Internet DRAFT - draft-mishra-bess-ipv4-only-pe-design
draft-mishra-bess-ipv4-only-pe-design
BESS Working Group G. Mishra
Internet-Draft Verizon Inc.
Intended status: Standards Track J. Tantsura
Expires: 8 January 2023 Microsoft, Inc.
M. Mishra
Cisco Systems
S. Madhavi
Juniper Networks, Inc.
Q. Yang
Arista Networks
A. Simpson
Nokia
S. Chen
Huawei Technologies
7 July 2022
IPv4-Only PE Design for IPv6-NLRI with IPv4-NH
draft-mishra-bess-ipv4-only-pe-design-02
Abstract
As Enterprises and Service Providers try to decide whether or not to
upgrade their brown field or green field MPLS/SR core to an IPv6
transport, Multiprotocol BGP (MP-BGP)now plays an important role in
the transition of their Provider (P) core network as well as Provider
Edge (PE) Edge network from IPv4 to IPv6. Operators must be able to
continue to support IPv4 customers when both the Core and Edge
networks are IPv4-Only.
This document details an important External BGP (eBGP) PE-CE Edge
IPv4-Only peering design that leverages the MP-BGP capability
exchange by using IPv4 peering as pure transport, allowing both IPv4
Network Layer Reachability Information (NLRI) and IPv6 Network Layer
Reachability Information (NLRI)to be carried over the same (Border
Gateway Protocol) BGP TCP session. The design change provides the
same Dual Stacking functionality that exists today with separate IPv4
and IPv6 BGP sessions as we have today. With this design change from
a control plane perspective a single IPv4 is required for both IPv4
and IPv6 routing updates and from a data plane forwarindg perspective
an IPv4 address need only be configured on the PE and CE interface
for both IPv4 and IPv6 packet forwarding.
This document provides a IPv4-Only PE design solution for use cases
where operators are not yet ready to migrate to IPv6 or SRv6 core and
would like to stay on IPv4-Only Core short to long term and maybe
even indefinitely. With this design, operators can now remain with
an IPv4-Only Core and do not have to migrate to an IPv6-Only Core.
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From a technical standpoint the underlay can remain IPv4 and still
transport IPv6 NLRI to support IPv6 customers, and so does not need
to be migrated to IPv6-Only underlay. With this IPv4-Only PE Design
solution , IPv4 addressing only needs to be provisioned for the
IPv4-Only PE-CE eBGP Edge peering design, thereby eliminating IPv6
provisioning at the Edge. This core and edge IPv4-Only peering
design can apply to any eBGP peering, public internet or private,
which can be either Core networks, Data Center networks, Access
networks or can be any eBGP peering scenario. This document provides
vendor specific test cases for the IPv4-Only peering design as well
as test results for the five major vendors stakeholders in the
routing and switching indusrty, Cisco, Juniper, Arista, Nokia and
Huawei. With the test results provided for the IPv4-Only Edge
peering design, the goal is that all other vendors around the world
that have not been tested will begin to adopt and implement this new
Best Current Practice for eBGP IPv4-Only Edge peering.
This Best Current Practice IPv4-only eBGP peering design
specification will help in use cases where operators are not yet
ready to migrate to IPv6 or SRv6 core or for very lage operator core
with thousdands of nodes where it maybe impractical to change the
underlay infrastructure to IPv6, and can now keep the existing IPv4
data plane IP, MPLS or SR-MPLS underlay intact indefinitely.
This document also defines a new IPv4 next hop encoding for IPv6 NLRI
over IPv4 Next Hop to uses 4 byte IPv4 address for the next hop and
not a IPv4 mapped IPv6 address. This encoding has been adopted by
the industry but has not been standardized until now with this
document.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 8 January 2023.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 6
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6-Only Edge Peering Architecture . . . . . . . . . . . . . 7
4.1. Problem Statement . . . . . . . . . . . . . . . . . . . . 7
4.2. IPv4-Only PE-CE Design Solution . . . . . . . . . . . . . 8
4.3. IPv4-Only Edge Peering Design . . . . . . . . . . . . . . 9
4.3.1. IPv4-Only Edge Peering Packet Walk . . . . . . . . . 9
4.3.2. 6to4 Softwire IPv4-Only Core packet walk . . . . . . 9
4.3.3. 4to6 Softwire IPv6-Only Core packet walk . . . . . . 11
4.4. RFC5549 and RFC8950 Applicability to IPv4-Only PE
Design . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.4.1. IPv4-Only Edge Peering design next-hop encoding . . . 14
4.4.2. IPv4-Only PE Design Next Hop Encoding . . . . . . . . 14
5. IPv4-Only PE Design Edge E2E Test Cases . . . . . . . . . . . 16
5.1. Test-1 E2E IPv4-Only PE-CE, Global Table over IPv4-Only
Core(6PE), 6to4 softwire . . . . . . . . . . . . . . . . 17
5.2. Test-2 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core, 6to4
Softwire . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3. Test-3 E2E IPv4-Only PE-CE, Global Table over IPv6-Only
Core (4PE), 4to6 Softwire . . . . . . . . . . . . . . . 18
5.4. Test-4 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core, 4to6
