< draft-ietf-bess-srv6-services-10.txt   draft-ietf-bess-srv6-services-11.txt >
BESS Working Group G. Dawra, Ed. BESS Working Group G. Dawra, Ed.
Internet-Draft LinkedIn Internet-Draft LinkedIn
Intended status: Standards Track C. Filsfils Intended status: Standards Track C. Filsfils
Expires: August 12, 2022 K. Talaulikar, Ed. Expires: August 20, 2022 K. Talaulikar, Ed.
Cisco Systems Cisco Systems
R. Raszuk R. Raszuk
NTT Network Innovations NTT Network Innovations
B. Decraene B. Decraene
Orange Orange
S. Zhuang S. Zhuang
Huawei Technologies Huawei Technologies
J. Rabadan J. Rabadan
Nokia Nokia
February 8, 2022 February 16, 2022
SRv6 BGP based Overlay Services SRv6 BGP based Overlay Services
draft-ietf-bess-srv6-services-10 draft-ietf-bess-srv6-services-11
Abstract Abstract
This document defines procedures and messages for SRv6-based BGP This document defines procedures and messages for SRv6-based BGP
services including L3VPN, EVPN, and Internet services. It builds on services including L3VPN, EVPN, and Internet services. It builds on
RFC4364 "BGP/MPLS IP Virtual Private Networks (VPNs)" and RFC7432 RFC4364 "BGP/MPLS IP Virtual Private Networks (VPNs)" and RFC7432
"BGP MPLS-Based Ethernet VPN". "BGP MPLS-Based Ethernet VPN".
Status of This Memo Status of This Memo
skipping to change at page 1, line 43 skipping to change at page 1, line 43
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-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
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 August 12, 2022. This Internet-Draft will expire on August 20, 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. SRv6 Services TLVs . . . . . . . . . . . . . . . . . . . . . 4 2. SRv6 Services TLVs . . . . . . . . . . . . . . . . . . . . . 4
3. SRv6 Service Sub-TLVs . . . . . . . . . . . . . . . . . . . . 5 3. SRv6 Service Sub-TLVs . . . . . . . . . . . . . . . . . . . . 5
3.1. SRv6 SID Information Sub-TLV . . . . . . . . . . . . . . 6 3.1. SRv6 SID Information Sub-TLV . . . . . . . . . . . . . . 6
3.2. SRv6 Service Data Sub-Sub-TLVs . . . . . . . . . . . . . 7 3.2. SRv6 Service Data Sub-Sub-TLVs . . . . . . . . . . . . . 7
3.2.1. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . 7 3.2.1. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . 8
4. Encoding SRv6 SID Information . . . . . . . . . . . . . . . . 9 4. Encoding SRv6 SID Information . . . . . . . . . . . . . . . . 10
5. BGP based L3 Service over SRv6 . . . . . . . . . . . . . . . 11 5. BGP based L3 Service over SRv6 . . . . . . . . . . . . . . . 11
5.1. IPv4 VPN Over SRv6 Core . . . . . . . . . . . . . . . . . 12 5.1. IPv4 VPN Over SRv6 Core . . . . . . . . . . . . . . . . . 12
5.2. IPv6 VPN Over SRv6 Core . . . . . . . . . . . . . . . . . 12 5.2. IPv6 VPN Over SRv6 Core . . . . . . . . . . . . . . . . . 13
5.3. Global IPv4 over SRv6 Core . . . . . . . . . . . . . . . 13 5.3. Global IPv4 over SRv6 Core . . . . . . . . . . . . . . . 13
5.4. Global IPv6 over SRv6 Core . . . . . . . . . . . . . . . 13 5.4. Global IPv6 over SRv6 Core . . . . . . . . . . . . . . . 13
6. BGP based Ethernet VPN (EVPN) over SRv6 . . . . . . . . . . . 13 6. BGP based Ethernet VPN (EVPN) over SRv6 . . . . . . . . . . . 14
6.1. Ethernet Auto-discovery Route over SRv6 Core . . . . . . 15 6.1. Ethernet Auto-discovery Route over SRv6 Core . . . . . . 15
6.1.1. Ethernet A-D per ES Route . . . . . . . . . . . . . . 15 6.1.1. Ethernet A-D per ES Route . . . . . . . . . . . . . . 16
6.1.2. Ethernet A-D per EVI Route . . . . . . . . . . . . . 15 6.1.2. Ethernet A-D per EVI Route . . . . . . . . . . . . . 16
6.2. MAC/IP Advertisement Route over SRv6 Core . . . . . . . . 16 6.2. MAC/IP Advertisement Route over SRv6 Core . . . . . . . . 17
6.2.1. MAC/IP Advertisement Route with MAC Only . . . . . . 17 6.2.1. MAC/IP Advertisement Route with MAC Only . . . . . . 18
6.2.2. MAC/IP Advertisement Route with MAC+IP . . . . . . . 17 6.2.2. MAC/IP Advertisement Route with MAC+IP . . . . . . . 18
6.3. Inclusive Multicast Ethernet Tag Route over SRv6 Core . . 18 6.3. Inclusive Multicast Ethernet Tag Route over SRv6 Core . . 19
6.4. Ethernet Segment Route over SRv6 Core . . . . . . . . . . 20 6.4. Ethernet Segment Route over SRv6 Core . . . . . . . . . . 21
6.5. IP Prefix Route over SRv6 Core . . . . . . . . . . . . . 20 6.5. IP Prefix Route over SRv6 Core . . . . . . . . . . . . . 21
6.6. EVPN Multicast Routes (Route Types 6, 7, 8) over SRv6 6.6. EVPN Multicast Routes (Route Types 6, 7, 8) over SRv6
Core . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Core . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 21 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 22
8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 22 8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 23
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
9.1. BGP Prefix-SID TLV Types Registry . . . . . . . . . . . . 23 9.1. BGP Prefix-SID TLV Types Registry . . . . . . . . . . . . 24
9.2. SRv6 Service Sub-TLV Types Registry . . . . . . . . . . . 23 9.2. SRv6 Service Sub-TLV Types Registry . . . . . . . . . . . 24
9.3. SRv6 Service Data Sub-Sub-TLV Types Registry . . . . . . 24 9.3. SRv6 Service Data Sub-Sub-TLV Types Registry . . . . . . 25
9.4. BGP SRv6 Service SID Flags Registry . . . . . . . . . . . 24 9.4. BGP SRv6 Service SID Flags Registry . . . . . . . . . . . 25
10. Security Considerations . . . . . . . . . . . . . . . . . . . 24 10. Security Considerations . . . . . . . . . . . . . . . . . . . 26
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 27
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
13.1. Normative References . . . . . . . . . . . . . . . . . . 27 13.1. Normative References . . . . . . . . . . . . . . . . . . 28
13.2. Informative References . . . . . . . . . . . . . . . . . 29 13.2. Informative References . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
1. Introduction 1. Introduction
SRv6 refers to Segment Routing instantiated on the IPv6 dataplane SRv6 refers to Segment Routing instantiated on the IPv6 dataplane
[RFC8402]. [RFC8402].
