< draft-ietf-6man-spring-srv6-oam-09.txt   draft-ietf-6man-spring-srv6-oam-10.txt >
6man Z. Ali 6man Z. Ali
Internet-Draft C. Filsfils Internet-Draft C. Filsfils
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: August 23, 2021 S. Matsushima Expires: October 10, 2021 S. Matsushima
Softbank Softbank
D. Voyer D. Voyer
Bell Canada Bell Canada
M. Chen M. Chen
Huawei Huawei
February 19, 2021 April 8, 2021
Operations, Administration, and Maintenance (OAM) in Segment Routing Operations, Administration, and Maintenance (OAM) in Segment Routing
Networks with IPv6 Data plane (SRv6) Networks with IPv6 Data plane (SRv6)
draft-ietf-6man-spring-srv6-oam-09 draft-ietf-6man-spring-srv6-oam-10
Abstract Abstract
This document describes how the existing IPv6 mechanisms for ping and This document describes how the existing IPv6 mechanisms for ping and
traceroute can be used in an SRv6 network. The document also traceroute can be used in an SRv6 network. The document also
specifies the OAM flag in the Segment Routing Header (SRH) for specifies the OAM flag in the Segment Routing Header (SRH) for
performing controllable and predictable flow sampling from segment performing controllable and predictable flow sampling from segment
endpoints. In addition, the document describes how a centralized endpoints. In addition, the document describes how a centralized
monitoring system performs a path continuity check between any nodes monitoring system performs a path continuity check between any nodes
within an SRv6 domain. within an SRv6 domain.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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 23, 2021. This Internet-Draft will expire on October 10, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Terminology and Reference Topology . . . . . . . . . . . 3 1.3. Terminology and Reference Topology . . . . . . . . . . . 4
2. OAM Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 5 2. OAM Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. O-flag in Segment Routing Header . . . . . . . . . . . . 5 2.1. O-flag in Segment Routing Header . . . . . . . . . . . . 5
2.1.1. O-flag Processing . . . . . . . . . . . . . . . . . . 6 2.1.1. O-flag Processing . . . . . . . . . . . . . . . . . . 6
2.2. OAM Operations . . . . . . . . . . . . . . . . . . . . . 7 2.2. OAM Operations . . . . . . . . . . . . . . . . . . . . . 7
3. Illustrations . . . . . . . . . . . . . . . . . . . . . . . . 8 3. Illustrations . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Ping in SRv6 Networks . . . . . . . . . . . . . . . . . . 8 3.1. Ping in SRv6 Networks . . . . . . . . . . . . . . . . . . 8
3.1.1. Classic Ping . . . . . . . . . . . . . . . . . . . . 8 3.1.1. Classic Ping . . . . . . . . . . . . . . . . . . . . 8
3.1.2. Pinging a SID . . . . . . . . . . . . . . . . . . . . 10 3.1.2. Pinging a SID . . . . . . . . . . . . . . . . . . . . 10
3.2. Traceroute . . . . . . . . . . . . . . . . . . . . . . . 10 3.2. Traceroute . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1. Classic Traceroute . . . . . . . . . . . . . . . . . 11 3.2.1. Classic Traceroute . . . . . . . . . . . . . . . . . 11
3.2.2. Traceroute to a SID . . . . . . . . . . . . . . . . . 12 3.2.2. Traceroute to a SID . . . . . . . . . . . . . . . . . 13
3.3. A Hybrid OAM Using O-flag . . . . . . . . . . . . . . . . 14 3.3. A Hybrid OAM Using O-flag . . . . . . . . . . . . . . . . 15
3.4. Monitoring of SRv6 Paths . . . . . . . . . . . . . . . . 16 3.4. Monitoring of SRv6 Paths . . . . . . . . . . . . . . . . 17
4. Implementation Status . . . . . . . . . . . . . . . . . . . . 18 4. Implementation Status . . . . . . . . . . . . . . . . . . . . 18
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18 5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . 20 9.1. Normative References . . . . . . . . . . . . . . . . . . 21
9.2. Informative References . . . . . . . . . . . . . . . . . 20 9.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
As Segment Routing with IPv6 data plane (SRv6) [RFC8402] simply adds As Segment Routing with IPv6 data plane (SRv6) [RFC8402] simply adds
a new type of Routing Extension Header, existing IPv6 OAM mechanisms a new type of Routing Extension Header, existing IPv6 OAM mechanisms
can be used in an SRv6 network. This document describes how the can be used in an SRv6 network. This document describes how the
existing IPv6 mechanisms for ping and trace route can be used in an existing IPv6 mechanisms for ping and traceroute can be used in an
SRv6 network. This includes illustrations of pinging an SRv6 SID for SRv6 network. This includes illustrations of pinging an SRv6 SID to
the SID connectivity checks and to validate the availability of a verify that the SID is reachable and is locally programmed at the
SID. This also includes illustrations for tracerouting to an SRv6 target node. This also includes illustrations for tracerouting to an
SID for hop-by-hop fault localization as well as path tracing to a SRv6 SID for hop-by-hop fault localization as well as path tracing to
SID. a SID.
The document also introduces enhancements for OAM mechanism for SRv6 The document also introduces enhancements for OAM mechanism for SRv6
networks for performing controllable and predictable flow sampling networks for performing controllable and predictable flow sampling
from segment endpoints using, e.g., IP Flow Information Export from segment endpoints using, e.g., IP Flow Information Export
(IPFIX) protocol [RFC7011]. Specifically, the document specifies the (IPFIX) protocol [RFC7011]. Specifically, the document specifies the
O-flag in SRH as a marking-bit in the user packets to trigger the O-flag in SRH as a marking-bit in the user packets to trigger the
telemetry data collection and export at the segment endpoints. telemetry data collection and export at the segment endpoints.
The document also outlines how centralized OAM technique in [RFC8403] The document also outlines how centralized OAM technique in [RFC8403]
can be extended for SRv6 to perform a path continuity check between can be extended for SRv6 to perform a path continuity check between
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SR: Segment Routing. SR: Segment Routing.
SRH: Segment Routing Header [RFC8754]. SRH: Segment Routing Header [RFC8754].
SRv6: Segment Routing with IPv6 Data plane. SRv6: Segment Routing with IPv6 Data plane.
TC: Traffic Class. TC: Traffic Class.
ICMPv6: ICMPv6 Specification [RFC4443]. ICMPv6: ICMPv6 Specification [RFC4443].
IS-IS: Intermediate System to Intermediate System
OSPF: Open Shortest Path First protocol [RFC2328]
IGP: Interior Gateway Protocols (e.g., OSPF, IS-IS).
BGP-LS: Border Gateway Protocol - Link State Extensions [RFC8571]
1.3. Terminology and Reference Topology 1.3. Terminology and Reference Topology
Throughout the document, the following terminology and simple Throughout the document, the following terminology and simple
topology is used for illustration. topology is used for illustration.
+--------------------------| N100 |---------------------------------+ +--------------------------| N100 |---------------------------------+
| | | |
| ====== link1====== link3------ link5====== link9------ ====== | | ====== link1====== link3------ link5====== link9------ ====== |
||N1||------||N2||------| N3 |------||N4||------| N5 |---||N7|| ||N1||------||N2||------| N3 |------||N4||------| N5 |---||N7||
|| ||------|| ||------| |------|| ||------| |---|| || || ||------|| ||------| |------|| ||------| |---|| ||
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| | | | | | | |
---+-- | ------ | --+--- ---+-- | ------ | --+---
|CE 1| +-------| N6 |---------+ |CE 2| |CE 1| +-------| N6 |---------+ |CE 2|
------ link7 | | link8 ------ ------ link7 | | link8 ------
------ ------
Figure 1 Reference Topology Figure 1 Reference Topology
In the reference topology: In the reference topology:
Node k has a classic IPv6 loopback address 2001:DB8:A:k::/128. Node k has a IPv6 loopback address 2001:db8::A:k::/128.
Nodes N1, N2, N4 and N7 are SRv6 capable nodes. Nodes N1, N2, N4 and N7 are SRv6-capable nodes.
Nodes N3, N5 and N6 are IPv6 nodes that are not SRv6 capable. Nodes N3, N5 and N6 are IPv6 nodes that are not SRv6-capable.
Such nodes are referred as classic IPv6 nodes. Such nodes are referred as classic IPv6 nodes.
CE1 and CE2 are Customer Edge devices of any data plane capability CE1 and CE2 are Customer Edge devices of any data plane capability
(e.g., IPv4, IPv6, L2, etc.). (e.g., IPv4, IPv6, L2, etc.).