Softwire . . . . . . . . . . . . . . . . . . . . . . . . 18
5.5. Test-5 E2E IPv4-Only PE-CE, Global Table over IPv4-Only
Core(6PE), 6to4 softwire -Inter-AS Option-B . . . . . . 19
5.6. Test-6 E2E IPv4-Only PE-CE, Global Table over IPv4-Only
Core(6PE), 6to4 softwire -Inter-AS Option-C . . . . . . 19
5.7. Test-7 E2E IPv4-Only PE-CE, VPN over IPv4-Only, 6to4
softwire -Inter-AS Option-B . . . . . . . . . . . . . . 20
5.8. Test-8 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core, 6to4
softwire -Inter-AS Option-C . . . . . . . . . . . . . . 20
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5.9. Test-9 E2E IPv4-Only PE-CE, Global Table over IPv6-Only
Core, 4to6 softwire -Inter-AS Option-B . . . . . . . . . 21
5.10. Test-10 E2E IPv4-Only PE-CE, Global Table over IPv6-Only
Core, 4to6 softwire -Inter-AS Option-C . . . . . . . . . 21
5.11. Test-11 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core, 4to6
softwire -Inter-AS Option-B . . . . . . . . . . . . . . 22
5.12. Test-12 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core, 4to6
softwire -Inter-AS Option-C . . . . . . . . . . . . . . 22
5.13. IPv4-Only PE-CE Operational Considerations Testing . . . 23
6. Operational Considerations . . . . . . . . . . . . . . . . . 23
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
8. Security Considerations . . . . . . . . . . . . . . . . . . . 25
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
11.1. Normative References . . . . . . . . . . . . . . . . . . 25
11.2. Informative References . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
As Enterprises and Service Providers upgrade their brown field or
green field MPLS/SR core to an IPv6 transport such as MPLS LDPv6, SR-
MPLSv6 or SRv6, Multiprotocol BGP (MP-BGP) now plays an important
role in the transition of the Provider (P) core networks and Provider
Edge (PE) edge networks from IPv4 to IPv6. Operators have a
requirement to support IPv6 customers and must be able to support
IPv6 address family and Sub-Address-Family Virtual Private Network
(VPN)-IPv6, and Multicast VPN IPv6 customers.
With this IPv4-only BGP peering design, only IPv4 is configured on
the PE-CE interface, the Provider Edge (PE) - Customer Edge (CE), the
IPv4 BGP peer is now used to carry IPv6 (Network Layer Reachability
Information) NLRI over an IPv4 next hop using 4 byte IPv4 next hop
encoding while continuing to forward both IPv4 and IPv6 packets. In
the framework of this design the PE is no longer Dual Stacked.
However in the case of the CE, PE-CE link CE side of the link is no
longer Dual Stacked, however all other internal links within the CE
domain may or maynot be Dual stacked.
MP-BGP specifies that the set of usable next-hop address families is
determined by the Address Family Identifier (AFI) and the Subsequent
Address Family Identifier (SAFI). Historically the AFI/SAFI
definitions for the IPv4 address family only have provisions for
advertising a Next Hop address that belongs to the IPv4 protocol when
advertising IPv4 or VPN-IPv4. [RFC8950] specifies the extensions
necessary to allow advertising IPv4 NLRI, Virtual Private Network
Unicast (VPN-IPv4) NLRI, Multicast Virtual Private Network (MVPN-
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IPv4) NLRI with a Next Hop address that belongs to the IPv6 protocol.
This comprises of an extended next hop encoding MP-REACH BGP
capability exchange to allow the address of the Next Hop for IPv4
NLRI, VPN-IPv4 NLRI and MVPN-IPv4 NLRI to also belong to the IPv6
Protocol. [RFC8950] defines the encoding of the Next Hop to
determine which of the protocols the address actually belongs to, and
a new BGP Capability allowing MP-BGP Peers to discover dynamically
whether they can exchange IPv4 NLRI and VPN-IPv4 NLRI with an IPv6
Next Hop.
With the IPv4-Only PE design, IPv6 NLRI will be carried over an IPv4
Next-hop. [RFC4798] and [RFC4659] specify how an IPv4 address can be
encoded inside the next-hop IPv6 address field when IPv6 NLRI needs
to be advertised with an IPv4 next hop. [RFC4798] defines how the
IPv4-mapped IPv6 address format specified in the IPv6 addressing
architecture [RFC4798] can be used for that purpose when the <AFI/
SAFI> is IPv6-Unicast <2/1>, Multicast <2/2>, and Labeled Unicast
<2/4>. [RFC4659] defines how the IPv4-mapped IPv6 address format as
well as a null Route Distinguisher as ::FFFF:192.168.1.1 (RD) can be
used for that purpose when the <AFI/SAFI> is VPN-IPv6 <2/128> MVPN-
IPv6 <2/129>. This IPv4-Only PE specification utilizes IPv6 NLRI
over IPv4 Next hop encoding adopted by the industy to not use IPv4
mapped IPv6 address defined above, and instead use 4 byte IPv4
address for the next hop which ultimately set the precedence for the
adoption of [RFC8950] for 4to6 Softwire IPv4 NLRI over IPv6 next-hop
using an IPv6 address for the next hop and not a IPv6 mapped IPv4
address. The IPv4 next hop encoding for cases where the NLRI
advertised is different from the next hop encoding such as where IPv6
NLRI is advertied with IPv4 next hop for for <AFI/SAFI> is
IPv6-Unicast <2/1>, Multicast <2/2>, and Labeled Unicast <2/4>.