BGP is used to advertise the reachability of prefixes of a particular BGP is used to advertise the reachability of prefixes of a particular
service from an egress PE to ingress PE nodes. service from an egress PE to ingress PE nodes.
SRv6 based BGP services refers to the Layer-3 and Layer-2 overlay SRv6 based BGP services refers to the Layer-3 and Layer-2 overlay
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The SRv6 Service TLVs are defined as two new TLVs of the BGP Prefix- The SRv6 Service TLVs are defined as two new TLVs of the BGP Prefix-
SID Attribute to achieve signaling of SRv6 SIDs for L3 and L2 SID Attribute to achieve signaling of SRv6 SIDs for L3 and L2
services. services.
o SRv6 L3 Service TLV: This TLV encodes Service SID information for o SRv6 L3 Service TLV: This TLV encodes Service SID information for
SRv6 based L3 services. It corresponds to the equivalent SRv6 based L3 services. It corresponds to the equivalent
functionality provided by an MPLS Label when received with a Layer functionality provided by an MPLS Label when received with a Layer
3 service route as defined in [RFC4364] [RFC4659] [RFC8950] 3 service route as defined in [RFC4364] [RFC4659] [RFC8950]
[RFC9136]. Some SRv6 Endpoint behaviors which MAY be encoded, but [RFC9136]. Some SRv6 Endpoint behaviors which MAY be encoded, but
not limited to, are End.DX4, End.DT4, End.DX6, End.DT6, etc. not limited to, are End.DX4, End.DT4, End.DX6, and End.DT6.
o SRv6 L2 Service TLV: This TLV encodes Service SID information for o SRv6 L2 Service TLV: This TLV encodes Service SID information for
SRv6 based L2 services. It corresponds to the equivalent SRv6 based L2 services. It corresponds to the equivalent
functionality provided by an MPLS Label1 for Ethernet VPN (EVPN) functionality provided by an MPLS Label1 for Ethernet VPN (EVPN)
Route-Types as defined in [RFC7432]. Some SRv6 Endpoint behaviors Route-Types as defined in [RFC7432]. Some SRv6 Endpoint behaviors
which MAY be encoded, but not limited to, are End.DX2, End.DX2V, which MAY be encoded, but not limited to, are End.DX2, End.DX2V,
End.DT2U, End.DT2M etc. End.DT2U, and End.DT2M.
When an egress PE is enabled for BGP Services over SRv6 data-plane, When an egress PE is enabled for BGP Services over SRv6 data-plane,
it signals one or more SRv6 Service SIDs enclosed in SRv6 Service it signals one or more SRv6 Service SIDs enclosed in SRv6 Service
TLV(s) within the BGP Prefix-SID Attribute attached to MP-BGP NLRIs TLV(s) within the BGP Prefix-SID Attribute attached to MP-BGP NLRIs
defined in [RFC4760] [RFC4659] [RFC8950] [RFC7432] [RFC4364] defined in [RFC4760] [RFC4659] [RFC8950] [RFC7432] [RFC4364]
[RFC9136] where applicable as described in Section 5 and Section 6. [RFC9136] where applicable as described in Section 5 and Section 6.
The support for BGP Multicast VPN (MVPN) Services [RFC6513] with SRv6 The support for BGP Multicast VPN (MVPN) Services [RFC6513] with SRv6
is outside the scope of this document. is outside the scope of this document.
The following depicts the SRv6 Service TLVs encoded in the BGP The following depicts the SRv6 Service TLVs encoded in the BGP
Prefix-SID Attribute: Prefix-SID Attribute:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Length | RESERVED | | TLV Type | TLV Length | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// SRv6 Service Sub-TLVs // | SRv6 Service Sub-TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SRv6 Service TLVs
o TLV Type (1 octet): This field is assigned values from the IANA o TLV Type (1 octet): This field is assigned values from the IANA
registry "BGP Prefix-SID TLV Types". It is set to 5 for SRv6 L3 registry "BGP Prefix-SID TLV Types". It is set to 5 for SRv6 L3
Service TLV. It is set to 6 for SRv6 L2 Service TLV. Service TLV. It is set to 6 for SRv6 L2 Service TLV.
o TLV Length (2 octets): Specifies the total length, in octets, of o TLV Length (2 octets): Specifies the total length, in octets, of
the TLV Value. the TLV Value.
o RESERVED (1 octet): This field is reserved; it SHOULD be set to 0 o RESERVED (1 octet): This field is reserved; it SHOULD be set to 0
by the sender and MUST be ignored by the receiver. by the sender and MUST be ignored by the receiver.
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o if the nexthop is changed, the TLVs, Sub-TLVs, and Sub-Sub-TLVs o if the nexthop is changed, the TLVs, Sub-TLVs, and Sub-Sub-TLVs
SHOULD be updated with the locally allocated SRv6 SID information. SHOULD be updated with the locally allocated SRv6 SID information.
Any unrecognized received Sub-TLVs and Sub-Sub-TLVs MUST be Any unrecognized received Sub-TLVs and Sub-Sub-TLVs MUST be
removed. removed.
3. SRv6 Service Sub-TLVs 3. SRv6 Service Sub-TLVs
The format of a single SRv6 Service Sub-TLV is depicted below: The format of a single SRv6 Service Sub-TLV is depicted below:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRv6 Service | SRv6 Service | SRv6 Service // | SRv6 Service | SRv6 Service | SRv6 Service //
| Sub-TLV | Sub-TLV | Sub-TLV // | Sub-TLV | Sub-TLV | Sub-TLV //
| Type | Length | value // | Type | Length | value //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SRv6 Service Sub-TLVs
o SRv6 Service Sub-TLV Type (1 octet): Identifies the type of SRv6 o SRv6 Service Sub-TLV Type (1 octet): Identifies the type of SRv6
service information. It is assigned values from the IANA Registry service information. It is assigned values from the IANA Registry
"SRv6 Service Sub-TLV Types". "SRv6 Service Sub-TLV Types".
o SRv6 Service Sub-TLV Length (2 octets): Specifies the total o SRv6 Service Sub-TLV Length (2 octets): Specifies the total
length, in octets, of the Sub-TLV Value field. length, in octets, of the Sub-TLV Value field.
o SRv6 Service Sub-TLV Value (variable): Contains data specific to o SRv6 Service Sub-TLV Value (variable): Contains data specific to
the Sub-TLV Type. In addition to fixed-length data, it contains the Sub-TLV Type. In addition to fixed-length data, it contains
other properties of the SRv6 Service encoded as a set of SRv6 other properties of the SRv6 Service encoded as a set of SRv6
Service Data Sub-Sub-TLVs whose format is described in Section 3.2 Service Data Sub-Sub-TLVs whose format is described in Section 3.2
below. below.
