MPLS-based Service Function Path(SFP) Consistency Verification
draft-lm-mpls-sfc-path-verification-01
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| Authors | Yao Liu , Greg Mirsky | ||
| Last updated | 2020-10-25 | ||
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draft-lm-mpls-sfc-path-verification-01
MPLS Working Group Y. Liu
Internet-Draft G. Mirsky
Intended status: Standards Track ZTE Corporation
Expires: April 28, 2021 October 25, 2020
MPLS-based Service Function Path(SFP) Consistency Verification
draft-lm-mpls-sfc-path-verification-01
Abstract
This document proposes a method to verify the correlation between
Service Function Chaining control and/or management plane view of the
specified Service Function Path and the state of its data. It works
for both SR service programming and MPLS-based NSH SFC.
This document defines the signaling of the Generic Associated Channel
(G-ACh) over a Service Function Path (SFP) with an MPLS forwarding
plane using the basic unit defined in RFC 8595. The document also
describes the processing of the G-ACh by the elements of the SFP.
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-
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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 April 28, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3
3. MPLS-based SFP Consistency Verification . . . . . . . . . . . 4
3.1. Special-purpose Label in SFC-MPLS Environment . . . . . . 5
3.1.1. G-ACh over SFC-MPLS . . . . . . . . . . . . . . . . . 6
3.2. MPLS-based SFP Consistency Verification . . . . . . . . . 6
3.3. SFC Info Sub-TLV . . . . . . . . . . . . . . . . . . . . 7
3.4. SFC Basic Unit FEC Sub-TLV . . . . . . . . . . . . . . . 8
3.5. Theory of Operation . . . . . . . . . . . . . . . . . . . 9
3.5.1. MPLS-based service programming . . . . . . . . . . . 10
3.5.2. Path Consistency in SFC-MPLS . . . . . . . . . . . . 10
3.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . 10
4. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5.1. SFC Validation TLV . . . . . . . . . . . . . . . . . . . 11
5.1.1. Sub-TLVs for SFC Validation TLV . . . . . . . . . . . 11
5.2. SFC Basic Unit sub-TLV . . . . . . . . . . . . . . . . . 12
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Normative References . . . . . . . . . . . . . . . . . . 12
6.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
Service Function Chain (SFC) defined in [RFC7665] as an ordered set
of service functions (SFs) to be applied to packets and/or frames,
and/or flows selected as a result of classification.
SFC can be achieved through a variety of encapsulation methods, such
as NSH [RFC8300], SR service programming
[I-D.ietf-spring-sr-service-programming] and MPLS-based NSH SFC
[RFC8595].
This document describes extensions to MPLS LSP ping [RFC8029]
mechanisms to support verification between the control/management
plane and the data plane state for both SR-MPLS service programming
and MPLS-based NSH SFC.
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An MPLS LSP ping is a component of the MPLS Operation,
Administration, and Maintenance (OAM) toolset. OAM packets used to
monitor a specific Service Function Path (SFP) can be transported
over a Generic Associated Channel (G-ACh). This document defines the
signaling of the G-ACh over an SFP with an MPLS forwarding plane
using the basic unit defined in [RFC8595]. The document also
describes the processing of the G-ACh by the elements of the SFP.
2. Conventions used in this document
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.2. Acronyms
SFC: Service Function Chain
SFF: Service Function Forwarder
SF: Service Function
SFI: Instance of an SF
SFP: Service Function Path
RSP: Rendered Service Path
SFC-MPLS: SFC over an MPLS forwarding plane
SPL: Special-Purpose Label
bSPL: Base SPL
eSPL: Extended SPL
GAL: Generic Associated Channel Label
ELI: Entropy Label Indicator
OAM: Operation, Administration, and Maintenance
G-ACh: Generic Associated Channel
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GAL: Generic Associated Channel Label
3. MPLS-based SFP Consistency Verification
MPLS echo request and reply messages [RFC8029] can be extended to
support the verification of the consistency of an MPLS-based Service
Function Path (SFP).
SR-MPLS/MPLS can be used to realize an SFP. Two methods have been
defined:
o [I-D.ietf-spring-sr-service-programming] describes how to achieve
service function chaining in SR-enabled MPLS and IPv6 networks.
In an SR-MPLS network, each SF is associated with an MPLS label.