A SID at node k with locator block 2001:DB8:B::/48 and function F A SID at node k with locator block 2001:db8:B::/48 and function F
is represented by 2001:DB8:B:k:F::. is represented by 2001:db8:B:k:F::.
Node N100 is a controller. Node N100 is a controller.
The IPv6 address of the nth Link between node i and j at the i The IPv6 address of the nth Link between node i and j at the i
side is represented as 2001:DB8:i:j:in::, e.g., the IPv6 address side is represented as 2001:db8:i:j:in::, e.g., the IPv6 address
of link6 (the 2nd link) between N3 and N4 at N3 in Figure 1 is of link6 (the 2nd link) between N3 and N4 at N3 in Figure 1 is
2001:DB8:3:4:32::. Similarly, the IPv6 address of link5 (the 1st 2001:db8:3:4:32::. Similarly, the IPv6 address of link5 (the 1st
link between N3 and N4) at node 3 is 2001:DB8:3:4:31::. link between N3 and N4) at node 3 is 2001:db8:3:4:31::.
2001:DB8:B:k:Cij:: is explicitly allocated as the END.X SID (refer 2001:db8:B:k:Cij:: is explicitly allocated as the END.X SID at
[I-D.ietf-spring-srv6-network-programming]) at node k towards node k towards neighbor node i via jth Link between node i and
neighbor node i via jth Link between node i and node k. e.g., node k. e.g., 2001:db8:B:2:C31:: represents END.X at N2 towards
2001:DB8:B:2:C31:: represents END.X at N2 towards N3 via link3 N3 via link3 (the 1st link between N2 and N3). Similarly,
(the 1st link between N2 and N3). Similarly, 2001:DB8:B:4:C52:: 2001:db8:B:4:C52:: represents the END.X at N4 towards N5 via
represents the END.X at N4 towards N5 via link10. link10. Please refer to [RFC8986] for description of END.X SID.
A SID list is represented as <S1, S2, S3> where S1 is the first A SID list is represented as <S1, S2, S3> where S1 is the first
SID to visit, S2 is the second SID to visit and S3 is the last SID SID to visit, S2 is the second SID to visit and S3 is the last SID
to visit along the SR path. to visit along the SR path.
(SA,DA) (S3, S2, S1; SL)(payload) represents an IPv6 packet with: (SA,DA) (S3, S2, S1; SL)(payload) represents an IPv6 packet with:
* IPv6 header with source address SA, destination addresses DA * IPv6 header with source address SA, destination addresses DA
and SRH as next-header and SRH as next-header
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* (payload) represents the the payload of the packet. * (payload) represents the the payload of the packet.
2. OAM Mechanisms 2. OAM Mechanisms
This section defines OAM enhancement for the SRv6 networks. This section defines OAM enhancement for the SRv6 networks.
2.1. O-flag in Segment Routing Header 2.1. O-flag in Segment Routing Header
[RFC8754] describes the Segment Routing Header (SRH) and how SR [RFC8754] describes the Segment Routing Header (SRH) and how SR
capable nodes use it. The SRH contains an 8-bit "Flags" field. This capable nodes use it. The SRH contains an 8-bit "Flags" field.
document defines the following bit in the SRH.Flags to carry the
O-flag: This document defines the following bit in the SRH Flags field to
carry the O-flag:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| |O| | | |O| |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Where: Where:
O-flag: OAM flag. O-flag: OAM flag in the SRH Flags field defined in [RFC8754] .
The document does not define any other flag in the SRH.Flags and
meaning and processing of any other bit in SRH.Flags is outside of
the scope of this document.
2.1.1. O-flag Processing 2.1.1. O-flag Processing
The O-flag in SRH is used as a marking-bit in the user packets to The O-flag in SRH is used as a marking-bit in the user packets to
trigger the telemetry data collection and export at the segment trigger the telemetry data collection and export at the segment
endpoints. endpoints.
This document does not specify the data elements that need to be This document does not specify the data elements that need to be
exported and the associated configurations. Similarly, this document exported and the associated configurations. Similarly, this document
does not define any formats for exporting the data elements. does not define any formats for exporting the data elements.
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are configured by the management plane through data set templates are configured by the management plane through data set templates
(e.g., as in IPFIX [RFC7012]). (e.g., as in IPFIX [RFC7012]).
Implementation of the O-flag is OPTIONAL. If a node does not support Implementation of the O-flag is OPTIONAL. If a node does not support
the O-flag, then upon reception it simply ignores it. If a node the O-flag, then upon reception it simply ignores it. If a node
supports the O-flag, it can optionally advertise its potential via supports the O-flag, it can optionally advertise its potential via
control plane protocol(s). control plane protocol(s).
When N receives a packet whose IPv6 DA is S and S is a local SID, the When N receives a packet whose IPv6 DA is S and S is a local SID, the
line S01 of the pseudo-code associated with the SID S, as defined in line S01 of the pseudo-code associated with the SID S, as defined in
section 4.3.1.1 of [RFC8754], is modified as follows for the O-flag section 4.3.1.1 of [RFC8754], is appended as follows for the O-flag
processing. processing.
S01.1. IF SRH.Flags.O-flag is set and local configuration permits S01.1. IF O-flag is set and local configuration permits
O-flag processing THEN O-flag processing {
a. Make a copy of the packet. a. Make a copy of the packet.
b. Send the copied packet, along with a timestamp b. Send the copied packet, along with a timestamp
to the OAM process for telemetry data collection to the OAM process for telemetry data collection
and export. ;; Ref1 and export. ;; Ref1
}
Ref1: An implementation SHOULD copy and record the timestamp as Ref1: An implementation SHOULD copy and record the timestamp as
soon as possible during packet processing. Timestamp or any other soon as possible during packet processing. Timestamp or any other
metadata is not metadata is not
carried in the packet forwarded to the next hop. carried in the packet forwarded to the next hop.
Please note that the O-flag processing happens before execution of Please note that the O-flag processing happens before execution of
regular processing of the local SID S. regular processing of the local SID S. Specifically, the line S01.1
of the pseudo-code specified in this document is inserted between
line S01 and S02 of the pseudo-code defined in section 4.3.1.1 of
[RFC8754].
Based on the requested information elements configured by the Based on the requested information elements configured by the
management plane through data set templates [RFC7012], the OAM management plane through data set templates [RFC7012], the OAM
process exports the requested information elements. The information process exports the requested information elements. The information
elements include parts of the packet header and/or parts of the elements include parts of the packet header and/or parts of the
packet payload for flow identification. The OAM process uses packet payload for flow identification. The OAM process uses
information elements defined in IPFIX [RFC7011] and PSAMP [RFC5476] information elements defined in IPFIX [RFC7011] and PSAMP [RFC5476]
for exporting the requested sections of the mirrored packets. for exporting the requested sections of the mirrored packets.
If the telemetry data from the ultimate segment in the segment-list If the telemetry data from the ultimate segment in the segment-list
is required, a penultimate segment SHOULD NOT be a Penultimate is required, a penultimate segment SHOULD NOT be a Penultimate
Segment Pop (PSP) SID. When the penultimate segment is a PSP SID, Segment Pop (PSP) SID. When the penultimate segment is a PSP SID,
the SRH will be removed and the O-bit will not be processed at the the SRH will be removed and the O-flag will not be processed at the
ultimate segment. ultimate segment.
The processing node SHOULD rate-limit the number of packets punted to The processing node SHOULD rate-limit the number of packets punted to
the OAM process to avoid hitting any performance impact. the OAM process to a configurable rate. This is to avoid hitting any
performance impact on the OAM and the telemetry collection processes.
Failure in implementing the rate limit can lead to a denial-of-
service attack, as detailed in Section 5.
The OAM process MUST NOT process the copy of the packet or respond to The OAM process MUST NOT process the copy of the packet or respond to
any upper-layer header (like ICMP, UDP, etc.) payload to prevent any upper-layer header (like ICMP, UDP, etc.) payload to prevent
multiple evaluations of the datagram. multiple evaluations of the datagram.
Specification of the OAM process or the external controller Specification of the OAM process or the external controller
operations are beyond the scope of this document. How to correlate operations are beyond the scope of this document. How to correlate
the data collected from different nodes at an external controller is the data collected from different nodes at an external controller is
also outside the scope of the document. Section 3 illustrates use of also outside the scope of the document. Section 3 illustrates use of
the SRH.Flags.O-flag for implementing a hybrid OAM mechanism, where the O-flag for implementing a hybrid OAM mechanism, where the
the "hybrid" classification is based on RFC7799 [RFC7799]. "hybrid" classification is based on RFC7799 [RFC7799].
