< draft-ietf-bess-evpn-optimized-ir-10.txt   draft-ietf-bess-evpn-optimized-ir-11.txt >
BESS Workgroup J. Rabadan, Ed. BESS Workgroup J. Rabadan, Ed.
Internet-Draft S. Sathappan Internet-Draft S. Sathappan
Intended status: Standards Track Nokia Intended status: Standards Track Nokia
Expires: May 12, 2022 W. Lin Expires: May 21, 2022 W. Lin
Juniper Networks Juniper Networks
M. Katiyar M. Katiyar
Versa Networks Versa Networks
A. Sajassi A. Sajassi
Cisco Systems Cisco Systems
November 8, 2021 November 17, 2021
Optimized Ingress Replication solution for Ethernet VPN (EVPN) Optimized Ingress Replication Solution for Ethernet VPN (EVPN)
draft-ietf-bess-evpn-optimized-ir-10 draft-ietf-bess-evpn-optimized-ir-11
Abstract Abstract
Network Virtualization Overlay networks using Ethernet VPN (EVPN) as Network Virtualization Overlay networks using Ethernet VPN (EVPN) as
control plane may use Ingress Replication or PIM (Protocol control plane may use Ingress Replication or PIM (Protocol
Independent Multicast)-based trees to convey the overlay Broadcast, Independent Multicast)-based trees to convey the overlay Broadcast,
Unknown unicast and Multicast (BUM) traffic. PIM provides an Unknown unicast and Multicast (BUM) traffic. PIM provides an
efficient solution to avoid sending multiple copies of the same efficient solution to avoid sending multiple copies of the same
packet over the same physical link, however it may not always be packet over the same physical link, however it may not always be
deployed in the Network Virtualization Overlay core network. Ingress deployed in the Network Virtualization Overlay core network. Ingress
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 12, 2022. This Internet-Draft will expire on May 21, 2022.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 6 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 6
3. Solution Requirements . . . . . . . . . . . . . . . . . . . . 8 3. Solution Requirements . . . . . . . . . . . . . . . . . . . . 8
4. EVPN BGP Attributes for Optimized Ingress Replication . . . . 9 4. EVPN BGP Attributes for Optimized Ingress Replication . . . . 9
5. Non-Selective Assisted-Replication (AR) Solution Description 13 5. Non-Selective Assisted-Replication (AR) Solution Description 13
5.1. Non-selective AR-REPLICATOR Procedures . . . . . . . . . 14 5.1. Non-selective AR-REPLICATOR Procedures . . . . . . . . . 14
5.2. Non-Selective AR-LEAF Procedures . . . . . . . . . . . . 16 5.2. Non-Selective AR-LEAF Procedures . . . . . . . . . . . . 17
5.3. RNVE Procedures . . . . . . . . . . . . . . . . . . . . . 19 5.3. RNVE Procedures . . . . . . . . . . . . . . . . . . . . . 19
6. Selective Assisted-Replication (AR) Solution Description . . 19 6. Selective Assisted-Replication (AR) Solution Description . . 20
6.1. Selective AR-REPLICATOR Procedures . . . . . . . . . . . 21 6.1. Selective AR-REPLICATOR Procedures . . . . . . . . . . . 21
6.2. Selective AR-LEAF Procedures . . . . . . . . . . . . . . 23 6.2. Selective AR-LEAF Procedures . . . . . . . . . . . . . . 23
7. Pruned-Flood-Lists (PFL) . . . . . . . . . . . . . . . . . . 25 7. Pruned-Flood-Lists (PFL) . . . . . . . . . . . . . . . . . . 26
7.1. A Pruned-Flood-List Example . . . . . . . . . . . . . . . 26 7.1. A Pruned-Flood-List Example . . . . . . . . . . . . . . . 26
8. AR Procedures for Single-IP AR-REPLICATORS . . . . . . . . . 27 8. AR Procedures for Single-IP AR-REPLICATORS . . . . . . . . . 28
9. AR Procedures and EVPN All-Active Multi-homing Split-Horizon 28 9. AR Procedures and EVPN All-Active Multi-homing Split-Horizon 28
9.1. Ethernet Segments on AR-LEAF Nodes . . . . . . . . . . . 28 9.1. Ethernet Segments on AR-LEAF Nodes . . . . . . . . . . . 29
9.2. Ethernet Segments on AR-REPLICATOR nodes . . . . . . . . 29 9.2. Ethernet Segments on AR-REPLICATOR nodes . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . . 30 10. Security Considerations . . . . . . . . . . . . . . . . . . . 30
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 31 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 32
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 31 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
14.1. Normative References . . . . . . . . . . . . . . . . . . 32 14.1. Normative References . . . . . . . . . . . . . . . . . . 32
14.2. Informative References . . . . . . . . . . . . . . . . . 32 14.2. Informative References . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction 1. Introduction
Ethernet Virtual Private Networks (EVPN) may be used as the control Ethernet Virtual Private Networks (EVPN) may be used as the control
plane for a Network Virtualization Overlay network [RFC8365]. plane for a Network Virtualization Overlay network [RFC8365].
Network Virtualization Edge (NVE) and Provider Edges (PE) devices Network Virtualization Edge (NVE) and Provider Edges (PE) devices
that are part of the same EVPN Broadcast Domain (BD) use Ingress that are part of the same EVPN Broadcast Domain (BD) use Ingress
Replication or PIM-based trees to transport the tenant's Broadcast, Replication or PIM-based trees to transport the tenant's Broadcast,
Unknown unicast and Multicast (BUM) traffic. Unknown unicast and Multicast (BUM) traffic.
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the need for PIM in the underlay. Assisted Replication defines the the need for PIM in the underlay. Assisted Replication defines the
roles of AR-REPLICATOR and AR-LEAF routers. The AR-LEAF is the roles of AR-REPLICATOR and AR-LEAF routers. The AR-LEAF is the
ingress NVE/PE attached to the Tenant System. The AR-LEAF sends a ingress NVE/PE attached to the Tenant System. The AR-LEAF sends a
single copy of a Broadcast or Multicast packet to a selected AR- single copy of a Broadcast or Multicast packet to a selected AR-
REPLICATOR that replicates the packet mutiple times to remote AR-LEAF REPLICATOR that replicates the packet mutiple times to remote AR-LEAF
or AR-REPLICATOR routers, and therefore "assisting" the ingress AR- or AR-REPLICATOR routers, and therefore "assisting" the ingress AR-
LEAF in delivering the Broadcast or Multicast traffic to the remote LEAF in delivering the Broadcast or Multicast traffic to the remote
NVEs/PEs attached to the same Broadcast Domain. Assisted-Replication NVEs/PEs attached to the same Broadcast Domain. Assisted-Replication
can use a single AR-REPLICATOR or two AR-REPLICATOR routers in the can use a single AR-REPLICATOR or two AR-REPLICATOR routers in the
path between the ingress AR-LEAF and the remote destination NVE/PEs. path between the ingress AR-LEAF and the remote destination NVE/PEs.
