< draft-thubert-v6ops-yada-yatt-02.txt   draft-thubert-v6ops-yada-yatt-03.txt >
v6ops P. Thubert, Ed. v6ops P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 1122, 4291 (if approved) 5 April 2022 Updates: 1122, 4291 (if approved) 7 April 2022
Intended status: Informational Intended status: Informational
Expires: 7 October 2022 Expires: 9 October 2022
Yet Another Double Address and Translation Technique Yet Another Double Address and Translation Technique
draft-thubert-v6ops-yada-yatt-02 draft-thubert-v6ops-yada-yatt-03
Abstract Abstract
This document provides a mechanism named YADA to extend the current This document provides a stepwise migration between IPv4 and IPv6
IPv4 Internet by interconnecting IPv4 realms via a common footprint with baby steps from an IPv4-only stack/gateway/ISP to an IPv6-only
called the shaft. YADA extends [INT-ARCHI] with the support of an version, that allows portions of the nodes and of the networks to
IP-in-IP format used to tunnel packets across the shaft. This remain IPv4, and reduces the need for dual stack and CG NATs between
document also provides a bump-in-the-stack method to enable YADA on a participating nodes. A first mechanism named YADA to augment the
legacy stack, e.g., to enable virtual machines without changing them. capacity of the current IPv4 Internet by interconnecting IPv4 realms
This document also provides a stateless address and IP header via a common footprint called the shaft. YADA extends RFC 1122 with
translation between YADA and IPv6 [IPv6] called YATT and extends the support of an IP-in-IP format used to forward the packet between
[IPv6-ADDRESSING] for the YATT format. YADA and YATT can take place parallel IPv4 realms. This document also provides a stateless
as a bump in the stack at either end, or within the network and address and IP header translation between YADA and IPv6 called YATT
enables an IPv6-only stack to dialog with an IPv4-only stack across a and extends RFC 4291 for the YATT format. The YADA and YATT formats
network that can be IPv6, IPv4, or mixed. YATT requires that the are interchangeable, and the stateless translation can take place as
IPv6 stack owns a prefix that derives from a YADA address and the a bump in the stack at either end, or within the network at any
IPv4 stack is capable of YADA, so it does not replace a generic 4 to router. This enables an IPv6-only stack to dialog with an IPv4-only
6 translation mechanism for any v6 to any v4. stack across a network that can be IPv6, IPv4, or mixed. YATT
requires that the IPv6 stack owns a prefix that derives from a YADA
address and that the IPv4 stack in a different realm is capable of
YADA, so it does not replace a generic 4 to 6 translation mechanism
for any v6 to any v4.
Status of This Memo Status of This Memo
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This Internet-Draft will expire on 7 October 2022. This Internet-Draft will expire on 9 October 2022.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction and Motivation . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Extending RFC 1122 . . . . . . . . . . . . . . . . . . . . . 6 3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Extending RFC 4291 . . . . . . . . . . . . . . . . . . . . . 6 4. Extending RFC 1122 . . . . . . . . . . . . . . . . . . . . . 8
5. YADA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Extending RFC 4291 . . . . . . . . . . . . . . . . . . . . . 8
6. YATT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. YADA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. The structure of the shaft . . . . . . . . . . . . . . . . . 11 7. YATT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 11 8. The structure of the shaft . . . . . . . . . . . . . . . . . 15
9. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 12 9. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 15
10. Security Considerations . . . . . . . . . . . . . . . . . . . 12 10. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 16
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 11. Security Considerations . . . . . . . . . . . . . . . . . . . 16
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
13.1. Normative References . . . . . . . . . . . . . . . . . . 13 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
13.2. Informative References . . . . . . . . . . . . . . . . . 13 14.1. Normative References . . . . . . . . . . . . . . . . . . 17
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13 14.2. Informative References . . . . . . . . . . . . . . . . . 17
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction and Motivation
This document defines baby steps from an IPv4-only stack/gateway/ISP At the time of this writing, the transition to IPv6 started 20 years
to an IPv6-only version. The goal is to end with dual stack and ago and large amounts of networks, hosts, and programs, are still
Carrier-Grade Network Address Translators (CG-NATs). The first step IPv4-only. The IPv4 and IPv6 camps are quite entrenched, and there's
called Yet Another Double Address (YADA) uses IPv4-only signaling. no indication that things will change any time soon.
The second step called Yet Another Translation Technique (YATT)
offers an IPv6-only signaling that is interchangeable with YADA, so During that endless transition, stacks must implements both protocols
any router or stack may turn one into the other, allowing the stack (aka dual stack) and a mechanism to use either based on the
or the link to be one version only. A YADA-enabled IPv4 stack can responsiveness (Happy Eyeballs). Service Providers must implement
thus talk to a YATT-enabled IPv6 stack with neither CG-NATs nor dual heavy weaponry called Carrier-Grade Network Address Translators (CG-
stack network in between, but a stack that is not aware of this NATs) to translate between protocols between legacy IPv4-only and
specification will still need a traditional NAT approach to IPv6-only stacks, and tunneling techniques such as DS-Lite and
communicate. 464XLAT to traverse portions of the network that support only one of
the IP versions. This means both CAPEX to install dual stack
infrastructures and NAT devices and OPEX to maintain them. The
current situation is often qualified as the worst of both worlds and
any indications is that it's here to stay, till each side suffered
enough and is ready for a compromise.