2.2. OAM Operations 2.2. OAM Operations
IPv6 OAM operations can be performed for any SRv6 SID whose behavior IPv6 OAM operations can be performed for any SRv6 SID whose behavior
allows Upper Layer Header processing for an applicable OAM payload allows Upper Layer Header processing for an applicable OAM payload
(e.g., ICMP, UDP). (e.g., ICMP, UDP).
Ping to a SID is used for SID connectivity checks and to validate the Ping to an SRv6 SID is used to verify that the SID is reachable and
availability of a SID. Traceroute to a SID is used for hop-by-hop is locally programmed at the target node. Traceroute to a SID is
fault localization as well as path tracing to a SID. Section 3 used for hop-by-hop fault localization as well as path tracing to a
illustrates the ICMPv6 based ping and the UDP based traceroute SID. Section 3 illustrates the ICMPv6 based ping and the UDP based
mechanisms for ping and traceroute to an SRv6 SID. Although this traceroute mechanisms for ping and traceroute to an SRv6 SID.
document only illustrates ICMP ping and UDP-based traceroute to an Although this document only illustrates ICMPv6 ping and UDP based
SRv6 SID, the procedures are equally applicable to other IPv6 OAM traceroute to an SRv6 SID, the procedures are equally applicable to
probing to an SRv6 SID (e.g., Bidirectional Forwarding Detection other IPv6 OAM probing to an SRv6 SID (e.g., Bidirectional Forwarding
(BFD) [RFC5880], Seamless BFD (SBFD) [RFC7880], TWAMP Light and STAMP Detection (BFD) [RFC5880], Seamless BFD (SBFD) [RFC7880], STAMP probe
probe message processing as described in [I-D.gandhi-spring-twamp- message processing [I-D.gandhi-spring-stamp-srpm], etc.).
srpm] and [I-D.gandhi-spring-stamp-srpm], respectively, etc.).
Specifically, as long as local configuration allows the Upper-layer Specifically, as long as local configuration allows the Upper-layer
Header processing of the applicable OAM payload for SRv6 SIDs, the Header processing of the applicable OAM payload for SRv6 SIDs, the
existing IPv6 OAM techniques can be used to target a probe to a existing IPv6 OAM techniques can be used to target a probe to a
(remote) SID. (remote) SID.
IPv6 OAM operations can be performed with the target SID in the IPv6 IPv6 OAM operations can be performed with the target SID in the IPv6
destination address without SRH or with SRH where the target SID is destination address without SRH or with SRH where the target SID is
the last segment. In general, OAM operations to a target SID may not the last segment. In general, OAM operations to a target SID may not
exercise all of its processing depending on its behavior definition. exercise all of its processing depending on its behavior definition.
For example, ping to an END.X SID (refer [I-D.ietf-spring-srv6- For example, ping to an END.X SID [RFC8986] only validates the SID is
network-programming]) at the target node only validates availability locally programmed at the target node and does not validate switching
of the SID and does not validate switching to the correct outgoing to the correct outgoing interface. To exercise the behavior of a
interface. To exercise the behavior of a target SID, the OAM target SID, the OAM operation SHOULD construct the probe in a manner
operation SHOULD construct the probe in a manner similar to a data similar to a data packet that exercises the SID behavior, i.e. to
packet that exercises the SID behavior, i.e. to include that SID as a include that SID as a transit SID in either an SRH or IPv6 DA of an
transit SID in either an SRH or IPv6 DA of an outer IPv6 header or as outer IPv6 header or as appropriate based on the definition of the
appropriate based on the definition of the SID behavior. SID behavior.
3. Illustrations 3. Illustrations
This section shows how some of the existing IPv6 OAM mechanisms can This section shows how some of the existing IPv6 OAM mechanisms can
be used in an SRv6 network. It also illustrates an OAM mechanism for be used in an SRv6 network. It also illustrates an OAM mechanism for
performing controllable and predictable flow sampling from segment performing controllable and predictable flow sampling from segment
endpoints. How centralized OAM technique in [RFC8403] can be endpoints. How centralized OAM technique in [RFC8403] can be
extended for SRv6 is also described in this Section. extended for SRv6 is also described in this Section.
3.1. Ping in SRv6 Networks 3.1. Ping in SRv6 Networks
The following subsections outline some use cases of the ICMP ping in The following subsections outline some use cases of the ICMPv6 ping
the SRv6 networks. in the SRv6 networks.
3.1.1. Classic Ping 3.1.1. Classic Ping
The existing mechanism to perform the connectivity checks, along the The existing mechanism to perform the reachability checks, along the
shortest path, continues to work without any modification. The shortest path, continues to work without any modification. The
initiator may be an SRv6 node or a classic IPv6 node. Similarly, the initiator may be an SRv6 node or a classic IPv6 node. Similarly, the
egress or transit may be an SRv6 capable node or a classic IPv6 node. egress or transit may be an SRv6-capable node or a classic IPv6 node.
If an SRv6 capable ingress node wants to ping an IPv6 address via an If an SRv6-capable ingress node wants to ping an IPv6 address via an
arbitrary segment list <S1, S2, S3>, it needs to initiate ICMPv6 ping arbitrary segment list <S1, S2, S3>, it needs to initiate ICMPv6 ping
with an SR header containing the SID list <S1, S2, S3>. This is with an SR header containing the SID list <S1, S2, S3>. This is
illustrated using the topology in Figure 1. Assume all the links illustrated using the topology in Figure 1. Assume all the links
have IGP metric 10 except both links between N2 and N3, which have have IGP metric 10 except both links between N2 and N3, which have
IGP metric set to 100. User issues a ping from node N1 to a loopback IGP metric set to 100. User issues a ping from node N1 to a loopback
of node 5, via segment list <2001:DB8:B:2:C31::, 2001:DB8:B:4:C52::>. of node 5, via segment list <2001:db8:B:2:C31::, 2001:db8:B:4:C52::>.
The SID behavior used in the example is End.X SID (refer [I-D.ietf- The SID behavior used in the example is End.X SID, as described in
spring-srv6-network-programming]) but the procedure is equally [RFC8986], but the procedure is equally applicable to any other
applicable to any other (transit) SID type. (transit) SID type.
Figure 2 contains sample output for a ping request initiated at node Figure 2 contains sample output for a ping request initiated at node
N1 to the loopback address of node N5 via a segment list N1 to the loopback address of node N5 via a segment list
<2001:DB8:B:2:C31::, 2001:DB8:B:4:C52::>. <2001:db8:B:2:C31::, 2001:db8:B:4:C52::>.
> ping 2001:DB8:A:5:: via segment-list 2001:DB8:B:2:C31::, > ping 2001:db8:A:5:: via segment-list 2001:db8:B:2:C31::,
2001:DB8:B:4:C52:: 2001:db8:B:4:C52::
Sending 5, 100-byte ICMP Echos to B5::, timeout is 2 seconds: Sending 5, 100-byte ICMPv6 Echos to B5::, timeout is 2 seconds:
!!!!! !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0.625 Success rate is 100 percent (5/5), round-trip min/avg/max = 0.625
/0.749/0.931 ms /0.749/0.931 ms
Figure 2 A sample ping output at an SRv6 capable node Figure 2 A sample ping output at an SRv6-capable node
All transit nodes process the echo request message like any other All transit nodes process the echo request message like any other
data packet carrying SR header and hence do not require any change. data packet carrying SR header and hence do not require any change.