As a result, an SFP can be encoded as a stack of MPLS labels and
pushed on top of the packet.
o [RFC8595] provides another method to realize SFC in an MPLS
network by means of using a logical representation of the Network
Service Header (NSH) in an MPLS label stack. This method,
throughout this document, is referred to as SFC over an MPLS data
plane (SFC-MPLS). When an MPLS label stack is used to carry a
logical NSH, a basic unit of representation is used, which can be
present one or more times in the label stack. This unit comprises
two MPLS labels, one carries a label to provide a context within
the SFC scope (the SFC Context Label), and the other carries a
label to show which SF is to be enacted (the SF Label). This two-
label unit is shown in Figure 1.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SFC Context Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The Basic Unit of MPLS Label Stack for SFC
In MPLS Label Switched Paths (LSPs), MPLS LSP ping [RFC8029] is used
to check the correctness of the data plane functioning and to verify
the data plane against the control plane.
The proposed extension of MPLS LSP ping allows verification of the
correlation between the control/management (if data model-based
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central controller used) plane and the data plane state in SR-MPLS/
MPLS-based SFC.
Generally, except for the designed specific functions, the packet
processing functions supported by SFs are limited. SFs may not
support control and/or management protocols operated over the G-ACh
defined n [RFC5586], e.g., MPLS OAM protocols like LSP ping. To
avoid such packets mishandled, SFFs are responsible for MPLS echo
request processing. To support that processing, the basic unit can
use the mechanism described in Section 3.1.
3.1. Special-purpose Label in SFC-MPLS Environment
When an SFC-MPLS is used, an SFF needs to identify an OAM packet with
the SFP scope. To achieve that, this specification first defines the
use of a base special-purpose label (bSPL) [RFC3032] or an extended
special-purpose label (eSPL) [RFC7274] (referred in this document as
SPL Unit) with the basic unit defined in [RFC8595]. And based on
that, the use of Generic Associated Channel Label (GAL) [RFC5586]
with the basic unit in the SFC-MPLS environment.
Special-purpose label (SPL), whether bSPL or eSPL, have special
significance in the data and control planes. An ability to use an
SPL in the basic unit allows for a closer functional match between
the NSH-based SFC and SFC-MPLS. For example, Entropy Label Indicator
(ELI) [RFC6790] with the basic unit can be used as the Flow ID TLV
[I-D.ietf-sfc-nsh-tlv] to allow an SFF to balance SFC flows among SFs
of the same type. An SPL MAY be used with the basic unit in SFC-
MPLS, as displayed in Figure 2. Note that an SPL unit MAY be present
in one or more basic units when MPLS label stacking is used to carry
the SFC information.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SFC Context Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPL Unit |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Special-purpose Label Unit with the Basic Unit of MPLS
Label Stack for SFC
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3.1.1. G-ACh over SFC-MPLS
SFC-MPLS environment could include instances of an SF (SFI) or SFC
proxies that cannot properly process control and/or management
protocol messages that are exchanged between nodes over the G-ACh
associated with the particular SFP. To support OAM over G-ACh, it is
beneficial to avoid handing over a test packet to the SFI or SFC
proxy. Hence, this specification defines that if the Generic
Associated Channel Label (GAL) immediately follows the SFC Context
label [RFC8595], then the packet is recognized as an SFP OAM packet.
Below are the processing rules of an SFP OAM packet by an SFF:
o An SFF MUST NOT pass the packet to a local SFI or SFC proxy.
o The SFF MUST decrement SF Label entry's TTL value. If the
resulting value equals zero, the SFF MUST pass the SFP OAM packet
to the control plane for processing. An implementation that
supports this specification MUST provide control to limit the rate
of SFP OAM packets passed to the control plane for processing.
o If the TTL value is not zero, the SFP OAM packet is processed as
defined in Section 6, Section 7, and Section 8 [RFC8595],
according to the type of MPLS forwarding used in the SFP.
3.2. MPLS-based SFP Consistency Verification
An MPLS SFC validation request/reply is an MPLS echo request/reply
that includes an SFC validation TLV (shown in Figure 3).
Nodes examine and process the TLV only if configured to do so; other
nodes MUST ignore the TLV and process the packet as a standard MPLS
echo packet.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type=TBA1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SFC Information Sub-TLV(s) |
~ ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SFC Validation TLV
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SFC Information Sub-TLV: The Sub-TLV, as presented in Figure 4, MUST
NOT be included in an MPLS SFC validation request.
3.3. SFC Info Sub-TLV
Upon receiving the SFC validation request, the SFF MUST respond with
an echo reply, which includes the SFC detailed information.
The SFC detailed information is recorded in SFC info sub-TLV.
Two types of sub-TLVs are defined in this section, and those are used
in MPLS-based service programming
[I-D.ietf-spring-sr-service-programming] and MPLS-based NSH [RFC8595]
respectively.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLV Type=TBA2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SFF Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Type | SR Proxy Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: SFC Info Sub-TLV for SR-MPLS-based Service Programming
Type TBA2 sub-TLV: used in SR-MPLS-based service programming
SFF Label: represents the SID of the SFF
SF Label: represents the service SID of the SF or SR proxy
SF Type: indicates the type of SF, such as DPI, firewall, etc.