The procedures that use a single AR-REPLICATOR are specified in The procedures that use a single AR-REPLICATOR (Non-Selective
Section 5, whereas Section 6 describes how multi-staged replication, Assisted-Replication Solution) are specified in Section 5, whereas
i.e., two AR-REPLICATOR routers in the path between the ingress AR- Section 6 describes how multi-staged replication, i.e., two AR-
LEAF and destination NVEs/PEs, is accomplished. REPLICATOR routers in the path between the ingress AR-LEAF and
destination NVEs/PEs, is accomplished (Selective Assisted-Replication
Solution). The Assisted-Replication procedures do not impact unknown
unicast traffic, which follows the same forwarding procedures as
known unicast traffic so that packet re-ordering does not occur.
Pruned-Flood-Lists is a method for the ingress NVE/PE to prune or Pruned-Flood-Lists is a method for the ingress NVE/PE to prune or
remove certain destination NVEs/PEs from a flood-list, depending on remove certain destination NVEs/PEs from a flood-list, depending on
the interest of those NVEs/PEs in receiving Broadcast, Multicast or the interest of those NVEs/PEs in receiving Broadcast, Multicast or
Unknown unicast. As specfied in [RFC8365], an NVE/PE builds a flood- Unknown unicast. As specfied in [RFC8365], an NVE/PE builds a flood-
list for BUM traffic based on the Next-Hops of the received EVPN list for BUM traffic based on the Next-Hops of the received EVPN
Inclusive Multicast Ethernet Tag routes for the Broadcast Domain. Inclusive Multicast Ethernet Tag routes for the Broadcast Domain.
While [RFC8365] states that the flood-list is used for all BUM While [RFC8365] states that the flood-list is used for all BUM
traffic, this document allows pruning certain Next-Hops from the traffic, this document allows pruning certain Next-Hops from the
list. As an example, suppose an ingress NVE creates a flood-list list. As an example, suppose an ingress NVE creates a flood-list
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[RFC7432], and they are described in Section 4. [RFC7432], and they are described in Section 4.
The Assisted-Replication solution described in this document is The Assisted-Replication solution described in this document is
focused on Network Virtualization Overlay networks (hence it uses IP focused on Network Virtualization Overlay networks (hence it uses IP
tunnels) and MPLS transport networks are out of scope. The Pruned- tunnels) and MPLS transport networks are out of scope. The Pruned-
Flood-Lists solution MAY be used in Network Virtualization Overlay Flood-Lists solution MAY be used in Network Virtualization Overlay
and MPLS transport networks. and MPLS transport networks.
Section 3 lists the requirements of the combined optimized Ingress Section 3 lists the requirements of the combined optimized Ingress
Replication solution, whereas Section 5 and Section 6 describe the Replication solution, whereas Section 5 and Section 6 describe the
Assisted-Replication solution, and Section 7 the Pruned-Flood-Lists Assisted-Replication solution (for Non-Selective and Selective
procedures, respectively), and Section 7 the Pruned-Flood-Lists
solution. solution.
2. Terminology and Conventions 2. Terminology and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
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- BD: Broadcast Domain, as defined in [RFC7432]. - BD: Broadcast Domain, as defined in [RFC7432].
- DF and NDF: Designated Forwarder and Non-Designated Forwarder, are - DF and NDF: Designated Forwarder and Non-Designated Forwarder, are
roles defined in NVE/PEs attached to Multi-Homed Tenant Systems, roles defined in NVE/PEs attached to Multi-Homed Tenant Systems,
as per [RFC7432] and [RFC8365]. as per [RFC7432] and [RFC8365].
- ES and ESI: Ethernet Segment and Ethernet Segment Identifier, as - ES and ESI: Ethernet Segment and Ethernet Segment Identifier, as
EVPN Multi-Homing concepts specified in [RFC7432]. EVPN Multi-Homing concepts specified in [RFC7432].
- EVI: EVPN Instance. An EVPN instance spanning the Provider Edge - EVI: EVPN Instance. A group of Provider Edge (PE) devices
(PE) devices participating in that EVPN, as specified in participating in the same EVPN service, as specified in [RFC7432].
[RFC7432].
- GRE: Generic Routing Encapsulation [RFC4023]. - GRE: Generic Routing Encapsulation [RFC4023].
- Ingress Replication forwarding mode: it refers to the Ingress - Ingress Replication forwarding mode: it refers to the Ingress
Replication behavior explained in [RFC7432]. It means sending an Replication behavior explained in [RFC7432]. It means sending an
Attachment Circuit BM packet copy to each remote PE/NVE in the BD Attachment Circuit BM packet copy to each remote PE/NVE in the BD
and sending an overlay BM packet only to the Attachment Circuits and sending an overlay BM packet only to the Attachment Circuits
and not other overlay tunnels. and not other overlay tunnels.
- IR-IP: local IP address of an NVE/PE that is used for the Ingress - IR-IP: local IP address of an NVE/PE that is used for the Ingress
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Multicast traffic without the need for PIM, while preserving the Multicast traffic without the need for PIM, while preserving the
packet order for unicast applications, i.e., unknown unicast packet order for unicast applications, i.e., unknown unicast
traffic should follow the same path as known unicast traffic. traffic should follow the same path as known unicast traffic.
This optimization is required in low-performance NVEs. This optimization is required in low-performance NVEs.
b. It reduces the flooded traffic in Network Virtualization Overlay b. It reduces the flooded traffic in Network Virtualization Overlay
networks where some NVEs do not need broadcast/multicast and/or networks where some NVEs do not need broadcast/multicast and/or
unknown unicast traffic. unknown unicast traffic.
c. The solution is compatible with [RFC7432] and [RFC8365] and has c. The solution is compatible with [RFC7432] and [RFC8365] and has
no impact on the EVPN procedures for BM traffic. In particular, no impact on the CE procedures for BM traffic. In particular,
the solution supports the following EVPN functions: the solution supports the following EVPN functions:
o All-active multi-homing, including the split-horizon and o All-active multi-homing, including the split-horizon and
Designated Forwarder (DF) functions. Designated Forwarder (DF) functions.
o Single-active multi-homing, including the DF function. o Single-active multi-homing, including the DF function.
o Handling of multi-destination traffic and processing of o Handling of multi-destination traffic and processing of
broadcast and multicast as per [RFC7432]. broadcast and multicast as per [RFC7432].