This document prepares for that time where the players will
effectively be ready for a compromise. An acceptable compromise must
provide both sides with way to remain as long as desired, while
eliminating the need for dual stack and CG-NATs between participating
nodes. Certainly, an effort must be asked on each side to reduce the
chasm, and that effort must come with enough benefits to effectively
encourage a majority of interested parties to make the step.
Yet Another Double Address (YADA) refers to effort that is asked from
the IPv4 side to support a new IP-in-IP model. YADA extends
[INT-ARCHI] with the support of an IP-in-IP format used to forward
the packet between parallel IPv4 realms. The proposed benefit is a
thousandfold increase of the IPv4-addressable domain by building
parallel realms each potentially the size of the current Internet.
Only the stacks that need to talk to a parallel realm need to evolve.
Routing and forwarding can remain IPv4-only with the same operations
as today, though new routers with YADA capabilities must be deployed
to route between realms.
Yet Another Translation Technique (YATT) refers to an effort to be
made by the IPv6 side to support a new IPv6 Prefix with special
properties, which impacts in particular source address selection
(SAS). YATT extends [IPv6-ADDRESSING] for the YATT format. The
proposed benefit is a prefix (say /32) per realm and a prefix (say
/64) per host in the realm. This address space may for instance
become handy for load balancing between physical servers / VMs / pods
that operate a service associated with the virtual server that owns
the host prefix.
The YADA and YATT formats are interchangeable, which means that the
translation is stateless and can take place as a bump in the stack at
either end or can be operated at line rate anywhere in the network by
an upgraded hardware. The routers that connect the shaft also
perform a stateless operation that can be achieved at line rate by
upgraded hardware. This is how the chasm between IPv4 and IPv6 can
be reduced, removing the need to deploy dual stack and CG-NATs
between participating nodes.
This document provides a stepwise migration between IPv4 and IPv6
with baby steps from an IPv4-only stack/gateway/ISP to YADA to YATT
to an IPv6-only version. The migration strategy allows portions of
the nodes and of the networks to remain IPv4. This enables an
IPv6-only stack to dialog with an IPv4-only stack across a network
that can be IPv6, IPv4, or mixed.
YATT requires that the IPv6 stack owns a prefix that derives from a
YADA address associated to a realm, even if there's absolutely no
IPv4 operation taking place in that realm. The resulting
connectivity without dual stack and CG-NAT is as follows:
* A legacy IPv4-only node can only talk within its realm. It can
talk to a IPv4 legacy node, and YADA IPv4-only node and a YATT
IPv6-only node, e.g., leveraging a bump-in-the-stack in the YATT
node if the network is IPv4-only.
* In addition, a YADA IPv4-only node can talk across realms to a
YADA IPv4-only node and to any YATT IPv6-only node.
* In addition, a YATT IPv6-only node can talk to all the IPv6
addressable space to any IPv6-only node.
Connectivity between an IPv4-only node and an IPv6-only node, or
between an IPv4-only node and a YADA node in different realm, still
requires a CG-NATs as of today, e.g., using the YATT format for the
IPv6 side in an unmodified CG-NAT.
2. Terminology
2.1. Glossary
This document often uses the following acronyms:
YADA: Yet Another Double Address
YATT: Yet Another Translation Technique
NAT: Network address Translation
IID: Interface ID
CG-NAT: Carrier Grade NAT
2.2. New Terms
This document often uses the following new terms:
IPv4 realm: A full IPv4 network like the current Internet. YADA
does not affect the traditional IPv4 operations within a realm.
The shaft: The shaft refers to a collection of IPv4 unicast and
multicast prefixes that are assigned to Inter-realm communications
and cannot be assigned to hosts or multicast groups within a
realm.
Realm address: An IPv4 address that derives from a shaft prefix.
Uni-realm address: A realm address that is unicast or anycast. A
realm may have more than one Uni-realm add ress.
Multi-realm address: A realm address that is multicast and denotes a
collection of realms.
YADA realm prefix: A prefix assigned to the shaft and from which
realm addresses can be derived.
YADA NAT prefix: A prefix assigned to the YADA bump-in-the-stack NAT
operation.
Double-A or YADA address: A YADA address is a tuple (realm address,
IPv4 address) where the IPv4 address is only significant within
the realm denoted by the realm address.
YATT Space: An IPv6 range that is assigned for YATT operation.
YATT prefix: An IPv6 prefix that is derived from a YADA address by
appending the YATT space prefix, the (truncated) realm address and
the IPv4 address.
YATT-IID: A 64-bit assigned constant that is used in YATT to
statelessly form an IPv6 address from a YATT prefix.
Multinternet: A collection of IPv4 realms interconnected using a
common shaft.
3. Operation
This document provides a stepwise migration between IPv4 and IPv6
with baby steps from an IPv4-only stack/gateway/ISP to an IPv6-only
version. The baby steps reduce the gap between the only versions and
teh associated need for dual stack and CG-NATs.