SR Proxy Type: It is defined in
[I-D.ietf-spring-sr-service-programming] and indicates the type of SR
proxy if it exists.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLV Type=TBA3 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SFC-FWD Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SFC context Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: SFC Info Sub-TLV for MPLS-based NSH
Figure 5 presents the format of a sub-TLV for MPLS-based NSH. The
fields are as follows:
Type TBA3 sub-TLV: used in MPLS-based NSH
SFC-FWD Type: indicates the forwarding type of the data plane, and
has the following values:
0x10: MPLS-based NSH [RFC8595] label swapping
0x11: MPLS-based NSH [RFC8595] label stacking
SFC context Label: The meaning of the SFC context label depends on
the SFC Type. If SFC-FWD Type is 0x10, the SFC context Label
represents SPI. If SFC-FWD Type is 0x11, the SFC context Label
represents the context label [RFC8595].
SF Label: The meaning of the SF label depends on the SFC-FWD Type.
If SFC Type is 0x10, the SF Label represents SI. If SFC Type is
0x11, the SF Label represents the SFI index [RFC8595].
SF Type: It is defined in [I-D.ietf-bess-nsh-bgp-control-plane] and
indicates the type of SF, such as DPI, firewall, etc.
3.4. SFC Basic Unit FEC Sub-TLV
Unlike standard MPLS forwarding, based on a single label, packet
forwarding defined in [RFC8595] is based on the basic unit of MPLS
label stack for SFC(SFC Context Label+SF Label). A new SFC Basic
Unit FEC sub-TLV with Type value (TBA4) is defined in this document.
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The SFC Basic Unit FEC sub-TLV MAY be used to carry the corresponding
FEC of the basic unit.
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 (RD) |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SF Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: SFC Basic Unit sub-TLV
The format of the basic unit sub-TLV is shown in Figure 6 and
includes the following fields:
Route Distinguisher (RD): 8 octets field in SFIR Route Type
specific NLRI [I-D.ietf-bess-nsh-bgp-control-plane].
SF Type: 2 octets. It is defined in [I-D.ietf-bess-nsh-bgp-
control-plane] and indicates the type of SF, such as DPI,
firewall, etc.
SFC Basic Unit sub-TLV is defined for Target FEC Stack TLV(Type 1
TLV).
A node that receives an LSP ping with the Target FEC Stack TLV and
the SFC Basic Unit FEC Sub-TLV included will check if it is its Route
Distinguisher and whether it advertised that Service Function Type.
If the validation is not passed, the SFF will generate an MPLS echo
reply with an error code as defined in [RFC8029].
3.5. Theory of Operation
An MPLS SFC validation request is an MPLS echo request with an SFC
validation TLV, and the echo request is sent with a label stack
corresponding to the SFP being tested. To trace SFC-MPLS, the
Generic Associated Channel Label (GAL) which immediately follows the
SFC Context label is also included.
Sending an SFC echo request to the control plane is triggered by one
of the following packet processing exceptions: IP TTL expiration,
MPLS TTL expiration, or the receiver is the terminal SFF for an SFP.
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After general packet sanity verifying [RFC8029], Section 3.5.1 and
Section 3.5.2 in this document separately describe the following
processing procedures in service programming and MPLS-based NSH.
After all SFFs on the SFP send back MPLS echo reply, the sender
collects information about all traversed SFFs and SFs on the rendered
service path (RSP).
3.5.1. MPLS-based service programming
[I-D.ietf-spring-sr-service-programming] describes how a service can
be associated with a SID to achieve service function chaining. In an
SR-MPLS network, the SFP is encoded as a stack of MPLS labels. That
stack is pushed on top of the packet.
Before generating an echo relpy, an SFF MUST parse through the label
stack until the next label is not a local service SID to get all the
SFs attached to the SFF on the SFP and record the corresponding
Label-stack-depth.
The SFF then sends an MPLS echo reply with all the SF information
recorded in SFC Information Sub-TLV, including the service SID and
the SF type.
3.5.2. Path Consistency in SFC-MPLS
[RFC8595] describes how Service Function Chaining (SFC) can be
achieved in an MPLS network using a logical representation of the
Network Service Header (NSH) in an MPLS label stack.
SFC forwarding can be achieved by label swapping, label stacking, or
the mix of both. When an SFF receives a packet containing an MPLS
label stack, it examines the top basic unit of MPLS label stack for
SFC, {SPI, SI} or {context label, SFI index}, to determine where to
send the packet next.
