Internet DRAFT - draft-ietf-bess-evpn-lsp-ping
draft-ietf-bess-evpn-lsp-ping
BESS Workgroup P. Jain
Internet-Draft A. Sajassi
Intended status: Standards Track S. Salam
Expires: 30 November 2023 Cisco
S. Boutros
Ciena
G. Mirsky
Ericsson
29 May 2023
LSP-Ping Mechanisms for EVPN and PBB-EVPN
draft-ietf-bess-evpn-lsp-ping-11
Abstract
LSP Ping is a widely deployed Operation, Administration, and
Maintenance mechanism in MPLS networks. This document describes
mechanisms for detecting data plane failures using LSP Ping in MPLS
based Ethernet VPN (EVPN) and Provider Backbone Bridging with EVPN
(PBB-EVPN) networks.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 30 November 2023.
Copyright Notice
Copyright (c) 2023 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
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Proposed Target FEC Stack Sub-TLVs . . . . . . . . . . . . . 4
4.1. EVPN MAC/IP Sub-TLV . . . . . . . . . . . . . . . . . . . 4
4.2. EVPN Inclusive Multicast Sub-TLV . . . . . . . . . . . . 7
4.3. EVPN Ethernet Auto-Discovery Sub-TLV . . . . . . . . . . 8
4.3.1. Ethernet TAG Value . . . . . . . . . . . . . . . . . 9
4.3.2. Per-ES EVPN Auto-Discovery Route with different
RDs . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.3.3. EVPN VPWS . . . . . . . . . . . . . . . . . . . . . . 10
4.4. EVPN IP Prefix Sub-TLV . . . . . . . . . . . . . . . . . 10
5. Encapsulation of OAM Ping Packets . . . . . . . . . . . . . . 12
6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Unicast Data-plane connectivity checks . . . . . . . . . 12
6.2. Inclusive Multicast Data-plane Connectivity Checks . . . 14
6.2.1. Ingress Replication . . . . . . . . . . . . . . . . . 14
6.2.2. Using P2MP P-tree . . . . . . . . . . . . . . . . . . 15
6.2.3. Controlling Echo Responses when using P2MP P-tree . . 16
6.3. EVPN Aliasing Data-plane connectivity check . . . . . . . 17
6.4. EVPN IP Prefix (RT-5) Data-plane connectivity check . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
8.1. Sub-TLV Type . . . . . . . . . . . . . . . . . . . . . . 18
8.2. Proposed new Return Codes . . . . . . . . . . . . . . . . 18
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
10. Normative References . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
[RFC7432] describes MPLS based EVPN technology. An EVPN comprises
CE(s) connected to PE(s). The PEs provide layer-2 EVPN among the
CE(s) over the MPLS core infrastructure. In EVPN networks, the PEs
advertise the MAC addresses learned from the locally connected CE(s),
along with MPLS Label, to remote PE(s) in the control plane using
multiprotocol BGP [RFC4760]. EVPN enables multihoming of CE(s)
connected to multiple PEs and load balancing of traffic to and from
multihomed CE(s).
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[RFC7623] describes the use of Provider Backbone Bridging [802.1ah]
with EVPN. PBB-EVPN maintains the Customer MAC (C-MAC) learning in
data plane and only advertises Provider Backbone MAC (B-MAC)
addresses in control plane using BGP.
Procedures for simple and efficient mechanisms to detect data plane
failures using LSP Ping in MPLS network are well defined in [RFC8029]
and [RFC6425]. The basic idea for the LSP Ping mechanism is to send
a MPLS Echo Request packet along the same data path as data packets
belonging to the same Forwarding Equivalent Class (FEC). The Echo
Request packet carries the FEC being verified in the Target FEC Stack
TLV [RFC8029]. Once the Echo Request packet reaches the end of the
MPLS path, it is sent to the control plane of the egress PE. The
Echo Request packet contains sufficient information to verify the
correctness of data plane operations and validate data plane against
the control plane. The Egress PE sends the results of the validation
in an Echo Reply packet to the originating PE of the Echo Request
packet.
This document defines procedures to detect data plane failures using
LSP Ping in MPLS networks deploying EVPN and PBB-EVPN. This document
defines four new Sub-TLVs for Target FEC Stack TLV with the purpose
of identifying the FEC on the Egress PE.