3.1. SRv6 SID Information Sub-TLV 3.1. SRv6 SID Information Sub-TLV
SRv6 Service Sub-TLV Type 1 is assigned for SRv6 SID Information Sub- SRv6 Service Sub-TLV Type 1 is assigned for SRv6 SID Information Sub-
TLV. This Sub-TLV contains a single SRv6 SID along with its TLV. This Sub-TLV contains a single SRv6 SID along with its
properties. Its encoding is depicted below: properties. Its encoding is depicted below:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRv6 Service | SRv6 Service | | | SRv6 Service | SRv6 Service | |
| Sub-TLV | Sub-TLV | | | Sub-TLV | Sub-TLV | |
| Type=1 | Length | RESERVED1 | | Type=1 | Length | RESERVED1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// SRv6 SID Value (16 octets) // | SRv6 SID Value (16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRv6 SID Flags| SRv6 Endpoint Behavior | RESERVED2 | | Svc SID Flags | SRv6 Endpoint Behavior | RESERVED2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// SRv6 Service Data Sub-Sub-TLVs // | SRv6 Service Data Sub-Sub-TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SRv6 SID Information Sub-TLV
o SRv6 Service Sub-TLV Type (1 octet): This field is set to 1 to o SRv6 Service Sub-TLV Type (1 octet): This field is set to 1 to
represent SRv6 SID Information Sub-TLV. represent SRv6 SID Information Sub-TLV.
o SRv6 Service Sub-TLV Length (2 octets): This field contains the o SRv6 Service Sub-TLV Length (2 octets): This field contains the
total length, in octets, of the Value field of the Sub-TLV. total length, in octets, of the Value field of the Sub-TLV.
o RESERVED1 (1 octet): SHOULD be set to 0 by the sender and MUST be o RESERVED1 (1 octet): SHOULD be set to 0 by the sender and MUST be
ignored by the receiver. ignored by the receiver.
o SRv6 SID Value (16 octets): Encodes an SRv6 SID as defined in o SRv6 SID Value (16 octets): Encodes an SRv6 SID as defined in
[RFC8986] [RFC8986]
o SRv6 SID Flags (1 octet): Encodes SRv6 SID Flags - none are o SRv6 Service SID Flags (1 octet): Encodes SRv6 Service SID Flags -
currently defined. SHOULD be set to 0 by the sender and MUST be none are currently defined. SHOULD be set to 0 by the sender and
ignored by the receiver. any unknown flags MUST be ignored by the receiver.
o SRv6 Endpoint Behavior (2 octets): Encodes SRv6 Endpoint behavior o SRv6 Endpoint Behavior (2 octets): Encodes SRv6 Endpoint behavior
codepoint value that is associated with SRv6 SID. The codepoints codepoint value that is associated with SRv6 SID. The codepoints
used are from the "SRv6 Endpoint Behavior" registry under the IANA used are from the "SRv6 Endpoint Behavior" registry under the IANA
"Segment Routing" parameters registry that was introduced by "Segment Routing" parameters registry that was introduced by
[RFC8986]. The opaque endpoint behavior (i.e., value 0xFFFF) or [RFC8986]. An unrecognized endpoint behavior MUST NOT be
an unrecognized endpoint behavior MUST NOT be considered invalid considered invalid by the receiver. The opaque endpoint behavior
by the receiver. (i.e., value 0xFFFF) MAY be used when the advertising router
wishes to abstract the actual behavior of it's locally
instantiated SRv6 SID.
o RESERVED2 (1 octet): SHOULD be set to 0 by the sender and MUST be o RESERVED2 (1 octet): SHOULD be set to 0 by the sender and MUST be
ignored by the receiver. ignored by the receiver.
o SRv6 Service Data Sub-Sub-TLV Value (variable): Used to advertise o SRv6 Service Data Sub-Sub-TLV Value (variable): Used to advertise
properties of the SRv6 SID. It is encoded as a set of SRv6 properties of the SRv6 SID. It is encoded as a set of SRv6
Service Data Sub-Sub-TLVs. Service Data Sub-Sub-TLVs.
When multiple SRv6 SID Information Sub-TLVs are present, the ingress When multiple SRv6 SID Information Sub-TLVs are present, the ingress
PE SHOULD use the SRv6 SID from the first instance of the Sub-TLV. PE SHOULD use the SRv6 SID from the first instance of the Sub-TLV.
skipping to change at page 7, line 37 skipping to change at page 7, line 52
The format of the SRv6 Service Data Sub-Sub-TLV is depicted below: The format of the SRv6 Service Data Sub-Sub-TLV is depicted below:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Data | Sub-Sub-TLV Length |Sub-Sub TLV // | Service Data | Sub-Sub-TLV Length |Sub-Sub TLV //
| Sub-Sub-TLV | | Value // | Sub-Sub-TLV | | Value //
| Type | | // | Type | | //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: SRv6 Service Data Sub-Sub-TLVs
o SRv6 Service Data Sub-Sub-TLV Type (1 octet): Identifies the type o SRv6 Service Data Sub-Sub-TLV Type (1 octet): Identifies the type
of Sub-Sub-TLV. It is assigned values from the IANA Registry of Sub-Sub-TLV. It is assigned values from the IANA Registry
"SRv6 Service Data Sub-Sub-TLVs". "SRv6 Service Data Sub-Sub-TLVs".
o SRv6 Service Data Sub-Sub-TLV Length (2 octets): Specifies the o SRv6 Service Data Sub-Sub-TLV Length (2 octets): Specifies the
total length, in octets, of the Sub-Sub-TLV Value field. total length, in octets, of the Sub-Sub-TLV Value field.
o SRv6 Service Data Sub-Sub-TLV Value (variable): Contains data o SRv6 Service Data Sub-Sub-TLV Value (variable): Contains data
specific to the Sub-Sub-TLV Type. specific to the Sub-Sub-TLV Type.
skipping to change at page 8, line 22 skipping to change at page 8, line 39
| Data Sub-Sub | Data Sub-Sub-TLV | Length | | Data Sub-Sub | Data Sub-Sub-TLV | Length |
| -TLV Type=1 | Length | | | -TLV Type=1 | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Locator Node | Function | Argument | Transposition | | Locator Node | Function | Argument | Transposition |
| Length | Length | Length | Length | | Length | Length | Length | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transposition | | Transposition |
| Offset | | Offset |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 5: SRv6 SID Structure Sub-Sub-TLV
o SRv6 Service Data Sub-Sub-TLV Type (1 octet): This field is set to o SRv6 Service Data Sub-Sub-TLV Type (1 octet): This field is set to
1 to represent SRv6 SID Structure Sub-Sub-TLV. 1 to represent SRv6 SID Structure Sub-Sub-TLV.
o SRv6 Service Data Sub-Sub-TLV Length (2 octets): This field o SRv6 Service Data Sub-Sub-TLV Length (2 octets): This field
contains a total length of 6 octets. contains a total length of 6 octets.
o Locator Block Length (1 octet): Contains the length of SRv6 SID o Locator Block Length (1 octet): Contains the length of SRv6 SID
Locator Block in bits. Locator Block in bits.
o Locator Node Length (1 octet): Contains the length of SRv6 SID o Locator Node Length (1 octet): Contains the length of SRv6 SID
skipping to change at page 9, line 20 skipping to change at page 9, line 39
bits that have been shifted out MUST be set to 0 in the SID value. bits that have been shifted out MUST be set to 0 in the SID value.
