Data Plane Failure Detection Mechanisms for EVPN over SRv6
draft-liu-bess-srv6-evpn-validation-01
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Yao Liu | ||
| Last updated | 2024-08-02 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
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draft-liu-bess-srv6-evpn-validation-01
BESS Y. Liu
Internet-Draft ZTE
Intended status: Standards Track 2 August 2024
Expires: 3 February 2025
Data Plane Failure Detection Mechanisms for EVPN over SRv6
draft-liu-bess-srv6-evpn-validation-01
Abstract
This document proposes extension for ICMPv6 to detect data plane
failures for EVPN over SRv6.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 3 February 2025.
Copyright Notice
Copyright (c) 2024 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. ICMPv6 Messages . . . . . . . . . . . . . . . . . . . . . . . 4
5. Validation Information Objects . . . . . . . . . . . . . . . 6
5.1. EVPN MAC/IP Object . . . . . . . . . . . . . . . . . . . 6
5.2. EVPN Inclusive Multicast Object . . . . . . . . . . . . . 8
5.3. EVPN Ethernet Auto-Discovery (A-D) Object . . . . . . . . 9
5.3.1. Ethernet Tag Value . . . . . . . . . . . . . . . . . 10
5.3.2. Per-ES EVPN Auto-Discovery Route with Different
RDs . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3.3. EVPN VPWS . . . . . . . . . . . . . . . . . . . . . . 11
5.4. EVPN IP Prefix Object . . . . . . . . . . . . . . . . . . 11
6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Unicast Data Plane Connectivity Checks . . . . . . . . . 13
6.2. Inclusive Multicast Data Plane Connectivity Checks . . . 14
6.3. EVPN Aliasing Data Plane Connectivity Check . . . . . . . 14
6.4. EVPN IP Prefix (RT-5) Data Plane Connectivity Check . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
[RFC7432] describes MPLS-based EVPN technology. An EVPN comprises
one or more Customer Edge devices (CEs) connected to one or more
Provider Edge devices (PEs). The PEs provide Layer 2 (L2) EVPN among
the CE(s) over the MPLS core infrastructure. In EVPN networks, the
PEs advertise the Media Access Control (MAC) addresses learned from
the locally connected CE(s), along with the 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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[RFC9252] defines procedures and messages for SRv6-based BGP
services, including Layer 3 VPN and EVPN over SRv6. To support
SRv6-based EVPN overlays, one or more SRv6 Service SIDs are
advertised with Route Types 1, 2, 3, and 5. The SRv6 Service SID(s)
per Route Type is advertised in SRv6 L2/L3 Service TLVs within the
BGP Prefix-SID attribute which is attached to MP-BGP NLRIs. The
existing NLRIs of MPLS-based EVPN are reused instead of defining new
ones, the NLRI encodings over SRv6 core are similar with those for
MPLS, the only difference is that the MPLS labels in the NLRIs carry
part of the SRv6 Service SIDs or they are set to Implicit NULL as
described in [RFC9252] Section 4.
For MPLS EVPN, [RFC9489] defines procedures to detect data plane
failures using LSP Ping in MPLS networks deploying EVPN. For EVPN
over SRv6, the requirements to detect data plane failures are
similar. This document proposes extension for ICMPv6 to fulfill such
requirements for EVPN over SRv6.
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
A-D:Auto-Discovery
BUM: Broadcast, Unknown Unicast, and Multicast
CE: Customer Edge device
C-MAC: Customer MAC
DF: Designated Forwarder
ES: Ethernet Segment
ESI: Ethernet Segment Identifier
EVI: EVPN Instance Identifier that globally identifies the EVPN
Instance
EVPN: Ethernet Virtual Private Network
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MAC-VRF: A Virtual Routing and Forwarding table for MAC addresses on
a PE
PE: Provider Edge device
VPWS: Virtual Private Wire Service
4. ICMPv6 Messages
[draft-liu-6man-icmp-verification] introduces the mechanism to verify
the data plane message in IPv6/SRv6 networks by extending ICMPv6
messages. Two new types of ICMPv6 validation messages, ICMPv6
Validation Request and ICMPv6 Validation Reply are defined. Like any
other ICMPv6 message, the messages are encapsulated in an IPv6
header.