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specific data plane encapsulation and the virtual identifiers specific data plane encapsulation and the virtual identifiers
being used, e.g.: VXLAN VNIs, NVGRE VSIDs or MPLS labels, as long being used, e.g.: VXLAN VNIs, NVGRE VSIDs or MPLS labels, as long
as the tunnel is IP-based. as the tunnel is IP-based.
4. EVPN BGP Attributes for Optimized Ingress Replication 4. EVPN BGP Attributes for Optimized Ingress Replication
This solution extends the [RFC7432] Inclusive Multicast Ethernet Tag This solution extends the [RFC7432] Inclusive Multicast Ethernet Tag
routes and attributes so that an NVE/PE can signal its optimized routes and attributes so that an NVE/PE can signal its optimized
Ingress Replication capabilities. Ingress Replication capabilities.
The Inclusive Multicast Ethernet Tag route as in [RFC7432] is shown The NLRI of the Inclusive Multicast Ethernet Tag route as in
in Figure 2 and it is used in this document without any modifications [RFC7432] is shown in Figure 2 and it is used in this document
to its format. The PMSI Tunnel Attribute's general format as in without any modifications to its format. The PMSI Tunnel Attribute's
[RFC7432] is used in this document, only a new Tunnel Type and new general format as in [RFC7432] (which takes it from [RFC6514]) is
flags are specified, as shown in Figure 3: used in this document, only a new Tunnel Type and new flags are
specified, as shown in Figure 3:
+---------------------------------+ +---------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------+ +---------------------------------+
| Ethernet Tag ID (4 octets) | | Ethernet Tag ID (4 octets) |
+---------------------------------+ +---------------------------------+
| IP Address Length (1 octet) | | IP Address Length (1 octet) |
+---------------------------------+ +---------------------------------+
| Originating Router's IP Addr | | Originating Router's IP Addr |
| (4 or 16 octets) | | (4 or 16 octets) |
+---------------------------------+ +---------------------------------+
Figure 2: EVPN Inclusive Multicast Tag route Figure 2: EVPN Inclusive Multicast Tag route's NLRI
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+---------------------------------+ +--+--+--+--+--+--+--+--+ +---------------------------------+ +--+--+--+--+--+--+--+--+
| Flags (1 octet) | -> |x |E |x | T |BM|U |L | | Flags (1 octet) | -> |x |E |x | T |BM|U |L |
+---------------------------------+ +--+--+--+--+--+--+--+--+ +---------------------------------+ +--+--+--+--+--+--+--+--+
| Tunnel Type (1 octets) | T = Assisted-Replication Type | Tunnel Type (1 octets) | T = Assisted-Replication Type
+---------------------------------+ BM = Broadcast and Multicast +---------------------------------+ BM = Broadcast and Multicast
| MPLS Label (3 octets) | U = Unknown unicast | MPLS Label (3 octets) | U = Unknown unicast
+---------------------------------+ x = unassigned +---------------------------------+ x = unassigned
| Tunnel Identifier (variable) | | Tunnel Identifier (variable) |
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In this document, the above Inclusive Multicast Ethernet Tag route In this document, the above Inclusive Multicast Ethernet Tag route
Figure 2 and PMSI Tunnel Attribute Figure 3 can be used in two Figure 2 and PMSI Tunnel Attribute Figure 3 can be used in two
different modes for the same BD: different modes for the same BD:
- Regular-IR route: in this route, Originating Router's IP Address, - Regular-IR route: in this route, Originating Router's IP Address,
Tunnel Type (0x06), MPLS Label and Tunnel Identifier MUST be used Tunnel Type (0x06), MPLS Label and Tunnel Identifier MUST be used
as described in [RFC7432] when Ingress Replication is in use. The as described in [RFC7432] when Ingress Replication is in use. The
NVE/PE that advertises the route will set the Next-Hop to an IP NVE/PE that advertises the route will set the Next-Hop to an IP
address that we denominate IR-IP in this document. When address that we denominate IR-IP in this document. When
advertised by an AR-LEAF node, the Regular-IR route MUST be advertised by an AR-LEAF node, the Regular-IR route MUST be
advertised with type T= AR-LEAF. advertised with type T set to 10 (AR-LEAF).
- Replicator-AR route: this route is used by the AR-REPLICATOR to - Replicator-AR route: this route is used by the AR-REPLICATOR to
advertise its AR capabilities, with the fields set as follows: advertise its AR capabilities, with the fields set as follows:
o Originating Router's IP Address MUST be set to an IP address of o Originating Router's IP Address MUST be set to an IP address of
the advertising router that is common to all the EVIs on the PE the advertising router that is common to all the EVIs on the PE
(usually this is a loopback address of the PE). (usually this is a loopback address of the PE).
+ The Tunnel Identifier and Next-Hop SHOULD be set to the same + The Tunnel Identifier and Next-Hop SHOULD be set to the same
IP address as the Originating Router's IP address when the IP address as the Originating Router's IP address when the
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the values in the Tunnel Identifier and Originating Router's the values in the Tunnel Identifier and Originating Router's
IP Address fields, the ingress NVE/PE will process the IP Address fields, the ingress NVE/PE will process the
received Replicator-AR route and will use the IP Address in received Replicator-AR route and will use the IP Address in
the Next-Hop field to create IP tunnels to the AR- the Next-Hop field to create IP tunnels to the AR-
REPLICATOR. REPLICATOR.
+ The Next-Hop address is referred to as the AR-IP and MUST be + The Next-Hop address is referred to as the AR-IP and MUST be
different from the IR-IP for a given PE/NVE, unless the different from the IR-IP for a given PE/NVE, unless the
procedures in Section 8 are followed. procedures in Section 8 are followed.
o Tunnel Type = Assisted-Replication Tunnel. Section 11 provides o Tunnel Type MUST be set to Assisted-Replication Tunnel.
the allocated type value. Section 11 provides the allocated type value.
o T (AR role type) = 01 (AR-REPLICATOR). o T (AR role type) MUST be set to 01 (AR-REPLICATOR).
o L (Leaf Information Required) = 0 (for non-selective AR) or 1 o L (Leaf Information Required) MUST be set to 0 (for non-
(for selective AR). selective AR), and MUST be set to 1 (for selective AR).