2. Specification of Requirements
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
AD: Auto Discovery
B-MAC: Backbone MAC Address
BUM: Broadcast, Unknown Unicast or Multicast
CE: Customer Edge Device
C-MAC: Customer MAC Address
DF: Designated Forwarder
ES: Ethernet Segment
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ESI: Ethernet Segment Identifier
EVI: EVPN Instance Identifier that globally identifies the EVPN
Instance
EVPN: Ethernet Virtual Private Network
FEC: Forwarding Equivalent Classs
G-ACh: Generic Associated Channel
GAL: G-ACh Label
OAM: Operations, Administration, and Maintenance
P2MP: Point-to-Multipoint
PBB-EVPN: Provider Backbone Bridge with EVPN
PE: Provider Edge Device
VPWS: Virtual Private Wire Service
4. Proposed Target FEC Stack Sub-TLVs
This document introduces four new Target FEC Stack Sub-TLVs that are
included in the MPLS Echo Request packet. The Echo Request packets
are used for connectivity check in data plane in EVPN and PBB-EVPN
networks. The target FEC stack Sub-TLVs MAY be used to validate that
an identifier for a given EVPN is programmed at the target node.
4.1. EVPN MAC/IP Sub-TLV
The EVPN MAC/IP Sub-TLV identifies the target MAC, MAC/IP binding for
ARP/ND, or IP address for an EVPN Instance Identifier (EVI) under
test at an egress PE. This Sub-TLV is included in the Echo Request
sent by a EVPN/PBB-EVPN PE to a Peer PE.
The EVPN MAC/IP Sub-TLV fields are derived from the MAC/IP
Advertisement route defined in Section 7.2 in [RFC7432] and have the
format as shown in Figure 1. The fields of EVPN MAC/IP Sub-TLV
should be set according to the following that is consistent with
[RFC7432] and [RFC7623]:
* The Route Distinguisher (RD) field is a 10-octet field and is set
to the RD of the MAC-VRF on the Peer PE.
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* The Ethernet TAG ID field can be 0 or a valid VLAN ID for EVPN
VLAN-aware bundle service [RFC7432]. For PBB-EVPN, the value of
this field is always 0 as per Section 5.2 of [RFC7623].
* The Ethernet Segment Identifier field is 10-octet field. For
EVPN, it is set to 0 for singlehomed ES or to a valid ESI ID for a
multihomed ES. For PBB-EVPN, the Ethernet Segment Identifier
field must be set to either 0 (for single-homed segments or
multihomed segments with per-I-SID load-balancing) or to MAX-ESI
(for multihomed segments with per-flow load-balancing) as describe
in Section 5.2 in [RFC7623].
* The MAC Addr Len field specifies the MAC length in bits. Only 48
bit MAC Addresses are supported as this document follows MAC
address length supported by [RFC7432].
* The MAC Address field is set to the 6-octet MAC address.
* The IP Address field is optional. When the IP Address field is
not present, the IP Addr Len field is set to 0. When the IP
Address field is present, the IP Addr Len field is in bits and is
either set to 32 for IPv4 or 128 for IPv6 address.
* The Must Be Zero fields are set to 0. The receiving PE should
ignore the Must Be Zero fields.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Segment Identifier |
| (10 octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Must Be Zero | MAC Addr Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address |
+ (6 Octets) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Must Be Zero | IP Addr Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (0, 4 or 16 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EVPN MAC Sub-TLV format
The MPLS Echo Request is sent by the ingress PE using the EVPN MPLS
label(s) associated with the MAC/IP advertisement route announced by
the egress PE and the MPLS transport label(s) to reach the egress PE.
In EVPN, MAC/IP Advertisement has multiple personality and it is used
for the following cases:
* This route with only MAC address and MPLS Label1 is used for
populating MAC-VRF and performing MAC forwarding.
* This route with MAC and IP addresses and only MPLS Label1 is used
for populating both MAC-VRF and ARP/ND tables (for ARP
suppression) as well as for performing MAC forwarding
* This route with MAC and IP addresses and both MPLS Label1 and
Label2 is used for populating MAC-VRF and IP-VRF tables as well as
for both MAC forwarding, and IP forwarding in case of symmetric
IRB.