[RFC4659] defines Null(RD) for <AFI/SAFI> is VPN-IPv6 <2/128> MVPN-
IPv6 <2/129> but now with a an official new IANA Capability code TBD
as value 10 "IPv4 Next Hop Encoding". The IETF standards have not
been updated with an IANA allocation Capability code for the IPv4
next hop encoding so this specification fixes that problem with an
IANA allocated capability codepoint which will now be used for any
eBGP or iBGP peering as well as the IPv4-Only PE design defined in
this specification.
With this IPv4-Only PE Design, BGP peer session can now be treated as
a pure TCP transport and carry both IPv4 and IPv6 NLRI at the
Provider Edge (PE) - Customer Edge (CE) over a single IPv4 TCP
session. This allows for the elimination of dual stack from the PE-
CE peering point, and now enable the peering to be IPv4-ONLY. The
elimination of IPv6 on the PE-CE peering points translates into OPEX
expenditure savings of point-to-point infrastructure links as well as
/127 address space savings and administration and network management
of both IPv4 and IPv6 BGP peers. This reduction decreases the number
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of PE-CE BGP peers by fifty percent, which is a tremendous cost
savings for operators. This also translates into Major CAPEX savings
as now operators do not have to migrate their underlay to IPv6 and
can remain indefinitely on IPv4-Only Core.
While the savings exists at the Edge eBGP PE-CE peering, on the core
side PE to Route Reflector (RR) peering carrying <AFI/SAFI> IPv4
<2/1>, VPN-IPV4 <2/128>, and Multicasat VPN <2/129>, there is no
savings as the Provider (P) Core is IPv4 Only and thus can only have
an IPv4 peer standard 4 byte next hop encoding to carrying IPv4 NLRI
IPV4 <2/1>, VPN-IPV4 <2/128>, and Multicasat VPN <2/129> over an IPv4
next hop.
This core and edge IPv4-Only peering design paradigm change can apply
to any eBGP peering, public internet or private, which can be either
Core networks, Data Center networks, Access networks or can be any
eBGP peering scenario. This document provides detailed vendor
specific test cases and test results for the IPv4-Only peering design
as well as successful test results between five major vendors
stakeholders in the routing and switching indusrty, Cisco, Juniper,
Arista, Nokia and Huawei. With the test results provided for the
IPv4-Only Edge peering design, the goal is that all other vendors
around the world that have not been tested will begin to adopt and
implement this new best practice for eBGP IPv4-Only Edge peering.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Terminology
Terminolgoy used in defining the IPv6-Only Edge specification.
AFBR: Address Family Border Router Provider Edge (PE).
Edge: PE-CE Edge Network Provider Edge - Customer Edge
Core: P Core Network Provider (P)
4to6 Softwire : IPv4 edge over an IPv6-Only core
6to4 Softwire: IPv6 edge over an IPv4-Only core
E2E: End to End
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4. IPv6-Only Edge Peering Architecture
4.1. Problem Statement
This specification addresses a real issue that has been discussed at
many operator with extremely large core networks around the world
related migration to IPv6 underlay transport which can be put off
indefinitely. Operators around the world are clamoring for a
solution that can help solve issues related to IPv4 address depletion
at these large IXP peering points. With this solution,
infrastructure networks such as Core networks, DC networks, Access
networks as well as any PE-CE public or private network can now
utilize this IPv4-Only Edge solution and reap the benefits
immediately on IPv6 address space saving and CAPEX and OPEX savings.
Problem Statement
Dual Stacked Dual Stacked
CE PE
+-------+ IPv4 BGP Peer +-------+
| |---------------| |
| CE | IPv6 BGP Peer | PE |
| |---------------| |
+-------+ +-------+
IPv4 forwarding IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 1: Problem Statement - Dual Stack Peering
________
Dual Stacked _____ / \ Dual Stacked
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | |0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv6-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv4 IPv6 BGP peer \ IP / MPLS / SR domain / IPv4 and IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
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Figure 2: Problem Statement - E2E Dual Stack Edge
4.2. IPv4-Only PE-CE Design Solution
The IPv4-Only Edge design solution provides a means of E2E single
protocol design solution extension of [RFC5565] Softwire Mesh
framework from the PE-CE Edge to the Core from ingres so egress
through the entire operators domain. This solution eliminates all
IPv4 addressing from end to end while still providing the same Dual
Stack functionality of IPv4 and IPv6 packet forwarding from a data
plane perspective by leveraging the [RFC8950] extended next hop
encoding so that IPv4 NLRI can be advertised over a single IPv6 pure
transport TCP session. This IPv4-Only E2E architecture eliminates
all IPv4 peering and IPv4 addressing E2E from the ingress CE to
ingress PE to egress PE to egress CE and all hops along the operator
E2E path.