Transposition Length of 0 indicates nothing is transposed and that Transposition Length of 0 indicates nothing is transposed and that
the entire SRv6 SID value is encoded in the SID Information Sub-TLV. the entire SRv6 SID value is encoded in the SID Information Sub-TLV.
In this case, the Transposition Offset MUST be set to 0. In this case, the Transposition Offset MUST be set to 0.
The size of the MPLS label field limits the bits transposed from the The size of the MPLS label field limits the bits transposed from the
SRv6 SID value into it. E.g., the size of MPLS label field in SRv6 SID value into it. E.g., the size of MPLS label field in
[RFC4364] [RFC8277] is 20 bits while in [RFC7432] is 24 bits. [RFC4364] [RFC8277] is 20 bits while in [RFC7432] is 24 bits.
As defined in [RFC8986], the sum of the Locator Block Length (LBL),
Locator Node Length (LNL), Function Length (FL), and Argument Length
(AL) fields MUST be less than or equal to 128. Additionally, the
following length checks also apply to the Transposition Length and
Transposition Offset fields:
The Transposition Offset MUST be less than LBL+LNL+FL+AL
The sum of Transposition Offset and Transposition Length MUST be
less than LBL+LNL+FL+AL
As an example, consider that the sum of the Locator Block and the As an example, consider that the sum of the Locator Block and the
Locator Node parts is 64. For an SRv6 SID where the entire Function Locator Node parts is 64. For an SRv6 SID where the entire Function
part of size 16 bits is transposed, then the transposition offset is part of size 16 bits is transposed, then the transposition offset is
set to 64 and the transposition length is set to 16. While for an set to 64 and the transposition length is set to 16. While for an
SRv6 SID where the Function length is 24 bits and only the lower SRv6 SID where the Function length is 24 bits and only the lower
order 20 bits are transposed (e.g. due to the limit of the MPLS label order 20 bits are transposed (e.g. due to the limit of the MPLS label
field size), then the transposition offset is set to 68 and the field size), then the transposition offset is set to 68 and the
transposition length is set to 20. transposition length is set to 20.
BGP speakers that do not support this specification may misinterpret, BGP speakers that do not support this specification may misinterpret,
on the reception of an SRv6-based BGP service route update, the part on the reception of an SRv6-based BGP service route update, the part
of the SRv6 SID encoded in MPLS label field(s) as MPLS label values of the SRv6 SID encoded in MPLS label field(s) as MPLS label values
for MPLS-based services. Implementations supporting this for MPLS-based services. Implementations supporting this
specification SHOULD provide a mechanism to control the advertisement specification MUST provide a mechanism to control the advertisement
of SRv6-based BGP service routes on a per-neighbor and per-service of SRv6-based BGP service routes on a per-neighbor and per-service
basis. The details of deployment designs and implementation options basis. The details of deployment designs and implementation options
are outside the scope of this document. are outside the scope of this document.
Arguments MAY be generally applicable for SIDs of only specific SRv6 Arguments may be generally applicable for SIDs of only specific SRv6
Endpoint behaviors (e.g., End.DT2M) and therefore the Argument length Endpoint behaviors (e.g., End.DT2M) and therefore the Argument length
MUST be set to 0 for SIDs where the Argument is not applicable. MUST be set to 0 for SIDs where the Argument is not applicable. A
receiver is unable to validate the applicability of arguments for
SRv6 Endpoint behaviors that are unknown to it and hence MUST ignore
SRv6 SIDs with arguments (indicated by non-zero argument length) with
unknown endpoint behaviors.
4. Encoding SRv6 SID Information 4. Encoding SRv6 SID Information
The SRv6 Service SID(s) for a BGP Service Prefix are carried in the The SRv6 Service SID(s) for a BGP Service Prefix are carried in the
SRv6 Services TLVs of the BGP Prefix-SID Attribute. SRv6 Services TLVs of the BGP Prefix-SID Attribute.
For certain types of BGP Services like L3VPN where a per-VRF SID For certain types of BGP Services like L3VPN where a per-VRF SID
allocation is used (i.e., End.DT4 or End.DT6 behaviors), the same SID allocation is used (i.e., End.DT4 or End.DT6 behaviors), the same SID
is shared across multiple NLRIs thus providing efficient packing. is shared across multiple NLRIs thus providing efficient packing.
However, for certain other types of BGP Services like EVPN VPWS where However, for certain other types of BGP Services like EVPN VPWS where
skipping to change at page 11, line 17 skipping to change at page 11, line 45
BGP egress nodes (egress PEs) advertise a set of reachable prefixes. BGP egress nodes (egress PEs) advertise a set of reachable prefixes.
Standard BGP update propagation schemes [RFC4271], which may make use Standard BGP update propagation schemes [RFC4271], which may make use
of route reflectors [RFC4456], are used to propagate these prefixes. of route reflectors [RFC4456], are used to propagate these prefixes.
BGP ingress nodes (ingress PEs) receive these advertisements and may BGP ingress nodes (ingress PEs) receive these advertisements and may
add the prefix to the RIB in an appropriate VRF. add the prefix to the RIB in an appropriate VRF.
Egress PEs which supports SRv6 based L3 services advertises overlay Egress PEs which supports SRv6 based L3 services advertises overlay
service prefixes along with a Service SID enclosed in an SRv6 L3 service prefixes along with a Service SID enclosed in an SRv6 L3
Service TLV within the BGP Prefix-SID Attribute. This TLV serves two Service TLV within the BGP Prefix-SID Attribute. This TLV serves two
purposes - first, it indicates that the egress PE supports SRv6 purposes - first, it indicates that the egress PE supports SRv6
overlay and the BGP ingress PE receiving this route MUST choose to overlay and the BGP ingress PE receiving this route MUST perform IPv6
perform IPv6 encapsulation and insert an SRH [RFC8754] when required; encapsulation and insert an SRH [RFC8754] when required; second, it
second, it indicates the value of the Service SID to be used in the indicates the value of the Service SID to be used in the
encapsulation. encapsulation.
The Service SID thus signaled only has local significance at the The Service SID thus signaled only has local significance at the
egress PE, where it may be allocated or configured on a per-CE or egress PE, where it may be allocated or configured on a per-CE or
per-VRF basis. In practice, the SID may encode a cross-connect to a per-VRF basis. In practice, the SID may encode a cross-connect to a
specific Address Family table (END.DT) or next-hop/interface (END.DX) specific Address Family table (END.DT) or next-hop/interface (END.DX)
as defined in [RFC8986]. as defined in [RFC8986].