The first step called YADA uses IPv4-only signaling. The second step
called Yet Another Translation Technique (YATT) offers an IPv6-only
signaling that is interchangeable with YADA, so any router or stack
may turn one into the other, allowing the stack or the link to be one
version only. A YADA-enabled IPv4 stack can thus talk to a YATT-
enabled IPv6 stack with neither CG-NATs nor dual stack network in
between, but a stack that is not aware of this specification will
still need a traditional NAT approach to communicate.
The effort in this specification is to provide enough value / The effort in this specification is to provide enough value /
incentive for an IPv4-only stack/gateway/ISP to make the step towards incentive for an IPv4-only stack/gateway/ISP to make the step towards
YADA, as a push towards IPv6, and for an IPv6-only stack to support YADA, as a push towards IPv6, and for an IPv6-only stack to support
YATT on top to pull IPv4 space in IPv6, with a low barrier for making YATT on top to pull IPv4 space in IPv6, with a low barrier for making
the baby step. For IPv4, going YADA expands the size/reach of the the baby step. For IPv4, going YADA expands the size/reach of the
Internet, and allows multiple parties to build their own IPv4 realm, Internet, and allows multiple parties to build their own IPv4 realm,
with control of interconnection with other realms. For an IPv6 node, with control of interconnection with other realms. For an IPv6 node,
supporting YATT provides connectivity to the YADA world, and supporting YATT provides connectivity to the YADA world, and
automatically assigns a prefix in the node. automatically assigns a prefix in the node.
skipping to change at page 5, line 6 skipping to change at page 8, line 6
multicast communications, and each realm needs at least one unicast multicast communications, and each realm needs at least one unicast
address in the shaft called its realm address. A YADA address is address in the shaft called its realm address. A YADA address is
formed by the tuple (realm address, IPv4 address) and is advertised formed by the tuple (realm address, IPv4 address) and is advertised
in DNS as a new double-A record. in DNS as a new double-A record.
YADA leverages IP-in-IP encapsulation to tunnel packets across the YADA leverages IP-in-IP encapsulation to tunnel packets across the
shaft while normal IPv4 operations happen within a realm. YADA shaft while normal IPv4 operations happen within a realm. YADA
requires a change in the stack in the YADA endpoints that communicate requires a change in the stack in the YADA endpoints that communicate
with other realms to support the IP-in-IP YADA encapsulation. YADA with other realms to support the IP-in-IP YADA encapsulation. YADA
also provides a bump in the stack method for legacy applications. also provides a bump in the stack method for legacy applications.
More in Section 5.
A second mechanism called Yet Another Translation Technique (YATT)
translates the YADA format into flat IPv6 [IPv6]. For unicast
addresses, YATT forms an IPv6 prefix by collating an well-known
assigned short prefix, the realm address (in the shaft), and the host
IPv4 address (locally significant within the realm). The resulting
IPv6 prefix is automatically owned by the host that owns the IPv4
address in the realm. YATT then forms an IPv6 address for that host
by collating a well-known Interface ID, so there's a one-to-one
relationship between the YADA and the IPv6 address derived from it.
More in Section 6. More in Section 6.
A second mechanism called YATT translates the YADA format into flat
IPv6 [IPv6]. While a YADA address pair can be seen as some foot
print in one level, the YATT prefix encompasses that same foot print
plus all the air above it. For unicast addresses, YATT forms an IPv6
prefix by collating an well-known assigned short prefix, the realm
address (in the shaft), and the host IPv4 address (locally
significant within the realm). The resulting IPv6 prefix is
automatically owned by the host that owns the IPv4 address in the
realm. YATT then forms an IPv6 address for that host by collating a
well-known Interface ID, so there's a one-to-one relationship between
the YADA and the IPv6 address derived from it. More in Section 7.
A key concept for this specification is that YADA (the IPv4 A key concept for this specification is that YADA (the IPv4
formulation) and YATT (the IPv6 formulation) represent the same formulation) and YATT (the IPv6 formulation) represent the same
thing. YADA uses IPv4 formats as plain IP-in-IP with no new thing. YADA uses IPv4 formats as plain IP-in-IP with no new
extension. YATT uses IPv6 format with the IPv4 addresses encoded on extension. YATT uses IPv6 format with the IPv4 addresses encoded on
the prefix. The formats are interchangeable, and a router can the prefix. The formats are interchangeable, and a router can
convert one to another as the packet flows over a next-hop link that convert one to another as the packet flows over a next-hop link that
can only carry the other address family. can only carry the other address family.
2. Terminology 4. Extending RFC 1122
2.1. Glossary
This document often uses the following acronyms:
YADA: Yet Another Double Address
YATT: Yet Another Translation Technique
NAT: Network address Translation
IID: Interface ID
CG-NAT: Carrier Grade NAT
2.2. New Terms
This document often uses the following new terms:
IPv4 realm: A full IPv4 network like the current Internet. YADA
does not affect the traditional IPv4 operations within a realm.
The shaft: The shaft refers to a collection of IPv4 unicast and
multicast prefixes that are assigned to Inter-realm communications
and cannot be assigned to hosts or multicast groups within a
realm.
Realm address: An IPv4 address that derives from a shaft prefix.
Uni-realm address: A realm address that is unicast or anycast. A
realm may have more than one Uni-realm add ress.