An NVE/PE configured as AR-REPLICATOR for a BD MUST advertise a An NVE/PE configured as AR-REPLICATOR for a BD MUST advertise a
Replicator-AR route for the BD and MAY advertise a Regular-IR route. Replicator-AR route for the BD and MAY advertise a Regular-IR route.
The advertisement of the Replicator-AR route will indicate the AR- The advertisement of the Replicator-AR route will indicate the AR-
LEAFs what outer IP DA, i.e., the AR-IP, they need to use for IP LEAFs what outer IP DA, i.e., the AR-IP, they need to use for IP
encapsulated BM frames that use Assisted Replication forwarding mode. encapsulated BM frames that use Assisted Replication forwarding mode.
The AR-REPLICATOR will forward an IP encapsulated BM frame in The AR-REPLICATOR will forward an IP encapsulated BM frame in
Assisted Replication forwarding mode if the outer IP DA matches its Assisted Replication forwarding mode if the outer IP DA matches its
AR-IP, but will forward in Ingress Replication forwarding mode if the AR-IP, but will forward in Ingress Replication forwarding mode if the
outer IP DA matches its IR-IP. outer IP DA matches its IR-IP.
In addition, this document also uses the Leaf Auto-Discovery route In addition, this document also uses the Leaf Auto-Discovery route
defined in [I-D.ietf-bess-evpn-bum-procedure-updates] in case the defined in [I-D.ietf-bess-evpn-bum-procedure-updates] in case the
selective AR mode is used. An AR-LEAF MAY send a Leaf A-D route in selective AR mode is used. An AR-LEAF MAY send a Leaf A-D route in
response to reception of a Replicator-AR route whose L flag is set. response to reception of a Replicator-AR route whose L flag is set.
It is only used for selective AR and its fields are set as follows: The Leaf Auto-Discovery route is only used for selective AR and the
fields of such route are set as follows:
o Originating Router's IP Address is set to the advertising o Originating Router's IP Address is set to the advertising
router's IP address (same IP used by the AR-LEAF in regular-IR router's IP address (same IP used by the AR-LEAF in regular-IR
routes). The Next-Hop address is set to the IR-IP, which routes). The Next-Hop address is set to the IR-IP, which
SHOULD be the same IP address as the advertising router's IP SHOULD be the same IP address as the advertising router's IP
address, when the NVE/PE originates the route, i.e., when the address, when the NVE/PE originates the route, i.e., when the
NVE/PE is not an ASBR as in section 10.2 of [RFC8365]. NVE/PE is not an ASBR as in section 10.2 of [RFC8365].
o Route Key is the "Route Type Specific" NLRI of the Replicator- o Route Key is the "Route Type Specific" NLRI of the Replicator-
AR route for which this Leaf Auto-Discovery route is generated. AR route for which this Leaf Auto-Discovery route is generated.
o The AR-LEAF constructs an IP-address-specific route-target as o The AR-LEAF constructs an IP-address-specific route-target,
indicated in [I-D.ietf-bess-evpn-bum-procedure-updates], by analogously to [I-D.ietf-bess-evpn-bum-procedure-updates], by
placing the IP address carried in the Next-Hop field of the placing the IP address carried in the Next-Hop field of the
received Replicator-AR route in the Global Administrator field received Replicator-AR route in the Global Administrator field
of the Community, with the Local Administrator field of this of the Community, with the Local Administrator field of this
Community set to 0. Note that the same IP-address-specific Community set to 0, and setting the Extended Communities
import route-target is auto-configured by the AR-REPLICATOR attribute of the Leaf Auto-Discovery route to that Community.
that sent the Replicator-AR, in order to control the acceptance The same IP-address-specific import route-target is auto-
of the Leaf Auto-Discovery routes. configured by the AR-REPLICATOR that sent the Replicator-AR
route, in order to control the acceptance of the Leaf Auto-
Discovery routes.
o The Leaf Auto-Discovery route MUST include the PMSI Tunnel o The Leaf Auto-Discovery route MUST include the PMSI Tunnel
attribute with the Tunnel Type set to AR, type set to AR-LEAF attribute with the Tunnel Type set to AR (Section 11), T (AR
and the Tunnel Identifier set to the IP address of the role type) set to AR-LEAF and the Tunnel Identifier set to the
advertising AR-LEAF. The PMSI Tunnel attribute MUST carry a IP address of the advertising AR-LEAF. The PMSI Tunnel
downstream-assigned MPLS label or VNI that is used by the AR- attribute MUST carry a downstream-assigned MPLS label or VNI
REPLICATOR to send traffic to the AR-LEAF. that is used by the AR-REPLICATOR to send traffic to the AR-
LEAF.
Each AR-enabled node MUST understand and process the AR type field in Each AR-enabled node understands and process the T (Assisted-
the PMSI Tunnel Attribute (Flags field) of the routes, and MUST Replication type) field in the PMSI Tunnel Attribute (Flags field) of
signal the corresponding type (AR-REPLICATOR or AR-LEAF type) the routes, and MUST signal the corresponding type (AR-REPLICATOR or
according to its administrative choice. AR-LEAF type) according to its administrative choice. An NVE/PE
following this specification is not expected to set the AR type field
to decimal 3 (which is a RESERVED value). If a route with the AR
type field set to decimal 3 is received by an AR-REPLICATOR or AR-
LEAF, the router will process the route as a Regular-IR route
advertised by an RNVE.
Each node attached to the BD may understand and process the BM/U Each node attached to the BD may understand and process the BM/U
flags (Pruned-Flood-Lists flags). Note that these BM/U flags may be flags (Pruned-Flood-Lists flags). Note that these BM/U flags may be
used to optimize the delivery of multi-destination traffic and their used to optimize the delivery of multi-destination traffic and their
use SHOULD be an administrative choice, and independent of the AR use SHOULD be an administrative choice, and independent of the AR
role. When the Pruned-Flood-List capability is enabled, the BM/U role. When the Pruned-Flood-List capability is enabled, the BM/U
flags can be used with the Regular-IR, Replicator-AR and Leaf Auto- flags can be used with the Regular-IR, Replicator-AR and Leaf Auto-
Discovery routes. Discovery routes.