When MPLS Echo Request is sent by an ingress PE, the contents of Echo
Request and the egress PE mode of operation (i.e., IRB mode or L2
mode) along with EVPN MPLS label of the packet, determine which of
the above three cases is this Echo Request for. When the egress PE
receives MAC/IP Sub-TLV containing only MAC address, the egress PE
validates the MAC state and forwarding. When the egress PE receives
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MAC/IP Sub-TLV containing both MAC and IP addresses and if the EVPN
label points to a MAC-VRF, then the egress PE validates the MAC state
and forwarding. If the egress PE is not configured in symmetric IRB
mode, it also validates ARP/ND state. However, if the EVPN label
points to an IP-VRF, then the egress PE validates IP state and
forwarding. Any other combinations, such as the egress PE receiving
MAC/IP Sub-TLV containing only MAC address but with EVPN label
pointing to an IP-VRF, should be considered invalid and Echo Reply
should be sent with the appropriate return code by the egress PE to
the ingress PE.
4.2. EVPN Inclusive Multicast Sub-TLV
The EVPN Inclusive Multicast Sub-TLV fields are based on the EVPN
Inclusive Multicast Tag route defined in [RFC7432] Section 7.3. This
TLV is included in the Echo Request sent to the EVPN peer PE by the
originator of request to verify the multicast connectivity state on
the peer PE(s) in EVPN and PBB-EVPN networks.
The EVPN Inclusive Multicast Sub-TLV has the format as shown in
Figure 2. The fields of this Sub-TLV should be set according to the
following that is consistent with [RFC7432] and [RFC7623]:
* The Route Distinguisher (RD) field is a 10-octet field and is set
to the RD of the MAC-VRF on the Peer PE.
* For EVPN, the Ethernet TAG ID field can be set to 0 or a valid
VLAN ID for EVPN VLAN-aware bundle service [RFC7432]. For PBB-
EVPN, the value of this field is set to Service Instance
Identifier (I-SID) value as per Section 5.3 of [RFC7623].
* The IP Addr Len field specifies length of the Originating Router's
IP Addr field in bits and it is either set to 32 for IPv4 or 128
for IPv6 address.
* The Originating Router's IP Addr field is set to IPv4 or IPv6
address of the peer PE.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Addr Len | |
+-+-+-+-+-+-+-+ |
~ Originating Router's IP Addr ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: EVPN Inclusive Multicast Sub-TLV format
Broadcast, unknown unicast or multicast (BUM) traffic can be sent
using ingress replication or P2MP P-tree in EVPN and PBB-EVPN
network. In case of ingress replication, the Echo Request is sent
using a label stack of [Transport label, Inclusive Multicast label]
to each egress PE participating in EVPN or PBB-EVPN. The inclusive
multicast label is the downstream assigned label announced by the
egress PE to which the Echo Request is being sent. The Inclusive
Multicast label is the inner label in the MPLS label stack.
When using P2MP P-tree in EVPN or PBB-EVPN, the Echo Request is sent
using P2MP P-tree transport label for inclusive P-tree arrangement or
using a label stack of [P2MP P-tree transport label, upstream
assigned EVPN Inclusive Multicast label] for the aggregate inclusive
P2MP P-tree arrangement as described in Section 6.
In case of EVPN, to emulate traffic coming from a multihomed site, an
additional EVPN Ethernet Auto-Discovery Sub-TLV in the Target FEC
stack TLV and ESI Split Horizon Group MPLS label as the bottom label,
are also included in the Echo Request packet. When using P2MP
P-tree, the ESI Split Horizon Group MPLS label is upstream assigned.
Please see Section 6.2.2 for operations using P2MP P-trees.
4.3. EVPN Ethernet Auto-Discovery Sub-TLV
The EVPN Ethernet Auto-Discovery (AD) Sub-TLV fields are based on the
EVPN Ethernet Auto-Discovery route advertisement defined in [RFC7432]
Section 7.1. EVPN Ethernet AD Sub-TLV applies to only EVPN.
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The EVPN Ethernet AD Sub-TLV has the format shown in Figure 3. The
fields of this Sub-TLV should be set according to the following that
is consistent with [RFC7432]:
* The Route Distinguisher (RD) field is a 10-octet field and is set
to the RD of the MAC-VRF on the Peer PE. Please see Section 4.3.2
below for the case when per-ES AD route is announced with
different RDs
* The Ethernet TAG ID field can be 0, MAX-ET or a valid VLAN ID as
described in Section 4.3.1 below.
* The Ethernet Segment Identifier field is 10-octet field and is set
to 0 for singlehomed ES or to a valid ESI ID for a multihomed ES.