Multi-realm address: A realm address that is multicast and denotes a
collection of realms.
YADA realm prefix: A prefix assigned to the shaft and from which
realm addresses can be derived.
YADA NAT prefix: A prefix assigned to the YADA bump-in-the-stack NAT
operation.
Double-A or YADA address: A YADA address is a tuple (realm address,
IPv4 address) where the IPv4 address is only significant within
the realm denoted by the realm address.
YATT Space: An IPv6 range that is assigned for YATT operation.
YATT prefix: An IPv6 prefix that is derived from a YADA address by
appending the YATT space prefix, the (truncated) realm address and
the IPv4 address.
YATT-IID: A 64-bit assigned constant that is used in YATT to
statelessly form an IPv6 address from a YATT prefix.
Multinternet: A collection of IPv4 realms interconnected using a
common shaft.
3. Extending RFC 1122
YADA extends [INT-ARCHI] to add the capability for an IPv4 host to YADA extends [INT-ARCHI] to add the capability for an IPv4 host to
recognize an special IP-in-IP format as an inter-realm IPv4 packet recognize an special IP-in-IP format as an inter-realm IPv4 packet
and process it accordingly. It also adds a new DNS double-A record and process it accordingly. It also adds a new DNS double-A record
format that denotes a YADA address. format that denotes a YADA address.
4. Extending RFC 4291 5. Extending RFC 4291
YATT extends [IPv6-ADDRESSING] to add the capability for an IPv4 host YATT extends [IPv6-ADDRESSING] to add the capability for an IPv4 host
to recognize an special IPv6 format as an YATT address embedding a to recognize an special IPv6 format as an YATT address embedding a
YADA address and process it accordingly. It also automatically YADA address and process it accordingly. It also automatically
derives the ownership of the YATT prefix associated to a owned YADA derives the ownership of the YATT prefix associated to a owned YADA
address. address.
5. YADA 6. YADA
YADA assigns IPv4 prefixes to a multinternet shaft; those prefixes YADA assigns IPv4 prefixes to a multinternet shaft; those prefixes
must be the same across all the realms that are interconnected by the must be the same across all the realms that are interconnected by the
shaft. Multiple prefixes can be assigned to the shaft for unicast shaft. Multiple prefixes can be assigned to the shaft for unicast
and multicast communications, and each realm needs at least one and multicast communications, and each realm needs at least one
unicast address in the shaft called its realm address. A YADA unicast address in the shaft called its realm address. A YADA
address is formed by the tuple (realm address, IPv4 address) and is address is formed by the tuple (realm address, IPv4 address) and is
advertised in DNS as a new double-A record. Because the YADA advertised in DNS as a new double-A record. Because the YADA
prefixes are assigned for YADA, a packet that has either source or prefixes are assigned for YADA, a packet that has either source or
destination IPV4 address derived from a shaft prefix is a YADA destination IPV4 address derived from a shaft prefix is a YADA
packet. packet.
YADA leverages IP-in-IP encapsulation to tunnel packets across the YADA leverages IP-in-IP encapsulation to tunnel packets across the
shaft for inter-realm communications, while the IPv4 operations shaft for inter-realm communications, while the IPv4 operations
within a realm are unaffected. The YADA address is found by using within a realm are unaffected. The YADA address is found by using
both inner and outer header and combining that information. The pair both inner and outer header and combining that information. The pair
of IP headers is seen by a YADA stack as a single larger header of IP headers is seen by a YADA stack as a single larger header
though a non-YADA forwarder only needs the outer header and plain though a non-YADA forwarder only needs the outer header and plain
IPv4 operations to forward. IPv4 operations on the outer IPv4 header to forward.
YADA requires a change in the stack in the YADA endpoints that
communicate with other realms to support the YADA encapsulation.
YADA also provides a bump in the stack method for legacy
applications. A stack that resolve a DNS name with a double-A record
indicating a different realm generates an IP-in-IP packet to signal
both the source and destination realms and the source and destination
IPv4 addresses within the respective realms.
Inside the source realm, the outer IPv4 header indicates the node's
IPv4 address as source, to remain topologically correct, and the
local realm address as source in the inner header, as shown in
Figure 2
<----------------------------- 20 bytes ----------------------------> <----------------------------- 20 bytes ---------------------------->
+------------ ... ------------+-----------------+-------------------+ +------------ ... ------------+-----------------+-------------------+
| IPv4 header fields | Source realm | destination realm | | IPv4 header fields | Source node | destination realm |
| | IPv4 Address | IPv4 Address | | (outer) | IPv4 Address | IPv4 Address |
+------------ ... ------------+-----------------+-------------------+ +------------ ... ------------+-----------------+-------------------+
| IPv4 header fields | Source node | destination node | | IPv4 header fields | Source realm | destination node |
| | IPv4 Address | IPv4 Address | | (inner) | IPv4 Address | IPv4 Address |
+------------ ... ------------+-----------------+-------------------+ +------------ ... ------------+-----------------+-------------------+
. Options . . Options .