Similarly, the egress node (IPv6 classic or SRv6 capable) does not Similarly, the egress node (IPv6 classic or SRv6-capable) does not
require any change to process the ICMPv6 echo request. For example, require any change to process the ICMPv6 echo request. For example,
in the ping example of Figure 2: in the ping example of Figure 2:
o Node N1 initiates an ICMPv6 ping packet with SRH as follows o Node N1 initiates an ICMPv6 ping packet with SRH as follows
(2001:DB8:A:1::, 2001:DB8:B:2:C31::) (2001:DB8:A:5::, (2001:db8:A:1::, 2001:db8:B:2:C31::) (2001:db8:A:5::,
2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::, SL=2, NH = ICMPv6)(ICMPv6 2001:db8:B:4:C52::, 2001:db8:B:2:C31::, SL=2, NH = ICMPv6)(ICMPv6
Echo Request). Echo Request).
o Node N2, which is an SRv6 capable node, performs the standard SRH o Node N2, which is an SRv6-capable node, performs the standard SRH
processing. Specifically, it executes the END.X behavior processing. Specifically, it executes the END.X behavior
(2001:DB8:B:2:C31::) and forwards the packet on link3 to N3. (2001:db8:B:2:C31::) and forwards the packet on link3 to N3.
o Node N3, which is a classic IPv6 node, performs the standard IPv6 o Node N3, which is a classic IPv6 node, performs the standard IPv6
processing. Specifically, it forwards the echo request based on processing. Specifically, it forwards the echo request based on
the DA 2001:DB8:B:4:C52:: in the IPv6 header. the DA 2001:db8:B:4:C52:: in the IPv6 header.
o Node N4, which is an SRv6 capable node, performs the standard SRH o Node N4, which is an SRv6-capable node, performs the standard SRH
processing. Specifically, it observes the END.X behavior processing. Specifically, it observes the END.X behavior
(2001:DB8:B:4:C52::) and forwards the packet on link10 towards N5. (2001:db8:B:4:C52::) and forwards the packet on link10 towards N5.
If 2001:DB8:B:4:C52:: is a PSP SID, The penultimate node (Node N4) If 2001:db8:B:4:C52:: is a PSP SID, The penultimate node (Node N4)
does not, should not and cannot differentiate between the data does not, should not and cannot differentiate between the data
packets and OAM probes. Specifically, if 2001:DB8:B:4:C52:: is a packets and OAM probes. Specifically, if 2001:db8:B:4:C52:: is a
PSP SID, node N4 executes the SID like any other data packet with PSP SID, node N4 executes the SID like any other data packet with
DA = 2001:DB8:B:4:C52:: and removes the SRH. DA = 2001:db8:B:4:C52:: and removes the SRH.
o The echo request packet at N5 arrives as an IPv6 packet with or o The echo request packet at N5 arrives as an IPv6 packet with or
without an SRH. If N5 receives the packet with SRH, it skips SRH without an SRH. If N5 receives the packet with SRH, it skips SRH
processing (SL=0). In either case, Node N5 performs the standard processing (SL=0). In either case, Node N5 performs the standard
IPv6/ ICMPv6 processing on the echo request and responds with the ICMPv6 processing on the echo request and responds with the echo
echo reply message. The echo reply message is IP routed. reply message to N1. The echo reply message is IP routed.
3.1.2. Pinging a SID 3.1.2. Pinging a SID
The classic ping described in the previous section applies equally to The classic ping described in the previous section applies equally to
perform SID connectivity checks and to validate the availability of a perform SID reachability check and to validate the SID is locally
remote SID. This is explained using an example in the following. programmed at the target node. This is explained using an example in
The example uses ping to an END SID (refer [I-D.ietf-spring-srv6- the following. The example uses ping to an END SID, as described in
network-programming]) but the procedure is equally applicable to ping [RFC8986], but the procedure is equally applicable to ping any other
any other SID behaviors. SID behaviors.
Consider the example where the user wants to ping a remote SID Consider the example where the user wants to ping a remote SID
2001:DB8:B:4::, via 2001:DB8:B:2:C31::, from node N1. The ICMPv6 2001:db8:B:4::, via 2001:db8:B:2:C31::, from node N1. The ICMPv6
echo request is processed at the individual nodes along the path as echo request is processed at the individual nodes along the path as
follows: follows:
o Node N1 initiates an ICMPv6 ping packet with SRH as follows o Node N1 initiates an ICMPv6 ping packet with SRH as follows
(2001:DB8:A:1::, 2001:DB8:B:2:C31::) (2001:DB8:B:4::, (2001:db8:A:1::, 2001:db8:B:2:C31::) (2001:db8:B:4::,
2001:DB8:B:2:C31::; SL=1; NH=ICMPv6)(ICMPv6 Echo Request). 2001:db8:B:2:C31::; SL=1; NH=ICMPv6)(ICMPv6 Echo Request).
o Node N2, which is an SRv6 capable node, performs the standard SRH o Node N2, which is an SRv6-capable node, performs the standard SRH
processing. Specifically, it executes the END.X behavior processing. Specifically, it executes the END.X behavior
(2001:DB8:B:2:C31::) on the echo request packet. If (2001:db8:B:2:C31::) on the echo request packet. If
2001:DB8:B:2:C31:: is a PSP SID, node N4 executes the SID like any 2001:db8:B:2:C31:: is a PSP SID, node N4 executes the SID like any
other data packet with DA = 2001:DB8:B:2:C31:: and removes the other data packet with DA = 2001:db8:B:2:C31:: and removes the
SRH. SRH.
o Node N3, which is a classic IPv6 node, performs the standard IPv6 o Node N3, which is a classic IPv6 node, performs the standard IPv6
processing. Specifically, it forwards the echo request based on processing. Specifically, it forwards the echo request based on
DA = 2001:DB8:B:4:: in the IPv6 header. DA = 2001:db8:B:4:: in the IPv6 header.
o When node N4 receives the packet, it processes the target SID o When node N4 receives the packet, it processes the target SID
(2001:DB8:B:4::). (2001:db8:B:4::).
o If the target SID (2001:DB8:B:4::) is not locally instantiated, o If the target SID (2001:db8:B:4::) is not locally instantiated,
the packet is discarded the packet is discarded
o If the target SID (2001:DB8:B:4::) is locally instantiated, the o If the target SID (2001:db8:B:4::) is locally instantiated, the
node processes the upper layer header. As part of the upper layer node processes the upper layer header. As part of the upper layer
header processing node N4 respond to the ICMPv6 echo request header processing node N4 respond to the ICMPv6 echo request
message and responds with the echo reply message. The echo reply message and responds with the echo reply message. The echo reply
message is IP routed. message is IP routed.
3.2. Traceroute 3.2. Traceroute
There is no hardware or software change required for traceroute There is no hardware or software change required for traceroute
operation at the classic IPv6 nodes in an SRv6 network. That operation at the classic IPv6 nodes in an SRv6 network. That
includes the classic IPv6 node with ingress, egress or transit roles. includes the classic IPv6 node with ingress, egress or transit roles.
skipping to change at page 11, line 17 skipping to change at page 11, line 24
The following subsections outline some use cases of the traceroute in The following subsections outline some use cases of the traceroute in
the SRv6 networks. the SRv6 networks.
3.2.1. Classic Traceroute 3.2.1. Classic Traceroute
The existing mechanism to traceroute a remote IP address, along the The existing mechanism to traceroute a remote IP address, along the
shortest path, continues to work without any modification. The shortest path, continues to work without any modification. The
initiator may be an SRv6 node or a classic IPv6 node. Similarly, the initiator may be an SRv6 node or a classic IPv6 node. Similarly, the
egress or transit may be an SRv6 node or a classic IPv6 node. egress or transit may be an SRv6 node or a classic IPv6 node.
If an SRv6 capable ingress node wants to traceroute to IPv6 address If an SRv6-capable ingress node wants to traceroute to IPv6 address
via an arbitrary segment list <S1, S2, S3>, it needs to initiate via an arbitrary segment list <S1, S2, S3>, it needs to initiate
traceroute probe with an SR header containing the SID list <S1, S2, traceroute probe with an SR header containing the SID list <S1, S2,
S3>. That is illustrated using the topology in Figure 1. Assume all S3>. That is illustrated using the topology in Figure 1. Assume all
the links have IGP metric 10 except both links between N2 and N3, the links have IGP metric 10 except both links between N2 and N3,
which have IGP metric set to 100. User issues a traceroute from node which have IGP metric set to 100. User issues a traceroute from node
N1 to a loopback of node 5, via segment list <2001:DB8:B:2:C31::, N1 to a loopback of node 5, via segment list <2001:db8:B:2:C31::,
2001:DB8:B:4:C52::>. The SID behavior used in the example is End.X 2001:db8:B:4:C52::>. The SID behavior used in the example is End.X
SID (refer [I-D.ietf-spring-srv6-network-programming]) but the SID, as described in [RFC8986], but the procedure is equally
procedure is equally applicable to any other (transit) SID type. applicable to any other (transit) SID type. Figure 3 contains sample
Figure 3 contains sample output for the traceroute request. output for the traceroute request.