* The Must Be Zero field is set to 0. The receiving PE should
ignore the Must Be Zero field.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Segment Identifier |
| (10 octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: EVPN Ethernet Auto-Discovery Sub-TLV format
4.3.1. Ethernet TAG Value
EVPN Ethernet AD Sub-TLV can be sent in the context of per-Ethernet
Segment (ES) or per-EVI. When an operator performs a connectivity
check for the BUM L2 service, Echo Request packet sent, MAY contain
EVPN Ethernet AD Sub-TLV to emulate traffic coming from a multihomed
site. In this case, the EVPN Ethernet AD Sub-TLV is added in per-ES
context. When Echo Request packet is sent for the connectivity check
for EVPN Aliasing state, the context for the EVPN Ethernet AD Sub-TLV
is per-EVI.
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Ethernet Tag field value in EVPN Ethernet AD Sub-TLV, MUST be set
according to the context:
* For per-ES context, the Ethernet Tag field in the sub-TLV MUST be
set to the reserved MAX-ET value [RFC7432]
* For per-EVI context, the Ethernet Tag field in the sub-TLV MUST be
set to the non-reserved value
4.3.2. Per-ES EVPN Auto-Discovery Route with different RDs
Section 8.2 of [RFC7432] specifies that a per-ES EVPN AD route for a
given multihomed ES, may be advertised more than once with different
RD values because many EVIs may be associated with the same ES and
Route Targets for all these EVIs may not fit in a single BGP Update
message. In this case, the RD value used in the EVPN Ethernet AD
Sub-TLV, MUST be the RD value received for the EVI in the per-ES EVPN
AD Route.
4.3.3. EVPN VPWS
LSP Ping can also be used to detect data plane failures for EVPN
Virtual Private Wire Service (VPWS) described in [RFC8214]. The Echo
Request packet carries EVPN Ethernet AD Sub-TLV with fields populated
from the EVPN Ethernet AD per EVI route announced by the egress PE
for the EVPN VPWS under test. The Echo Request is sent by the
ingress PE using the EVPN MPLS label associated with the EVPN
Ethernet AD route announced by the egress PE and the MPLS transport
label(s) to reach the egress PE.
The egress PE process the Echo Request packet and perform checks for
the EVPN Ethernet AD Sub-TLV present in the Target FEC Stack TLV as
described in Section 4.4 in [RFC8029] and respond according to
[RFC8029] processing rule. Egress PE can identify that the Echo
Request is for EVPN VPWS instance as EVI (identified by the RD) for
EVPN VPWS is different from that for EVPN. The egress PE will use
the information from the EVPN Ethernet AD Sub-TLV in the Target FEC
Stack TLV and validate the VLAN state for the EVPN VPWS under test.
For the success case, the egress PE will reply with Return Code 3 -
"Replying router is an egress for the FEC at stack-depth".
4.4. EVPN IP Prefix Sub-TLV
The EVPN IP Prefix Sub-TLV identifies the IP Prefix for an EVI under
test at a peer PE.
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The EVPN IP Prefix Sub-TLV fields are derived from the IP Prefix
Route (RT-5) advertisement defined in [RFC9136]. This sub-TLV
applies to only EVPN.
The EVPN IP Prefix Sub-TLV has the format shown in Figure 4. The
total length (not shown) of this sub-TLV MUST be either 32 bytes (if
IPv4 addresses are carried) or 56 bytes (if IPv6 addresses are
carried). The IP prefix and gateway IP address MUST be from the same
IP address family, as described in Section 3.1 of [RFC9136].
The fields of EVPN IP Prefix Sub-TLV should be set according to the
following that is consistent with [RFC9136]:
* The Route Distinguisher (RD) field is a 10-octet field and is set
to the RD of the IP-VRF on the Peer PE.
* The Ethernet TAG ID field can be 0 or a valid VLAN ID for EVPN
VLAN-aware bundle service [RFC7432].
* The Ethernet Segment Identifier field is 10-octet field and is set
to a valid ESI ID if ESI is used as Overlay Index as per
Section 3.1 of [RFC9136]. Otherwise the Ethernet Segment
Identifier field is set to all 0s.
* The IP Prefix Len field specifies the number of bits in the IP
Prefix field. It is set to between 0 and 32 for IPv4 or between 0
to 128 for IPv6.