The SRv6 Service SID SHOULD be routable within the AS of the egress The SRv6 Service SID SHOULD be routable within the AS of the egress
PE and serves the dual purpose of providing reachability between PE and serves the dual purpose of providing reachability between
skipping to change at page 11, line 41 skipping to change at page 12, line 20
behavior. behavior.
When steering for SRv6 services is based on shortest path forwarding When steering for SRv6 services is based on shortest path forwarding
(e.g., best-effort or IGP Flexible Algorithm (e.g., best-effort or IGP Flexible Algorithm
[I-D.ietf-lsr-flex-algo]) to the egress PE, the ingress PE [I-D.ietf-lsr-flex-algo]) to the egress PE, the ingress PE
encapsulates the IPv4 or IPv6 customer packet in an outer IPv6 header encapsulates the IPv4 or IPv6 customer packet in an outer IPv6 header
(using H.Encaps or H.Encaps.Red flavors specified in [RFC8986]) where (using H.Encaps or H.Encaps.Red flavors specified in [RFC8986]) where
the destination address is the SRv6 Service SID associated with the the destination address is the SRv6 Service SID associated with the
related BGP route update. Therefore, the ingress PE SHOULD perform related BGP route update. Therefore, the ingress PE SHOULD perform
resolvability check for the SRv6 Service SID before considering the resolvability check for the SRv6 Service SID before considering the
received prefix for the BGP best path computation. The result of an received prefix for the BGP best path computation. The resolvability
SRv6 Service SID resolvability (e.g., when provided via IGP Flexible is evaluated as per [RFC4271]. If the SRv6 SID is reachable via more
Algorithm) can be ignored if the ingress PE has a local policy that than one forwarding table, local policy is used to determine which
allows an alternate steering mechanism to reach the egress PE. The table to use. The result of an SRv6 Service SID resolvability (e.g.,
details of such steering mechanisms are outside the scope of this when provided via IGP Flexible Algorithm) can be ignored if the
document. ingress PE has a local policy that allows an alternate steering
mechanism to reach the egress PE. The details of such steering
mechanisms are outside the scope of this document.
For service over SRv6 core, the egress PE sets the next-hop to one of For service over SRv6 core, the egress PE sets the next-hop to one of
its IPv6 addresses. Such an address MAY be covered by the SRv6 its IPv6 addresses. Such an address MAY be covered by the SRv6
Locator from which the SRv6 Service SID is allocated. The next-hop Locator from which the SRv6 Service SID is allocated. The next-hop
is used for tracking the reachability of the egress PE based on is used for tracking the reachability of the egress PE based on
existing BGP procedures. existing BGP procedures.
When the BGP route is received at an ingress PE is colored with a When the BGP route is received at an ingress PE is colored with a
Color Extended community and a valid SRv6 Policy is available, the Color Extended community and a valid SRv6 Policy is available, the
steering for service flows is performed as described in Section 8 of steering for service flows is performed as described in Section 8 of
skipping to change at page 14, line 29 skipping to change at page 15, line 14
When steering for SRv6 services is based on shortest path forwarding When steering for SRv6 services is based on shortest path forwarding
(e.g., best-effort or IGP Flexible Algorithm (e.g., best-effort or IGP Flexible Algorithm
[I-D.ietf-lsr-flex-algo]) to the egress PE, the ingress PE [I-D.ietf-lsr-flex-algo]) to the egress PE, the ingress PE
encapsulates the customer Layer 2 Ethernet packet in an outer IPv6 encapsulates the customer Layer 2 Ethernet packet in an outer IPv6
header (using H.Encaps.L2 or H.Encaps.L2.Red flavors specified in header (using H.Encaps.L2 or H.Encaps.L2.Red flavors specified in
[RFC8986]) where the destination address is the SRv6 Service SID [RFC8986]) where the destination address is the SRv6 Service SID
associated with the related BGP route update. Therefore, the ingress associated with the related BGP route update. Therefore, the ingress
PE SHOULD perform resolvability check for the SRv6 Service SID before PE SHOULD perform resolvability check for the SRv6 Service SID before
considering the received prefix for the BGP best path computation. considering the received prefix for the BGP best path computation.
The result of an SRv6 Service SID resolvability (e.g., when provided Therefore, the ingress PE SHOULD perform resolvability check for the
via IGP Flexible Algorithm) can be ignored if the ingress PE has a SRv6 Service SID before considering the received prefix for the BGP
local policy that allows an alternate steering mechanism to reach the best path computation. The resolvability is evaluated as per
[RFC4271]. If the SRv6 SID is reachable via more than one forwarding
table, local policy is used to determine which table to use. The
result of an SRv6 Service SID resolvability (e.g., when provided via
IGP Flexible Algorithm) can be ignored if the ingress PE has a local
policy that allows an alternate steering mechanism to reach the
egress PE. The details of such steering mechanisms are outside the egress PE. The details of such steering mechanisms are outside the
scope of this document. scope of this document.
For service over SRv6 core, the egress PE sets the next-hop to one of For service over SRv6 core, the egress PE sets the next-hop to one of
its IPv6 addresses. Such an address MAY be covered by the SRv6 its IPv6 addresses. Such an address MAY be covered by the SRv6
Locator from which the SRv6 Service SID is allocated. The next-hop Locator from which the SRv6 Service SID is allocated. The next-hop
is used for tracking the reachability of the egress PE based on is used for tracking the reachability of the egress PE based on
existing BGP procedures. existing BGP procedures.
When the BGP route is received at an ingress PE is colored with a When the BGP route is received at an ingress PE is colored with a
skipping to change at page 15, line 25 skipping to change at page 16, line 15
+---------------------------------------+ +---------------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------------+ +---------------------------------------+
|Ethernet Segment Identifier (10 octets)| |Ethernet Segment Identifier (10 octets)|
+---------------------------------------+ +---------------------------------------+
| Ethernet Tag ID (4 octets) | | Ethernet Tag ID (4 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS label (3 octets) | | MPLS label (3 octets) |
+---------------------------------------+ +---------------------------------------+
Figure 6: EVPN Route Type 1
6.1.1. Ethernet A-D per ES Route 6.1.1. Ethernet A-D per ES Route
Ethernet A-D per ES route NLRI encoding over SRv6 core is as per Ethernet A-D per ES route NLRI encoding over SRv6 core is as per
[RFC7432]. [RFC7432].
