IPv6-Only PE Design for IPv4-NLRI All SAFI over IPv6-NH
draft-mishra-bess-ipv4nlri-all-safi-ipv6nh-00
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Author | Gyan Mishra | ||
| Last updated | 2022-01-11 | ||
| Replaced by | draft-mishra-bess-ipv6-only-pe-design-all-safi | ||
| RFC stream | (None) | ||
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draft-mishra-bess-ipv4nlri-all-safi-ipv6nh-00
BESS Working Group G. Mishra
Internet-Draft Verizon Inc.
Intended status: Best Current Practice 11 January 2022
Expires: 15 July 2022
IPv6-Only PE Design for IPv4-NLRI All SAFI over IPv6-NH
draft-mishra-bess-ipv4nlri-all-safi-ipv6nh-00
Abstract
As Enterprises and Service Providers 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) Inter-AS peering
network from IPv4 to IPv6. Operators must be able to continue to
support IPv4 customers when both the Core and Edge networks are
IPv6-Only.
This document details an important External BGP (eBGP) PE-PE Inter-AS
IPv6-Only peering design that leverages the MP-BGP capability
exchange by using IPv6 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 for all Address Family Identifiers
(AFI) and Subsequent Address Family Identifiers(SAFI). 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
IPv6-Only peer is required for both IPv4 and IPv6 routing updates and
from a data plane forwarindg perspective an IPv6 address need only be
configured on the PE to PE Inter-AS peering interface for both IPv4
and IPv6 packet forwarding. This document extends the IPv6-Only PE-
CE peering architecture defined in
[I-D.ietf-bess-ipv6-only-pe-design] to PE-PE inter-as peering
architecture where the 4to6 softwire is now extended to Inter-AS L3
VPN options Option-A, Option-AB and Option-C and now applies to all
AFI/SAFI ubiquitously. As service providers migrate to Segment
Routing architecture SR-MPLS and SRv6, VPN overlay exsits as well,
and thus Inter-AS options Option-A, Option-AB and Option-C are still
applicable and thus this extension of IPv6-Only peering architecure
extension to Inter-AS peering is very relevant to Segment Routing as
well.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on 15 July 2022.
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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 6
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. IPv6-Only Edge Peering Architecture . . . . . . . . . . . . . 6
4.1. Problem Statement . . . . . . . . . . . . . . . . . . . . 6
4.2. IPv6-Only PE-CE Design Solution . . . . . . . . . . . . . 7
4.3. IPv6-Only Edge Peering Design . . . . . . . . . . . . . . 8
4.3.1. IPv6-Only Edge Peering Packet Walk . . . . . . . . . 8
4.3.2. 6to4 Softwire IPv4-Only Core packet walk . . . . . . 9
4.3.3. 4to6 Softwire IPv6-Only Core packet walk . . . . . . 10
4.4. RFC5549 and RFC8950 Applicability . . . . . . . . . . . . 12
4.4.1. IPv6-Only Edge Peering design next-hop encoding . . . 13
4.4.2. RFC8950 updates to RFC5549 applicability . . . . . . 13
5. IPv6-Only PE Design Edge E2E Design for all AFI/SAFI . . . . 14
5.1. Design Solution-1 E2E IPv6-Only PE-CE, Global Table over
IPv4-Only Core(6PE), 6to4 softwire . . . . . . . . . . . 14
5.2. Design Solution-2 E2E IPv6-Only PE-CE, VPN over IPv4-Only
Core, 6to4 Softwire . . . . . . . . . . . . . . . . . . . 15
5.3. Design Solution-3 E2E IPv6-Only PE-CE, Global Table over
IPv6-Only Core (4PE), 4to6 Softwire . . . . . . . . . . . 15
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5.4. Design Solution-4 E2E IPv6-Only PE-CE, VPN over IPv6-Only
Core, 4to6 Softwire . . . . . . . . . . . . . . . . . . . 16
5.5. Design Solution-5 E2E Inter-AS Option B and AB, 4to6
Softwire . . . . . . . . . . . . . . . . . . . . . . . . 16
5.6. IPv6-Only PE-CE Operational Considerations Testing . . . 17
6. IPv6-Only PE ALL AFI/SFI Operational Considerations . . . . . 17
7. Vendor Implementations and Operator Deployments . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
12.1. Normative References . . . . . . . . . . . . . . . . . . 19
12.2. Informative References . . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 23
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 IPv4 customers and must be able to support
IPv4 address family and Sub-Address-Family Virtual Private Network
(VPN)-IPv4, and Multicast VPN IPv4 customers.