* The IP prefix field is set to a 4-octet IPv4 address (with
trailing 0 bits to make 32 bits in all) or 16-octet IPv6 address
(with trailing 0 bits to make 128 bits in all). The address
family of this field is inferred from the sub-TLV length field, as
discussed above.
* The Gateway (GW) IP Address field is set to a 4-octet IPv4 address
or 16-octet IPv6 address if it's used as an Overlay Index for the
IP prefixes. If the GW IP Address is not being used, it must be
set to 0 as described in Section 3.1 of [RFC9136]. The address
family of this field is inferred from the sub-TLV length field, as
discussed above.
* The Must Be Zero field is set to 0. The receiving PE should
ignore the Must Be Zero field.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Segment Identifier |
| (10 octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Must Be Zero | IP Prefix Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ IP Prefix (4 or 16 Octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ GW IP Address (4 or 16 Octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: EVPN IP Prefix Sub-TLV format
The MPLS Echo Request is sent by the ingress PE using the EVPN MPLS
label(s) associated with the IP Prefix route announced by the egress
PE and the MPLS transport label(s) to reach the egress PE.
5. Encapsulation of OAM Ping Packets
The MPLS Echo Request IP/UDP packets MUST be encapsulated with the
Transport and EVPN Label(s) followed by the Generic Associated
Channel Label (GAL) [RFC5586] which is the bottom most label. The
GAL is followed by a Generic Associated Channel Header carrying
IPv4(0x0021) or IPv6(0x0057) Channel Type. The code points for IPv4
and IPv6 channels are defined in Generic Associated Channel (G-ACh)
Parameters by IANA.
6. Operations
6.1. Unicast Data-plane connectivity checks
Figure 5 is an example of a PBB-EVPN network. CE1 is dual-homed to
PE1 and PE2. Assume, PE1 announced a MAC route with RD 192.0.2.1:00
and B-MAC 00-AA-00-BB-00-CC and with MPLS label 16001 for EVI 10.
Similarly, PE2 announced a MAC route with RD 203.0.113.2:00 and B-MAC
00-AA-00-BB-00-CC and with MPLS label 16002.
On PE3, when an operator performs a connectivity check for the B-MAC
address 00-AA-00-BB-00-CC on PE1, the operator initiates an LSP Ping
request with the target FEC stack TLV containing EVPN MAC Sub-TLV in
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the Echo Request packet. The Echo Request packet is sent with the
{Transport Label(s) to reach PE1, EVPN Label = 16001, GAL} MPLS label
stack and IP ACH Channel header. Once the Echo Request packet
reaches PE1, PE1 will use the GAL and the IP ACH Channel header to
determine that the packet is IPv4 or IPv6 OAM Packet. The PE1 will
process the packet and perform checks for the EVPN MAC Sub-TLV
present in the Target FEC Stack TLV as described in Section 4.4 in
[RFC8029] and respond according to [RFC8029] processing rules.
+-----------------+
| |
| |
+----+ AC1 +-----+ +-----+ +----+
| CE1|------| | | PE3 |-----| CE2|
+----+\ | PE1 | IP/MPLS | | +----+
\ +-----+ Network +-----+
\ | |
AC2\ +-----+ |
\ | | |
\| PE2 | |
+-----+ |
| |
+-----------------+
<-802.1Q-> <------PBB over MPLS------> <-802.1Q->
Figure 5: PBB-EVPN network
Similarly, on PE3, when an operator performs a connectivity check for
the B-MAC address 00-AA-00-BB-00-CC on PE2, the operator initiates an
LSP Ping request with the target FEC stack TLV containing EVPN MAC
Sub-TLV in the Echo Request packet. The Echo Request packet is sent
with the {MPLS transport Label(s) to reach PE2, EVPN Label = 16002,
GAL} MPLS label stack and IP ACH Channel header.
LSP Ping operation for unicast data plane connectivity checks in
EVPN, are similar to those described above for PBB-EVPN except that
the checks are for C-MAC addresses instead of B-MAC addresses.
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In EVPN network, an operator can also perform MAC state test using
aliasing label for the MAC to verify the MAC state on the egress
multihoming PE that did not learn the MAC from the multihomed CE on a
local ESI but has announced Ethernet AD per-EVI and per-ESI routes
for the ESI. This is due to the fact that MAC state on multihoming
PEs that did not learn the MAC locally, get created from EVPN MAC/IP
route advertisement from the multihoming PE that has learned the CE's
MAC address locally.