Solution applicable to
any Edge peering scenario - IXP, Core, DC, Access, etc
+-------+ +-------+
| | IPv4 Only | |
| CE |----------------| PE |
| | IPv4 BGP Peer | |
+-------+ +-------+
IPv4 forwarding IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 3: IPv4-Only Solution Applicability
________
IPv4-Only _____ / \ IPv4-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | |0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay ===== ==0 | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv6 BGP peer \IP / MPLS / SR domain / IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
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Figure 4: E2E VPN Solution
4.3. IPv4-Only Edge Peering Design
4.3.1. IPv4-Only Edge Peering Packet Walk
The IPv4-Only Edge Peering design utilizes two key E2E Softwire Mesh
Framework scenario's, 4to6 softwire and 6to4 softwire. The Softwire
mesh framework concept is based on the overlay and underlay MPLS or
SR based technology framework, where the underlay is the transport
layer and the overlay is a Virtual Private Network (VPN) layer, and
is the the tunneled virtualization layer containing the customer
payload. The concept of a 6to4 Softwire is based on transmission of
IPv6 packets at the edge of the network by tunneling the IPv6 packets
over an IPv4-Only Core. The concept of a 4to6 Softwire is also based
on transmission of IPv4 packets at the edge of the network by
tunneling the IPv4 packets over an IPv6-Only Core.
This document describes End to End (E2E) test scenarios that follow a
packet flow from IPv4-Only attachment circuit from ingress PE-CE to
egress PE-CE tracing the routing protocol control plane and data
plane forwarding of IPv4 packets in a 4to6 softwire or 6to4 softwire
within the IPv4-Only or IPv6-Only Core network. In both secneario we
are focusing on IPv4 packets and the control plane and data plane
forwarding aspects of IPv4 packets from the PE-CE Edge network over
an IPv4-Only P (Provider) core network or IPv6-Only P (Provider) core
network. With this IPv4-Only Edge peering design, the Softwire Mesh
Framework is not extended beyond the Provider Edge (PE) and continues
to terminate on the PE router.
4.3.2. 6to4 Softwire IPv4-Only Core packet walk
6to4 softwire where IPv4-Edge eBGP IPv4 peering where IPv6 packets at
network Edge traverse a IPv4-Only Core
In the scenario where IPv6 packets originating from a PE-CE edge are
tunneled over an MPLS or Segment Routing IPv4 underlay core network,
the PE and CE only have an IPv6 address configured on the interface.
In this scenario the IPv6 packets that ingress the CE from within the
CE AS are over an IPv4-Only interface and are forwarded to an IPv6
NLRI destination prefix learned from the Pure Transport Single IPv4
BGP Peer. In the IPv4-Only Edge peering architecture the PE is
IPv4-Only as all PE-CE interfaces are IPv4-Only. However, on the CE,
the PE-CE interface is the only interface that is IPv4-Only and all
other interfaces may or may not be IPv4-Only. Following the data
plane packet flow, IPv4 packets are forwarded from the ingress CE to
the IPv4-Only ingress PE where the VPN label imposition push per
prefix, per-vrf, per-CE occurs and the labeled packet is forwarded
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over a 6to4 softwire IPv4-Only core, to the egress PE where the VPN
label disposition pop occurs and the native IPv4 packet is forwarded
to the egress CE. In the reverse direction IPv4 packets are
forwarded from the egress CE to egress PE where the VPN label
imposition per prefix, per-vrf, per-CE push occurs and the labeled
packet is forwarded back over the 6to4 softwire IPv4-Only core, to
the ingress PE where the VPN label disposition pop occurs and the
native IPv4 packet is forwarded to the ingress CE. . The
functionality of the IPv4 forwarding plane in this scenario is
identical from a data plane forwarding perspective to Dual Stack IPv4
forwarding scenario.
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+--------+ +--------+
| IPv4 | | IPv4 |
| Client | | Client |
| Network| | Network|
+--------+ +--------+
| \ / |
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| / \ |
+--------+ +--------+
| AFBR | | AFBR |
+--| IPv4/6 |---| IPv4/6 |--+
| +--------+ +--------+ |
+--------+ | | +--------+
| IPv4 | | | | IPv4 |
| Client | | | | Client |
| Network|------| IPv4 |-------| Network|
+--------+ | only | +--------+
| |
| +--------+ +--------+ |
+--| AFBR |---| AFBR |--+
| IPv4/6 | | IPv4/6 |
+--------+ +--------+
| \ / |
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| / \ |
+--------+ +--------+
| IPv6 | | IPv4 |
| Client | | Client |
| Network| | Network|
+--------+ +--------+
Figure 5: 6to4 Softwire - IPv6 Edge over an IPv4-Only Core
4.3.3. 4to6 Softwire IPv6-Only Core packet walk
4to6 softwire where IPv4-Edge eBGP IPv4 peering where IPv6 packets at
network Edge traverse a IPv6-Only Core
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In the scenario where IPv6 packets originating from a PE-CE edge are
tunneled over an MPLS or Segment Routing IPv4 underlay core network,
the PE and CE only have an IPv4 address configured on the interface.