As described in Section 3.1.1, the packet with GAL is recognized by
the SFF as an SFP OAM packet. The SFF then decrements SF Label
entry's TTL value. If the resulting value equals zero, the SFF
passes the SFP OAM packet to the control plane for processing. The
system that supports ths specification generates a reply message,
including in it the SFC info sub-TLV as desribed in Section 3.3.
3.6. Discussion
In [RFC8595], it says, "when an SFF receives a packet from any
component of the SFC system (classifier, SFI, or another SFF), it
MUST discard any packets with TTL set to zero". To trace SFC, it
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should be changed to allow punting the packet to the control plane
though under throttling control.
4. Security Considerations
This specification defines the processing of an SFP OAM packet. Such
packets could be used as an attack vector. A system that supports
this specification MUST provide control to limit the rate of SFP OAM
packets sent to the control plane for processing.
5. IANA Considerations
This document requests assigning type values for TLVs and sub-TLVs
from the IANA "Multiprotocol Label Switching (MPLS) Label Switched
Paths (LSPs) Ping Parameters" registry as described in the sub-
sections below.
5.1. SFC Validation TLV
IANA is requested to assign a type from the Standards Action range of
the "TLVs" registry according to Table 1:
+-------+----------------+---------------+
| Value | Description | Reference |
+-------+----------------+---------------+
| TBA1 | SFC Validation | This document |
+-------+----------------+---------------+
Table 1: Type Value for SFC Validation TLV
5.1.1. Sub-TLVs for SFC Validation TLV
Two sub-TLVs of SFC Validation TLV is defined in this document
according to Table 2.
+-------+-------------------------------------------+---------------+
| Value | Description | Reference |
+-------+-------------------------------------------+---------------+
| TBA2 | Info for SR-MPLS- | This document |
| | based Service Programming | |
| TBA3 | Info for MPLS-based NSH | This document |
+-------+-------------------------------------------+---------------+
Table 2: Sub-TLV Values for SFC Validation TLV
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5.2. SFC Basic Unit sub-TLV
IANA is requested to assign a type from the Standards Action range of
the "Sub-TLVs for TLV Types 1, 16, and 21" registry according to
Table 3:
+-------+----------------+---------------+
| Value | Description | Reference |
+-------+----------------+---------------+
| TBA4 | SFC Basic Unit | This document |
+-------+----------------+---------------+
Table 3: Type Value for SFC Basic Unit sub-TLV
6. References
6.1. Normative References
[I-D.ietf-bess-nsh-bgp-control-plane]
Farrel, A., Drake, J., Rosen, E., Uttaro, J., and L.
Jalil, "BGP Control Plane for the Network Service Header
in Service Function Chaining", draft-ietf-bess-nsh-bgp-
control-plane-18 (work in progress), August 2020.
[I-D.ietf-spring-sr-service-programming]
Clad, F., Xu, X., Filsfils, C., daniel.bernier@bell.ca,
d., Li, C., Decraene, B., Ma, S., Yadlapalli, C.,
Henderickx, W., and S. Salsano, "Service Programming with
Segment Routing", draft-ietf-spring-sr-service-
programming-03 (work in progress), September 2020.
[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>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[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>.
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[RFC7274] Kompella, K., Andersson, L., and A. Farrel, "Allocating
and Retiring Special-Purpose MPLS Labels", RFC 7274,
DOI 10.17487/RFC7274, June 2014,
<https://www.rfc-editor.org/info/rfc7274>.
[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>.
[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
"Network Service Header (NSH)", RFC 8300,
DOI 10.17487/RFC8300, January 2018,
<https://www.rfc-editor.org/info/rfc8300>.
[RFC8595] Farrel, A., Bryant, S., and J. Drake, "An MPLS-Based
Forwarding Plane for Service Function Chaining", RFC 8595,
DOI 10.17487/RFC8595, June 2019,
<https://www.rfc-editor.org/info/rfc8595>.
6.2. Informative References
[I-D.ietf-sfc-nsh-tlv]
Wei, Y., Elzur, U., and S. Majee, "Network Service Header
Metadata Type 2 Variable-Length Context Headers", draft-
ietf-sfc-nsh-tlv-03 (work in progress), May 2020.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
Authors' Addresses
Liu & Mirsky Expires April 28, 2021 [Page 13]
Internet-Draft LSP Ping for SFC October 2020
Liu Yao
ZTE Corporation
No. 50 Software Ave, Yuhuatai Distinct
Nanjing
China
Email: liu.yao71@zte.com.cn
Greg Mirsky
ZTE Corporation
Email: gregimirsky@gmail.com
Liu & Mirsky Expires April 28, 2021 [Page 14]