IXP are also facing IPv4 address depletion at their peering points,
which are large Layer 2 transit backbones that service providers peer
and exchange IPv4 and IPv6 Network Layer Reachability Information
(NLRI). Today, these transit exchange points are Dual Stacked. With
this IPv6-only BGP peering design, only IPv6 is configured on the PE-
PE inter-as peering interface, the Inter-AS Provider Edge (PE) -
Provider Edge (PE), the IPv6 BGP peer is now used to carry IPv4
(Network Layer Reachability Information) NLRI over an IPv6 next hop
using IPv6 next hop encoding defined in [RFC8950], while continuing
to forward both IPv4 and IPv6 packets. In the framework of this
design the ASBRs providing Inter-AS options peering PE to PE
extending L3 VPN services is now no longer 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.
The current specification for carrying IPv4 NLRI of a given address
family via a Next Hop of a different address family is now defined in
[RFC8950], and specifies the extended next hop encoding MP-REACH
capability extension necessary to do so. This comprises an extension
of the AFI/SAFI definitions to allow the address of the Next Hop for
IPv4 NLRI or VPN-IPv4 NLRI to belong to either the IPv4 or the IPv6
protocol, the encoding of the Next Hop information to determine which
of the protocols the address belongs to, and a new BGP Capability
allowing MP-BGP peers to dynamically discover whether they can
exchange IPv4 NLRI and VPN- IPv4 NLRI with an IPv6 Next Hop.
With the new extensions defined in [RFC8950] supporting NLRI and next
hop address family mismatch, the 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 IPv6 TCP
session. This allows for the elimination of dual stack from the PE-
PE Inter-AS peering point, and now enable the Inter-AS peering to be
IPv6-ONLY. The elimination of IPv4 Inter Provider ASBR tie point,
PE-PE Inter-AS peering points translates into OPEX expenditure
savings of point-to-point infrastructure links as well as /31 address
space savings and administration and network management of both IPv4
and IPv6 BGP peers. This reduction decreases the number of PE-PE
Inter-AS options BGP peers by fifty percent, which is a tremendous
cost savings for operators.
While the savings exists at the Edge eBGP PE-PE Inter-AS peering, on
the core side PE to Route Reflector (RR) peering carrying <AFI/SAFI>
IPv4 <1/1>, VPN-IPV4 <1/128>, and Multicasat VPN <1/129>, there is no
savings as the Provider (P) Core is IPv6 Only and thus can only have
an IPv6 peer and must use [RFC8950] extended next hop encoding to
carrying IPv4 NLRI IPV4 <2/1>, VPN-IPV4 <2/128>, and Multicast VPN
<2/129> over an IPv6 next hop.
This document details an important External BGP (eBGP) PE-PE Inter-AS
IPv6-Only peering design that leverages the MP-BGP capability
exchange by using IPv6 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
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Gateway Protocol) BGP TCP session for all Address Family Identifiers
(AFI) and Subsequent Address Family Identifiers(SAFI). 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
IPv6-Only peer is required for both IPv4 and IPv6 routing updates and
from a data plane forwarindg perspective an IPv6 address need only be
configured on the PE to PE Inter-AS peering interface for both IPv4
and IPv6 packet forwarding. This document extends the IPv6-Only PE-
CE peering architecture defined in
[I-D.ietf-bess-ipv6-only-pe-design] to PE-PE inter-as peering
architecture where the 4to6 softwire is now extended to Inter-AS L3
VPN options Option-A, Option-AB and Option-C and now applies to all
AFI/SAFI ubiquitously. As service providers migrate to Segment
Routing architecture SR-MPLS and SRv6, VPN overlay exsits as well,
and thus Inter-AS options Option-A, Option-AB and Option-C are still
applicable and thus this extension of IPv6-Only peering architecure
extension to Inter-AS peering is relevant to Segment Routing.