Non-optimized Ingress Replication NVEs/PEs will be unaware of the new Non-optimized Ingress Replication NVEs/PEs will be unaware of the new
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directly from the source node to the destination node without being directly from the source node to the destination node without being
replicated by any intermediate node. replicated by any intermediate node.
Note that known unicast forwarding is not impacted by this solution, Note that known unicast forwarding is not impacted by this solution,
i.e., unknown unicast SHALL follow the same path as known unicast i.e., unknown unicast SHALL follow the same path as known unicast
traffic. traffic.
5.1. Non-selective AR-REPLICATOR Procedures 5.1. Non-selective AR-REPLICATOR Procedures
An AR-REPLICATOR is defined as an NVE/PE capable of replicating An AR-REPLICATOR is defined as an NVE/PE capable of replicating
incoming BM (Broadcast and Multicast) traffic received on an overlay incoming BM traffic received on an overlay tunnel to other overlay
tunnel to other overlay tunnels and local Attachment Circuits. The tunnels and local Attachment Circuits. The AR-REPLICATOR signals its
AR-REPLICATOR signals its role in the control plane and understands role in the control plane and understands where the other roles (AR-
where the other roles (AR-LEAF nodes, RNVEs and other AR-REPLICATORs) LEAF nodes, RNVEs and other AR-REPLICATORs) are located. A given AR-
are located. A given AR-enabled BD service may have zero, one or enabled BD service may have zero, one or more AR-REPLICATORs. In our
more AR-REPLICATORs. In our example in Figure 4, PE1 and PE2 are example in Figure 4, PE1 and PE2 are defined as AR-REPLICATORs. The
defined as AR-REPLICATORs. The following considerations apply to the following considerations apply to the AR-REPLICATOR role:
AR-REPLICATOR role:
a. The AR-REPLICATOR role SHOULD be an administrative choice in any a. The AR-REPLICATOR role SHOULD be an administrative choice in any
NVE/PE that is part of an AR-enabled BD. This administrative NVE/PE that is part of an AR-enabled BD. This administrative
option to enable AR-REPLICATOR capabilities MAY be implemented as option to enable AR-REPLICATOR capabilities MAY be implemented as
a system level option as opposed to as a per-BD option. a system level option as opposed to as a per-BD option.
b. An AR-REPLICATOR MUST advertise a Replicator-AR route and MAY b. An AR-REPLICATOR MUST advertise a Replicator-AR route and MAY
advertise a Regular-IR route. The AR-REPLICATOR MUST NOT advertise a Regular-IR route. The AR-REPLICATOR MUST NOT
generate a Regular-IR route if it does not have local attachment generate a Regular-IR route if it does not have local attachment
circuits (AC). If the Regular-IR route is advertised, the circuits (AC). If the Regular-IR route is advertised, the
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o If the destination IP address matches its AR-IP, the AR- o If the destination IP address matches its AR-IP, the AR-
REPLICATOR MUST forward the BM packet to its flooding list (ACs REPLICATOR MUST forward the BM packet to its flooding list (ACs
and overlay tunnels) excluding the non-BM overlay tunnels. The and overlay tunnels) excluding the non-BM overlay tunnels. The
AR-REPLICATOR will ensure the traffic is not sent back to the AR-REPLICATOR will ensure the traffic is not sent back to the
originating AR-LEAF. originating AR-LEAF.
o If the encapsulation is MPLSoGRE or MPLSoUDP and the received o If the encapsulation is MPLSoGRE or MPLSoUDP and the received
BD label (or label that the AR-REPLICATOR advertised in the BD label (or label that the AR-REPLICATOR advertised in the
Replicator-AR route) is not the bottom of the stack, the AR- Replicator-AR route) is not the bottom of the stack, the AR-
REPLICATOR MUST copy the rest of the labels when forwarding REPLICATOR MUST copy the all the labels below the BD label and
them to the egress overlay tunnels. propagate them when forwarding the packet to the egress overlay
tunnels.
- The AR-REPLICATOR/LEAF nodes will build an Unknown unicast flood- - The AR-REPLICATOR/LEAF nodes will build an Unknown unicast flood-
list composed of Attachment Circuits and overlay tunnels to the list composed of Attachment Circuits and overlay tunnels to the
IR-IP Addresses of the remote nodes in the BD. Some of those IR-IP Addresses of the remote nodes in the BD. Some of those
overlay tunnels MAY be flagged as non-U (Unknown unicast) overlay tunnels MAY be flagged as non-U (Unknown unicast)
receivers based on the U flag received from the remote nodes in receivers based on the U flag received from the remote nodes in
the BD. the BD.
o When an AR-REPLICATOR/LEAF receives an unknown unicast packet o When an AR-REPLICATOR/LEAF receives an unknown unicast packet
on an Attachment Circuit, it will forward the unknown unicast on an Attachment Circuit, it will forward the unknown unicast
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a. The AR-LEAF role SHOULD be an administrative choice in any NVE/PE a. The AR-LEAF role SHOULD be an administrative choice in any NVE/PE
that is part of an AR-enabled BD. This administrative option to that is part of an AR-enabled BD. This administrative option to
enable AR-LEAF capabilities MAY be implemented as a system level enable AR-LEAF capabilities MAY be implemented as a system level
option as opposed to as per-BD option. option as opposed to as per-BD option.
b. In this non-selective AR solution, the AR-LEAF MUST advertise a b. In this non-selective AR solution, the AR-LEAF MUST advertise a
single Regular-IR inclusive multicast route as in [RFC7432]. The single Regular-IR inclusive multicast route as in [RFC7432]. The
AR-LEAF SHOULD set the Assisted-Replication Type field to AR- AR-LEAF SHOULD set the Assisted-Replication Type field to AR-
LEAF. Note that although this field does not make any difference LEAF. Note that although this field does not make any difference
for the egress nodes when creating an EVPN destination to the AR- for the remote nodes when creating an EVPN destination to the AR-
LEAF, this field is useful for an easy operation and LEAF, this field is useful for an easy operation and
troubleshooting of the BD. troubleshooting of the BD.