> traceroute 2001:DB8:A:5:: via segment-list 2001:DB8:B:2:C31::, > traceroute 2001:db8:A:5:: via segment-list 2001:db8:B:2:C31::,
2001:DB8:B:4:C52:: 2001:db8:B:4:C52::
Tracing the route to 2001:DB8:A:5:: Tracing the route to 2001:db8:A:5::
1 2001:DB8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec 1 2001:db8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec
DA: 2001:DB8:B:2:C31::, DA: 2001:db8:B:2:C31::,
SRH:(2001:DB8:A:5::, 2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::, SL=2) SRH:(2001:db8:A:5::, 2001:db8:B:4:C52::, 2001:db8:B:2:C31::, SL=2)
2 2001:DB8:2:3:31:: 0.721 msec 0.810 msec 0.795 msec 2 2001:db8:2:3:31:: 0.721 msec 0.810 msec 0.795 msec
DA: 2001:DB8:B:4:C52::, DA: 2001:db8:B:4:C52::,
SRH:(2001:DB8:A:5::, 2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::, SL=1) SRH:(2001:db8:A:5::, 2001:db8:B:4:C52::, 2001:db8:B:2:C31::, SL=1)
3 2001:DB8:3:4::41:: 0.921 msec 0.816 msec 0.759 msec 3 2001:db8:3:4::41:: 0.921 msec 0.816 msec 0.759 msec
DA: 2001:DB8:B:4:C52::, DA: 2001:db8:B:4:C52::,
SRH:(2001:DB8:A:5::, 2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::, SL=1) SRH:(2001:db8:A:5::, 2001:db8:B:4:C52::, 2001:db8:B:2:C31::, SL=1)
4 2001:DB8:4:5::52:: 0.879 msec 0.916 msec 1.024 msec 4 2001:db8:4:5::52:: 0.879 msec 0.916 msec 1.024 msec
DA: 2001:DB8:A:5:: DA: 2001:db8:A:5::
Figure 3 A sample traceroute output at an SRv6 capable node Figure 3 A sample traceroute output at an SRv6-capable node
In the sample traceroute output, the information displayed at each In the sample traceroute output, the information displayed at each
hop is obtained using the contents of the "Time Exceeded" or hop is obtained using the contents of the "Time Exceeded" or
"Destination Unreachable" ICMPv6 responses. These ICMPv6 responses "Destination Unreachable" ICMPv6 responses. These ICMPv6 responses
are IP routed. are IP routed.
Please note that information for hop2 is returned by N3, which is a In the sample traceroute output, the information for link3 is
classic IPv6 node. Nonetheless, the ingress node is able to display returned by N3, which is a classic IPv6 node. Nonetheless, the
SR header contents as the packet travels through the IPv6 classic ingress node is able to display SR header contents as the packet
node. This is because the "Time Exceeded Message" ICMPv6 message can travels through the IPv6 classic node. This is because the "Time
contain as much of the invoking packet as possible without the ICMPv6 Exceeded Message" ICMPv6 message can contain as much of the invoking
packet exceeding the minimum IPv6 MTU [RFC4443]. The SR header is packet as possible without the ICMPv6 packet exceeding the minimum
also included in these ICMPv6 messages initiated by the classic IPv6 IPv6 MTU [RFC4443]. The SR header is also included in these ICMPv6
transit nodes that are not running SRv6 software. Specifically, a messages initiated by the classic IPv6 transit nodes that are not
node generating ICMPv6 message containing a copy of the invoking running SRv6 software. Specifically, a node generating ICMPv6
packet does not need to understand the extension header(s) in the message containing a copy of the invoking packet does not need to
invoking packet. understand the extension header(s) in the invoking packet.
The segment list information returned for the first hop is returned The segment list information returned for the first hop is returned
by N2, which is an SRv6 capable node. Just like for the second hop, by N2, which is an SRv6-capable node. Just like for the second hop,
the ingress node is able to display SR header contents for the first the ingress node is able to display SR header contents for the first
hop. hop.
There is no difference in processing of the traceroute probe at an There is no difference in processing of the traceroute probe at an
IPv6 classic node and an SRv6 capable node. Similarly, both IPv6 IPv6 classic node and an SRv6-capable node. Similarly, both IPv6
classic and SRv6 capable nodes may use the address of the interface classic and SRv6-capable nodes may use the address of the interface
on which probe was received as the source address in the ICMPv6 on which probe was received as the source address in the ICMPv6
response. ICMP extensions defined in [RFC5837] can be used to also response. ICMPv6 extensions defined in [RFC5837] can be used to also
display information about the IP interface through which the datagram display information about the IP interface through which the datagram
would have been forwarded had it been forwardable, and the IP next would have been forwarded had it been forwardable, and the IP next
hop to which the datagram would have been forwarded, the IP interface hop to which the datagram would have been forwarded, the IP interface
upon which a datagram arrived, the sub-IP component of an IP upon which a datagram arrived, the sub-IP component of an IP
interface upon which a datagram arrived. interface upon which a datagram arrived.
The information about the IP address of the incoming interface on The IP address of the interface on which the traceroute probe was
which the traceroute probe was received by the reporting node is very received is useful. This information can also be used to verify if
useful. This information can also be used to verify if SIDs SIDs 2001:db8:B:2:C31:: and 2001:db8:B:4:C52:: are executed correctly
2001:DB8:B:2:C31:: and 2001:DB8:B:4:C52:: are executed correctly by by N2 and N4, respectively. Specifically, the information displayed
N2 and N4, respectively. Specifically, the information displayed for for the second hop contains the incoming interface address
the second hop contains the incoming interface address 2001:db8:2:3:31:: at N3. This matches with the expected interface
2001:DB8:2:3:31:: at N3. This matches with the expected interface bound to END.X behavior 2001:db8:B:2:C31:: (link3). Similarly, the
bound to END.X behavior 2001:DB8:B:2:C31:: (link3). Similarly, the
information displayed for hop5 contains the incoming interface information displayed for hop5 contains the incoming interface
address 2001:DB8:4:5::52:: at N5. This matches with the expected address 2001:db8:4:5::52:: at N5. This matches with the expected
interface bound to the END.X behavior 2001:DB8:B:4:C52:: (link10). interface bound to the END.X behavior 2001:db8:B:4:C52:: (link10).
3.2.2. Traceroute to a SID 3.2.2. Traceroute to a SID
The classic traceroute described in the previous section applies The classic traceroute described in the previous section applies
equally to traceroute a remote SID behavior, as explained using an equally to traceroute a remote SID behavior, as explained using an
example in the following. The example uses traceroute to an END SID example in the following. The example uses traceroute to an END SID,
(refer [I-D.ietf-spring-srv6-network-programming]) but the procedure as described in [RFC8986], but the procedure is equally applicable to
is equally applicable to tracerouting any other SID behaviors. tracerouting any other SID behaviors.
Please note that traceroute to a SID is exemplified using UDP probes. Please note that traceroute to a SID is exemplified using UDP probes.
However, the procedure is equally applicable to other implementations However, the procedure is equally applicable to other implementations
of traceroute mechanism. of traceroute mechanism. The UDP encoded message to traceroute a SID
uses the UDP ports assigned by IANA for "traceroute use".
Consider the example where the user wants to traceroute a remote SID Consider the example where the user wants to traceroute a remote SID
2001:DB8:B:4::, via 2001:DB8:B:2:C31::, from node N1. The traceroute 2001:db8:B:4::, via 2001:db8:B:2:C31::, from node N1. The traceroute
probe is processed at the individual nodes along the path as follows: probe is processed at the individual nodes along the path as follows:
o Node N1 initiates a traceroute probe packet with a monotonically o Node N1 initiates a traceroute probe packet with a monotonically
increasing value of hop count and SRH as follows (2001:DB8:A:1::, increasing value of hop count and SRH as follows (2001:db8:A:1::,
2001:DB8:B:2:C31::) (2001:DB8:B:4::, 2001:DB8:B:2:C31::; SL=1; 2001:db8:B:2:C31::) (2001:db8:B:4::, 2001:db8:B:2:C31::; SL=1;
NH=UDP)(Traceroute probe). NH=UDP)(Traceroute probe).
o When node N2 receives the packet with hop-count = 1, it processes o When node N2 receives the packet with hop-count = 1, it processes
the hop count expiry. Specifically, the node N2 responses with the hop count expiry. Specifically, the node N2 responses with
the ICMPv6 message (Type: "Time Exceeded", Code: "Hop limit the ICMPv6 message (Type: "Time Exceeded", Code: "Hop limit
exceeded in transit"). The ICMPv6 response is IP routed. exceeded in transit"). The ICMPv6 response is IP routed.
o When Node N2 receives the packet with hop-count > 1, it performs o When Node N2 receives the packet with hop-count > 1, it performs
the standard SRH processing. Specifically, it executes the END.X the standard SRH processing. Specifically, it executes the END.X
behavior (2001:DB8:B:2:C31::) on the traceroute probe. If behavior (2001:db8:B:2:C31::) on the traceroute probe. If
2001:DB8:B:2:C31:: is a PSP SID, node N4 executes the SID like any 2001:db8:B:2:C31:: is a PSP SID, node N4 executes the SID like any
other data packet with DA = 2001:DB8:B:2:C31:: and removes the other data packet with DA = 2001:db8:B:2:C31:: and removes the
SRH. SRH.
o When node N3, which is a classic IPv6 node, receives the packet o When node N3, which is a classic IPv6 node, receives the packet
with hop-count = 1, it processes the hop count expiry. with hop-count = 1, it processes the hop count expiry.
