface for the ISATAP daemon and a userforwarding plane nexus for its associated logical interfaces. ISATAP interface identifier: an IPv6 interface identifier with an embedded IPv4 address constructed as specified in section 6.1. ISATAP address: an IPv6 unicast address assigned on an ISATAP interface with an on-link prefix and an ISATAP interface identifier. locator: an IPv4 address-to-interface mapping, i.e., a node's IPv4 address and the index for it's associated interface. locator set: a set of locators associated with a tunnel interface, where each locator in the set belongs to the same site. 4. ISATAP Conceptual Model ISATAP nodes typically act as a host on someinterfaces and as a router on other interfaces; the distinction between host and router is made perare advertising interface. ISATAPIPv6 interfaces that provide a point-to-multipoint abstraction for IPv6-in-IPv4 tunneling. They provide a userforwarding plane nexus (used by the ISATAP driver) for tunneling packets on behalf oftheir associated logical interfaces. They also provide a control plane interface (used by the ISATAP daemon) for tunnel configuration signaling between the ISATAP daemon and prospective peers (e.g., via IPv6 Neighbor Discovery messages, DNS queries, etc.).signaling. The ISATAP driver sends tunneledencapsulates packets via the node's IPv4 stackfor transmission according to the sending interface's encapsulation parameters.parameters associated with its logical interfaces. It also determines the correct interface to receive each tunneled packet after decapsulation via a forwarding table lookup.decapsulation, and provides an embedded gateway function. The ISATAP daemon configures and manages tunnels via an API provided by the ISATAP driver API.driver. Each such configured tunnel provides a nexus for multiple applications using IPv6 addresses as application identifiers. Each such application identifier provides a nexus for multiple sessions. In summary, each configured tunnel provides a point-to-point connection between peers that can support multiple applications and multiple instances of each application. 5. Node Requirements ISATAP nodes implement the common functionality required by [NODEREQ] as well asThe following example diagram depicts the additional features specified in this document. 6. Addressing Requirements 6.1 ISATAP Interface IdentifiersISATAP interface identifiersconceptual model: <-- IPv6-enabled applications --> +----+ +---------------------------------------------+ |I D| | IPv6 Stack | |S a| | | |A e| | <-- IPv6 addresses --> | |T m| | +--+ +--+ +--+ +--+ +--+ +--+ +--+ +--+ | |A o| | |v6| |v6| |v6| |v6| |v6| |v6| |v6| ... |v6| | |P n| | +--+ +-++ ++-+ ++-+ ++++ ++-+ +-++ +-++ | +-+--+ +---/---/----|----|---/-|--|-\----|--------|--+ | / / | | / | | \ | | <----+ x / / | | / | | \ | | I | / / +--++ +++-+ +--++ ++-++ +-+-+ S | / / |tun| |tun| |tun| |tun| ... |tun| A | / / +-+-+ +--++ +-+-+ ++--+ +-+-+ T | / / | \ | / | A | x / / x | x \ | / x | P | | / / | | | \ | / | | | +--+---+---+ +------+---+ +-----+-+-++ +--------+-+ D | |ISATAP I/F| |ISATAP I/F| |ISATAP I/F| .. |ISATAP I/F| r | | (site 1) | | (site 1) | | (site 3) | | (site n) | i | +---+----+++ +-++-----+-+ +-+-----+-++ +------+---+ v | | | \ / | | | | \ | e | | | \/ | | | | \ | r | | | /\ | | | | \ | <----+ +---|----|-/--\-|-----|-----|-----|-----\ -------|---+ | +-+-+ +++-+ +++-+ +-+-+ +-+-+ +-+-+ +--++ +-+-+ | | |loc| |loc| |loc| |loc| |loc| |loc| |loc| .. |loc| | | +-+-+ +--++ +---+ +---+ +-+-+ +-+-+ +-+-+ +-+-+ | | | / / / \ | / / | | | / / +---+ \ | / / | | | / / / \ | / / | | | / / / IPv4 Stack \ | / / | +-+-+-+--+-+--+--------+--+------+++------+-+------+-+ |IPv4 I/F| |IPv4 I/F| |IPv4 I/F| .... |IPv4 I/F| |(site 1)| |(site 2)| |(site 3)| |(site n)| +--------+ +--------+ +--------+ +--------+ 5. Node Requirements ISATAP nodes observe the common functionality requirements in [NODEREQ] and the DNS requirements in ([MECH], section 2.2). They also implement the additional features specified in this document. 6. Addressing Requirements 6.1 ISATAP Interface Identifiers ISATAP interface identifiers are constructed in Modified EUI-64 format ([ADDR], appendix A). They are formed by concatenating the 24-bit IANA OUI (00-00-5E), the 8-bit hexadecimal value 0xFE, and a 32-bit IPv4 address in network byte order ([AUTH], section 3.4).order. The format for ISATAP interface identifiers is given below (where 'u' is the IEEE univeral/local bit, 'g' is the IEEE group/individual bit, and the 'm' bits represent the concatenated IPv4 address): |0 1|1 3|3 4|4 6| |0 5|6 1|2 7|8 3| +----------------+----------------+----------------+----------------+ |000000ug00000000|0101111011111110|mmmmmmmmmmmmmmmm|mmmmmmmmmmmmmmmm| +----------------+----------------+----------------+----------------+ When the IPv4 address is known to be globally unique, the 'u' bit is set to 1; otherwise, the 'u' bit is set to 0 ([ADDR], section 2.5.1). See: Appendix DC for additional non-normative details. 6.2 ISATAP Addresses Any IPv6 unicast address ([ADDR], section 2.5) that contains an ISATAP interface identifier constructed as specified in section 6.1 and an on-link prefix on an ISATAP interface is considered an ISATAP address. 6.3 Multicast/Anycast ISATAP interfaces recognize a node's required IPv6 multicast/anycast addresses ([ADDR], section 2.8). For IPv6 multicast addresses of interest to local applications, ISATAP nodes join the corresponding Organization-Local Scope IPv4 multicast groups ([RFC2529], section 6) on each interface that appears in an ISATAP interface's locator set (see: section 7.2). IPv6 multicast addresses of interest include a node's required multicast addresses, and may also include e.g, the 'All_DHCP_Relay_Agents_and_Servers' and 'All_DHCP_Servers' multicast addresses (i.e., if the node is configured as a DHCPv6 server [RFC3315][RFC3633]), multicast addresses discovered via MLD [RFC2710],etc. Considerations for IPv6 anycast appear in [ANYCAST]. 6.4 Source/Target Link Layer Address Options Source/Target Link Layer Address Options ([RFC2461], section 4.6.1) for ISATAP have the following format: +-------+-------+-------+-------+-------+-------+-------+--------+ | Type |Length | 0 | 0 | IPv4 Address | +-------+-------+-------+-------+-------+-------+-------+--------+ Type: 1 for Source Link-layer address. 