6.2. Inclusive Multicast Data-plane Connectivity Checks
6.2.1. Ingress Replication
Assume PE1 announced an Inclusive Multicast route for EVI 10, with RD
192.0.2.1:00, Ethernet Tag (ISID 10), PMSI tunnel attribute Tunnel
type set to ingress replication and downstream assigned inclusive
multicast MPLS label 17001. Similarly, PE2 announced an Inclusive
Multicast route for EVI 10, with RD 203.0.113.2:00, Ethernet Tag
(ISID 10), PMSI tunnel attribute Tunnel type set to ingress
replication and downstream assigned inclusive multicast MPLS label
17002.
Given CE1 is dual-homed to PE1 and PE2, assume that PE1 is the DF for
ISID 10 for the port corresponding to the ESI 11aa.22bb.33cc.
44dd.5500.
When an operator at PE3 initiates a connectivity check for the
inclusive multicast on PE1, the operator initiates an LSP Ping
request with the target FEC stack TLV containing EVPN Inclusive
Multicast Sub-TLV in the Echo Request packet. The Echo Request
packet is sent with the {Transport Label(s) to reach PE1, EVPN Incl.
Multicast Label = 17001, GAL} MPLS label stack and IP ACH Channel
header. Once the Echo Request packet reaches PE1, PE1 will use the
GAL and the IP ACH Channel header to determine that the packet is
IPv4 or IPv6 OAM Packet. The packet will have EVPN Inclusive
multicast label. PE1 will process the packet and perform checks for
the EVPN Inclusive Multicast Sub-TLV present in the Target FEC Stack
TLV as described in Section 4.4 in [RFC8029] and respond according to
[RFC8029] processing rules. For the success case, PE1 will reply
with Return Code 3 - "Replying router is an egress for the FEC at
stack-depth".
Similarly, an operator at PE3, may initiate an LSP Ping to PE2 with
the target FEC stack TLV containing EVPN Inclusive Multicast sub-TLV
in the Echo Request packet. The Echo Request packet is sent with the
{transport Label(s) to reach PE2, EVPN Incl. Multicast Label =
17002, GAL} MPLS label stack and IP ACH Channel header. Once the
Echo Request packet reaches PE2, PE2 will use the GAL and the IP ACH
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Channel header to determine that the packet is IPv4 or IPv6 OAM
Packet. The processing on PE2 will be similar to the that on PE1 as
described above and for the success case, PE2 will reply with Return
Code 3 - "Replying router is an egress for the FEC at stack-depth" as
per [RFC8029].
In case of EVPN, in the Echo Request packet, an EVPN Ethernet AD Sub-
TLV and the associated MPLS Split Horizon Label above the GAL in the
MPLS label stack, may be added to emulate traffic coming from a
multihomed site. The Split Horizon label is used by leaf PE(s)
attached to the same multihomed site to not forward packets back to
the multihomed site. If the behavior on a leaf PE is to not forward
the packet to the multihomed site on the ESI identified by EVPN
Ethernet AD Sub-TLV because of Split Horizon filtering, the PE will
reply with a Return Code indicating that "Replying router is egress
for the FEC at the stack depth. In addition, the BUM packets are
dropped on the ES corresponding to the ESI received in EVPN Ethernet
AD Sub-TLV because of the Split Horizon Group filtering" as described
in Section 8.
6.2.2. Using P2MP P-tree
Both inclusive P-Tree and aggregate inclusive P-tree can be used in
EVPN or PBB-EVPN networks.
When using an inclusive P-tree arrangement, p2mp p-tree transport
label itself is used to identify the L2 service associated with the
Inclusive Multicast Route, this L2 service could be a customer
Bridge, or a Provider Backbone Bridge.
For an Inclusive P-tree arrangement, when an operator performs a
connectivity check for the multicast L2 service, the operator
initiates an LSP Ping request with the target FEC stack TLV
containing EVPN Inclusive Multicast Sub-TLV in the Echo Request
packet. The Echo Request packet is sent over P2MP LSP with the {P2MP
P-tree label, GAL} MPLS label stack and IP ACH Channel header.
When using Aggregate Inclusive P-tree, a PE announces an upstream
assigned MPLS label along with the P-tree ID, so both the p2mp p-tree
MPLS transport label and the upstream MPLS label can be used to
identify the L2 service.