Specifically, the node N3 responses with the ICMPv6 message (Type: Specifically, the node N3 responses with the ICMPv6 message (Type:
"Time Exceeded", Code: "Hop limit exceeded in Transit"). The "Time Exceeded", Code: "Hop limit exceeded in Transit"). The
ICMPv6 response is IP routed. ICMPv6 response is IP routed.
o When node N3, which is a classic IPv6 node, receives the packet o When node N3, which is a classic IPv6 node, receives the packet
with hop-count > 1, it performs the standard IPv6 processing. with hop-count > 1, it performs the standard IPv6 processing.
Specifically, it forwards the traceroute probe based on DA Specifically, it forwards the traceroute probe based on DA
2001:DB8:B:4:: in the IPv6 header. 2001:db8:B:4:: in the IPv6 header.
o When node N4 receives the packet with DA set to the local SID o When node N4 receives the packet with DA set to the local SID
2001:DB8:B:4::, it processes the END SID. 2001:db8:B:4::, it processes the END SID.
o If the target SID (2001:DB8:B:4::) is not locally instantiated, o If the target SID (2001:db8:B:4::) is not locally instantiated,
the packet is discarded. the packet is discarded.
o If the target SID (2001:DB8:B:4::) is locally instantiated, the o If the target SID (2001:db8:B:4::) is locally instantiated, the
node processes the upper layer header. As part of the upper layer node processes the upper layer header. As part of the upper layer
header processing node N4 responses with the ICMPv6 message (Type: header processing node N4 responses with the ICMPv6 message (Type:
Destination unreachable, Code: Port Unreachable). The ICMPv6 Destination unreachable, Code: Port Unreachable). The ICMPv6
response is IP routed. response is IP routed.
Figure 4 displays a sample traceroute output for this example. Figure 4 displays a sample traceroute output for this example.
> traceroute 2001:DB8:B:4:C52:: via segment-list 2001:DB8:B:2:C31:: > traceroute 2001:db8:B:4:C52:: via segment-list 2001:db8:B:2:C31::
Tracing the route to SID 2001:DB8:B:4:C52:: Tracing the route to SID 2001:db8:B:4:C52::
1 2001:DB8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec 1 2001:db8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec
DA: 2001:DB8:B:2:C31::, DA: 2001:db8:B:2:C31::,
SRH:(2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::; SL=1) SRH:(2001:db8:B:4:C52::, 2001:db8:B:2:C31::; SL=1)
2 2001:DB8:2:3:31:: 0.721 msec 0.810 msec 0.795 msec 2 2001:db8:2:3:31:: 0.721 msec 0.810 msec 0.795 msec
DA: 2001:DB8:B:4:C52::, DA: 2001:db8:B:4:C52::,
SRH:(2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::; SL=0) SRH:(2001:db8:B:4:C52::, 2001:db8:B:2:C31::; SL=0)
3 2001:DB8:3:4:41:: 0.921 msec 0.816 msec 0.759 msec 3 2001:db8:3:4:41:: 0.921 msec 0.816 msec 0.759 msec
DA: 2001:DB8:B:4:C52::, DA: 2001:db8:B:4:C52::,
SRH:(2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::; SL=0) SRH:(2001:db8:B:4:C52::, 2001:db8:B:2:C31::; SL=0)
Figure 4 A sample output for hop-by-hop traceroute to a SID Figure 4 A sample output for hop-by-hop traceroute to a SID
3.3. A Hybrid OAM Using O-flag 3.3. A Hybrid OAM Using O-flag
This section illustrates a hybrid OAM mechanism using the the This section illustrates a hybrid OAM mechanism using the the O-flag.
SRH.Flags.O-flag. Without loss of the generality, the illustration Without loss of the generality, the illustration assumes N100 is a
assumes N100 is a centralized controller. centralized controller.
The illustration is different than the In-situ OAM defined in [I.D- The illustration is different than the In-situ OAM defined in [I.D-
draft-ietf-ippm-ioam-data]. This is because In-situ OAM records draft-ietf-ippm-ioam-data]. This is because In-situ OAM records
operational and telemetry information in the packet as the packet operational and telemetry information in the packet as the packet
traverses a path between two points in the network [I.D-draft-ietf- traverses a path between two points in the network [I.D-draft-ietf-
ippm-ioam-data]. The illustration in section 3 does not require the ippm-ioam-data]. The illustration in this subsection does not
recording of OAM data in the packet. require the recording of OAM data in the packet.
The illustration does not assume any formats for exporting the data The illustration does not assume any formats for exporting the data
elements or the data elements that need to be exported. elements or the data elements that need to be exported.
Consider the example where the user wants to monitor sampled IPv4 VPN Consider the example where the user wants to monitor sampled IPv4 VPN
999 traffic going from CE1 to CE2 via a low latency SR policy P 999 traffic going from CE1 to CE2 via a low latency SR policy P
installed at Node N1. To exercise a low latency path, the SR Policy installed at Node N1. To exercise a low latency path, the SR Policy
P forces the packet via segments 2001:DB8:B:2:C31:: and P forces the packet via segments 2001:db8:B:2:C31:: and
2001:DB8:B:4:C52::. The VPN SID at N7 associated with VPN 999 is 2001:db8:B:4:C52::. The VPN SID at N7 associated with VPN 999 is
2001:DB8:B:7:DT999::. 2001:DB8:B:7:DT999:: is a USP SID. N1, N4, 2001:db8:B:7:DT999::. 2001:db8:B:7:DT999:: is a USP SID. N1, N4,
and N7 are capable of processing SRH.Flags.O-flag but N2 is not and N7 are capable of processing O-flag but N2 is not capable of
capable of processing SRH.Flags.O-flag. N100 is the centralized processing O-flag. N100 is the centralized controller capable of
controller capable of processing and correlating the copy of the processing and correlating the copy of the packets sent from nodes
packets sent from nodes N1, N4, and N7. N100 is aware of N1, N4, and N7. N100 is aware of O-flag processing capabilities.
SRH.Flags.O-flag processing capabilities. Controller N100 with the Controller N100 with the help from nodes N1, N4, N7 and implements a
help from nodes N1, N4, N7 and implements a hybrid OAM mechanism hybrid OAM mechanism using the O-flag as follows:
using the SRH.Flags.O-flag as follows:
o A packet P1:(IPv4 header)(payload) is sent from CE1 to Node N1. o A packet P1:(IPv4 header)(payload) is sent from CE1 to Node N1.
o Node N1 steers the packet P1 through the Policy P. Based on a o Node N1 steers the packet P1 through the Policy P. Based on a
local configuration, Node N1 also implements logic to sample local configuration, Node N1 also implements logic to sample
traffic steered through policy P for hybrid OAM purposes. traffic steered through policy P for hybrid OAM purposes.