2 for Target Link-layer address. Length: 1 (in units of 8 octets). IPv4 Address: A 32 bit IPv4 address, in network byte order ([AUTH], section 3.4).order. ISATAP nodes use the specifications in ([MECH], section 3.8) that pertain to sending and receiving Source/Target Link Layer Address Options. 7. Configuration and Management Requirements 7.1 Network Management ISATAP nodes MAY support network management; those that do SHOULD support the following MIBs: [FTMIB][IPMIB][TUNMIB][TCPMIB][UDPMIB].This document defines no new MIB tables, nor extensions to any existing MIB tables. Objects found in the MIBs listed above[FTMIB][IPMIB][TUNMIB] are supported as described in the following subsections. 7.2 The ifRcvAddressTable The ISATAP driver maintains ifRcvAddressTable as a bidirectional association of locators with tunnel interfaces. Each locator in the table includes a preferredan IPv4 address-to-interface mapping (i.e., a preferredan IPv4 ipAddressEntry in the node's ipAddressTable) and a list of associated tunnel interfaces. Each tunnel interface in the table has a tunnelIfEntry and a list of associated locators, i.e., a "locator set". The ISATAP driver implements the following conceptual functions to manage and search the ifRcvAddressTable: 7.2.1 RcvTableAdd(locator, tunnel_interface) Creates a bidirectional association in the ifRcvAddressTable between the locator and tunnel interface, i.e., adds the locator to the tunnel interface's locator set and adds the tunnel interface to the locator's association list. Returns success or failure. 7.2.2 RcvTableDel(locator, tunnel_interface) Deletes ifRcvAddressTable entries according to the locator and tunnel interface callingarguments as follows: - if both arguments are NULL, garbage-collects the entire table. - if both arguments are non-NULL, deletes the locator from the tunnel interface's locator set and deletes the tunnel interface from the locator's association list. - if the locator is non-NULL and tunnel interface is NULL, deletes the locator from the locator sets of all tunnel interfaces. - if the locator is NULL and the tunnel interface is non-NULL, deletes the tunnel interface from the association lists of all locators. Returns success or failure. 7.2.3 RcvTableLocate(packet) Searches the ifRcvAddressTable to locate the correct tunnel interface to decapsulate a packet. First, determines the locator that matches the packet's IPv4 destination address and ifIndex for the interface the packet arrived on. Next, checks each tunnel interface in the locator's association list for anexact matchmatches of tunnelIfEncapsMethod with the packet's encapsulation type and an exact match oftunnelIfRemoteInetAddress with the packet's IPv4 source address. If there is no match on the packet's IPv4 source address, a tunnel interface with a matching tunnelIfEncapsMethod and with tunnelIfRemoteInetAddress set to 0.0.0.0 is selected. If there are multiple matches, a tunnel interface with tunnelIfLocalInetAddress that matches the packet's IPv4 destination address is preferred. Returns a pointer to a tunnel interface if a match is found; else NULL. 7.3 ISATAP Driver API The ISATAP driver implements an API for calling processes,used by, e.g., the ISATAP daemons,daemon, startup scripts, manual command line entry, kernel processes, etc. Access MUST be restricted to privileged users and applications. The API provides primitives for sending/receiving control plane messages as well as creating, deleting, modifying,ISATAP nodes implement the basic and otherwise managing tunnel interfaces. An example (i.e., non- normative) API is given in Appendix B.advanced APIs for IPv6 [RFC3493][RFC3542]. 7.4 ISATAP Interface Creation/Configuration ISATAP interfaces are created via the tunnelIfConfigTable, which results in simultaneous creation of a tunnelIfEntry and a companion ipv6InterfaceEntry. Each ISATAP interface configures a locator set, where each locator in the set represents an IPv4 address-to- interfaceaddress-to-interface mapping for the same site (or, represents a mapping that is routable on the global Internet). AnISATAP interfaceinterfaces MUST NOT configure a locator set that spans multiple sites. ISATAP interfaces configure the following values for objects in tunnelIfEntry: - tunnelIfEncapsMethod is set to an IANATunnelType for "isatap". - tunnelIfLocalInetAddress is set to an IPv4 address from the interface's locator set. - tunnelIfRemoteInetAddress is set to 0.0.0.0 to denote wildcard match for remote tunnel endpoints. - other read-write objects in the tunnelIfEntry are configured as for any tunnel interface. ISATAP interfaces also configureare configured as advertising IPv6 interfaces and set the following values for objects in ipv6InterfaceEntry: - ipv6InterfaceType is set to "tunnel". - ipv6InterfacePhysicalAddress is set to an octet string of zero length to indicate that this IPv6 interface does not have a physical address. - ipv6InterfaceForwarding and, if necessary,and ip6Forwarding for the node are set to "forwarding". - other read-write objects in ipv6InterfaceEntry are configured as for any IPv6 interface. Finally,ISATAP interfaces create an ipv6RouterAdvertEntry for the ISATAP interface is created in ipv6RouterAdvertTableand set its ipv6RouterAdvertIfIndex object is setto the same value as ipv6InterfaceIfIndex. Other objects in ipv6RouterAdvertEntry are configured as for any IPv6 router. IPv6 address selection rules for ISATAP interfaces are specified in [RFC3484]. 7.5 Dynamic Creation ofConfigured TunnelsTunnel Creation/Configuration Configured tunnels are normally created by the ISATAP daemon in dynamic response to a tunnel creation request. Configured tunnel interfaces are configuredrequest as foran ISATAP interfaces (see: section 7.4), except thatinterface's associated logical interface; they inherit the locator set of their associated ISATAP interface. Configured tunnels set the following values for objects in tunnelIfEntry: - tunnelIfEncapsMethod is set to an appropriate IANATunnelType value. - tunnelIfLocalInetAddress is set to an IPv4 address from the interface's locator set. - tunnelIfRemoteInetAddress is normallyset to a specifican IPv4 address for a remotethe node at the far end of the tunnel, i.e., configured tunnelstunnel. - other read-write objects in the tunnelIfEntry are normallyconfigured as point-to-point. Also, tunnelIfEncapsMethodfor the new entryany tunnel interface. Configured tunnels set values for objects in ipv6InterfaceEntry as follows: - ipv6InterfaceType is set to an IANATunnelType appropriate for the method of encapsulation. Configured tunnels MAY be "bound""tunnel". - ipv6InterfacePhysicalAddress is set to an ISATAP interface such that they inherit the ISATAP interface's locator set, e.g., for easeoctet string of management andzero length to avoid misconfigurations. Configured tunnels MAY also be createdindicate that this IPv6 interface does not have a physical address. - other read-write objects in ipv6InterfaceEntry are configured as independent entities and configure their own locator set, but (asfor ISATAP interfaces) they MUST NOT configure a locator set that spans multiple sites.any IPv6 interface. IPv6 address selection rules for configured tunnel interfaces are specified in [RFC3484]. 