The 24-bit ESI label field of the ESI label extended community The 24-bit ESI label field of the ESI label extended community
carries the whole or a portion of the Argument part of the SRv6 SID carries the whole or a portion of the Argument part of the SRv6 SID
when the ESI filtering approach is used along with the Transposition when the ESI filtering approach is used along with the Transposition
Scheme of encoding (Section 4) and otherwise set to Implicit NULL Scheme of encoding (Section 4) and otherwise set to Implicit NULL
value. In either case, the value is set in the high order 20 bits value. In either case, the value is set in the high order 20 bits
skipping to change at page 16, line 47 skipping to change at page 17, line 39
+---------------------------------------+ +---------------------------------------+
| IP Address Length (1 octet) | | IP Address Length (1 octet) |
+---------------------------------------+ +---------------------------------------+
| IP Address (0, 4, or 16 octets) | | IP Address (0, 4, or 16 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS Label1 (3 octets) | | MPLS Label1 (3 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS Label2 (0 or 3 octets) | | MPLS Label2 (0 or 3 octets) |
+---------------------------------------+ +---------------------------------------+
Figure 7: EVPN Route Type 2
NLRI encoding over SRv6 core is similar to [RFC7432] with the NLRI encoding over SRv6 core is similar to [RFC7432] with the
following changes: following changes:
o MPLS Label1: Is associated with the SRv6 L2 Service TLV. This o MPLS Label1: Is associated with the SRv6 L2 Service TLV. This
24-bit field carries the whole or a portion of the Function part 24-bit field carries the whole or a portion of the Function part
of the SRv6 SID when the Transposition Scheme of encoding of the SRv6 SID when the Transposition Scheme of encoding
(Section 4) is used and otherwise set to Implicit NULL value. In (Section 4) is used and otherwise set to Implicit NULL value. In
either case, the value is set in the high order 20 bits (e.g., as either case, the value is set in the high order 20 bits (e.g., as
0x000030 in the case of Implicit NULL). When using the 0x000030 in the case of Implicit NULL). When using the
Transposition Scheme, the Transposition Length MUST be less than Transposition Scheme, the Transposition Length MUST be less than
skipping to change at page 18, line 43 skipping to change at page 19, line 35
| 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 Address | | Originating Router's IP Address |
| (4 or 16 octets) | | (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
Figure 8: EVPN Route Type 3
NLRI encoding over SRv6 core is similar to [RFC7432]. NLRI encoding over SRv6 core is similar to [RFC7432].
PMSI Tunnel Attribute [RFC6514] is used to identify the P-tunnel used PMSI Tunnel Attribute [RFC6514] is used to identify the P-tunnel used
for sending broadcast, unknown unicast, or multicast (BUM) traffic. for sending broadcast, unknown unicast, or multicast (BUM) traffic.
The format of PMSI Tunnel Attribute is encoded as follows over SRv6 The format of PMSI Tunnel Attribute is encoded as follows over SRv6
Core: Core:
+---------------------------------------+ +---------------------------------------+
| Flag (1 octet) | | Flag (1 octet) |
+---------------------------------------+ +---------------------------------------+
| Tunnel Type (1 octet) | | Tunnel Type (1 octet) |
+---------------------------------------+ +---------------------------------------+
| MPLS label (3 octet) | | MPLS label (3 octet) |
+---------------------------------------+ +---------------------------------------+
| Tunnel Identifier (variable) | | Tunnel Identifier (variable) |
+---------------------------------------+ +---------------------------------------+
Figure 9: PMSI Tunnel Attribute
o Flag: zero value defined per [RFC7432] o Flag: zero value defined per [RFC7432]
o Tunnel Type: defined per [RFC6514] o Tunnel Type: defined per [RFC6514]
o MPLS label: This 24-bit field carries the whole or a portion of o MPLS label: This 24-bit field carries the whole or a portion of
the Function part of the SRv6 SID when ingress replication is used the Function part of the SRv6 SID when ingress replication is used
and the Transposition Scheme of encoding (Section 4) is used and and the Transposition Scheme of encoding (Section 4) is used and
otherwise, it is set as defined in [RFC6514]. When using the otherwise, it is set as defined in [RFC6514]. When using the
Transposition Scheme, the Transposition Length MUST be less than Transposition Scheme, the Transposition Length MUST be less than
or equal to 24 and less than or equal to the Function Length. or equal to 24 and less than or equal to the Function Length.
skipping to change at page 20, line 24 skipping to change at page 21, line 26
| 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 Address | | Originating Router's IP Address |
| (4 or 16 octets) | | (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
Figure 10: EVPN Route Type 4
NLRI encoding over SRv6 core is similar to [RFC7432]. NLRI encoding over SRv6 core is similar to [RFC7432].
SRv6 Service TLVs within the BGP Prefix-SID attribute are not SRv6 Service TLVs within the BGP Prefix-SID attribute are not
advertised along with this route. The processing of the route has advertised along with this route. The processing of the route has
not changed - it remains as described in [RFC7432]. not changed - it remains as described in [RFC7432].
6.5. IP Prefix Route over SRv6 Core 6.5. IP Prefix Route over SRv6 Core
EVPN Route Type 5 is used to advertise IP address reachability EVPN Route Type 5 is used to advertise IP address reachability
through MP-BGP to all other PEs in a given EVPN instance. The IP through MP-BGP to all other PEs in a given EVPN instance. The IP
skipping to change at page 21, line 21 skipping to change at page 22, line 21
+---------------------------------------+ +---------------------------------------+
| IP Prefix Length (1 octet) | | IP Prefix Length (1 octet) |
+---------------------------------------+ +---------------------------------------+
| IP Prefix (4 or 16 octets) | | IP Prefix (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
| GW IP Address (4 or 16 octets) | | GW IP Address (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS Label (3 octets) | | MPLS Label (3 octets) |
+---------------------------------------+ +---------------------------------------+
Figure 11: EVPN Route Type 5
NLRI encoding over SRv6 core is similar to [RFC9136] with the NLRI encoding over SRv6 core is similar to [RFC9136] with the
following change: following change:
o MPLS Label: This 24-bit field carries the whole or a portion of o MPLS Label: This 24-bit field carries the whole or a portion of
the Function part of the SRv6 SID when the Transposition Scheme of the Function part of the SRv6 SID when the Transposition Scheme of
encoding (Section 4) is used and otherwise set to Implicit NULL encoding (Section 4) is used and otherwise set to Implicit NULL
value. In either case, the value is set in the high order 20 bits value. In either case, the value is set in the high order 20 bits
(e.g., as 0x000030 in the case of Implicit NULL). When using the (e.g., as 0x000030 in the case of Implicit NULL). When using the
Transposition Scheme, the Transposition Length MUST be less than Transposition Scheme, the Transposition Length MUST be less than
or equal to 24 and less than or equal to the Function Length. or equal to 24 and less than or equal to the Function Length.
skipping to change at page 21, line 47 skipping to change at page 23, line 4
6.6. EVPN Multicast Routes (Route Types 6, 7, 8) over SRv6 Core 6.6. EVPN Multicast Routes (Route Types 6, 7, 8) over SRv6 Core
These routes do not require the advertisement of SRv6 Service TLVs These routes do not require the advertisement of SRv6 Service TLVs
along with them. Similar to EVPN Route Type 4, the BGP Nexthop is along with them. Similar to EVPN Route Type 4, the BGP Nexthop is
equal to the IPv6 address of egress PE. equal to the IPv6 address of egress PE.