In this scenario the IPv6 packets that ingress the CE from within the
CE AS are over an IPv4-Only interface and are forwarded to an IPv6
NLRI destination prefix learned from the Pure Transport Single IPv4
BGP Peer. In the IPv4-Only Edge peering architecture the PE is
IPv4-Only as all PE-CE interfaces are IPv4-Only. However, on the CE,
the PE-CE interface is the only interface that is IPv4-Only and all
other interfaces may or may not be IPv4-Only. Following the data
plane packet flow, IPv6 packets are forwarded from the ingress CE to
the IPv4-Only ingress PE where the VPN label imposition push per
prefix, per-vrf, per-CE occurs and the labeled packet is forwarded
over a 4to6 softwire IPv6-Only core, to the egress PE where the VPN
label disposition pop occurs and the native IPv6 packet is forwarded
to the egress CE. In the reverse direction IPv6 packets are
forwarded from the egress CE to egress PE where the VPN label
imposition per prefix, per-vrf, per-CE push occurs and the labeled
packet is forwarded back over the 4to6 softwire IPv6-Only core, to
the ingress PE where the VPN label disposition pop occurs and the
native IPv6 packet is forwarded to the ingress CE. . The
functionality of the IPv4 forwarding plane in this scenario is
identical from a data plane forwarding perspective to Dual Stack IPv4
/ IPv6 forwarding scenario.
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+--------+ +--------+
| IPv4 | | IPv4 |
| Client | | Client |
| Network| | Network|
+--------+ +--------+
| \ / |
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| / \ |
+--------+ +--------+
| AFBR | | AFBR |
+--| IPv4/6 |---| IPv4/6 |--+
| +--------+ +--------+ |
+--------+ | | +--------+
| IPv6 | | | | IPv6 |
| Client | | | | Client |
| Network|------| IPv6 |-------| Network|
+--------+ | only | +--------+
| |
| +--------+ +--------+ |
+--| AFBR |---| AFBR |--+
| IPv4/6 | | IPv4/6 |
+--------+ +--------+
| \ / |
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| / \ |
+--------+ +--------+
| IPv4 | | IPv4 |
| Client | | Client |
| Network| | Network|
+--------+ +--------+
Figure 6: 4to6 Softwire - IPv4 Edge over an IPv6-Only Core
4.4. RFC5549 and RFC8950 Applicability to IPv4-Only PE Design
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4.4.1. IPv4-Only Edge Peering design next-hop encoding
This section describes [RFC8950] next hop encoding updates to
[RFC5549] applicability to this specification. IPv4-Only eBGP Edge
PE-CE peering to carry IPv4 Unicast NLRI <AFI/SAFI> IPv4 <1/1> over
an IPv6 next hop BGP capability extended hop encoding IANA capability
codepoint value 5 defined is applicable to both [RFC5549] and
[RFC8950] as IPv4 Unicast NLRI <AFI/SAFI> IPv4 <1/1> does not change
in the RFC updates.
IPv4 packets over an IPv6-Only core 4to6 Softwire E2E packet flow is
part of the IPv6-Only PE design and this same style next hop encoding
applies to 6to4 Softwire IPv6 NLRI over IPv4 next hop with 4 byte
Next hop encoding and not IPv4 mapped IPv6 address. [RFC8950]
updates [RFC5549] for <AFI/SAFI> VPN-IPV4 <1/128>, and Multicasat VPN
<1/129>
4.4.2. IPv4-Only PE Design Next Hop Encoding
This section describes IPv4 Next Hop Encoding for IPv6 NLRI over an
IPv4 Next hop.
With the IPv4-Only PE design, IPv6 NLRI will be carried over an IPv4
Next-hop. [RFC4798] and [RFC4659] specify how an IPv4 address can be
encoded inside the next-hop IPv6 address field when IPv6 NLRI needs
to be advertised with an IPv4 next hop. [RFC4798] defines how the
IPv4-mapped IPv6 address format specified in the IPv6 addressing
architecture [RFC4798] can be used for that purpose when the <AFI/
SAFI> is IPv6-Unicast <2/1>, Multicast <2/2>, and Labeled Unicast
<2/4>. [RFC4659] defines how the IPv4-mapped IPv6 address format as
well as a null Route Distinguisher as ::FFFF:192.168.1.1 (RD) can be
used for that purpose when the <AFI/SAFI> is VPN-IPv6 <2/128> MVPN-
IPv6 <2/129>. This IPv4-Only PE specification utilizes IPv6 NLRI
over IPv4 Next hop encoding adopted by the industy to not use IPv4
mapped IPv6 address defined above, and instead use 4 byte IPv4
address for the next hop which ultimately set the precedence for the
adoption of [RFC8950] for 4to6 Softwire IPv4 NLRI over IPv6 next-hop.
The IPv4 next hop encoding for cases where the NLRI advertised is
different from the next hop encoding such as where IPv6 NLRI is
advertied with IPv4 next hop for for <AFI/SAFI> is IPv6-Unicast
<2/1>, Multicast <2/2>, and Labeled Unicast <2/4>. [RFC4659] defines
Null(RD) for <AFI/SAFI> is VPN-IPv6 <2/128> MVPN-IPv6 <2/129> but now
with a an official new IANA Capability code TBD as value 10 "IPv4
Next Hop Encoding". The IETF standards have not been updated with an
IANA allocation Capability code for the IPv4 next hop encoding so
this specification fixes that with an IANA allocated codepoint which
will now be used for any eBGP or iBGP peering as well as the
IPv4-Only PE design defined in this specification.