This document details an important External BGP (eBGP) PE-PE Inter-AS
IPv6-Only peering design that leverages the MP-BGP capability
exchange by using IPv6 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 for the following Address Family
Identifiers (AFI) and Subsequent Address Family Identifiers(SAFI) to
be carried over IPv6-Only Inter-AS peerings described in detail in
this document: <AFI/SAFI> IPv4 Unicast <1/1>, IPv4 Multicast
<1/2>,VPN-IPV4 <1/128>, Multicasat VPN <1/129>, BGP-LU IPV4 (4PE)
<1/4>, BGP-LU IPV4 <1/4>
This document details an important External BGP (eBGP) PE-PE Inter-AS
IPv6-Only peering design that leverages the MP-BGP capability
exchange by using IPv6 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 for all remaining Address Family
Identifiers (AFI) and Subsequent Address Family Identifiers(SAFI)
below as well that can be carried over IPv6-Only Inter-AS peerings:
<AFI/SAFI> MCAST-VPN [RFC6514] <1/5>, NLRI Multi-Segment Pseudowires
[RFC7267] <1/6>, BGP Tunnel Encapsulation SAFI [RFC9012] <1/7>,
MCAST-VPLS [RFC7117] <1/8>, BGP SFC [RFC9015] <1/9>, Tunnel SAFI
[I-D.nalawade-kapoor-tunnel-safi] <1/6>, Virtual Private LAN Service
(VPLS) [RFC4761] and [RFC6074] <1/5>, BGP MDT SAFI [RFC6037] <1/66>,
BGP 4to6 SAFI [RFC5747] <1/67>, BGP 6to4 SAFI draft xx <1/8>, Layer 1
VPN Auto-Discovery [RFC5195] <1/69>, BGP EVPNs [RFC7432] <1/70>, BGP-
LS (VPLS) [RFC7752] <1/71>, BGP-LS-EVPN [RFC7752] <72/>, SR-TE Policy
SAFI draftxx <1/73>, BGP 6to4 SAFI draft xx <1/8>, SDN WAN
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Capabilities draftxx <1/74>, Routing Policy SAFI draftxx <1/75>,
Classful-Transport SAFI draftxx <1/76>, Tunneled Traffic FlowSpec
draftxx <1/77>, MCAST-TREE SAFI draft xx <1/78>, Route Target
Constraints [RFC4684] <1/132>, Dissemination of Flow Specification
Rules [RFC8955] <1/133>, L3 VPN Dissemination of Flow Specification
Rules [RFC8955] <1/1344>, VPN Auto-Discovery SAFI draftxx <1/140>
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
4. IPv6-Only Edge Peering Architecture
4.1. Problem Statement
This specification addresses a real issue that has been discussed at
many operator groups around the world related to IXP major peering
points where hundreds of AS's have both IPv4 and IPv6 dual stacked
peering. IPv4 address depletion have been a major issue issue for
many years now. 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 IXPs as well
as all infrastructure networks such as Core networks, DC networks,
Access networks as well as any PE-CE public or private network can
now utilize this IPv6-Only Edge solution and reap the benefits
immediately on IPv4 address space saving.
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IXP 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 - IXP 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
Figure 2: Problem Statement - E2E Dual Stack Edge
4.2. IPv6-Only PE-CE Design Solution
The IPv6-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 IPv6-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
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E2E path.