+------------ ... --------------------------------------------------+ +------------ ... --------------------------------------------------+
| | | |
. Data . . Data .
| | | |
+-------------------------------------------------------------------+ +-------------------------------------------------------------------+
Figure 2: YADA format in the source realm Figure 2: YADA format in the source realm
YADA requires a change in the stack in the YADA endpoints that YADA also requires a change for the routers that serve the shaft.
communicate with other realms to support the YADA encapsulation. Those routers play a special role for packets that are delivered from
YADA also provides a bump in the stack method for legacy the shaft to the destination realm, and for ICMP errors across
applications. YADA also requires a change for the routers that serve realms. All other IPv4 nodes in the realm continue to operate
the shaft. Those routers play a special role for packets that are routing and forwarding as before.
delivered from the shaft to the destination realm, and for ICMP
errors across realms. All other IPv4 nodes in the realm continue to
operate as before.
Routers serving the shaft advertise the shaft prefix(es) in their Routers serving the shaft advertise the shaft prefix(es) in their
respective realms, and their realm addresses within the shaft, as respective realms, and their realm addresses within the shaft, as
host routes for unicast and anycast addresses. A stack that resolve host routes for unicast and anycast addresses.
a DNS name with a double-A record indicating a different realm
generates an IP-in-IP packet, with the outer header indicating the Inside the source realm, the IPv4 destination in the outer header is
source and destination realms, and the inner header indicating the an address is the shaft and it is attracted by a router that serves
source and destination IPv4 addresses within the respective realms, the shaft in the source realm. The packet source in the outer header
as shown in Figure 3. The packet is forwarded down the shaft as is, is the address of the source node in the local realm, so the packet
using the normal longest match or multicast operation. does not defeat BCP 38 rules in the ISP network, as shown in
Figure 3.
| | | |
/------|------------|--------------------------------- /------|------------|---------------------------------
/ | | / / | | /
/ | | | | / / | | | | /
/ | |--------|---| Source Node / / | |--------|---| Source Node /
/ | / | / / / | / | / /
/ | /. +---|---- outer(src=src-realm / / | /. <--|---- outer(src=src-addr /
/ |/ . |/ . dst=dst-realm) /
/ |------------| . inner(src=src-realm /
/ . . . . dst=dst-addr) /
/ . . . . /
/ . . . . /
-----------------------------------------------------/
| | |
| |
| |
Figure 3: Packets Entering the shaft
When the packet reaches the shaft, the router that serves the shaft
swaps the inner and outer source IPv4 address, so the packet remains
topologically correct inside the shaft, as shown in Figure 4.
<----------------------------- 20 bytes ---------------------------->
+------------ ... ------------+-----------------+-------------------+
| IPv4 header fields | Source realm | destination realm |
| (outer) | IPv4 Address | IPv4 Address |
+------------ ... ------------+-----------------+-------------------+
| IPv4 header fields | Source node | destination node |
| (inner) | IPv4 Address | IPv4 Address |
+------------ ... ------------+-----------------+-------------------+
. Options .
+------------ ... --------------------------------------------------+
| |
. Data .
| |
+-------------------------------------------------------------------+
Figure 4: YADA format inside the shaft
Based on longest match, the router forwards the packet inside the
shaft following the host route to a router that serves the
destination realm, as shown in Figure 5.
| |
/------|------------|---------------------------------
/ | | /
/ | | | | /
/ | |--------|---| Source Node /
/ | / | / /
/ | /. + | / outer(src=src-realm /
/ |/ . | |/ . dst=dst-realm) / / |/ . | |/ . dst=dst-realm) /
/ |------------| . inner(src=src-addr / / |------------| . inner(src=src-addr /
/ . . | . . dst=dst-addr) / / . . | . . dst=dst-addr) /
/ . . | . . / / . . | . . /
/ . . | . . / / . . | . . /
-----------------------------------------------------/ -----------------------------------------------------/
| | | | | | | |
| | | forwarded unchanged | | | forwarded unchanged
| | | down the shaft | | | down the shaft
v v
Figure 3: Packets Entering the shaft Figure 5: Packets Entering the shaft
The packet destination is an address is the shaft and it is attracted That router swaps the destination address in the inner and outer
by a router that serves the shaft and advertises its prefixes in the headers and forwards within its realm to the final destination, as
source realm. Based on longest match, the router forwards the packet shown in Figure 6.
inside the shaft following the host route to a router that serves the
destination realm. That router swaps the destination address in the
inner and outer headers and forwards within its realm to the final
destination, as shown in Figure 4.
<----------------------------- 20 bytes ----------------------------> <----------------------------- 20 bytes ---------------------------->
+------------ ... ------------+-----------------+-------------------+ +------------ ... ------------+-----------------+-------------------+
| IPv4 header fields | Source realm | destination node | | IPv4 header fields | Source realm | destination node |
| | IPv4 Address | IPv4 Address | | (outer) | IPv4 Address | IPv4 Address |
+------------ ... ------------+-----------------+-------------------+ +------------ ... ------------+-----------------+-------------------+
| IPv4 header fields | Source node | destination realm | | IPv4 header fields | Source node | destination realm |
| | IPv4 Address | IPv4 Address | | (inner) | IPv4 Address | IPv4 Address |
+------------ ... ------------+-----------------+-------------------+ +------------ ... ------------+-----------------+-------------------+
. Options . . Options .