For ease of reading, the format of ICMPv6 Validation Request is shown
in Figure 1. As per [RFC4884], the Extension Structure contains one
Extension Header followed by one or more ICMP Extension Objects.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |Sequence Number| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. ICMP Extension Structure .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Validation Request
When applied in the ICMPv6 Validation Request message, a new type of
ICMP Extension Object, Validation Information Object, is defined in
[draft-liu-6man-icmp-verification] to carry the information related
with the SRv6 SID to be verified. The format of ICMP Extension
Object is shown in figure 2.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num | C-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| // (Object payload) // |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Validation Information Object
In this object, the C-Type is used to indicate the type of the
information that needs to be verified which is carried in the object
payload. The new values of of C-Type and the corresponding object
payload defined in this document for EVPN are given below:
C-Type Object Payload
-------- -----------
10 EVPN MAC/IP
11 EVPN Inclusive Multicast
12 EVPN Ethernet Auto-Discovery
13 EVPN IP Prefix
The detailed formats and usages of these objects are described in
section 5.
The format of ICMPv6 Validation Reply defined in [draft-liu-6man-
icmp-verification] is shown in Figure 3, the value of the Code field
indicates the validation result.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |Sequence Number| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: ICMPv6 Validation Reply
The ICMPv6 Validation Request packets are used for connectivity
checks in the data plane in EVPN networks. The Validation
Information Objects can be used to validate that an identifier for a
given EVPN is programmed at the target node.
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The ICMPv6 Validation Request for EVPN can be sent with the SRv6
Service SID as the IPv6 destination address without SRH encapsulated,
or when the ICMPv6 Validation Request is sent with SRH the SRv6
Service SID is set the last segment of the SRH.
Once the ICMPv6 Validation Request reaches the target egress PE, the
egress PE, as the final destination of the IPv6 packet, will proceed
to process the next header in the packet, i.e, the ICMPv6 Validation
Request. Then the PE will perform checks for the information present
in the Validation Information Object, that is, the PE will check
whether the information carried in the Validation Information Object
is programmed locally, and whether it is valid. If the above two
conditions are both met, the egress PE will generate an ICMPv6
Validation Reply with Code 0 ("Validation passed"). Otherwise, the
return code is 3 ("Information mismatch"), which indicates the EVPN
information carried in the ICMPv6 Validation Request is not reachable
from the egress PE.
5. Validation Information Objects
This document introduces several new Validation Information Objects
that can be carried in the ICMPv6 Validation Request.
5.1. EVPN MAC/IP Object
The EVPN MAC/IP Object identifies the target MAC, MAC/IP binding for
ARP/ND, or IP address for an EVI under test at an egress PE. This
Object is included in the ICMPv6 Validation Request sent by an EVPN
PE to a peer PE. the format of the EVPN MAC/IP Object is shown in
figure 4.
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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 4: EVPN MAC/IP Object
The fields of the EVPN MAC/IP Object are derived from the MAC/IP
Advertisement route defined in Section 7.2 of [RFC7432]. The fields
of the EVPN MAC/IP Object should be set according to the following,
which is consistent with [RFC7432] and [RFC7623]:
* The Ethernet Tag ID field can be 0 or a valid VLAN ID for EVPN
VLAN-aware bundle service [RFC7623].
* The Ethernet Segment Identifier field is a 10-octet field. For
EVPN, it is set to 0 for a single-homed ES or to a valid ESI ID
for a multihomed ES.
* The MAC Addr Len field specifies the MAC length in bits. Only
48-bit MAC addresses are supported as this document follows the
MAC address length supported by [RFC7623].
* 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
set to either 32 for IPv4 addresses or 128 for IPv6 addresses.
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* The Must Be Zero fields are set to 0. The receiving PE should
ignore the Must Be Zero fields.
As described in [RFC9489] section 4.1. In EVPN, the MAC/IP
Advertisement route has multiple uses and is used for the following
cases:
* This route with only a 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 and IP forwarding in the case of symmetric Integrated
Routing and Bridging (IRB).