7.6 Reconfigurations Due to IPv4 Address Changes When a locator becomes deprecated (e.g., whenan IPv4 address is removed from an IPv4 interface) theinterface, its corresponding locator SHOULD be removed from all tunnel interface associationslocator sets via RcvTableDel(locator, NULL). Also, all tunnel interfacesNULL); tunnelIfEntrys that used the deprecatedIPv4 address as tunnelIfLocalInetAddress SHOULD also configure a different local IPv4 address from their remaining locator set. When a new IPv4 address is added to an IPv4 interface, the node MAY add the corresponding new locator to thea tunnel interface's locator set for one or more tunnel interfacesvia RcvTableAdd(locator, tunnel_interface), and MAY also set tunnelIfLocalInetAddress for tunnel interfaces referenced by the updated forwarding entriesits tunnelIfEntry to the new address. Methods for triggering the above changes, and for communicating IPv4 addresschanges to remote nodes,are out of scope. 8. Automatic Tunneling ISATAP nodes use the basic tunneling mechanisms specified in [MECH]. The following additional specifications are also used: 8.1 Encapsulation The ISATAP driver encapsulates IPv6 packets in IPv4using various encapsulation methods, including ip-protocol-41 (e.g., 6over4 [RFC2529], 6to4 [RFC3056], IPv6-in-IPv4 configured tunnels [MECH], isatap, etc.), UDP [STD0006][STD6] port 3544, and others. AH [RFC2402] and/or ESP [RFC2406]Security processing and header(e.g., [RFC2402][RFC2406], etc.), upper layer fragmentation [RFC3542] and header compression for the packet's inner headers are performed prior to encapsulation. 8.1.1 NAT Traversal Native IPv6 and/or ip-protocol-41 encapsulation provides sufficient functionality to support peer-to-peercommunications when bothbetween peers that reside within the same site (i.e., the same enterprise network). When the remote peer resides withinis in a different site, NAT traversal via UDP/IPv4 encapsulation MAY be necessary. When an ISATAP node determines that NAT traversal is necessary to reach a particular peer, it encapsulates IPv6 packets using UDP/IPv4 encapsulation with a UDP destinationport of 3544.3544 encapsulation. This determination may come through, e.g., first attempting communications via ip- protocol-41ip-protocol-41 then failing over to UDP/IPv4 port 3544 encapsulation, administrative knowledge that a NAT traversal will occur alongis on the path, etc. When UDP/IPv4 port 3544 encapsulation is used, the specifications in this document apply the same as for any form of encapsulation supported by ISATAP.8.1.2 Multicast ISATAP interfaces encapsulate packets with IPv6 multicast destination addresses using a mapped Organization-Local Scope IPv4 multicast address ([RFC2529], section 6) as the destination address in the encapsulating IPv4 header. 8.2 Tunnel MTU and Fragmentation Encapsulated packets sent by the ISATAP driver may incurrequire host-based IPv4 fragmentation,fragmentation in order to satisfy the 1280 byte IPv6 minimum MTU, e.g., when the underlying physicallink has a small IPv4 MTU [BCP0048]. In such cases, host-based IPv4[BCP48]. While this intentional fragmentation is required to satisfy the 1280 byte IPv6 minimum MTU, and isnot considered harmful [FRAG]. On the other hand,harmful, unmitigated IPv4 fragmentation caused by the network can cause poor performance.performance [FRAG]. For example, since the minimum IPv4 fragment size is only 8 bytes [STD0005], network middleboxes could shred[STD5], a single 1280 byte tunneledencapsulated packet could be shredded by the network into as many as 160 IPv4 fragments.fragments with obvious negative performance implications. ISATAP uses the MTU and fragmentation specifications in ([MECH], section 3.2) and the Maximum Reassembly Unit (MRU) specifications in ([MECH], section 3.6), which provide sufficient measures for avoiding excessive IPv4 fragmentation in certain controlled environments (e.g., 3GPP operator networks, enterprise networks, etc). To minimize IPv4 fragmentation and improve performance in general use case scenarios, ISATAP nodes SHOULD add the following simple instrumentation to the IPv4 reassembly cache: When the initial fragment of an encapsulated packet arrives, the packet's IPv4 reassembly timer is set to 1 second (i.e., the worst case store-and-forward delay budget for a 1280 byte packet). If an encapsulated packet's IPv4 reassembly timer expires: - If enough contiguous leading bytes of the packet have arrived (see: section 8.6), reassemble the packet from all fragments received. (Otherwise, garbage-collect the reassembly buffer and return from processing.) During reassembly, copyusing zero-filled or,or heuristically-chosen replacement data bytes in place of any missing fragments. (Otherwise, garbage-collect the reassembly buffer and return from processing.) - Mark the packet as "INCOMPLETE", and also mark it with a "TOTAL_BYTES"an "ACTUAL_BYTES" length that encodes the totalactual number of data bytes in fragments that arrived. - Deliver the packet to the ISATAP driver as though reassembly had succeeded. - Dodriver, and do not send an ICMPv4 "time exceeded" message [STD0005].[STD5]. Appendix CB provides informative text on the derivation of the 1280 byte IPv6 minimum MTU. 8.3 Handling ICMPv4 Errors ISATAP interfaces SHOULD process ARP failures and persistent ICMPv4 errors as link-specific information indicating that a path to a neighbor may have failed ([RFC2461], section 7.3.3). 8.4 Link-Local Addresses ISATAP interfaces use link local addresses constructed as specified in section 6.1 of this document. 