c. In a BD where there are no AR-REPLICATORs due to the AR- c. In a BD where there are no AR-REPLICATORs due to the AR-
REPLICATORs being down or reconfigured, the AR-LEAF MUST use REPLICATORs being down or reconfigured, the AR-LEAF MUST use
regular Ingress Replication, based on the remote Regular-IR regular Ingress Replication, based on the remote Regular-IR
Inclusive Multicast Routes as described in [RFC7432]. This may Inclusive Multicast Routes as described in [RFC7432]. This may
happen in the following cases: happen in the following cases:
o The AR-LEAF has a list of AR-REPLICATORs for the BD, but it o The AR-LEAF has a list of AR-REPLICATORs for the BD, but it
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o A single AR-REPLICATOR MAY be selected for all the BM packets o A single AR-REPLICATOR MAY be selected for all the BM packets
received on the AR-LEAF attachment circuits (ACs) for a given received on the AR-LEAF attachment circuits (ACs) for a given
BD. This selection is a local decision and it does not have BD. This selection is a local decision and it does not have
to match other AR-LEAF's selections within the same BD. to match other AR-LEAF's selections within the same BD.
o An AR-LEAF MAY select more than one AR-REPLICATOR and do o An AR-LEAF MAY select more than one AR-REPLICATOR and do
either per-flow or per-BD load balancing. either per-flow or per-BD load balancing.
o In case of a failure of the selected AR-REPLICATOR, another o In case of a failure of the selected AR-REPLICATOR, another
AR-REPLICATOR SHOULD be selected. AR-REPLICATOR SHOULD be selected by the AR-LEAF.
o When an AR-REPLICATOR is selected for a given flow or BD, the o When an AR-REPLICATOR is selected for a given flow or BD, the
AR-LEAF MUST send all the BM packets targeted to that AR- AR-LEAF MUST send all the BM packets targeted to that AR-
REPLICATOR using the forwarding information given by the REPLICATOR using the forwarding information given by the
Replicator-AR route for the chosen AR-REPLICATOR, with tunnel Replicator-AR route for the chosen AR-REPLICATOR, with tunnel
type = 0x0A (AR tunnel). The underlay destination IP address type = 0x0A (AR tunnel). The underlay destination IP address
MUST be the AR-IP advertised by the AR-REPLICATOR in the MUST be the AR-IP advertised by the AR-REPLICATOR in the
Replicator-AR route. Replicator-AR route.
o An AR-LEAF MAY change the AR-REPLICATOR(s) selection o An AR-LEAF MAY change the AR-REPLICATOR(s) selection
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| (BD-1) | | (BD-1) | | (BD-1) | | (BD-1) | | (BD-1) | | (BD-1) |
| LEAF-set1 | |LEAF-set-1 | |LEAF-set-2 | | LEAF-set1 | |LEAF-set-1 | |LEAF-set-2 |
+--+-----+--+ +--+-----+--+ +--+-----+--+ +--+-----+--+ +--+-----+--+ +--+-----+--+
| | | | | | | | | | | |
VM11 VM12 TS3 TS4 VM31 VM32 VM11 VM12 TS3 TS4 VM31 VM32
Figure 5: Selective AR scenario Figure 5: Selective AR scenario
The solution is called "selective" because a given AR-REPLICATOR MUST The solution is called "selective" because a given AR-REPLICATOR MUST
replicate the BM traffic to only the AR-LEAFs that requested the replicate the BM traffic to only the AR-LEAFs that requested the
replication (as opposed to all the AR-LEAF nodes) and MAY replicate replication (as opposed to all the AR-LEAF nodes) and MUST replicate
the BM traffic to the RNVEs. The same AR roles defined in Section 4 the BM traffic to the RNVEs (if there are any). The same AR roles
are used here, however the procedures are different. defined in Section 4 are used here, however the procedures are
different.
The Selective AR procedures create multiple AR-LEAF-sets in the EVPN The Selective AR procedures create multiple AR-LEAF-sets in the EVPN
BD, and builds single-hop trees among AR-LEAFs of the same set (AR- BD, and builds single-hop trees among AR-LEAFs of the same set (AR-
LEAF->AR-REPLICATOR->AR-LEAF), and two-hop trees among AR-LEAFs of LEAF->AR-REPLICATOR->AR-LEAF), and two-hop trees among AR-LEAFs of
different sets (AR-LEAF->AR-REPLICATOR->AR-REPLICATOR->AR-LEAF). different sets (AR-LEAF->AR-REPLICATOR->AR-REPLICATOR->AR-LEAF).
Compared to the Selective solution, the Non-Selective AR method Compared to the Selective solution, the Non-Selective AR method
assumes that all the AR-LEAFs of the BD are in the same set and assumes that all the AR-LEAFs of the BD are in the same set and
always create two-hop trees among AR-LEAFs. While the Selective always create two-hop trees among AR-LEAFs. While the Selective
solution is more efficient than the Non-Selective solution in multi- solution is more efficient than the Non-Selective solution in multi-
stage IP fabrics, the trade-off is additional signaling and an stage IP fabrics, the trade-off is additional signaling and an
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Likewise, PE2 will only add NVE3 to its selective AR-LEAF-set Likewise, PE2 will only add NVE3 to its selective AR-LEAF-set
for BD-1, and exclude NVE1/NVE2. for BD-1, and exclude NVE1/NVE2.
o When a node defined and operating as a Selective AR-REPLICATOR o When a node defined and operating as a Selective AR-REPLICATOR
receives a packet on an overlay tunnel, it will do a tunnel receives a packet on an overlay tunnel, it will do a tunnel
destination IP lookup and if the destination IP address is the destination IP lookup and if the destination IP address is the
AR-REPLICATOR AR-IP Address, the node MUST replicate the AR-REPLICATOR AR-IP Address, the node MUST replicate the
packet to: packet to:
+ local Attachment Circuits + local Attachment Circuits
+ overlay tunnels in the Selective AR-LEAF-set, excluding the + overlay tunnels in the Selective AR-LEAF-set, excluding the
overlay tunnel to the source AR-LEAF. overlay tunnel to the source AR-LEAF.
+ overlay tunnels to the RNVEs if the tunnel source IP + overlay tunnels to the RNVEs if the tunnel source IP
address is the IR-IP of an AR-LEAF. In any other case, the address is the IR-IP of an AR-LEAF. In any other case, the
AR-REPLICATOR MUST NOT replicate the BM traffic to remote AR-REPLICATOR MUST NOT replicate the BM traffic to remote
RNVEs. In other words, only the first-hop selective AR- RNVEs. In other words, only the first-hop selective AR-
REPLICATOR will replicate to all the RNVEs. REPLICATOR will replicate to all the RNVEs.