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With this specification when VPN-IPv6 AFI/SAFI 2/128, MVPN-IPv6 AFI/
SAFI 2/129 is used, the next-hop address is encoded as an IPv4
address with a length of 12 bytes. The next-hop address is now
encoded for VPN-IPv6 AFI/SAFI with a length of 12 bytes. The 12 byte
next hop includes 4 byte IPv4 address plus 8 byte Route
Distinguisher. This document modifies how the next-hop address is
encoded to accommodate all existing implementations and bring
consistency with VPN-IPv6, MVPN-IPv6 and 6PE. As all known and
deployed implementations are interoperable today and use the new
proposed encoding, the change does not break existing
interoperability. This change is applicable to all iBGP and eBGP
peering as well as the IPv4-Only PE, PE-CE edge and Inter-AS peering
design for the IPv4 next hop encoding E2E test case of IPv4 packets
over and IPv4-Only core 6to4 Softwire. In this test case IPv6
Unicast NLRI <AFI/SAFI> IPv4 <1/1> is advertised over the PE to RR
core peering 6to4 softwire in <AFI/SAFI> VPN-IPV6 <2/128> MVPN-IPv6
<2/129>. In this test cases label allocation mode comes into play
which is discussed in a subsequent section.
This document defines with the new IANA BGP Capability codepoint
allocation next hop encoding of MP_REACH_NLRI with:
* Specifically, this document allows advertising the MP_REACH_NLRI
attribute [RFC2545] with this content:
Advertising with [RFC2545] MP_REACH_NLRI with:
* AFI = 2
* SAFI = 1, 2 or 4
* Length of Next Hop Address = 4
* Specifically, this document allows advertising the MP_REACH_NLRI
attribute [RFC2545] with this content:
Advertising with [RFC2545] MP_REACH_NLRI with:
* AFI = 2
* SAFI = 128 or 129
* Length of Next Hop Address = 8
* Next Hop Address = VPN-IPv4 address of next hop with an 8-octet RD
set to zero.
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5. IPv4-Only PE Design Edge E2E Test Cases
Proof of conept interoperability testing of the 4 test cases between
the 5 vendors Cisco, Juniper, Arista, Nokia and Huawei.
Cisco, Juniper, Arista, Nokia, Huawei, platform, code revision and
test results for all use cases
Cisco: Edge Router- XR ASR 9910 IOS XR 7.4.1, Core Router- NCS 6000
7.2.2, CRS-X 6.7.4
Juniper: Edge Router- MX platform MX480, MX960, Core Router- PTX
Platform PTX5000, PTC10K8 (JUNOS and EVO) Release 20.4R2
Nokia: Edge and Core-7750 Service Router, Release R21
Huawei: Edge and Core-VRPv8, Release VRP-V800R020C10
Arista:
Intra-AS tests PE-CE Edge Peering IPv4-Only Core, IPv6-Only Core,
Global Table (GRT) and IP VPN
AFI/SAFI IPv4-Unicast SAFI IPv6-Unicast SAFI
IPv4 Core:
Test-1 Global table (6PE)
Test-2 IP VPN
Global table IPv6
IPv6 Core:
Test-3 Global table
Test-4 IP VPN
Inter-AS Options tests IPv4-Only Core, IPv6-Only Core, Global
Table (GRT) and IP VPN
AFI/SAFI VPN and MVPN
IPv4-Only Core
Test-5 Global table 6PE Option-B (Segmented LSP stitched IPv4 Core -
Inter-AS Link IPv6-Only PE - IPv4 Core)
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Test-6 Global table 6PE Option-C (Redistribute IPv4 Loopbacks into
BGP-LU AFI/SAFI 2/6)
Test-7 IP VPN Inter AS Option-B (Segmented LSP stitched IPv4 Core -
Inter-AS Link IPv6-Only PE - IPv4 Core)
Test-8 IP VPN Inter AS Option-C (Redistribute IPv4 Loopbacks into
BGP-LU AFI/SAFI 2/6)
IPv6-Only Core
Test-9 Global table Option-B
Test-10 Global table Option-C
Test-11 IP VPN Inter AS Option-B
Test-12 IP VPN Inter AS Option-C
5.1. Test-1 E2E IPv4-Only PE-CE, Global Table over IPv4-Only Core(6PE),
6to4 softwire
________
IPv4-Only _____ / \ IPv4-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | |_ | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv4 BGP peer \ MPLS / SR domain / IPv4 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 7: Test-1 E2E IPv4-Only PE-CE, Global Table over IPv4-Only
Core (6PE)
5.2. Test-2 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core, 6to4 Softwire
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________
IPv4-Only _____ / \ IPv4-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | 0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv4 BGP peer \ MPLS / SR domain / IPv4 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 8: Test-2 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core
Huawei: Edge and Core-VRPv8, Release VRP-V800R020C10
5.3. Test-3 E2E IPv4-Only PE-CE, Global Table over IPv6-Only Core
(4PE), 4to6 Softwire
________
IPv4-Only _____ / \ IPv4-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | |_ | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv4 BGP peer \ MPLS / SR domain / IPv4 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 9: Test-3 E2E IPv4-Only PE-CE, Global Table over IPv6-Only
Core (4PE)
5.4. Test-4 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core, 4to6 Softwire
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________
IPv4-Only _____ / \ IPv4-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | 0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv4 BGP peer \ MPLS / SR domain / IPv4 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 10: Test-4 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core