8.5 Neighbor Discovery over Tunnels The specification in ([MECH], section 3.8) is used; the additional specification for neighbor discovery in section 9 of this document are also used. 8.6 Decapsulation/Filtering ISATAP nodes typically arrange for the ISATAP driver to receive all IPv4-encapsulated IPv6 packets that are addressed to one of the node's IPv4 addresses. Examples include ip-protocol-41 (e.g., 6to4, 6over4, configured tunnels, isatap, etc.), UDP/IPv4 port 3544, and others. The ISATAP driver uses the decapsulation and filtering specifications in ([MECH], section 3.6), and processes each packet according to the following steps: 1. Locate the correct tunnel interface to receive the packet (see: section 7.2.3). If not found, silently discard the packet and return from processing. 2. If the tunnel uses header compression, reconstitute headers. If header reconstitution fails, silently discard the packet and return from processing. 3. Verify that the packet's IPv4 source address is correct for the encapsulated IPv6 source address. For packets received on a configured tunnel interface, verification is exactly as specified in ([MECH], section 3.6). For packets received on an ISATAP interface, the IPv4 source address is correct if: - the IPv6 source address is an ISATAP address that embeds the IPv4 source address in its interface identifier, or: - the IPv6 source address is the address of an IPv6 neighbor on an ISATAP interface associated with the locator that matched the packet (see: section 7.2.3), or: - the IPv4 source address is a member of the Potential Router List (see: section 9.1). If the IPv4 source address is incorrect, silently discard the packet and return from processing. 4. Perform IPv4 ingress filtering (optional; disabled by default) then decapsulate the packet.packet but do not discard encapsulating headers. If the IPv6 source address is invalid (see: [MECH], section 3.6), silently discard the packet and return from processing. For UDP port 3544 packets received on an ISATAP interface, if the IPv6 source address is an ISATAP link local address with the 'u' bit set to 0 and an embedded IPv4 address that does not match the IPv4 source address (see: section 6), rewrite the IPv6 source address to inform upper layers of the sender's mapped UDP port number and IPv4 source address. Specific rules for rewriting the IPv6 source address are established during ISATAP interface configuration. Next, discard encapsulating headers and continue processing the encapsulated IPv6 packet.5. Perform ingress filtering on the IPv6 source address (see: [MECH], section 3.6). Next, determine the correct transport protocol listener [FLOW] if the packet is destined to the localhost; otherwise, perform an IPv6 forwarding table lookup and site border/firewall filtering (see: [UNIQUE], section 6). If the packet cannot be delivered, the driver SHOULD send an ICMPv6 Destination Unreachable message ([RFC2463], section 3.2) to the packet's source. The message SHOULD select as its source address an IPv6 address from the outgoing interface (if the packet was destined to the localhost) or an ingress-wise correct IPv6 address from the interface that would have forwarded the packet had it not been filtered. The Code field of the message is set as follows: - if there is no route to the destination, the Code field is set to 0 (see: [RFC2463], section 3.1). - if communication with the destination is administratively prohibited, the Code field is set to 1 ([RFC2463], section 3.1). - if the packet is destined to the localhost, but the transport protocol has no listener, the Code field is set to 4 ([RFC2463], section 3.1). - if the packet's destination is beyond the scope of the source address, the Code field is set to 2 (see: IANA Considerations). - if the packet was dropped due to ingress filtering policies, the Code field is set to 5 (see: IANA Considerations). - if the packet is dropped due to a reject route, the Code field is set to 6 (see: IANA Considerations). - if the packet was received on a point-to-point link and destined to an address within a subnet assigned to that same link, or if the reason for the failure to deliver cannot be mapped to any of the specific conditions listed above, the Code field is set to 3 ([RFC2463], section 3.2). After sending the ICMPv6 Destination Unreachable message, discard the packet and return from processing. 6. If the packet is "INCOMPLETE" (see section 8.2) sendprepare an authenticated, unsolicited Router Advertisement message ([RFC2461], section 6.2.4) with an MTU option that encodes the maximum of "ACTUAL_BYTES" and (68 bytes minus the size of encapsulating headers.) The IPv6 destination address in the Router Advertisement message is set to the packet's IPv6 source address with anaddress, and the message is reverse-encapsulated and returned to the node that sent the "INCOMPLETE" packet, i.e., it is NOT presented to the native IPv6 stack for transmission. The 68 byte minimum MTU optionis due to the requirement that encodes "TOTAL_BYTES".every Internet module must be able to forward a datagram of 68 octets without further fragmentation ([STD5], Internet Protocol, section 3.2). 7. Discard encapsulating headers. If the packet was destined to a remote host, forward the packet and return from processing. Otherwise, apply AH [RFC2402] or ESP [RFC2406]security processing (if necessary),(e.g., [RFC2402][RFC2406], etc.), and deliverplace the decapsulatedpacket by placing itin a buffer for upper layers. The buffer may be, e.g., the IPv6 reassembly cache, an application's mapped data buffer [RFC3542], etc. If there is clear evidence that upper layer reassembly has stalled, an ICMPv6 Packet Too Big message [RFC1981] MAY be sent to the packet's source address with an MTU value indicating a size that islikely to incur successful reassembly. Some applications may realize greater efficiency by accepting partial information from "INCOMPLETE" packets (see: section 8.2) and requesting selective retransmission of missing portions. 