Solution applicable to
any Edge peering scenario - IXP, Core, DC, Access, etc
+-------+ +-------+
| | IPv6 Only | |
| CE |----------------| PE |
| | IPv6 BGP Peer | |
+-------+ +-------+
IPv4 forwarding IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 3: IPv6-Only Solution Applicability
________
IPv6-Only _____ / \ IPv6-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | |0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv6-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
Figure 4: E2E VPN Solution
4.3. IPv6-Only Edge Peering Design
4.3.1. IPv6-Only Edge Peering Packet Walk
The IPv6-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
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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 IPv6-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 IPv6-Only P (Provider) core network or IPv4-Only P (Provider) core
network. With this IPv6-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 IPv6-Edge eBGP IPv6 peering where IPv4 packets at
network Edge traverse a IPv4-Only Core
In the scenario where IPv4 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 IPv4 packets that ingress the CE from within the
CE AS are over an IPv6-Only interface and are forwarded to an IPv4
NLRI destination prefix learned from the Pure Transport Single IPv6
BGP Peer. In the IPv6-Only Edge peering architecture the PE is
IPv6-Only as all PE-CE interfaces are IPv6-Only. However, on the CE,
the PE-CE interface is the only interface that is IPv6-Only and all
other interfaces may or may not be IPv6-Only. Following the data
plane packet flow, IPv4 packets are forwarded from the ingress CE to
the IPv6-Only ingress PE where the VPN label imposition push per
prefix, per-vrf, per-CE occurs and the labeled packet is forwarded
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 IPv6-Edge eBGP IPv6 peering where IPv4 packets at
network Edge traverse a IPv6-Only Core
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In the scenario where IPv4 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 IPv4 packets that ingress the CE from within the
CE AS are over an IPv6-Only interface and are forwarded to an IPv4
NLRI destination prefix learned from the Pure Transport Single IPv6
BGP Peer. In the IPv6-Only Edge peering architecture the PE is
IPv6-Only as all PE-CE interfaces are IPv6-Only. However, on the CE,
the PE-CE interface is the only interface that is IPv6-Only and all
other interfaces may or may not be IPv6-Only. Following the data
plane packet flow, IPv4 packets are forwarded from the ingress CE to
the IPv6-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 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 4to6 softwire IPv6-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 |--+
| +--------+ +--------+ |
+--------+ | | +--------+
| 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
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4.4.1. IPv6-Only Edge Peering design next-hop encoding
This section describes [RFC8950] next hop encoding updates to
[RFC5549] applicability to this specification. IPv6-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 design vendor interoperaiblity test cases and
in that respect is applicable as [RFC8950] updates [RFC5549] for
<AFI/SAFI> VPN-IPV4 <1/128>, and Multicasat VPN <1/129>
4.4.2. RFC8950 updates to RFC5549 applicability
This section describes the [RFC8950] next hop encoding updates to
[RFC5549]
In [RFC5549] when AFI/SAFI 1/128 is used, the next-hop address is
encoded as an IPv6 address with a length of 16 or 32 bytes. This
document modifies how the next-hop address is encoded to accommodate
all existing implementations and bring consistency with VPNv4oIPv4
and VPNv6oIPv6. The next-hop address is now encoded as a VPN-IPv6
address with a length of 24 or 48 bytes [RFC8950] (see Sections 3 and
6.2 of this document). This change addresses Erratum ID 5253
(Err5253). As all known and deployed implementations are
interoperable today and use the new proposed encoding, the change
does not break existing interoperability. Updates to [RFC8950] is
applicable to the IPv6-Only PE-CE edge design for the IPv6 next hop
encoding E2E test case of IPv4 packets over and IPv6-Only core 4to6
Softwire. In this test case IPv4 Unicast NLRI <AFI/SAFI> IPv4 <1/1>
is advertised over the PE to RR core peering 4to6 softwire in <AFI/
SAFI> VPN-IPV4 <1/128>. In this test case label allocation mode
comes into play which is discussed in section 8.9.
[RFC5549] next hop encoding of MP_REACH_NLRI with:
* NLRI= NLRI as per current AFI/SAFI definition
Advertising with [RFC4760] MP_REACH_NLRI with:
* AFI = 1
* SAFI = 128 or 129
* Length of Next Hop Address = 16 or 32
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* NLRI= NLRI as per current AFI/SAFI definition
[RFC8950] next hop encoding of MP_REACH_NLRI with:
* NLRI= NLRI as per current AFI/SAFI definition
Advertising with [RFC4760] MP_REACH_NLRI with:
* AFI = 1
* SAFI = 128 or 129
* Length of Next Hop Address = 24 or 48
* Next Hop Address = VPN-IPv6 address of next hop with an 8-octet RD
set to zero (potentially followed by the link-local VPN-IPv6
address of the next hop with an 8-octet RD is set to zero).