7. Implementation Status 7. Implementation Status
[Note to RFC Editor: This section needs to be removed before [Note to RFC Editor: This section needs to be removed before
publication as RFC.] publication as RFC.]
The [I-D.matsushima-spring-srv6-deployment-status] describes the The [I-D.matsushima-spring-srv6-deployment-status] describes the
current deployment and implementation status of SRv6 which also current deployment and implementation status of SRv6 which also
includes the BGP services over SRv6 as specified in this document. includes the BGP services over SRv6 as specified in this document.
8. Error Handling 8. Error Handling
In case of any errors encountered while processing SRv6 Service TLVs, In case of any errors encountered while processing SRv6 Service TLVs,
the details of the error SHOULD be logged for further analysis. the details of the error SHOULD be logged for further analysis.
If multiple instances of SRv6 L3 Service TLV is encountered, all but If multiple instances of SRv6 L3 Service TLV are encountered, all but
the first instance MUST be ignored. the first instance MUST be ignored.
If multiple instances of SRv6 L2 Service TLV is encountered, all but If multiple instances of SRv6 L2 Service TLV are encountered, all but
the first instance MUST be ignored. the first instance MUST be ignored.
An SRv6 Service TLV is considered malformed in the following cases: An SRv6 Service TLV is considered malformed in the following cases:
o the TLV Length is less than 1 o the TLV Length is less than 1
o the TLV Length is inconsistent with the length of BGP Prefix-SID o the TLV Length is inconsistent with the length of BGP Prefix-SID
attribute attribute
o at least one of the constituent Sub-TLVs is malformed o at least one of the constituent Sub-TLVs is malformed
skipping to change at page 23, line 15 skipping to change at page 24, line 18
Any TLV or Sub-TLV or Sub-Sub-TLV is not considered malformed because Any TLV or Sub-TLV or Sub-Sub-TLV is not considered malformed because
of failing any semantic validation of its Value field. of failing any semantic validation of its Value field.
SRv6 overlay service requires Service SID for forwarding. The treat- SRv6 overlay service requires Service SID for forwarding. The treat-
as-withdraw action [RFC7606] MUST be performed when at least one as-withdraw action [RFC7606] MUST be performed when at least one
malformed SRV6 Service TLV is present in the BGP Prefix-SID malformed SRV6 Service TLV is present in the BGP Prefix-SID
attribute. attribute.
SRv6 SID value in SRv6 SID Information Sub-TLV is invalid when SID SRv6 SID value in SRv6 SID Information Sub-TLV is invalid when SID
Structure Sub-Sub-TLV transposition length is greater than the number Structure Sub-Sub-TLV transposition length is greater than the number
of bits of the label field or addition of transposition offset and of bits of the label field or if any of the conditions for the fields
length is greater than 128. The transposition offset and length MUST of the sub-sub-TLV as specified in Section 3.2.1 is not met. The
be 0 when the Sub-Sub-TLV is advertised along with routes where transposition offset and length MUST be 0 when the Sub-Sub-TLV is
transposition scheme is not applicable (e.g., for Global IPv6 Service advertised along with routes where transposition scheme is not
[RFC2545] where there is no label field). The path having such applicable (e.g., for Global IPv6 Service [RFC2545] where there is no
Prefix-SID Attribute should be ineligible during the selection of the label field). The path having such Prefix-SID Attribute without any
best path for the corresponding prefix. valid SRv6 SID information MUST be considered ineligible during the
selection of the best path for the corresponding prefix.
9. IANA Considerations 9. IANA Considerations
9.1. BGP Prefix-SID TLV Types Registry 9.1. BGP Prefix-SID TLV Types Registry
This document introduces two new TLV Types of the BGP Prefix-SID This document introduces two new TLV Types of the BGP Prefix-SID
attribute. IANA has assigned Type values in the registry "BGP attribute. IANA has assigned Type values in the registry "BGP
Prefix-SID TLV Types" as follows: Prefix-SID TLV Types" as follows:
Value Type Reference Value Type Reference
-------------------------------------------- --------------------------------------------
4 Deprecated <this document> 4 Deprecated <this document>
5 SRv6 L3 Service TLV <this document> 5 SRv6 L3 Service TLV <this document>
6 SRv6 L2 Service TLV <this document> 6 SRv6 L2 Service TLV <this document>
Figure 12: BGP Prefix-SID TLV Types
The value 4 previously corresponded to the SRv6-VPN SID TLV, which The value 4 previously corresponded to the SRv6-VPN SID TLV, which
was specified in previous versions of this document and used by early was specified in previous versions of this document and used by early
implementations of this specification. It was deprecated and implementations of this specification. It was deprecated and
replaced by the SRv6 L3 Service and SRv6 L2 Service TLVs. replaced by the SRv6 L3 Service and SRv6 L2 Service TLVs.
9.2. SRv6 Service Sub-TLV Types Registry 9.2. SRv6 Service Sub-TLV Types Registry
IANA is requested to create and maintain a new registry called "SRv6 IANA is requested to create and maintain a new registry called "SRv6
Service Sub-TLV Types" under the "Border Gateway Protocol (BGP) Service Sub-TLV Types" under the "Border Gateway Protocol (BGP)
Parameters" registry. The allocation policy for this registry is: Parameters" registry. The allocation policy for this registry is:
0 : Reserved 0 : Reserved
1-127 : IETF Review 1-127 : IETF Review
128-254 : First Come First Served 128-254 : First Come First Served
255 : Reserved 255 : Reserved
Figure 13: SRv6 Service Sub-TLV Types Allocation Policy
The following Sub-TLV Type is defined in this document: The following Sub-TLV Type is defined in this document:
Value Type Reference Value Type Reference
---------------------------------------------------- ----------------------------------------------------
1 SRv6 SID Information Sub-TLV <this document> 1 SRv6 SID Information Sub-TLV <this document>
Figure 14: SRv6 Service Sub-TLV Types
9.3. SRv6 Service Data Sub-Sub-TLV Types Registry 9.3. SRv6 Service Data Sub-Sub-TLV Types Registry
IANA is requested to create and maintain a new registry called "SRv6 IANA is requested to create and maintain a new registry called "SRv6
Service Data Sub-Sub-TLV Types" under the "Border Gateway Protocol Service Data Sub-Sub-TLV Types" under the "Border Gateway Protocol
(BGP) Parameters" registry. The allocation policy for this registry (BGP) Parameters" registry. The allocation policy for this registry
is: is:
0 : Reserved 0 : Reserved
1-127 : IETF Review 1-127 : IETF Review
128-254 : First Come First Served 128-254 : First Come First Served
255 : Reserved 255 : Reserved
Figure 15: SRv6 Service Data Sub-Sub-TLV Types Allocation Policy
The following Sub-Sub-TLV Type is defined in this document: The following Sub-Sub-TLV Type is defined in this document:
Value Type Reference Value Type Reference
---------------------------------------------------- ----------------------------------------------------
1 SRv6 SID Structure Sub-Sub-TLV <this document> 1 SRv6 SID Structure Sub-Sub-TLV <this document>
Figure 16: SRv6 Service Data Sub-Sub-TLV Types
9.4. BGP SRv6 Service SID Flags Registry 9.4. BGP SRv6 Service SID Flags Registry
IANA is requested to create and maintain a new registry called "BGP IANA is requested to create and maintain a new registry called "BGP
SRv6 Service SID Flags" under the "Border Gateway Protocol (BGP) SRv6 Service SID Flags" under the "Border Gateway Protocol (BGP)
Parameters" registry. The allocation policy for this registry is Parameters" registry. The allocation policy for this registry is
IETF Review and all 8 bit positions of the flags are currently IETF Review and all 8 bit positions of the flags are currently
unassigned. unassigned.