The above descriptions are still applicable for SRv6 EVPN, the only
difference is that MPLS Label1 and Label2 are replaced by SRv6 L2
Service SID enclosed in an SRv6 L2 Service TLV and SRv6 L3 Service
SID enclosed in an SRv6 L3 Service TLV separately.
When an ICMPv6 Echo Request is sent by an ingress PE, the contents of
the ICMPv6 Validation Request and the egress PE mode of operation
(i.e., IRB mode or L2 mode) along with SRv6 Service SID of the packet
determine which of the three cases above this Echo Request is for.
When the egress PE receives the EVPN MAC/IP Object containing only
the MAC address, the egress PE validates the MAC state and
forwarding. When the egress PE receives the EVPN MAC/IP Object
containing both MAC and IP addresses and if the SRv6 Service SID
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 SRv6 Service
SID points to an IP-VRF, then the egress PE validates IP state and
forwarding. Any other combinations (e.g., the egress PE receiving
the EVPN MAC/IP Object containing only the MAC address but with the
SRv6 Service SID pointing to an IP-VRF) should be considered invalid,
and the egress PE should send an ICMPv6 Validation Reply with the
appropriate Code to the ingress PE.
5.2. EVPN Inclusive Multicast Object
Inclusive Multicast Ethernet Tag Route over SRv6 Core are described
in [RFC9252] section 6.3. [draft-ietf-bess-mvpn-evpn-sr-p2mp] further
describes how to realized P-Tunnels by SRv6 P2MP trees.
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The multicast connectivity state validation for EVPN over SRv6 will
described in further version of the draft.
5.3. EVPN Ethernet Auto-Discovery (A-D) Object
The fields in the EVPN Ethernet A-D Object are based on the EVPN
Ethernet A-D route advertisement defined in Section 7.1 of [RFC7432].
RFC9252 section 6.1 describes EVPN Ethernet A-D route over SRv6 Core.
Ethernet A-D routes are Route Type 1, as defined in [RFC7432], and
may be used to achieve split-horizon filtering, fast convergence, and
aliasing. EVPN Route Type 1 is also used in EVPN-VPWS as well as in
EVPN-flexible cross-connect, mainly to advertise point-to-point
service IDs.
The EVPN Ethernet A-D Object only applies to EVPN.
The EVPN Ethernet A-D Object has the format shown in Figure 5. The
fields of this Object should be set according to the following, which
is consistent with [RFC7432] and [RFC9252]:
* 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 5.3.2
for the case when a per-ES A-D 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 5.3.1.
* The Ethernet Segment Identifier field is a 10-octet field and is
set to 0 for a single-homed 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.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: EVPN Ethernet A-D Object
5.3.1. Ethernet Tag Value
The EVPN Ethernet A-D Object can be sent in the context of per-ES or
per-EVI. When an operator performs a connectivity check for the BUM
L2 service, an ICMPv6 Validation Request is sent with the EVPN
Ethernet A-D Object to emulate traffic coming from a multihomed site.
In this case, the EVPN Ethernet A-D Object is added in the per-ES
context. When an ICMPv6 Validation Request is sent for the
connectivity check for EVPN Aliasing state, the context for the EVPN
Ethernet A-D Object is per-EVI.
The Ethernet Tag field value in the EVPN Ethernet A-D Object MUST be
set according to the context:
* For the per-ES context, the Ethernet Tag field in the Object MUST
be set to the reserved MAX-ET value [RFC7432].
* For the per-EVI context, the Ethernet Tag field in the Object MUST
be set to the non-reserved value.
5.3.2. Per-ES EVPN Auto-Discovery Route with Different RDs
Section 8.2 of [RFC7432] specifies that a per-ES EVPN A-D 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 A-D
Object MUST be the RD value received for the EVI in the per-ES EVPN
A-D route.
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5.3.3. EVPN VPWS
This mechanism can also be used to detect data plane failures for the
EVPN VPWS ([RFC8214]) over SRv6 described in [RFC9252] section 6.1.2.