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For an Aggregate Inclusive P-tree arrangement, when an operator
performs a connectivity check for the multicast L2 service, the
operator initiates an LSP Ping request with the target FEC stack TLV
containing EVPN Inclusive Multicast Sub-TLV in the Echo Request
packet. The Echo Request packet is sent over P2MP LSP using the IP-
ACH Control channel with the {P2MP P-tree label, EVPN Upstream
assigned Multicast Label, GAL} MPLS label stack and IP ACH Channel
header.
The Leaf PE(s) of the p2mp tree will process the packet and perform
checks for the EVPN Inclusive Multicast Sub-TLV present in the Target
FEC Stack TLV as described in Section 4.4 in [RFC8029] and respond
according to [RFC8029] processing rules. For the success case, the
Leaf PE will reply with Return Code 3 - "Replying router is an egress
for the FEC at stack-depth".
In case of EVPN, in the Echo Request packet, an EVPN Ethernet AD Sub-
TLV and the associated MPLS Split Horizon Label above the GAL in MPLS
label stack, may be added to emulate traffic coming from a multihomed
site. In case of p2mp p-tree, the Split Horizon Label is upstream
assigned and is received by all the leaf PEs of the p2mp-ptree. The
Split Horizon label is used by leaf PE(s) attached to the same
multihomed site not to forward packets back to the multihomed site.
If the behavior on a leaf PE is to not forward the packet to the
multihomed site on the ESI in EVPN Ethernet AD Sub-TLV because of
Split Horizon filtering, the PE will reply with a Return Code
indicating that "Replying router is egress for the FEC at the stack
depth. In addition, the BUM packets are dropped on the ES
corresponding to the ESI received in EVPN Ethernet AD Sub-TLV because
of the Split Horizon Group filtering" as described in Section 8. If
the leaf PE does not have the ESI identified in the EVPN Ethernet AD
Sub-TLV, the PE can reply with a Return Code indicating that
"Replying router is egress for the FEC at the stack depth. In
addition, the BUM packets are forwarded because there is no ES
corresponding to the ESI received in EVPN Ethernet AD Sub-TLV".
6.2.3. Controlling Echo Responses when using P2MP P-tree
The procedures described in [RFC6425] for preventing congestion of
Echo Responses (Echo Jitter TLV) and limiting the Echo Reply to a
single egress node (Node Address P2MP Responder Identifier TLV) can
be applied to LSP Ping in EVPN and PBB-EVPN when using P2MP P-trees
for broadcast, multicast, and unknown unicast traffic.
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6.3. EVPN Aliasing Data-plane connectivity check
Assume PE1 announced an Ethernet AD per-EVI Route with the ESI set to
CE1 system ID and MPLS label 19001, and PE2 an Ethernet AD per-EVI
Route with the ESI set to CE1 system ID and MPLS label 19002.
At PE3, when an operator performs a connectivity check for the
aliasing aspect of the EVPN Ethernet AD route on PE1, the operator
initiates an LSP Ping request with the target FEC stack TLV
containing EVPN Ethernet AD Sub-TLV in the Echo Request packet. The
Echo Request packet is sent with the {Transport label(s) to reach
PE1, EVPN Ethernet AD Label 19001, GAL} MPLS label stack and IP ACH
Channel header.
When PE1 receives the packet it will process the packet and perform
checks for the EVPN Ethernet AD Sub-TLV present in the Target FEC
Stack TLV as described in Section 4.4 in [RFC8029] and respond
according to [RFC8029] processing rules.
6.4. EVPN IP Prefix (RT-5) Data-plane connectivity check
Assume PE1 in Figure 5, announced an IP Prefix Route (RT-5) with an
IP prefix reachable behind CE1 and MPLS label 20001. When an
operator on PE3 performs a connectivity check for the IP prefix on
PE1, the operator initiates an LSP Ping request with the target FEC
stack TLV containing EVPN IP Prefix Sub-TLV in the Echo Request
packet. The Echo Request packet is sent with the {Transport label(s)
to reach PE1, EVPN IP Prefix Label 20001 } MPLS label stack.
When PE1 receives the packet it will process the packet and perform
checks for the EVPN IP Prefix Sub-TLV present in the Target FEC Stack
TLV as described in Section 4.4 in [RFC8029] and respond according to
[RFC8029] processing rules.
7. Security Considerations
The proposal introduced in this document does not introduce any new
security considerations beyond that already apply to [RFC7432],
[RFC7623] and [RFC6425]. Furthermore, the security considerations
discussed in [RFC8029] apply to this document and need to be
considered. As described in [RFC8029], these security considerations
are:
* Denial-of-Service (DoS) attack, by sending MPLS echo requests/
replies to LSRs and thereby increasing their workload.