9. Neighbor Discovery for ISATAP Interfaces ISATAP nodes use the neighbor discovery mechanisms specified in [RFC2461] along with securing mechanisms (e.g., [SEND]) to create/ change neighbor cache entries and to provide control plane signaling for automatic tunnel configuration. ISATAP interfaces also implement the following specifications: 9.1 Conceptual Model Of A Host To the list of Conceptual Data Structures ([RFC2461], section 5.1), ISATAP interfaces add: Potential Router List A set of entries about potential routers; used to support the mechanisms specified in section 184.108.40.206. Each entry ("PRL(i)") has an associated timer ("TIMER(i)"), and an IPv4 address ("V4ADDR(i)") that represents a router's advertising ISATAP interface. 9.2 Router and Prefix Discovery 9.2.1 Router Specification As permitted by ([RFC2461], section 6.2.6), the ISATAP daemon SHOULD send unicastThe Router Advertisement messages to the soliciting node's address when the solicitation's source addressSpecification in ([RFC2461], section 6.2) is not the unspecified address. (Routerused. Router Advertisements sent on ISATAP interfaces MAY include information delegated via DHCPv6 [RFC3633]). RoutersRouter Advertisements sent on ISATAP interfaces MUST NOT sendinclude a prefix optionsoption containing a preferred lifetime greater than the valid lifetime. 9.2.2 Host Specification The Host Specification in ([RFC2461], section 6.3) is used. ISATAP interfaces add the following specifications: 220.127.116.11 Host Variables To the list of host variables ([RFC2461], section 6.3.2), ISATAP interfaces add: PrlRefreshInterval Time in seconds between successive refreshments of the PRL after initialization. It SHOULD be no less than 3600 seconds.The designated value of all 1's (0xffffffff) represents infinity. Default: 3600 seconds MinRouterSolicitInterval Minimum time in seconds between successive solicitations of the same advertising ISATAP interface. The designated value of all 1's (0xffffffff) represents infinity. Default: 900 seconds18.104.22.168 Potential Router List Initialization ISATAP nodes provision an ISATAP interface's PRL with IPv4 addresses discovered via manual configuration,a DNS fully-qualified domain name (FQDN) [STD0013],[STD13], manual configuration, a DHCPv4 option, a DHCPv4 vendor-specific option, or an unspecified alternate method. FQDNs are established via manual configuration or an unspecified alternate method. FQDNs are resolved into IPv4 addresses through lookup in a static host file,querying the DNS service, querying a site-specific name service, static host file lookup, or an unspecified alternate method. When the node provisions an ISATAP interface's PRL with IPv4 addresses, it sets a timer for the interface (e.g., PrlRefreshIntervalTimer) to PrlRefreshInterval seconds. The node re- initializes the PRL as specified above when PrlRefreshIntervalTimer expires, or when an asynchronous re-initialization event occurs. When the node re-initializes the PRL, it resets PrlRefreshIntervalTimer to PrlRefreshInterval seconds. 22.214.171.124 Processing Received Router Advertisements TheTo the list of checks for validating Router Advertisement messages ([RFC2461], section 6.1.1), ISATAP daemon processesinterfaces add: - IP Source Address is an ISATAP link-local address that embeds V4ADDR(i) for some PRL(i). Valid Router Advertisements (RAs)received on an ISATAP interface are processed exactly as specified in ([RFC2461], section 6.3.4). The DHCPv6 specification [RFC3315] is the stateful mechanism associated with the M and O bits. When the ISATAP daemon receives a6.3.4) except that, for unicast Router Advertisement withAdvertisements that include an MTU option from a router atoption, the far end of a tunnel, it recordsMTU value does not alter the ISATAP interface LinkMTU. Instead, the advertisedMTU value,value is recorded, e.g., in the node'sIPv6 routingforwarding table. If the MTU valueIPv6 destination address is less than the MTUone of the tunnel interface,node's own unicast addresses, the MTU value is recorded insuch a waythat the node will performupper layer fragmentation (i.e., above the IPv4 link layer)[RFC3542] will be used to reduce the size of the IPv4encapsulated packets it sendssent via the router. The recorded value is aged as for IPv6 path MTU information [RFC1981]. For Router Advertisement messages that include prefix options, Route information options [DEFLT] and/or non-zero values in the Router Lifetime, the ISATAP daemon resets TIMER(i) to schedule the next solicitation event (see: section 126.96.36.199). Let "MIN_LIFETIME" be the minimum value in the Router Lifetime or the lifetime(s) encoded in options included in the RA message. Then, TIMER(i) is reset as follows: TIMER(i) = MAX((0.5 * MIN_LIFETIME), MinRouterSolicitInterval)188.8.131.52 Sending Router Solicitations To the list of events after which RSsRouter Solicitation messages may be sent ([RFC2461], section 6.3.2),6.3.7), ISATAP interfaces add: - TIMER(i) for some PRL(i) expires. Since unsolicited Router Solicitations MAYAdvertisements may be sentincomplete (and, since multicast unsolicited Router Advertisements may not arrive) ISATAP nodes schedule periodic events to solicit Router Advertisements from certain PRL(i)'s. When this periodic solicitation is used, after sending the initial solicitation and receiving a valid Router Advertisement message from PRL(i) with a non-zero Router Lifetime the node sets TIMER(i) to schedule the first periodic event. The TIMER(i) value SHOULD be set such that the next periodic event will trigger a solicited Router Advertisement message before the expiration of remaining lifetimes stored for this PRL(i), including the Router Lifetime, Valid Lifetimes received in Prefix Information Options, and Route Lifetimes received in Route Information Options [DEFLT]. The TIMER(i) value MUST be set to no less than MinRouterSolicitInterval seconds, where MinRouterSolicitInterval is configurable for the node with a conservative default value. When TIMER(i) expires, the node sends Router Solicitation messages as specified in ([RFC2461], section 6.3.7) except that the messages use an ISATAP link-local address that embeds V4ADDR(i) for some PRL(i)as the IPv6 destination address (i.e., instead of the All-Routers multicast address.address). If remaining lifetimes for this PRL(i) have not yet expired and the PRL(i) is still in use, TIMER(i) is reset as described above. 