The ICMPv6 Validation Request carries the EVPN Ethernet A-D Object
with fields populated from the EVPN Ethernet A-D per-EVI route
announced by the egress PE for the EVPN VPWS under test. The ICMPv6
Validation Request is sent by the ingress PE using the SRv6 service
SID associated with the EVPN Ethernet A-D route announced by the
egress PE and the transport encapsulations (e.g., SRv6, IP) to reach
the egress PE.
The egress PE processes the ICMPv6 Validation Request packet and
performs checks for the EVPN Ethernet A-D Object. The egress PE can
identify that the ICMPv6 Validation Request is for the EVPN VPWS
instance as EVI (identified by the RD) for EVPN VPWS is different
from EVI assigned for EVPN. The egress PE will use the information
from the EVPN Ethernet A-D Object and validate the VLAN state for the
EVPN VPWS under test. For the success case, the egress PE will reply
with Code 0 ("Validation passed").
5.4. EVPN IP Prefix Object
The EVPN IP Prefix Object identifies the IP prefix for an EVI under
test at a peer PE.
EVPN Route Type 5 is used to advertise IP address reachability
through MP-BGP to all other PEs in a given EVPN instance as defined
in [RFC9136]. RFC9252 section 6.5 describes IP Prefix Route over
SRv6 Core.
The EVPN IP Prefix Object fields are derived from the IP Prefix route
(RT-5) advertisement defined in [RFC9136] and [RFC9252]. This Object
only applies to EVPN.
The EVPN IP Prefix Object has the format shown in Figure 6. The
total length (not shown) of this Object 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 the EVPN IP Prefix Object should be set according to
the following, which is consistent with [RFC9136] and [RFC9252]:
* The Route Distinguisher (RD) field is a 10-octet field and is set
to the RD of the IP-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].
* The Ethernet Segment Identifier field is a 10-octet field and is
set to a valid ESI ID if the ESI is used as an Overlay Index as
per Section 3.1 of [RFC9136]. Otherwise, the Ethernet Segment
Identifier field is set to 0.
* The IP Prefix Len field specifies the number of bits in the IP
Prefix field. It is set to a value 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 a 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 a 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.
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) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 6: EVPN IP Prefix Object
The ICMPv6 Validation Request is sent by the ingress PE using the
SRv6 service SID associated with the IP Prefix route announced by the
egress PE and the possible transport encapsulations(e.g, SRv6 segment
list) to reach the egress PE.
6. Operations
6.1. Unicast Data Plane Connectivity Checks
Figure 7 is an example of a EVPN network. CE1 is dual-homed to PE1
and PE2. Assume that PE1 announced a MAC route with RD 192.0.2.1:00
and C-MAC 00-AA-00-BB-00-CC and with SRv6 Sevice SID A:2:101:: for
EVI 10. Similarly, PE2 announced a MAC route with RD 203.0.113.2:00
and C-MAC 00-AA-00-BB-00-CC and with SRv6 Sevice SID B:2:101::.
On PE3, when an operator performs a connectivity check for the C-MAC
address 00-AA-00-BB-00-CC on PE1, the operator initiates an ICMPv6
Validation Request containing the EVPN MAC/IP Object. The ICMPv6
Validation Request packet is sent with the {SRv6 segment list to
reach PE1, SRv6 Service SID = A:2:101::} . Once the ICMPv6 Validation
Request packet encapsulated with SRH reaches PE1, PE1 as the final
destination of the IPv6 packet, will proceed to process the next
header in the packet, i.e, the ICMPv6 Validation Request. Then PE1
will process the packet and perform checks for the EVPN MAC/IP Object
and return the ICMPv6 Validation Reply with the code indicating the
validation result.
+------------------+
| |
| |
+----+ +-----+ +-----+ +----+
| CE1|------| | | PE3 |-----| CE2|
+----+\ | PE1 | SRv6 | | +----+
\ +-----+ Network +-----+
\ | |
\ +-----+ |
\ | | |
\| PE2 | |
+-----+ |
| |
+------------------+
<------EVPN over SRv6-------->
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Figure 7: EVPN Network
6.2. Inclusive Multicast Data Plane Connectivity Checks
To be completed.