Specification for the sampling logic is beyond the scope of this Specification for the sampling logic is beyond the scope of this
document. Consider the case where packet P1 is classified as a document. Consider the case where packet P1 is classified as a
packet to be monitored via the hybrid OAM. Node N1 sets packet to be monitored via the hybrid OAM. Node N1 sets O-flag
SRH.Flags.O-flag during encapsulation required by policy P. As during encapsulation required by policy P. As part of setting the
part of setting the SRH.Flags.O-flag, node N1 also sends a O-flag, node N1 also sends a timestamped copy of the packet P1:
timestamped copy of the packet P1: (2001:DB8:A:1::, (2001:db8:A:1::, 2001:db8:B:2:C31::) (2001:db8:B:7:DT999::,
2001:DB8:B:2:C31::) (2001:DB8:B:7:DT999::, 2001:DB8:B:4:C52::, 2001:db8:B:4:C52::, 2001:db8:B:2:C31::; SL=2; O-flag=1;
2001:DB8:B:2:C31::; SL=2; O-flag=1; NH=IPv4)(IPv4 header)(payload) NH=IPv4)(IPv4 header)(payload) to a local OAM process. The local
to a local OAM process. The local OAM process sends a full or OAM process sends a full or partial copy of the packet P1 to the
partial copy of the packet P1 to the controller N100. The OAM controller N100. The OAM process includes the recorded timestamp,
process includes the recorded timestamp, additional OAM additional OAM information like incoming and outgoing interface,
information like incoming and outgoing interface, etc. along with etc. along with any applicable metadata. Node N1 forwards the
any applicable metadata. Node N1 forwards the original packet original packet towards the next segment 2001:db8:B:2:C31::.
towards the next segment 2001:DB8:B:2:C31::.
o When node N2 receives the packet with SRH.Flags.O-flag set, it o When node N2 receives the packet with O-flag set, it ignores the
ignores the SRH.Flags.O-flag. This is because node N2 is not O-flag. This is because node N2 is not capable of processing the
capable of processing the O-flag. Node N2 performs the standard O-flag. Node N2 performs the standard SRv6 SID and SRH
SRv6 SID and SRH processing. Specifically, it executes the END.X processing. Specifically, it executes the END.X behavior
(refer [I-D.ietf-spring-srv6-network-programming]) behavior (2001:db8:B:2:C31::) as described in [RFC8986] and forwards the
(2001:DB8:B:2:C31::) and forwards the packet P1 (2001:DB8:A:1::, packet P1 (2001:db8:A:1::, 2001:db8:B:4:C52::)
2001:DB8:B:4:C52::) (2001:DB8:B:7:DT999::, 2001:DB8:B:4:C52::, (2001:db8:B:7:DT999::, 2001:db8:B:4:C52::, 2001:db8:B:2:C31::;
2001:DB8:B:2:C31::; SL=1; O-flag=1; NH=IPv4)(IPv4 header)(payload) SL=1; O-flag=1; NH=IPv4)(IPv4 header)(payload) over link 3 towards
over link 3 towards Node N3. Node N3.
o When node N3, which is a classic IPv6 node, receives the packet P1 o When node N3, which is a classic IPv6 node, receives the packet P1
, it performs the standard IPv6 processing. Specifically, it , it performs the standard IPv6 processing. Specifically, it
forwards the packet P1 based on DA 2001:DB8:B:4:C52:: in the IPv6 forwards the packet P1 based on DA 2001:db8:B:4:C52:: in the IPv6
header. header.
o When node N4 receives the packet P1 (2001:DB8:A:1::, o When node N4 receives the packet P1 (2001:db8:A:1::,
2001:DB8:B:4:C52::) (2001:DB8:B:7:DT999::, 2001:DB8:B:4:C52::, 2001:db8:B:4:C52::) (2001:db8:B:7:DT999::, 2001:db8:B:4:C52::,
2001:DB8:B:2:C31::; SL=1; O-flag=1; NH=IPv4)(IPv4 2001:db8:B:2:C31::; SL=1; O-flag=1; NH=IPv4)(IPv4
header)(payload), it processes the SRH.Flags.O-flag. As part of header)(payload), it processes the O-flag. As part of processing
processing the O-flag, it sends a timestamped copy of the packet the O-flag, it sends a timestamped copy of the packet to a local
to a local OAM process. The local OAM process sends a full or OAM process. The local OAM process sends a full or partial copy
partial copy of the packet P1 to the controller N100. The OAM of the packet P1 to the controller N100. The OAM process includes
process includes the recorded timestamp, additional OAM the recorded timestamp, additional OAM information like incoming
information like incoming and outgoing interface, etc. along with and outgoing interface, etc. along with any applicable metadata.
any applicable metadata. Node N4 performs the standard SRv6 SID Node N4 performs the standard SRv6 SID and SRH processing on the
and SRH processing on the original packet P1. Specifically, it original packet P1. Specifically, it executes the END.X behavior
executes the END.X behavior (2001:DB8:B:4:C52::) and forwards the (2001:db8:B:4:C52::) and forwards the packet P1 (2001:db8:A:1::,
packet P1 (2001:DB8:A:1::, 2001:DB8:B:7:DT999::) 2001:db8:B:7:DT999::) (2001:db8:B:7:DT999::, 2001:db8:B:4:C52::,
(2001:DB8:B:7:DT999::, 2001:DB8:B:4:C52::, 2001:DB8:B:2:C31::; 2001:db8:B:2:C31::; SL=0; O-flag=1; NH=IPv4)(IPv4 header)(payload)
SL=0; O-flag=1; NH=IPv4)(IPv4 header)(payload) over link 10 over link 10 towards Node N5.
towards Node N5.
o When node N5, which is a classic IPv6 node, receives the packet o When node N5, which is a classic IPv6 node, receives the packet
P1, it performs the standard IPv6 processing. Specifically, it P1, it performs the standard IPv6 processing. Specifically, it
forwards the packet based on DA 2001:DB8:B:7:DT999:: in the IPv6 forwards the packet based on DA 2001:db8:B:7:DT999:: in the IPv6
header. header.
o When node N7 receives the packet P1 (2001:DB8:A:1::, o When node N7 receives the packet P1 (2001:db8:A:1::,
2001:DB8:B:7:DT999::) (2001:DB8:B:7:DT999::, 2001:DB8:B:4:C52::, 2001:db8:B:7:DT999::) (2001:db8:B:7:DT999::, 2001:db8:B:4:C52::,
2001:DB8:B:2:C31::; SL=0; O-flag=1; NH=IPv4)(IPv4 2001:db8:B:2:C31::; SL=0; O-flag=1; NH=IPv4)(IPv4
header)(payload), it processes the SRH.Flags.O-flag. As part of header)(payload), it processes the O-flag. As part of processing
processing the O-flag, it sends a timestamped copy of the packet the O-flag, it sends a timestamped copy of the packet to a local
to a local OAM process. The local OAM process sends a full or OAM process. The local OAM process sends a full or partial copy
partial copy of the packet P1 to the controller N100. The OAM of the packet P1 to the controller N100. The OAM process includes
process includes the recorded timestamp, additional OAM the recorded timestamp, additional OAM information like incoming
information like incoming and outgoing interface, etc. along with and outgoing interface, etc. along with any applicable metadata.
any applicable metadata. Node N4 performs the standard SRv6 SID Node N4 performs the standard SRv6 SID and SRH processing on the
and SRH processing on the original packet P1. Specifically, it original packet P1. Specifically, it executes the VPN SID
executes the VPN SID (2001:DB8:B:7:DT999::) and based on lookup in (2001:db8:B:7:DT999::) and based on lookup in table 100 forwards
table 100 forwards the packet P1 (IPv4 header)(payload) towards CE the packet P1 (IPv4 header)(payload) towards CE 2.
2.
o The controller N100 processes and correlates the copy of the o The controller N100 processes and correlates the copy of the
packets sent from nodes N1, N4 and N7 to find segment-by-segment packets sent from nodes N1, N4 and N7 to find segment-by-segment
delays and provide other hybrid OAM information related to packet delays and provide other hybrid OAM information related to packet
P1. P1.
o The process continues for any other sampled packets. o The process continues for any other sampled packets.
3.4. Monitoring of SRv6 Paths 3.4. Monitoring of SRv6 Paths
skipping to change at page 17, line 11 skipping to change at page 17, line 32
networks with MPLS data plane. This document describes how the networks with MPLS data plane. This document describes how the
concept can be used to perform path monitoring in an SRv6 network concept can be used to perform path monitoring in an SRv6 network
from a centralized controller. from a centralized controller.
In the reference topology in Figure 1, N100 uses an IGP protocol like In the reference topology in Figure 1, N100 uses an IGP protocol like
OSPF or ISIS to get the topology view within the IGP domain. N100 OSPF or ISIS to get the topology view within the IGP domain. N100
can also use BGP-LS to get the complete view of an inter-domain can also use BGP-LS to get the complete view of an inter-domain
topology. The controller leverages the visibility of the topology to topology. The controller leverages the visibility of the topology to
monitor the paths between the various endpoints. monitor the paths between the various endpoints.