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* Obfuscating the state of the MPLS data-plane liveness by spoofing,
hijacking, replaying, or otherwise tampering with MPLS echo
Requests and replies.
* Obtaining information about the network by an unauthorized source
using an LSP ping.
There are mitigations described in [RFC8029]. The same mitigations
can be applied to the LSP Ping procedures described in this draft and
thus this document doesn't require additional security considerations
beyond the one described in [RFC8029].
The proposal does not introduce any new privacy concerns because
these TLVs contain the same information that are present in data
packets and EVPN routes.
8. IANA Considerations
8.1. Sub-TLV Type
This document defines four new Sub-TLV type to be included in Target
FEC Stack TLV (TLV Type 1, 16 and 21) [RFC9041] in Echo Request and
Echo Reply messages in EVPN and PBB-EVPN network.
IANA is requested to assign lowest 4 free values for the four Sub-
TLVs listed below from the Standards Action" (0-16383) range, in the
"Sub-TLVs for TLV Types 1, 16, and 21" sub-registry, in the "TLVs"
registry in the "Multiprotocol Label Switching (MPLS) Label Switched
Paths (LSPs) Ping Parameters" name space:
* EVPN MAC/IP Sub-TLV
* EVPN Inclusive Multicast Sub-TLV
* EVPN Auto-Discovery Sub-TLV
* EVPN IP Prefix Sub-TLV
8.2. Proposed new Return Codes
[RFC8029] defines values for the Return Code field of Echo Reply.
This document proposes two new Return Codes, which SHOULD be included
in the Echo Reply message by a PE in response to Echo Request message
in EVPN and PBB-EVPN network.
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IANA is requested to assign 2 lowest free values for the 2 Return
Codes listed below from the Return Codes" registry in the
"Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs)
Ping Parameters" name space:
* Replying router is egress for the FEC at the stack depth. In
addition, the BUM packets are dropped on the ES corresponding to
the ESI received in EVPN Ethernet AD Sub-TLV because of the Split
Horizon Group filtering.
* Replying router is egress for the FEC at the stack depth. In
addition, the BUM packets are forwarded because there is no ES
corresponding to the ESI received in EVPN Ethernet AD Sub-TLV.
9. Acknowledgments
The authors would like to thank Loa Andersson, Alexander Vainshtein,
Ron Sdayoor, Jim Guichard, Lars Eggert, John Scudder, Eric Vyncke,
Warren Kumari, Patrice Brissette and Weiguo Hao for their valuable
comments.
10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<https://www.rfc-editor.org/info/rfc5586>.
[RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
Failures in Point-to-Multipoint MPLS - Extensions to LSP
Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
<https://www.rfc-editor.org/info/rfc6425>.
[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>.
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[RFC7623] Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
Henderickx, "Provider Backbone Bridging Combined with
Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
September 2015, <https://www.rfc-editor.org/info/rfc7623>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[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>.
[RFC8214] Boutros, S., Sajassi, A., Salam, S., Drake, J., and J.
Rabadan, "Virtual Private Wire Service Support in Ethernet
VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017,
<https://www.rfc-editor.org/info/rfc8214>.
[RFC9041] Andersson, L., Chen, M., Pignataro, C., and T. Saad,
"Updating the MPLS Label Switched Paths (LSPs) Ping
Parameters IANA Registry", RFC 9041, DOI 10.17487/RFC9041,
July 2021, <https://www.rfc-editor.org/info/rfc9041>.
[RFC9136] Rabadan, J., Ed., Henderickx, W., Drake, J., Lin, W., and
A. Sajassi, "IP Prefix Advertisement in Ethernet VPN
(EVPN)", RFC 9136, DOI 10.17487/RFC9136, October 2021,
<https://www.rfc-editor.org/info/rfc9136>.
Authors' Addresses
Parag Jain
Cisco
Canada
Email: paragj@cisco.com
Ali Sajassi
Cisco
United States of America
Email: sajassi@cisco.com
Samer Salam
Cisco
Canada
Email: ssalam@cisco.com
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Sami Boutros
Ciena
United States of America
Email: sboutros@ciena.com
Greg Mirsky
Ericsson
United States of America
Email: gregimirsky@gmail.com
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