9.3 Address Resolution and Neighbor Unreachability Detection 9.3.1 Address Resolution The specification in ([RFC2461], section 7.2) is used. ISATAP addresses for which the neighbor/router'sneighbor's link-layer address cannot otherwise be determined (e.g., from a neighbor cache entry) are resolved to link-layer addresses by a static computation, i.e., the last four octets are treated as an IPv4 address. Hosts SHOULD perform an initial reachability confirmation by sending Neighbor Solicitation message(s) and receiving a Neighbor Advertisement message (NS messages are sent to the target's unicast address).message. Routers MAY perform this initial reachability confirmation, but this might not scale in all environments. All nodes MUST send solicited Neighbor Advertisements on ISATAP interfaces ([RFC2461], section 7.2.4).9.3.2 Neighbor Unreachability Detection Hosts SHOULD perform Neighbor Unreachability Detection ([RFC2461], section 7.3). Routers MAY perform neighbor unreachability detection, but this might not scale in all environments. 10. Other Requirements for Control Plane Signaling 10.1 Domain Name System (DNS) The specifications in ([MECH], section 2.2) are used. AdditionalSecurity considerations Security considerations are found in [DNSOPV6]. 10.2 Linklocal Multicast Name Resolution (LLMNR) ISATAP nodes SHOULD implement Link Local Multicast Name Resolution [LLMNR], since they will commonly be deployedin environments (e.g., home networks, ad-hoc networks, etc.) with no DNS service. 10.3 Node Information Queriesthe normative references apply. Also: - ISATAP nodes MAY implement Node Information Queries as specified in [NIQUERY], since they may help the querier discover some subset ofobserve the responder's addresses. 11. Security considerations Thesecurity considerations outlined in the normative references apply; also:[SENDPS]; use of (e.g., [RFC2402][RFC2406], etc.) is not always feasible. - site border routers SHOULD install a black holereject route for the IPv6 prefix FC00::/7 to insure that packets with local IPv6 destination addresses will not be forwarded outside of the site via a default route. - administrators MUST ensure that lists of IPv4 addresses representing the advertising ISATAP interfaces of PRL members are well maintained. 12.11. IANA Considerations The IANA is instructed to specify the format for Modified EUI-64 address construction ([ADDR], Appendix A) in the IANA Ethernet Address Block. The text in Appendix DC of this document is offered as an example specification. The current version of the IANA registry for Ether Types can be accessed atat: http://www.iana.org/assignments/ethernet-numbers. The IANA is instructed to assign the new ICMPv6 code field types found in Appendix ED of this document for the ICMPv6 Destination Unreachable message. The policy for assigning new ICMPv6 code field types is First Come First Served, as defined in [RFC2434].[BCP26]. The current version of the IANA registry for ICMPv6 type numbers can be accessed atat: http://www.iana.org/assignments/icmpv6-parameters. 13.12. IAB Considerations [RFC3424] ("IAB Considerations for UNilateral Self-Address Fixing (UNSAF) Across Network Address Translation") section 4 requires that any proposal supporting NAT traversal must explicitly address the following considerations: 13.112.1 Problem Definition The specific problem being solved is enabling IPv6 connectivity for ISATAP nodes that are unable to communicate via ip-protocol-41 or native IPv6. 13.212.2 Exit Strategy ISATAP nodes use UDP/IPv4 encapsulation for NAT traversal as a last resort. As soon as native IPv6 or ip-protocol-41 support becomes available, ISATAP nodes will naturally cease using UDP/IPv4 encapsulation. 13.312.3 Brittleness UDP/IPv4 encapsulation with ISATAP introduces brittleness into the system in several ways: the discovery process assumes a certain classification of devices based on their treatment of UDP; the mappings need to be continuously refreshed, and addressing structure may cause some hosts located beyond a common NAT to be unreachable from each other. ISATAP assumes a certain classification of devices based on their treatment of UDP. There could be devices that would not fit into one of these molds, and hence would be improperly classified by ISATAP. The bindings allocated from the NAT need to be continuously refreshed. Since the timeouts for these bindings is very implementation specific, the refresh interval cannot easily be determined. When the binding is not being actively used to receive traffic, but to wait for an incoming message, the binding refresh will needlessly consume network bandwidth. 13.412.4 Requirements for a Long Term Solution The devices that implement the IPv4 NAT service should in the future also become IPv6 routers. 14.13. Acknowledgments The ideas in this document are not original, and the authors acknowledge the original architects. Portions of this work were sponsored through SRI International internal projects and government contracts. Government sponsors include Monica Farah-Stapleton and Russell Langan (U.S. Army CECOM ASEO), and Dr. Allen Moshfegh (U.S. Office of Naval Research). SRI International sponsors include Dr. Mike Frankel, J. Peter Marcotullio, Lou Rodriguez, and Dr. Ambatipudi Sastry. The following are acknowledged for providing peer review input: Jim Bound, Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader, Ole Troan, Vlad Yasevich. The following are acknowledged for their significant contributions: Alain Durand, Hannu Flinck, Jason Goldschmidt, Nathan Lutchansky, Karen Nielsen, Mohan Parthasarathy, Chirayu Patel, Art Shelest, Pekka Savola, Margaret Wasserman, Brian Zill. The authors acknowledge the work of Quang Nguyen on "Virtual Ethernet" 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. IAB considerations are the same as for Teredo. The diagram in section 4 was inspired by a similar diagram in RFC 3371. The following individuals are acknowledged for their helpful insights on path MTU discovery: Jari Arkko, Iljitsch van Beijnum, Jim Bound, Ralph Droms, Alain Durand, Jun-ichiro itojun Hagino, Brian Haberman, Bob Hinden, Christian Huitema, Kevin Lahey, Hakgoo Lee, Matt Mathis, Jeff Mogul, Erik Nordmark, Soohong Daniel Park, Chirayu Patel, Michael Richardson, Pekka Savola, Hesham Soliman, Mark Smith, Dave Thaler, Michael Welzl, Lixia Zhang and the members of the Nokia NRC/ COM Mountain View team. "...and I'm one step ahead of the shoe shine, Two steps away from the county line, Just trying to keep my customers satisfied, Satisfi-i-ied!" - Paul Simon, 1969 Appendix A. Major