+------------ ... --------------------------------------------------+ +------------ ... --------------------------------------------------+
| | | |
. Data . . Data .
| | | |
+-------------------------------------------------------------------+ +-------------------------------------------------------------------+
Figure 4: YADA format in the destination realm Figure 6: YADA format in the destination realm
In normal conditions, the stack of the destination node recognizes In normal conditions, the stack of the destination node recognizes
the YADA format and replies accordingly. the YADA format and replies accordingly.
| |
| | | | | |
| | | | | |
/------|----|-------|--------------------------------- /------|----|-------|---------------------------------
/ | | | | | / / | | | | | /
/ | | | | | / / | | | | | /
skipping to change at page 9, line 23 skipping to change at page 12, line 43
/ | /. +---|----> outer(src=src-realm / / | /. +---|----> outer(src=src-realm /
/ |/ . |/ . dst=dst-addr) / / |/ . |/ . dst=dst-addr) /
/ |------------| . inner(src=src-addr / / |------------| . inner(src=src-addr /
/ . . . . dst=realm-addr) / / . . . . dst=realm-addr) /
/ . . . . / / . . . . /
/ . . . . / / . . . . /
-----------------------------------------------------/ -----------------------------------------------------/
destinations swapped at shaft egress destinations swapped at shaft egress
Figure 5: Packets Outgoing the shaft Figure 7: Packets Outgoing the shaft
In case of an error down the path or at the destination, if an ICMP In case of an error down the shaft or in the destination realm, if an
message is generated by a node that is not YADA-aware, the message ICMP message is generated by a node that is not YADA-aware, the
reaches the router that serves the shaft in the source realm. If the message reaches the router that serves the shaft in the source realm.
inner header is present in the ICMP payload, then the Router extracts If the inner header is present in the ICMP payload, then the Router
it and forwards to the packet source. If the destination stack does extracts it and forwards to the packet source. If the destination
not support YADA and decapsulates, the message reaches the router stack does not support YADA and decapsulates, the message reaches the
that serves the destination realm which logs and drops. based on the router that serves the destination realm which logs and drops. based
log, the node may be updated, or the DNS records may be fixed to on the log, the node may be updated, or the DNS records may be fixed
avoid pointing on a node that does not support YADA. to avoid pointing on a node that does not support YADA.
YADA requires the assignment of a second IPv4 prefix, this time for a YADA requires the assignment of a second IPv4 prefix, this time for a
internal NATing operation. A bump-in-the-stack intercepts the DNS internal NATing operation. A bump-in-the-stack intercepts the DNS
lookups, and when the response yields a double-A record with a lookups, and when the response yields a double-A record with a
foreign realm, the record is augmented with an IPv4 address taken foreign realm, the record is augmented with an IPv4 address taken
from a local NAT pool. When the stack sends a packet to that from a local NAT pool. When the stack sends a packet to that
particular address, the bump-in-the-stack translates to the YADA particular address, the bump-in-the-stack translates to the YADA
format, using the information in the double-A record for the format, using the information in the double-A record for the
destination, and the local realm as source realm. The other way destination, and the local realm as source realm. The other way
around, if a packet arrives with a YADA format but the stack does not around, if a packet arrives with a YADA format but the stack does not
support it, the bump-in-the-stack allocates an address from the pool, support it, the bump-in-the-stack allocates an address from the pool,
and NATs to IPv4 using that address as source. and NATs to IPv4 using that address as source.
YADA was initially published as USPTO 7,356,031, filed in February YADA was initially published as USPTO 7,356,031, filed in February
2002. 2002.
6. YATT 7. YATT
A second mechanism called YATT translates the YADA format into flat A second mechanism called YATT translates the YADA format into flat
IPv6. IPv6.
+-----+---------------+--------------+-----------------------------+ +-----+---------------+--------------+-----------------------------+
|YATT | Realm | IPv4 | Well-Known | |YATT | Realm | IPv4 | Well-Known |
|Space| Address | Address | IID | |Space| Address | Address | IID |
+-----+- -------------+--------------+-----------------------------+ +-----+- -------------+--------------+-----------------------------+
<- YADA <- YADA
prefix -> prefix ->
<-------- YATT prefix ----------> <-------- YATT prefix ---------->
Figure 6: YATT format Figure 8: YATT format
For unicast addresses, YATT forms an IPv6 prefix by collating an For unicast addresses, YATT forms an IPv6 prefix by collating an
well-known assigned short prefix called the YATT space, the realm well-known assigned short prefix called the YATT space, the realm
address, and the host IPv4 address (locally significant within the address, and the host IPv4 address (locally significant within the
realm). The resulting IPv6 prefix is automatically owned by the host realm). The resulting IPv6 prefix is automatically owned by the host
that owns the IPv4 address in the realm. that owns the IPv4 address in the realm.