5.5. Test-5 E2E IPv4-Only PE-CE, Global Table over IPv4-Only Core(6PE),
6to4 softwire -Inter-AS Option-B
Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv4-Only Core|----|IPv4-Only Core|--|PE|-|CE|
| | | | |0=Underlay==0 | |0==Underlay==0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 11: Test-5 E2E IPv4-Only PE-CE, Global Table over
IPv4-Only Core (6PE) - Inter-AS Option-B
5.6. Test-6 E2E IPv4-Only PE-CE, Global Table over IPv4-Only Core(6PE),
6to4 softwire -Inter-AS Option-C
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Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv4-Only Core|----|IPv4-Only Core|--|PE|-|CE|
| | | | |0=Underlay==0 | |0==Underlay==0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 12: Test-6 E2E IPv4-Only PE-CE, Global Table over
IPv4-Only Core (6PE) - Inter-AS Option-C
5.7. Test-7 E2E IPv4-Only PE-CE, VPN over IPv4-Only, 6to4 softwire -
Inter-AS Option-B
Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv4-Only Core|----|IPv4-Only Core|--|PE|-|CE|
| | | | |0=Overlay===0 | |0==Overlay===0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 13: Test-7 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core -
Inter-AS Option-B
5.8. Test-8 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core, 6to4 softwire
-Inter-AS Option-C
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Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv4-Only Core|----|IPv4-Only Core|--|PE|-|CE|
| | | | |0=Overlay===0 | |0==Overlay===0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 14: Test-8 E2E IPv4-Only PE-CE, VPN over IPv4-Only Core -
Inter-AS Option-C
5.9. Test-9 E2E IPv4-Only PE-CE, Global Table over IPv6-Only Core, 4to6
softwire -Inter-AS Option-B
Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv6-Only Core|----|IPv6-Only Core|--|PE|-|CE|
| | | | |0=Underlay==0 | |0==Underlay==0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 15: Test-9 E2E IPv4-Only PE-CE, Global Table over
IPv6-Only Core - Inter- AS Option-B
5.10. Test-10 E2E IPv4-Only PE-CE, Global Table over IPv6-Only Core,
4to6 softwire -Inter-AS Option-C
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Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv6-Only Core|--- |IPv6-Only Core|--|PE|-|CE|
| | | | |0=Underlay==0 | |0==Underlay==0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 16: Test-10 E2E IPv4-Only PE-CE, Global Table over
IPv6-Only Core - Inter-AS Option-C
5.11. Test-11 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core, 4to6
softwire -Inter-AS Option-B
Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv6-Only Core|--- |IPv6-Only Core|--|PE|-|CE|
| | | | |0=Overlay===0 | |0==Overlay===0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 17: Test-11 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core -
Inter-AS Option-B
5.12. Test-12 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core, 4to6
softwire -Inter-AS Option-C
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Inter-AS ASBR-ASBR link is IPv6-Only PE
IPv6-Only __________ __________ IPv6-Only
PE / CE / \ / \ PE / CE
+--+ +----+ / \ / \ +--+ +--+
| | | | | AS 1 \ | AS 2 \ | | | |
| | | | | \IPv6| \ | | | |
|CE|-| PE |--| IPv6-Only Core|--- |IPv6-Only Core|--|PE|-|CE|
| | | | |0=Overlay===0 | |0==Overlay===0| | | | |
+--+ +----+ \ / \ / +--+ +--+
IPv6 BGP peer \ MPLS/SR / \ MPLS/SR / IPv6 BGP peer
IPv4 forwarding \_________/ \_________/ IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 18: Test-12 E2E IPv4-Only PE-CE, VPN over IPv6-Only Core -
Inter-AS Option-C
5.13. IPv4-Only PE-CE Operational Considerations Testing
Ping CE to PE when destination prefix is withdrawn
Traceroute CE to PE and test all ICMPv4 and ICMPv6 type codes
+-------+ +-------+
| | IPv4 Only | |
| CE |----------------| PE |
| | IPv4 BGP Peer | |
+-------+ +-------+
IPv4 forwarding IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 19: Ping and Trace Test Case
6. Operational Considerations
With a single IPv4 Peer carrying both IPv4 and IPv6 NLRI there are
some operational considerations in terms of what changes and what
does not change.
What does not change with a single IPv6 transport peer carrying IPv4
NLRI and IPv6 NLRI below:
Routing Policy configuration is still separate for IPv4 and IPv6
configured by capability as previously.
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Layer 1, Layer 2 issues such as one-way fiber or fiber cut will
impact both IPv4 and IPv6 as previously.
If the interface is in the Admin Down state, the IPv6 peer would go
down, and IPv4 NLRI and IPv6 NLRI would be withdrawn as previously.
Changes resulting from a single IPv4 transport peer carrying IPv4
NLRI and IPv6 NLRI below:
Physical interface is no longer dual stacked.
Any change in IPv4 address will impact both IPv4 and IPv6 NLRI
exchange.
Single BFD session for both IPv4 and IPv6 NLRI fate sharing as the
session is now tied to the transport, which now is only IPv4 address
family.
Both IPv4 and IPv6 peer now exists under the IPv4 address family
configuration.