Changes Major changes from earlier versions to version 17: - changed first words in title from "Intra-site" to "Internet/site" to more accurately represent the functionality. -new section on configuration/management. - new appendices on tunnel driver API;IPv6 minimum MTU; IANA considerations. - expanded section on MTU and fragmentation. - expanded sections on encapsulation/decapsulation. - specified relation to IPv6 Node Requirements. - introduced distinction between control; user planes. - specified multicast mappings. - revised neighbor discovery, address autoconfiguration, IANA considerations and security considerations sections. Appendix B. Example ISATAP Driver API An ISATAP driver API should include primitives for sending and receiving control plane messages as well as primitives for tunnel configuration/management such as the following non-normative examples: B.1 ISATAP_SEND, ISATAP_RECEIVE Primitives Description: Sends/Receives control plane messages via the ISATAP driver (e.g., via a routing socket, etc.) B.2 ISATAP_CREATE Primitive Description: Creates a new tunnel interface and an associated IP interface by creating a row in tunnelIfConfigTable. Also optionally configures read-write objects for the tunnel interface and adds locators to the receive address table via RcvTableAdd(locator, tunnel_interface). Required parameter: - tunnelIfEncapsMethod. Optional parameters: - attributes for configuring read-write objects. - list of locators to associate with tunnel interface. Returns: - ifIndex for the new tunnel interface, or a failure code. B.3 ISATAP_DELETE Primitive Description: Deletes an existing tunnel interface by deleting the corresponding row in tunnelIfConfigTable. Also frees its locators via RcvTableDel(NULL, tunnel_interface). Required parameter: - ifIndex. Returns: - success or a failure code. B.4 ISATAP_CONFIG Primitive Description: Configures attributes for an existing tunnel interface. Also adds new locators via RcvTableAdd(locator, tunnel_interface) and deletes old locators via RcvTableDel(locator, tunnel_interface). Required parameter: - ifIndex. Optional parameters: - read-write objects for the tunnel interface. - list of locators to associate with tunnel interface. - list of locators to delete from association. Returns: - success or a failure code. B.5 ISATAP_BIND Primitive Description: Binds (or, creates then binds) a configured tunnel interface to an ISATAP interface. The configured tunnel interface inherits the ISATAP interface's locator set and the ISATAP interface uses the encapsulation parameters associated with the bound configured tunnel interface. Required parameter: - ifIndex for the ISATAP interface. - ifIndex for the configured tunnel interface, or NULL. Conditional parameter: - if ifIndex for the configured tunnel is NULL, tunnelIfEncapsMethod. Optional parameters: - attributes for configuring read-write objects for the configured tunnel interface. Returns: - ifIndex for the configured tunnel, or a failure code. B.6 ISATAP_GET Primitive Description: Copies configuration attributes from system table entries associated with the specified tunnel interface into a calling process' buffer. Required parameter: - ifIndexto IPv6 Node Requirements. - address of a buffer in calling process's memory.introduced distinction between control; forwarding planes. - number of bytes available in the user's buffer. Returns:specified multicast mappings. - Number of bytes written into the calling process' buffer, or a failure code.revised neighbor discovery, address autoconfiguration, IANA considerations and security considerations sections. Appendix C.B. The IPv6 minimum MTU The 1280 byte IPv6 minimum MTU was proposed by Steve Deering and agreed through working group consensus in November 1997 discussions on the IPv6 mailing list. The size was chosen to allow extra room for link layer encapsulations without exceeding the Ethernet MTU of 1500 bytes, i.e., the practical physical cell size of the Internet. The 1280 byte MTU also provides a fixed upper bound for the size of IPv6 packets/fragments with a maximum store-and-forward delay budget of ~1 second assuming worst-case link speeds of ~10Kbps [BCP0048],[BCP48], thus providing a convenient value for use in reassembly buffer timer settings. Finally, the 1280 byte MTU allows transport connections (e.g., TCP) to configure a large-enough maximum segment size for improved performance even if the IPv4 interface that will send the tunneled packets uses a smaller MTU. Appendix D.C. Modified EUI-64 Addresses in the IANA Ethernet Address Block Modified EUI-64 addresses ([ADDR], Appendix A) in the IANA Ethernet Address Block are formed as the concatenation of the 24-bit IANA OUI (00-00-5E) with a 40-bit extension identifier. They have the following appearance in memory (bits transmitted right-to-left within octets, octets transmitted left-to-right): 0 23 63 | OUI | extension identifier | 000000ug00000000 01011110xxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx When the first two octets of the extension identifier encode the hexadecimal value 0xFFFE, the remainder of the extension identifier encodes a 24-bit vendor-supplied id as follows: 0 23 39 63 | OUI | 0xFFFE | vendor-supplied id | 000000ug00000000 0101111011111111 11111110xxxxxxxx xxxxxxxxxxxxxxxx When the first octet of the extension identifier encodes the hexadecimal value 0xFE, the remainder of the extension identifier encodes a 32-bit IPv4 address, as specified in ([ISATAP], section 6.1) andaddress as follows: 0 23 31 63 | OUI | 0xFE | IPv4 address | 000000ug00000000 0101111011111110 xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx Modified EUI-64 format interface identifiers are formed by inverting the "u" bit, i.e., the "u" bit is set to one (1) to indicate universal scope and it is set to zero (0) to indicate local scope ([ADDR], section 2.5.1). Appendix E.D. Proposed ICMPv6 Code Field Types Three new ICMPv6 Code Field Type definitions are proposed for the ICMPv6 Destination Unreachable message. The first proposes a new definition for a currently-unassigned code type (2) in the ICMPv6 Type Numbers registry; the others propose new definitions for code types (5) and (6). The code type field definition proposals appear below: Type Name Reference ---- ------------------------- --------- 1 Destination Unreachable [RFC2463] Code 2 - beyond the