Depending on assignment, the leftmost piece realm prefix may be Depending on assignment, the leftmost piece realm prefix may be
truncated if it is well-known, to allow the YATT space and the realm truncated if it is well-known, to allow the YATT space and the realm
address to fit in a 32-bit DWORD. This way, the YATT prefix can be a address to fit in a 32-bit DWORD. This way, the YATT prefix can be a
skipping to change at page 10, line 47 skipping to change at page 14, line 26
YADA prefix is 240.0.0.0/6. In that case the values perfectly YADA prefix is 240.0.0.0/6. In that case the values perfectly
overlap and the YATT format becomes as follows: overlap and the YATT format becomes as follows:
+-----+----------+----------------+---------------------------------+ +-----+----------+----------------+---------------------------------+
| Realm Address | IPv4 Host | Well-Known | | Realm Address | IPv4 Host | Well-Known |
| in 240.0.0.0/6 | Public Address | IID | | in 240.0.0.0/6 | Public Address | IID |
+-----+- --------+----+-----------+---------------------------------+ +-----+- --------+----+-----------+---------------------------------+
<--- 32 bits ---><--- 32 bits ---><------------ 64 bits ------------> <--- 32 bits ---><--- 32 bits ---><------------ 64 bits ------------>
<------ YATT IPv6 prefix -------> <------ YATT IPv6 prefix ------->
Figure 7: YATT format using 240.0.0.0/6 Figure 9: YATT format using 240.0.0.0/6
In that case, the NAT operation is a plain insertion. Depending on In that case, the NAT operation is a plain insertion. Depending on
the assignment, it might be that the Realm address must be placed in the assignment, it might be that the Realm address must be placed in
full after YATT space. In that case, the length of the YATT prefix full after YATT space. In that case, the length of the YATT prefix
will be more than 64 bits. will be more than 64 bits.
Also, since 240.0.0.0/6 is currently unassigned, using it for the Also, since 240.0.0.0/6 is currently unassigned, using it for the
shaft would allow literally to reuse every ASN and every IPv4 address shaft would allow literally to reuse every ASN and every IPv4 address
currently available in the Internet in each and every other realm and currently available in the Internet in each and every other realm and
reallocate them in any fashion desirable in that realm. reallocate them in any fashion desirable in that realm.
skipping to change at page 11, line 23 skipping to change at page 15, line 5
YADA realm prefix in both IPv4 and YATT forms. YADA realm prefix in both IPv4 and YATT forms.
If the network is IPv4 only, the packets are still generated using If the network is IPv4 only, the packets are still generated using
IP-in-IP, and the YATT NAT operation may happen at the router that IP-in-IP, and the YATT NAT operation may happen at the router that
delivers the packet in the destination realm, if it is v6-only, or in delivers the packet in the destination realm, if it is v6-only, or in
the destination host, if its stack is v6-only. the destination host, if its stack is v6-only.
YATT was initially published as USPTO 7,764,686, filed in December YATT was initially published as USPTO 7,764,686, filed in December
2002. 2002.
7. The structure of the shaft 8. The structure of the shaft
A 10 miles view of the shaft could be as follows: it is implemented A 10 miles view of the shaft could be as follows: it is implemented
in one IXP, spans all realms, and each realm has one address in the in one IXP, spans all realms, and each realm has one address in the
shaft, with one router serving that realm. The address of the realm shaft, with one router serving that realm. The address of the realm
is encoded in a loopback in the router, and advertised through an IGP is encoded in a loopback in the router, and advertised through an IGP
inside the shaft, while BGP is used inside the realms but not inside inside the shaft, while BGP is used inside the realms but not inside
the shaft. The shaft has a single large prefix that is advertised in the shaft. The shaft has a single large prefix that is advertised in
each realm by the router that serves the shaft, and that is each realm by the router that serves the shaft, and that is
disaggregated into host routes inside the shaft. disaggregated into host routes inside the shaft.
skipping to change at page 11, line 46 skipping to change at page 15, line 28
over the world. A realm may be multihomed to be reached from a over the world. A realm may be multihomed to be reached from a
different physical instance of the shaft, meaning that the shaft is different physical instance of the shaft, meaning that the shaft is
composed of either more prefixes or the shaft prefix is composed of either more prefixes or the shaft prefix is
disaggregated. Multiple routers will serve the same realm with high disaggregated. Multiple routers will serve the same realm with high
availability and load balancing taking place inside the shaft to availability and load balancing taking place inside the shaft to
maintain connectivity. Some shafts may be deployed to interconnect maintain connectivity. Some shafts may be deployed to interconnect
only a subset of the realms, in which case those shafts would share a only a subset of the realms, in which case those shafts would share a
specific prefix that would not be advertised outside the concerned specific prefix that would not be advertised outside the concerned
realms. realms.
8. Applicability 9. Applicability
YADA And YATT enable communication between YADA-enabled IPv4 nodes YADA And YATT enable communication between YADA-enabled IPv4 nodes
across realms, and with IPv6 nodes that own a YADA address from which across realms, and with IPv6 nodes that own a YADA address from which
a YATT address can be derived. Communication from a legacy IPv4 a YATT address can be derived. Communication from a legacy IPv4
application/stack that is not YADA-enabled, or to an IPv6 address application/stack that is not YADA-enabled, or to an IPv6 address
that is not a YATT address, is not provided. that is not a YATT address, is not provided.