* NLRI= NLRI as per current AFI/SAFI definition
5. IPv6-Only PE Design Edge E2E Design for all AFI/SAFI
Proof of conept interoperability testing of the 4 test cases bet
5.1. Design Solution-1 E2E IPv6-Only PE-CE, Global Table over IPv4-Only
Core(6PE), 6to4 softwire
________
IPv6-Only _____ / \ IPv6-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | |_ | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv6 BGP peer \ MPLS / SR domain / IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 7: Design Solution-1 E2E IPv6-Only PE-CE, Global
Table over IPv4-Only Core (6PE)
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Cisco, Juniper, Arista, Nokia, Huawei code and platform and test
results.
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
Tested v4 edge over v6 core in a virtual setup using vMX platforrm
and 20.4R2 and LDPv6 as underlay, but there were some data plane
forwarding issues. Tested same setup on latest release 21.4 and it
worked. Investigating what the minimum version is for this setup to
work.
Arista:
Nokia: Edge and Core-7750 Service Router, Release R21
Huawei: Edge and Core-VRPv8, Release VRP-V800R020C10
5.2. Design Solution-2 E2E IPv6-Only PE-CE, VPN over IPv4-Only Core,
6to4 Softwire
________
IPv6-Only _____ / \ IPv6-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | 0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv4-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv6 BGP peer \ MPLS / SR domain / IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 8: Design Solution-2 E2E IPv6-Only PE-CE, VPN over
IPv4-Only Core
5.3. Design Solution-3 E2E IPv6-Only PE-CE, Global Table over IPv6-Only
Core (4PE), 4to6 Softwire
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________
IPv6-Only _____ / \ IPv6-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | |_ | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv6-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv6 BGP peer \ MPLS / SR domain / IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 9: Design Solution-3 E2E IPv6-Only PE-CE, Global
Table over IPv6-Only Core (4PE)
5.4. Design Solution-4 E2E IPv6-Only PE-CE, VPN over IPv6-Only Core,
4to6 Softwire
________
IPv6-Only _____ / \ IPv6-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | 0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv6-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv6 BGP peer \ MPLS / SR domain / IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 10: Design Solution-4 E2E IPv6-Only PE-CE, VPN over
IPv6-Only Core
5.5. Design Solution-5 E2E Inter-AS Option B and AB, 4to6 Softwire
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________
IPv6-Only _____ / \ IPv6-Only
PE / CE / \__/ \___ PE / CE
+----+ +----+ / \ +------+ +-----+
| | | | | 0====VPN Overlay Tunnel ==0| | | | |
| | | | | \ | | | |
| CE |--| PE |--\ IPv6-Only Core |----| PE |---| CE |
| | | | \0=========Underlay =======0| | | | |
+----+ +----+ \ __/ +------+ +-----+
IPv6 BGP peer \ MPLS / SR domain / IPv6 BGP peer
IPv4 forwarding \__ __ / IPv4 forwarding
IPv6 forwarding \_______/ \_____/ IPv6 forwarding
Figure 11: Design Solution-5 E2E E2E Inter-AS Option B and AB
over IPv6-Only Core
5.6. IPv6-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
+-------+ +-------+
| | IPv6 Only | |
| CE |----------------| PE |
| | IPv6 BGP Peer | |
+-------+ +-------+
IPv4 forwarding IPv4 forwarding
IPv6 forwarding IPv6 forwarding
Figure 12: Ping and Trace Test Case
6. IPv6-Only PE ALL AFI/SFI Operational Considerations
With a single IPv6 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 IPv6 transport peer carrying IPv4
NLRI and IPv6 NLRI below:
Physical interface is no longer dual stacked.