scope of source address 5 - source address failed ingress policy 6 - reject route to destination Normative References [STD0003][BCP14] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [BCP26] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [STD3] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, October 1989. [STD0005][STD5] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981. [STD0006][STD6] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August 1980. [RFC1981] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery for IP version 6", RFC 1981, August 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC2461] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [RFC2463] Conta, A., and S. Deering, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 2463, December 1998. [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 Domains without Explicit Tunnels", RFC 2529, March 1999. [RFC3424] Daigle, L. and IAB, "IAB Considerations for UNilateral Self- Address Fixing (UNSAF) Across Network Address Translation", RFC 3424, November 2002. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. Stevens, "Basic Socket Interface Extensions for IPv6", RFC 3493, February 2003. [RFC3542] Stevens, W., Thomas, M., Nordmark, E. and T. Jinmei, "Advanced Sockets Application Program Interface (API) for IPv6", RFC 3542, May 2003. [RFC3582] Abley, J., Black, B. and V. Gill, "Goals for IPv6 Site- Multihoming Architectures", RFC 3582, August 2003. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003. [ADDR] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", draft-ietf-ipv6-addr-arch-v4 (workdraft-ietf-ipv6-addr-arch-v4, Work in progress),Progress, October 2003. [AUTH] Reynolds, J. and R. Braden, "Instructions to Request for Comments (RFC) Authors", draft-rfc-editor-rfc2223bis (work in progress), August 2003.[DEFLT] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", draft-ietf-ipv6-router-selection (workdraft-ietf-ipv6-router-selection, Work in progress),Progress, December 2003. [ISATAP] Templin, F., Gleeson, T., Talwar, M. and D. Thaler, "Internet/Site Automatic Tunnel Addressing Protocol", draft-ietf- ngtrans-isatap (work in progress), February 2004. [LLMNR] Esibov, L., Aboba, B. and D. Thaler, "Linklocal Multicast Name Resolution", draft-ietf-dnsext-mdns (work in progress), January 2004.[MECH] Gilligan, R. and E. Nordmark, "Basic Transition Mechanisms for IPv6 Hosts and Routers", draft-ietf-v6ops-mech-v2 (workdraft-ietf-v6ops-mech-v2, Work in progress),Progress, February 2003. [NODEREQ] Loughney, J., "IPv6 Node Requirements", draft-ietf-ipv6-node- requirements (workrequirements, Work in progress),Progress, October 2003. [UNIQUE] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", draft-ietf-ipv6-unique-local-addr (workdraft-ietf-ipv6-unique-local-addr, Work in progress),Progress, January 2004. Informative References [BCP0048][BCP48] Dawkins, S., Montenegro, G., Kojo, M. and V. Magret, "End- to-end"End-to- end Performance Implications of Slow Links", BCP 48, RFC 3150, July 2001. [STD0013][STD13] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC2402] Kent, S. and R. Atkinson, "IP Authentication Header", RFC 2402, November 1998. [RFC2406] Kent, S. and R. Atkinson, "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998. [RFC2491] Armitage, G., Schulter, P., Jork, M. and G. Harter, "IPv6 over Non-Broadcast Multiple Access (NBMA) networks", RFC 2491, January 1999. [RFC2492] Armitage, G., Schulter, P. and M. Jork, "IPv6 over ATM Networks", RFC 2492, January 1999. [RFC2710] Deering, S., Fenner, W. and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999.[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [ANYCAST] Hagino, J. and K. Ettikan, "An Analysis of IPv6 Anycast", draft-ietf-ipngwg-ipv6-anycast-analysis (workdraft-ietf-ipngwg-ipv6-anycast-analysis, Work in progress),Progress, June 2003. [DNSOPV6] Durand, A., Ihren, J., and Savola P., "Operational Considerations and Issues with IPv6 DNS", draft-ietf-dnsop-ipv6-dns- issues, work-in-progress, January 2004.[FLOW] Rajahalme, J., Conta, A., Carpenter, B. and S. Deering, "IPv6 Flow Label Specification", draft-ietf-ipv6-flow-label (workdraft-ietf-ipv6-flow-label, Work in progress),Progress, December 2003. [FRAG] Mogul, J. and C. Kent, "Fragmentation Considered Harmful", In Proc. SIGCOMM '87 Workshop on Frontiers in Computer Communications Technology. August, 1987. [FTMIB] Haberman, B. and M. Wasserman, "IP Forwarding Table MIB", draft-ietf-ipv6-rfc2096-update (workdraft-ietf-ipv6-rfc2096-update, Work in progress),Progress, August 2003. [IPMIB] Routhier, S., "Management Information Base for the Internet Protocol (IP)", draft-ietf-ipv6-rfc2011-update (workdraft-ietf-ipv6-rfc2011-update, Work in progress),Progress, September 2003. [NIQUERY] Crawford, M., "IPv6 Node Information Queries", draft-ietf- ipngwg-icmp-name-lookups (work in progress), June 2003.[SEND] Arkko, J., Kempf, J., Sommerfield, B., Zill, B. and P. Nikander, "Secure Neighbor Discovery (SEND)", draft-ietf-send-ndopt (workdraft-ietf-send-ndopt, Work in progress),Progress, October 2003. [TCPMIB] Raghunarayan, R., "Management Information Base for the Transmission Control Protocol (TCP)", draft-ietf-ipv6-rfc2012-update (work[SENDPS] Nikander, P., Kempf, J. and E. Nordmark, "IPv6 Neighbor Discovery Trust Models and Threats", draft-ietf-send-psreq, Work in progress), NovemberProgress, October 2003. [TUNMIB] Thaler, D., "IP Tunnel MIB", draft-ietf-ipv6-inet-tunnel-mib (workdraft-ietf-ipv6-inet-tunnel-mib, Work in progress),Progress, January 2004. [UDPMIB] Raghunarayan, R., "Management Information Base for the Transmission Control Protocol (TCP)", draft-ietf-ipv6-rfc2012-update (work in progress), November 2003.Authors' Addresses Fred L. Templin Nokia 313 Fairchild Drive Mountain View, CA 94110 US Phone: +1 650 625 2331 EMail: firstname.lastname@example.org Tim Gleeson Cisco Systems K.K. Shinjuku Mitsu Building 2-1-1 Nishishinjuku, Shinjuku-ku Tokyo 163-0409 Japan EMail: email@example.com Mohit Talwar Microsoft Corporation One Microsoft Way Redmond, WA 98052-6399 US Phone: +1 425 705 3131 EMail: firstname.lastname@example.org Dave Thaler Microsoft Corporation One Microsoft Way Redmond, WA 98052-6399 US Phone: +1 425 703 8835 EMail: email@example.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. 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