10. Security Considerations 10. Security Considerations
skipping to change at page 25, line 6 skipping to change at page 26, line 22
option to protect BGP sessions is found in [RFC5925], while [RFC6952] option to protect BGP sessions is found in [RFC5925], while [RFC6952]
includes an analysis of BGP keying and authentication issues. includes an analysis of BGP keying and authentication issues.
This document does not introduce new services or BGP NLRI types but This document does not introduce new services or BGP NLRI types but
extends the signaling of existing ones for SRv6. Therefore, the extends the signaling of existing ones for SRv6. Therefore, the
security considerations for the respective BGP services BGP IPv4 over security considerations for the respective BGP services BGP IPv4 over
IPv6 NH [RFC8950], BGP IPv6 L3VPN [RFC4659], BGP IPv6 [RFC2545], BGP IPv6 NH [RFC8950], BGP IPv6 L3VPN [RFC4659], BGP IPv6 [RFC2545], BGP
EVPN [RFC7432] and IP EVPN [RFC9136] also apply. EVPN [RFC7432] and IP EVPN [RFC9136] also apply.
SRv6 operates within a trusted SR domain with filtering of traffic at SRv6 operates within a trusted SR domain with filtering of traffic at
the domain boundaries. These and other security aspects of SRv6 are the domain boundaries. There is an assumed trust model such that any
discussed in the security considerations of [RFC8402] [RFC8754] and node adding an SRH to the packet is assumed to be allowed to do so
apply for the deployment of BGP services using SRv6. The SRv6 SIDs and there is the optional SRH HMAC TLV for validation when such an
used for the BGP Services in this document are defined in [RFC8986] assumption is not valid. These and other security aspects of SRv6
and hence the security considerations of that document also apply. are discussed in the security considerations of [RFC8402] [RFC8754]
The service flows between PE routers using SRv6 SIDs advertised via and apply for the deployment of BGP services using SRv6. The SRv6
BGP are expected to be limited within the trusted SR domain (e.g., SIDs used for the BGP Services in this document are defined in
within a single AS or between multiple ASes within a single provider [RFC8986] and hence the security considerations of that document also
network). Precaution should be taken to ensure that the BGP service apply. The service flows between PE routers using SRv6 SIDs
information (including associated SRv6 SID) advertised via BGP advertised via BGP are expected to be limited within the trusted SR
sessions are limited to peers within this trusted SR domain. The domain (e.g., within a single AS or between multiple ASes within a
security consideration section of [RFC8669] discusses mechanisms to single provider network). Precaution should be taken to ensure that
prevent leaking of BGP Prefix-SID attribute, that carries SRv6 SID, the BGP service information (including associated SRv6 SID)
outside the SR domain. advertised via BGP sessions are limited to peers within this trusted
SR domain. The security consideration section of [RFC8669] discusses
mechanisms to prevent leaking of BGP Prefix-SID attribute, that
carries SRv6 SID, outside the SR domain.
If these BGP session provisioning and BGP filtering mechanisms are If these BGP session provisioning and BGP filtering mechanisms are
not implemented properly, it may be possible for nodes outside the SR not implemented properly, it may be possible for nodes outside the SR
domain to learn the VPN Service SIDs and use them to direct traffic domain to learn the VPN Service SIDs and use them to direct traffic
into VPN networks from outside the SR domain. However, the data into VPN networks from outside the SR domain. However, the data
packet filtering mechanism that secures SRv6 usage in an SR domain as packet filtering mechanism that secures SRv6 usage in an SR domain as
described in [RFC8402] [RFC8754] would prevent packets addressed to described in [RFC8402] [RFC8754] would prevent packets addressed to
SRv6 SIDs from outside the SR domain from entering the SR domain. SRv6 SIDs from outside the SR domain from entering the SR domain.
11. Acknowledgments 11. Acknowledgments
The authors of this document would like to thank Stephane Litkowski, The authors of this document would like to thank Stephane Litkowski,
Rishabh Parekh, Xiejingrong, Rajesh M, Mustapha Aissaoui, Alexander Rishabh Parekh, Xiejingrong, Rajesh M, Mustapha Aissaoui, Alexander
Vainshtein, Eduard Metz, Shraddha Hegde, and Eduard Vasilenko for Vainshtein, Eduard Metz, Shraddha Hegde, Eduard Vasilenko, and Ron
their comments and review of this document. The authors would also Bonica for their comments and review of this document. The authors
like to thank Matthew Bocci for his document shepherd review and would also like to thank Matthew Bocci for his document shepherd
Martin Vigoureux for his AD review that resulted in helpful comments review and Martin Vigoureux for his AD review that resulted in
for improving this document. helpful comments for improving this document.
12. Contributors 12. Contributors
Satoru Matsushima Satoru Matsushima
SoftBank SoftBank
Email: satoru.matsushima@g.softbank.co.jp Email: satoru.matsushima@g.softbank.co.jp
Dirk Steinberg Dirk Steinberg
Steinberg Consulting Steinberg Consulting
skipping to change at page 30, line 17 skipping to change at page 31, line 30
A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex- A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
algo-18 (work in progress), October 2021. algo-18 (work in progress), October 2021.
[I-D.ietf-spring-segment-routing-policy] [I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft- P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-16 (work in progress), ietf-spring-segment-routing-policy-16 (work in progress),
January 2022. January 2022.
[I-D.matsushima-spring-srv6-deployment-status] [I-D.matsushima-spring-srv6-deployment-status]
Matsushima, S., Filsfils, C., Ali, Z., Li, Z., and K. Matsushima, S., Filsfils, C., Ali, Z., Li, Z., Rajaraman,
Rajaraman, "SRv6 Implementation and Deployment Status", K., and A. Dhamija, "SRv6 Implementation and Deployment
draft-matsushima-spring-srv6-deployment-status-11 (work in Status", draft-matsushima-spring-srv6-deployment-status-12
progress), February 2021. (work in progress), February 2022.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006, RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>. <https://www.rfc-editor.org/info/rfc4272>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925, Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>. June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/ [RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
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