+ overlay tunnels to the remote Selective AR-REPLICATORs if + overlay tunnels to the remote Selective AR-REPLICATORs if
the tunnel source IP address is an IR-IP of its own AR- the tunnel source IP address (of the encapsulated packet
LEAF-set. In any other case, the AR-REPLICATOR MUST NOT that arrived on the overlay tunnel) is an IR-IP of its own
AR-LEAF-set. In any other case, the AR-REPLICATOR MUST NOT
replicate the BM traffic to remote AR-REPLICATORs. When replicate the BM traffic to remote AR-REPLICATORs. When
doing this replication, the tunnel destination IP address doing this replication, the tunnel destination IP address
is the AR-IP of the remote Selective AR-REPLICATOR. The is the AR-IP of the remote Selective AR-REPLICATOR. The
tunnel destination IP AR-IP will be an indication for the tunnel destination IP AR-IP will be an indication for the
remote Selective AR-REPLICATOR that the packet needs remote Selective AR-REPLICATOR that the packet needs
further replication to its AR-LEAFs. further replication to its AR-LEAFs.
A Selective AR-REPLICATOR data path implementation MUST be compatible A Selective AR-REPLICATOR data path implementation MUST be compatible
with the following rules: with the following rules:
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The rest of the procedures will follow what is described in sections The rest of the procedures will follow what is described in sections
Section 5 and Section 6. Section 5 and Section 6.
9. AR Procedures and EVPN All-Active Multi-homing Split-Horizon 9. AR Procedures and EVPN All-Active Multi-homing Split-Horizon
This section extends the procedures for the cases where two or more This section extends the procedures for the cases where two or more
AR-LEAF nodes are attached to the same Ethernet Segment, and two or AR-LEAF nodes are attached to the same Ethernet Segment, and two or
more AR-REPLICATOR nodes are attached to the same Ethernet Segment in more AR-REPLICATOR nodes are attached to the same Ethernet Segment in
the BD. The mixed case, that is, an AR-LEAF node and an AR- the BD. The mixed case, that is, an AR-LEAF node and an AR-
REPLICATOR node are attached to the same Ethernet Segment, is out of REPLICATOR node are attached to the same Ethernet Segment, would
scope. require extended procedures and it is out of scope.
9.1. Ethernet Segments on AR-LEAF Nodes 9.1. Ethernet Segments on AR-LEAF Nodes
If VXLAN or NVGRE are used, and if the Split-horizon is based on the If VXLAN or NVGRE are used, and if the Split-horizon is based on the
tunnel IP SA and "Local-Bias" as described in [RFC8365], the Split- tunnel IP Source Address and "Local-Bias" as described in [RFC8365],
horizon check will not work if there is an Ethernet-Segment shared the Split-horizon check will not work if there is an Ethernet-Segment
between two AR-LEAF nodes, and the AR-REPLICATOR replaces the tunnel shared between two AR-LEAF nodes, and the AR-REPLICATOR replaces the
IP Source Address of the packets with its own AR-IP. tunnel IP Source Address of the packets with its own AR-IP.
In order to be compatible with the IP Source Address split-horizon In order to be compatible with the IP Source Address split-horizon
check, the AR-REPLICATOR MAY keep the original received tunnel IP check, the AR-REPLICATOR MAY keep the original received tunnel IP
Source Address when replicating packets to a remote AR-LEAF or RNVE. Source Address when replicating packets to a remote AR-LEAF or RNVE.
This will allow AR-LEAF nodes to apply Split-horizon check procedures This will allow AR-LEAF nodes to apply Split-horizon check procedures
for BM packets, before sending them to the local Ethernet-Segment. for BM packets, before sending them to the local Ethernet-Segment.
Even if the AR-LEAF's IP Source Address is preserved when replicating Even if the AR-LEAF's IP Source Address is preserved when replicating
to AR-LEAFs or RNVEs, the AR-REPLICATOR MUST always use its IR-IP as to AR-LEAFs or RNVEs, the AR-REPLICATOR MUST always use its IR-IP as
the IP Source Address when replicating to other AR-REPLICATORs. the IP Source Address when replicating to other AR-REPLICATORs.
skipping to change at page 29, line 22 skipping to change at page 29, line 37
mechanisms provide the required split-horizon behavior in non- mechanisms provide the required split-horizon behavior in non-
selective or selective AR. selective or selective AR.
Note that if the AR-REPLICATOR implementation keeps the received Note that if the AR-REPLICATOR implementation keeps the received
tunnel IP Source Address, the use of uRPF (unicast Reverse Path tunnel IP Source Address, the use of uRPF (unicast Reverse Path
Forwarding) checks in the IP fabric based on the tunnel IP Source Forwarding) checks in the IP fabric based on the tunnel IP Source
Address MUST be disabled. Address MUST be disabled.
9.2. Ethernet Segments on AR-REPLICATOR nodes 9.2. Ethernet Segments on AR-REPLICATOR nodes
Ethernet Segments associated with one or more AR-REPLICATOR nodes AR-REPLICATOR nodes attached to the same all-active Ethernet Segment
SHOULD follow "Local-Bias" procedures for EVPN all-active multi- will follow "Local-Bias" procedures [RFC8365], as follows:
homing, as follows:
a. For BUM traffic received on a local AR-REPLICATOR's Attachment a. For BUM traffic received on a local AR-REPLICATOR's Attachment
Circuit, "Local-Bias" procedures as in [RFC8365] SHOULD be Circuit, "Local-Bias" procedures as in [RFC8365] MUST be
followed. followed.
b. For BUM traffic received on an AR-REPLICATOR overlay tunnel with b. For BUM traffic received on an AR-REPLICATOR overlay tunnel with
AR-IP as the IP Destination Address, "Local-Bias" SHOULD also be AR-IP as the IP Destination Address, "Local-Bias" MUST also be
followed. That is, traffic received with AR-IP as IP Destination followed. That is, traffic received with AR-IP as IP Destination
Address will be treated as though it had been received on a local Address will be treated as though it had been received on a local
Attachment Circuit that is part of the Ethernet Segment and will Attachment Circuit that is part of the Ethernet Segment and will
be forwarded to all local Ethernet Segments, irrespective of be forwarded to all local Ethernet Segments, irrespective of
their DF or NDF state. their DF or NDF state.
c. BUM traffic received on an AR-REPLICATOR overlay tunnel with IR- c. BUM traffic received on an AR-REPLICATOR overlay tunnel with IR-
IP as the IP Destination Address, will follow regular [RFC8365] IP as the IP Destination Address, will follow regular [RFC8365]
"Local-Bias" rules and will not be forwarded to local Ethernet "Local-Bias" rules and will not be forwarded to local Ethernet
Segments that are shared with the AR-LEAF or AR-REPLICATOR Segments that are shared with the AR-LEAF or AR-REPLICATOR
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d. In cases where the AR-REPLICATOR supports a single IP address, d. In cases where the AR-REPLICATOR supports a single IP address,
the IR-IP and the AR-IP are the same IP address, as discussed in the IR-IP and the AR-IP are the same IP address, as discussed in
Section 8. The received BUM traffic will be treated as in 'b' Section 8. The received BUM traffic will be treated as in 'b'
above if the received VNI is the AR-VNI, and as in 'c' if the VNI above if the received VNI is the AR-VNI, and as in 'c' if the VNI
is the IR-VNI. is the IR-VNI.