Since the YATT translation is stateless, the header translation can Since the YATT translation is stateless, the header translation can
happen anywhere in the network, e.g., as a bump in the stack at happen anywhere in the network, e.g., as a bump in the stack at
either end, or within the network, e.g., at the routers that serve either end, or within the network, e.g., at the routers that serve
skipping to change at page 12, line 36 skipping to change at page 16, line 18
parallel realms and changing (only) the stack on the hosts that parallel realms and changing (only) the stack on the hosts that
require inter-realm communication and specific routers at the require inter-realm communication and specific routers at the
ingress of the realms ingress of the realms
* A YADA node can talk (using IPv4) to a YATT node (using IPv6) with * A YADA node can talk (using IPv4) to a YATT node (using IPv6) with
a stateless translation. The translation can happen anywhere in a stateless translation. The translation can happen anywhere in
the network or in the stack. the network or in the stack.
* a YATT node being an IPv6 can talk to any other IPv6 nodes. * a YATT node being an IPv6 can talk to any other IPv6 nodes.
9. Backwards Compatibility 10. Backwards Compatibility
YADA operation does not affect the intra-realm communication. The YADA operation does not affect the intra-realm communication. The
only affected stacks are the endpoints that communicate between only affected stacks are the endpoints that communicate between
realms leveraging YADA. realms leveraging YADA.
10. Security Considerations 11. Security Considerations
11. IANA Considerations YADA introduces an IP-in-IP format that might be used to obfuscate an
IP address impersonation performed in the inner header. A proper
implemetation of BCP 38 should thus include the capability to
recognize a YADA format and look in the source IP field that
expresses the source realm in the inner header.
Upgrading the rules in his Broadband Network Gateways (BNGs)
represents additional work for an ISP, which should be done before
the shaft addresses are routable within the ISP network, and whether
the ISP intends to provide improved NAT functions in the home
gateways and CPEs.
12. IANA Considerations
This document requires the creation of a registry for IPv4 YADA realm This document requires the creation of a registry for IPv4 YADA realm
prefixes, and the assignment of at least one YADA realm prefix. prefixes, and the assignment of at least one YADA realm prefix.
This document requires the creation of a registry for IPv4 YADA NAT This document requires the creation of a registry for IPv4 YADA NAT
prefixes, and the assignment of at least one YADA NAT prefix. prefixes, and the assignment of at least one YADA NAT prefix.
This document requires the creation of a new record in the Resource This document requires the creation of a new record in the Resource
Record (RR) TYPEs subregistry of the Domain Name System (DNS) Record (RR) TYPEs subregistry of the Domain Name System (DNS)
Parameters. The new record would be of type AA meaning a YADA Parameters. The new record would be of type AA meaning a YADA
address. address.
12. Acknowledgments 13. Acknowledgments
The author wishes to recognize the pioneer work done by Brian
carpenter in the space of IPv4 augmentation with
[I-D.carpenter-aeiou]
The author wishes to thank Greg Skinner as the first reviewer/ The author wishes to thank Greg Skinner as the first reviewer/
contributor to this work. contributor to this work. Also Dave Bell, to remind that even if
routing is not touched much inside an IPv4 realm vs. the current art,
there is still work for the ISP, e.g., update the BCP 38 rules in the
BNGs.
13. References 14. References
13.1. Normative References 14.1. Normative References
[IPv4] Postel, J., "Internet Protocol", STD 5, RFC 791, [IPv4] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981, DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>. <https://www.rfc-editor.org/info/rfc791>.
[INT-ARCHI] [INT-ARCHI]
Braden, R., Ed., "Requirements for Internet Hosts - Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989, DOI 10.17487/RFC1122, October 1989,
<https://www.rfc-editor.org/info/rfc1122>. <https://www.rfc-editor.org/info/rfc1122>.
skipping to change at page 13, line 39 skipping to change at page 17, line 41
[IPv6-ADDRESSING] [IPv6-ADDRESSING]
Hinden, R. and S. Deering, "IP Version 6 Addressing Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>. 2006, <https://www.rfc-editor.org/info/rfc4291>.
[IPv6] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [IPv6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
13.2. Informative References 14.2. Informative References
[NAT-DEPLOY] [NAT-DEPLOY]
Palet Martinez, J., "Additional Deployment Guidelines for Palet Martinez, J., "Additional Deployment Guidelines for
NAT64/464XLAT in Operator and Enterprise Networks", NAT64/464XLAT in Operator and Enterprise Networks",
RFC 8683, DOI 10.17487/RFC8683, November 2019, RFC 8683, DOI 10.17487/RFC8683, November 2019,
<https://www.rfc-editor.org/info/rfc8683>. <https://www.rfc-editor.org/info/rfc8683>.
[I-D.carpenter-aeiou]
Carpenter, B. E., "Address Extension by IP Option Usage
(AEIOU)", Work in Progress, Internet-Draft, draft-
carpenter-aeiou-00, 21 March 1994,
<https://datatracker.ietf.org/doc/html/draft-carpenter-
aeiou-00>.
Author's Address Author's Address
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems, Inc Cisco Systems, Inc
Building D Building D
45 Allee des Ormes - BP1200 45 Allee des Ormes - BP1200
06254 Mougins - Sophia Antipolis 06254 Mougins - Sophia Antipolis
France France
Phone: +33 497 23 26 34 Phone: +33 497 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
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