Fate sharing of IPv4 and IPv6 address family from a logical
perspective now carried over a single physical IPv4 peer.
From an operations perspective, prior to elimination of IPv6 peers,
an audit is recommended to identify and IPv4 and IPv6 peering
incongruencies that may exist and to rectify them. No operational
impacts or issues are expected with this change.
With MPLS VPN overlay, per-CE next-hop label allcoation mode where
both IPv4 and IPv6 prefixes have the same label in no table lookup
pop-n-forward mode should be taken into consideration.
7. IANA Considerations
This document defines a new Capability Code to indicate the Extended
Next Hop Encoding capability in the [RFC5492] Capabilities Optional
Parameter. The value for this new Capability Code is 10, which is in
the range set aside for allocation using the "IETF Review" policy
defined in [RFC5226].
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8. Security Considerations
The extensions defined in this document allow BGP to propagate
reachability information about IPv6 prefixes over an MPLS or SR
IPv4-Only core network. As such, no new security issues are raised
beyond those that already exist in BGP-4 and the use of MP-BGP for
IPv6. Both IPv4 and IPv6 peers exist under the IPv6 address family
configuration. The security features of BGP and corresponding
security policy defined in the ISP domain are applicable. For the
inter-AS distribution of IPv4 routes according to case (a) of
Section 4 of this document, no new security issues are raised beyond
those that already exist in the use of eBGP for IPv6 [RFC2545].
9. Acknowledgments
Thanks to Kaliraj Vairavakkalai, Linda Dunbar, Aijun Wang, Eduardfor
Vasilenko, Joel Harlpern, Michael McBride, Ketan Talaulikar for
review comments.
10. Contributors
The following people contributed substantive text to this document:
Mohana Sundari
EMail: mohanas@juniper.net
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol
Extensions for IPv6 Inter-Domain Routing", RFC 2545,
DOI 10.17487/RFC2545, March 1999,
<https://www.rfc-editor.org/info/rfc2545>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
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[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <https://www.rfc-editor.org/info/rfc5492>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8277] Rosen, E., "Using BGP to Bind MPLS Labels to Address
Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,
<https://www.rfc-editor.org/info/rfc8277>.
11.2. Informative References
[I-D.ietf-idr-dynamic-cap]
Chen, E. and S. R. Sangli, "Dynamic Capability for BGP-4",
Work in Progress, Internet-Draft, draft-ietf-idr-dynamic-
cap-16, 21 October 2021, <https://www.ietf.org/archive/id/
draft-ietf-idr-dynamic-cap-16.txt>.
[RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur,
"BGP-MPLS IP Virtual Private Network (VPN) Extension for
IPv6 VPN", RFC 4659, DOI 10.17487/RFC4659, September 2006,
<https://www.rfc-editor.org/info/rfc4659>.
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
R., Patel, K., and J. Guichard, "Constrained Route
Distribution for Border Gateway Protocol/MultiProtocol
Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684,
November 2006, <https://www.rfc-editor.org/info/rfc4684>.
[RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur,
"Connecting IPv6 Islands over IPv4 MPLS Using IPv6
Provider Edge Routers (6PE)", RFC 4798,
DOI 10.17487/RFC4798, February 2007,
<https://www.rfc-editor.org/info/rfc4798>.
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[RFC4925] Li, X., Ed., Dawkins, S., Ed., Ward, D., Ed., and A.
Durand, Ed., "Softwire Problem Statement", RFC 4925,
DOI 10.17487/RFC4925, July 2007,
<https://www.rfc-editor.org/info/rfc4925>.
[RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
Layer Reachability Information with an IPv6 Next Hop",
RFC 5549, DOI 10.17487/RFC5549, May 2009,
<https://www.rfc-editor.org/info/rfc5549>.
[RFC5565] Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh
Framework", RFC 5565, DOI 10.17487/RFC5565, June 2009,
<https://www.rfc-editor.org/info/rfc5565>.
[RFC6074] Rosen, E., Davie, B., Radoaca, V., and W. Luo,
"Provisioning, Auto-Discovery, and Signaling in Layer 2
Virtual Private Networks (L2VPNs)", RFC 6074,
DOI 10.17487/RFC6074, January 2011,
<https://www.rfc-editor.org/info/rfc6074>.
[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
2012, <https://www.rfc-editor.org/info/rfc6513>.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
<https://www.rfc-editor.org/info/rfc6514>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8950] Litkowski, S., Agrawal, S., Ananthamurthy, K., and K.
Patel, "Advertising IPv4 Network Layer Reachability
Information (NLRI) with an IPv6 Next Hop", RFC 8950,
DOI 10.17487/RFC8950, November 2020,
<https://www.rfc-editor.org/info/rfc8950>.
Authors' Addresses
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
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Jeff Tantsura
Microsoft, Inc.
Email: jefftant.ietf@gmail.com
Mankamana Mishra
Cisco Systems
821 Alder Drive,
MILPITAS
Email: mankamis@cisco.com
Sudha Madhavi
Juniper Networks, Inc.
Email: smadhavi@juniper.net
Qing Yang
Arista Networks
Email: qyang@arista.com
Adam Simpson
Nokia
Email: adam.1.simpson@nokia.com
Shuanglong Chen
Huawei Technologies
Email: chenshuanglong@huawei.com
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