10. Security Considerations 10. Security Considerations
The Security Considerations in [RFC7432] and [RFC8365] apply to this The Security Considerations in [RFC7432] and [RFC8365] apply to this
document. document. The Security Considerations related to the Leaf Auto-
Discovery route in [I-D.ietf-bess-evpn-bum-procedure-updates] apply
too.
In addition, the Assisted-Replication method introduced by this In addition, the Assisted-Replication method introduced by this
document may bring some new risks for the successful delivery of BM document may bring some new risks for the successful delivery of BM
traffic. Unicast traffic is not affected by Assisted-Replication traffic. Unicast traffic is not affected by Assisted-Replication
(although Unknown unicast traffic is affected by the Pruned-Flood- (although Unknown unicast traffic is affected by the Pruned-Flood-
Lists procedures). The forwarding of Broadcast and Multicast (BM) Lists procedures). The forwarding of Broadcast and Multicast (BM)
traffic is modified; and BM traffic from the AR-LEAF nodes will be traffic is modified; and BM traffic from the AR-LEAF nodes will be
attracted by the existence of AR-REPLICATORs in the BD. An AR-LEAF attracted by the existence of AR-REPLICATORs in the BD. An AR-LEAF
will forward BM traffic to its selected AR-REPLICATOR, therefore an will forward BM traffic to its selected AR-REPLICATOR, therefore an
attack on the AR-REPLICATOR could impact the delivery of the BM attack on the AR-REPLICATOR could impact the delivery of the BM
traffic using that node. traffic using that node. Also, an attack on the AR-REPLICATOR and
change of the advertised AR type will modify the selection on the AR-
LEAF nodes. If no other AR-REPLICATOR is selected, the AR-LEAF nodes
will be forced to use Ingress Replication forwarding mode, which will
impact on their performance, since the AR-LEAF nodes are usually
NVEs/PEs with poor replication performance.
This document introduces the ability for the AR-REPLICATOR to forward This document introduces the ability for the AR-REPLICATOR to forward
traffic received on an overlay tunnel to another overlay tunnel. The traffic received on an overlay tunnel to another overlay tunnel. The
reader may interpret that this introduces the risk of BM loops. That reader may interpret that this introduces the risk of BM loops. That
is, an AR-LEAF receiving a BM encapsulated packet that the AR-LEAF is, an AR-LEAF receiving a BM encapsulated packet that the AR-LEAF
originated in the first place, due to one or two AR-REPLICATORs originated in the first place, due to one or two AR-REPLICATORs
"looping" the BM traffic back to the AR-LEAF. The procedures in this "looping" the BM traffic back to the AR-LEAF. The procedures in this
document prevent these BM loops, since the AR-REPLICATOR will always document prevent these BM loops, since the AR-REPLICATOR will always
forward the BM traffic using the correct tunnel IP Destination forward the BM traffic using the correct tunnel IP Destination
Address that instructs the remote nodes how to forward the traffic. Address (or correct VNI in case of single-IP AR-REPLICATORs) that
This is true in both the Non-Selective and Selective modes defined in instructs the remote nodes how to forward the traffic. This is true
this document. However, a wrong implementation of the procedures in in both the Non-Selective and Selective modes defined in this
this document may lead to those unexpected BM loops. document. However, a wrong implementation of the procedures in this
document may lead to those unexpected BM loops.
The Selective mode provides a multi-staged replication solution, The Selective mode provides a multi-staged replication solution,
where a proper configuration of all the AR-REPLICATORs will avoid any where a proper configuration of all the AR-REPLICATORs will avoid any
issues. A mix of mistakenly configured Selective and Non-Selective issues. A mix of mistakenly configured Selective and Non-Selective
AR-REPLICATORs in the same BD could theoretically create packet AR-REPLICATORs in the same BD could theoretically create packet
duplication in some AR-LEAFs, however this document specifies a fall duplication in some AR-LEAFs, however this document specifies a fall
back solution to Non-Selective mode in case the AR-REPLICATORs back solution to Non-Selective mode in case the AR-REPLICATORs
advertised an inconsistent AR Replication mode. advertised an inconsistent AR Replication mode.
This document allows the AR-REPLICATOR to preserve the tunnel IP
Source Address of the AR-LEAF (as an option) when forwarding BM
packets from an overlay tunnel to another overlay tunnel. Preserving
the AR-LEAF IP Source Address makes the "Local Bias" filtering
procedures possible for AR-LEAF nodes that are attached to the same
Ethernet Segment. If the AR-REPLICATOR does not preserve the AR-LEAF
IP Source Address, AR-LEAF nodes attached to all-active Ethernet
Segments will cause packet duplication on the multi-homed CE.
The AR-REPLICATOR nodes are, by design, using more bandwidth than
[RFC7432] PEs or [RFC8365] NVEs would use. Certain network events or
unexpected low performance may exceed the AR-REPLICATOR local
bandwidth and cause service disruption.
Finally, the use of PFL as in Section 7, should be handled with care. Finally, the use of PFL as in Section 7, should be handled with care.
An intentional or unintentional misconfiguration of the BDs on a An intentional or unintentional misconfiguration of the BDs on a
given leaf node may result in the leaf not receiving the required BM given leaf node may result in the leaf not receiving the required BM
or Unknown unicast traffic. or Unknown unicast traffic.
11. IANA Considerations 11. IANA Considerations
IANA has allocated the following Border Gateway Protocol (BGP) IANA has allocated the following Border Gateway Protocol (BGP)
Parameters: Parameters:
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