Any change in IPv6 address or DAD state 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 IPv6 address
family.
Both IPv4 and IPv6 peer now exists under the IPv6 address family
configuration.
Fate sharing of IPv4 and IPv6 address family from a logical
perspective now carried over a single physical IPv6 peer.
From an operations perspective, prior to elimination of IPv4 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. Vendor Implementations and Operator Deployments
Vendor implementations are with Cisco, Juniper, Nokia, Arista and
Huawei
8. IANA Considerations
There are not any IANA considerations.
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9. Security Considerations
The extensions defined in this document allow BGP to propagate
reachability information about IPv4 prefixes over an MPLS or SR
IPv6-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 IPv6 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].
10. Acknowledgments
Thanks to Kaliraj Vairavakkalai, Linda Dunbar, Aijun Wang, Eduardfor
Vasilenko, Joel Harlpern, Michael McBride, Ketan Talaulikar for
review comments.
11. Contributors
The following people contributed substantive text to this document:
Mohana Sundari
EMail: mohanas@juniper.net
12. References
12.1. Normative References
[I-D.ietf-bess-ipv6-only-pe-design]
Mishra, G., Mishra, M., Tantsura, J., Madhavi, S., Yang,
Q., Simpson, A., and S. Chen, "IPv6-Only PE Design for
IPv4-NLRI with IPv6-NH", Work in Progress, Internet-Draft,
draft-ietf-bess-ipv6-only-pe-design-00, 20 September 2021,
<https://www.ietf.org/archive/id/draft-ietf-bess-ipv6-
only-pe-design-00.txt>.
[I-D.nalawade-kapoor-tunnel-safi]
Nalawade, G., "BGP Tunnel SAFI", Work in Progress,
Internet-Draft, draft-nalawade-kapoor-tunnel-safi-05, 29
June 2006, <https://www.ietf.org/archive/id/draft-
nalawade-kapoor-tunnel-safi-05.txt>.
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[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>.
[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>.
[RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
<https://www.rfc-editor.org/info/rfc4761>.
[RFC5195] Ould-Brahim, H., Fedyk, D., and Y. Rekhter, "BGP-Based
Auto-Discovery for Layer-1 VPNs", RFC 5195,
DOI 10.17487/RFC5195, June 2008,
<https://www.rfc-editor.org/info/rfc5195>.
[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>.
[RFC5747] Wu, J., Cui, Y., Li, X., Xu, M., and C. Metz, "4over6
Transit Solution Using IP Encapsulation and MP-BGP
Extensions", RFC 5747, DOI 10.17487/RFC5747, March 2010,
<https://www.rfc-editor.org/info/rfc5747>.
[RFC6037] Rosen, E., Ed., Cai, Y., Ed., and IJ. Wijnands, "Cisco
Systems' Solution for Multicast in BGP/MPLS IP VPNs",
RFC 6037, DOI 10.17487/RFC6037, October 2010,
<https://www.rfc-editor.org/info/rfc6037>.
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[RFC7117] Aggarwal, R., Ed., Kamite, Y., Fang, L., Rekhter, Y., and
C. Kodeboniya, "Multicast in Virtual Private LAN Service
(VPLS)", RFC 7117, DOI 10.17487/RFC7117, February 2014,
<https://www.rfc-editor.org/info/rfc7117>.
[RFC7267] Martini, L., Ed., Bocci, M., Ed., and F. Balus, Ed.,
"Dynamic Placement of Multi-Segment Pseudowires",
RFC 7267, DOI 10.17487/RFC7267, June 2014,
<https://www.rfc-editor.org/info/rfc7267>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[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>.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
[RFC9015] Farrel, A., Drake, J., Rosen, E., Uttaro, J., and L.
Jalil, "BGP Control Plane for the Network Service Header
in Service Function Chaining", RFC 9015,
DOI 10.17487/RFC9015, June 2021,
<https://www.rfc-editor.org/info/rfc9015>.
12.2. Informative References
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[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>.
[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>.
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[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>.
Author's Address
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
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