6.3. EVPN Aliasing Data Plane Connectivity Check
Still taking the network in Figure 7 as an example, assume PE1
announced an Ethernet A-D per-EVI route with the ESI set to CE1
system ID and SRv6 Service SID A:2:101::. Additionally, assume PE2
announced an Ethernet A-D per-EVI route with the ESI set to CE1
system ID and SRv6 Service SID B:2:101::.
At PE3, when an operator performs a connectivity check for the
aliasing aspect of the EVPN Ethernet A-D route on PE1, the operator
initiates an ICMPv6 Validation Request with the EVPN Ethernet A-D
Object. The ICMPv6 Validation Request packet is sent with the
SRH{SRv6 Segment List to reach PE1, SRv6 Service SID A:2:101::} and
IPv6 header.
When PE1 receives the packet, it will process the packet and perform
checks for the EVPN Ethernet A-D Object present in the packet and
return the ICMPv6 Validation Reply with the code indicating the
validation result.
6.4. EVPN IP Prefix (RT-5) Data Plane Connectivity Check
Assume PE1 in Figure 7 announced an IP Prefix route (RT-5) with an IP
prefix reachable behind CE1 and SRv6 Sevice SID A:2:101::. When an
operator on PE3 performs a connectivity check for the IP prefix on
PE1, the operator initiates an ICMPv6 Validation Request with the
EVPN IP Prefix Object included. The ICMPv6 Validation Request packet
is sent with the SRH{SRv6 Segment List to reach PE1, SRv6 Service SID
A:2:101::} and IPv6 header.
When PE1 receives the packet, it will process the packet and perform
checks for the EVPN IP Prefix Object present in the packet and return
the ICMPv6 Validation Reply with the code indicating the validation
result.
7. IANA Considerations
TBA
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8. Security Considerations
Security considerations discussed in [RFC4443], [RFC4884] and
[RFC9252] apply to this document.
To protect against unauthorized sources using validation request
messages to obtain network information, it is RECOMMENDED that
implementations provide a means of checking the source addresses of
validation request messages against an access list before accepting
the message.
The validation mechanism SHOULD be only used in the limited domain.
The validation request contains the control plane information,
policies should be implemented on the edge devices of the domain to
prevent the information from being leaked into other domains.
In order to protect local resources, implementations SHOULD rate-
limit incoming ICMP Request messages.
This document does not introduce any new privacy concerns because
these Objects contain the same information that are present in data
packets and EVPN routes.
9. References
9.1. Normative References
[I-D.liu-6man-icmp-verification]
Liu, Y. and Y. Liu, "Extending ICMPv6 for SRv6-related
Information Validation", Work in Progress, Internet-Draft,
draft-liu-6man-icmp-verification-05, 11 June 2024,
<https://datatracker.ietf.org/doc/html/draft-liu-6man-
icmp-verification-05>.
[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>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
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[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
"Extended ICMP to Support Multi-Part Messages", RFC 4884,
DOI 10.17487/RFC4884, April 2007,
<https://www.rfc-editor.org/info/rfc4884>.
[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>.
[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>.
[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>.
[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>.
[RFC9252] Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene,
B., Zhuang, S., and J. Rabadan, "BGP Overlay Services
Based on Segment Routing over IPv6 (SRv6)", RFC 9252,
DOI 10.17487/RFC9252, July 2022,
<https://www.rfc-editor.org/info/rfc9252>.
9.2. Informative References
[RFC9489] Jain, P., Sajassi, A., Salam, S., Boutros, S., and G.
Mirsky, "Label Switched Path (LSP) Ping Mechanisms for
EVPN and Provider Backbone Bridging EVPN (PBB-EVPN)",
RFC 9489, DOI 10.17487/RFC9489, November 2023,
<https://www.rfc-editor.org/info/rfc9489>.
Author's Address
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Yao Liu
ZTE
Nanjing
China
Email: liu.yao71@zte.com.cn
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