The controller N100 advertises an END (refer [I-D.ietf-spring-srv6- The controller N100 advertises an END SID [RFC8986]
network-programming]) SID 2001:DB8:B:100:1::. To monitor any 2001:db8:B:100:1::. To monitor any arbitrary SRv6 paths, the
arbitrary SRv6 paths, the controller can create a loopback probe that controller can create a loopback probe that originates and terminates
originates and terminates on Node N100. To distinguish between a on Node N100. To distinguish between a failure in the monitored path
failure in the monitored path and loss of connectivity between the and loss of connectivity between the controller and the network, Node
controller and the network, Node N100 runs a suitable mechanism to N100 runs a suitable mechanism to monitor its connectivity to the
monitor its connectivity to the monitored network. monitored network.
The loopback probes are exemplified using an example where controller The loopback probes are exemplified using an example where controller
N100 needs to verify a segment list <2001:DB8:B:2:C31::, N100 needs to verify a segment list <2001:db8:B:2:C31::,
2001:DB8:B:4:C52::>: 2001:db8:B:4:C52::>:
o N100 generates an OAM packet (2001:DB8:A:100::, o N100 generates an OAM packet (2001:db8:A:100::,
2001:DB8:B:2:C31::)(2001:DB8:B:100:1::, 2001:DB8:B:4:C52::, 2001:db8:B:2:C31::)(2001:db8:B:100:1::, 2001:db8:B:4:C52::,
2001:DB8:B:2:C31::, SL=2)(OAM Payload). The controller routes the 2001:db8:B:2:C31::, SL=2)(OAM Payload). The controller routes the
probe packet towards the first segment, which is probe packet towards the first segment, which is
2001:DB8:B:2:C31::. 2001:db8:B:2:C31::.
o Node N2 executes the END.X behavior (2001:DB8:B:2:C31::) and o Node N2 executes the END.X behavior (2001:db8:B:2:C31::) and
forwards the packet (2001:DB8:A:100::, forwards the packet (2001:db8:A:100::,
2001:DB8:B:4:C52::)(2001:DB8:B:100:1::, 2001:DB8:B:4:C52::, 2001:db8:B:4:C52::)(2001:db8:B:100:1::, 2001:db8:B:4:C52::,
2001:DB8:B:2:C31::, SL=1)(OAM Payload) on link3 to N3. 2001:db8:B:2:C31::, SL=1)(OAM Payload) on link3 to N3.
o Node N3, which is a classic IPv6 node, performs the standard IPv6 o Node N3, which is a classic IPv6 node, performs the standard IPv6
processing. Specifically, it forwards the packet based on the DA processing. Specifically, it forwards the packet based on the DA
2001:DB8:B:4:C52:: in the IPv6 header. 2001:db8:B:4:C52:: in the IPv6 header.
o Node N4 executes the END.X behavior (2001:DB8:B:4:C52::) and o Node N4 executes the END.X behavior (2001:db8:B:4:C52::) and
forwards the packet (2001:DB8:A:100::, forwards the packet (2001:db8:A:100::,
2001:DB8:B:100:1::)(2001:DB8:B:100:1::, 2001:DB8:B:4:C52::, 2001:db8:B:100:1::)(2001:db8:B:100:1::, 2001:db8:B:4:C52::,
2001:DB8:B:2:C31::, SL=0)(OAM Payload) on link10 to N5. 2001:db8:B:2:C31::, SL=0)(OAM Payload) on link10 to N5.
o Node N5, which is a classic IPv6 node, performs the standard IPv6 o Node N5, which is a classic IPv6 node, performs the standard IPv6
processing. Specifically, it forwards the packet based on the DA processing. Specifically, it forwards the packet based on the DA
2001:DB8:B:100:1:: in the IPv6 header. 2001:db8:B:100:1:: in the IPv6 header.
o Node N100 executes the standard SRv6 END behavior. It o Node N100 executes the standard SRv6 END behavior. It
decapsulates the header and consume the probe for OAM processing. decapsulates the header and consume the probe for OAM processing.
The information in the OAM payload is used to detect any missing The information in the OAM payload is used to detect any missing
probes, round trip delay, etc. probes, round trip delay, etc.
The OAM payload type or the information carried in the OAM probe is a The OAM payload type or the information carried in the OAM probe is a
local implementation decision at the controller and is outside the local implementation decision at the controller and is outside the
scope of this document. scope of this document.
4. Implementation Status 4. Implementation Status
This section is to be removed prior to publishing as an RFC. This section is to be removed prior to publishing as an RFC.
See [I-D.matsushima-spring-srv6-deployment-status] for updated See [I-D.matsushima-spring-srv6-deployment-status] for updated
deployment and interoperability reports. deployment and interoperability reports.
5. Security Considerations 5. Security Considerations
This document does not define any new protocol extensions and relies This document does not define any new protocol extensions and relies
on existing procedures defined for ICMP. This document does not on existing procedures defined for ICMPv6.
impose any additional security challenges to be considered beyond
security considerations described in [RFC4884], [RFC4443], [RFC0792], [RFC8754] defines the notion of an SR domain and use of SRH within
and [RFC8754]. the SR domain. The use of OAM procedures described in this document
is restricted to an SR domain. For example, similar to the SID
manipulation, O-flag manipulation is not considered as a threat
within the SR domain. Procedures for securing an SR domain are
defined the section 5.1 and section 7 of [RFC8754].
As noted in section 7.1 of [RFC8754], compromised nodes within the SR
domain may mount attacks. The O-flag may be set by an attacking node
attempting a denial-of-service attack on the OAM process at the
segment endpoint node. An implementation correctly implementing the
rate limiting in section 2.1.1 is not susceptible to that denial-of-
service attack. Additionally, SRH Flags are protected by the HMAC
TLV, as described in Section 2.1.2.1 of [RFC8754].
This document does not impose any additional security challenges to
be considered beyond security threats described in [RFC4884],
[RFC4443], [RFC0792], and [RFC8754].
6. IANA Considerations 6. IANA Considerations
This document requests that IANA allocate the following registrations This document requests that IANA allocate the following registrations
in the "Segment Routing Header Flags" sub-registry for the "Internet in the "Segment Routing Header Flags" sub-registry for the "Internet
Protocol Version 6 (IPv6) Parameters" registry maintained by IANA: Protocol Version 6 (IPv6) Parameters" registry maintained by IANA:
+-------+------------------------------+---------------+ +-------+------------------------------+---------------+
| Bit | Description | Reference | | Bit | Description | Reference |
+=======+==============================+===============+ +=======+==============================+===============+
skipping to change at page 20, line 4 skipping to change at page 20, line 33
Germany Germany
Email: fbrockne@cisco.com Email: fbrockne@cisco.com
Darren Dukes Darren Dukes
Cisco Systems, Inc. Cisco Systems, Inc.
Email: ddukes@cisco.com Email: ddukes@cisco.com
Cheng Li Cheng Li
Huawei Huawei
Email: chengli13@huawei.com Email: chengli13@huawei.com
Faisal Iqbal Faisal Iqbal
Individual Individual
Email: faisal.ietf@gmail.com Email: faisal.ietf@gmail.com
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>. <https://www.rfc-editor.org/info/rfc8754>.
9.2. Informative References 9.2. Informative References
[I-D.gandhi-spring-stamp-srpm] [I-D.gandhi-spring-stamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B. Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B.
Janssens, "Performance Measurement Using Simple TWAMP Janssens, "Performance Measurement Using Simple TWAMP
(STAMP) for Segment Routing Networks", draft-gandhi- (STAMP) for Segment Routing Networks", draft-gandhi-
spring-stamp-srpm-04 (work in progress), January 2021. spring-stamp-srpm-04 (work in progress), January 2021.
[I-D.gandhi-spring-twamp-srpm] [I-D.ietf-ippm-ioam-data]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B. Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields
Janssens, "Performance Measurement Using TWAMP Light for for In-situ OAM", draft-ietf-ippm-ioam-data-11 (work in
Segment Routing Networks", draft-gandhi-spring-twamp- progress), November 2020.
srpm-11 (work in progress), October 2020.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-28 (work in
progress), December 2020.
[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., and K.
Rajaraman, "SRv6 Implementation and Deployment Status", Rajaraman, "SRv6 Implementation and Deployment Status",
draft-matsushima-spring-srv6-deployment-status-10 (work in draft-matsushima-spring-srv6-deployment-status-10 (work in
progress), December 2020. progress), December 2020.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981, RFC 792, DOI 10.17487/RFC0792, September 1981,
<https://www.rfc-editor.org/info/rfc792>. <https://www.rfc-editor.org/info/rfc792>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89, Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006, RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>. <https://www.rfc-editor.org/info/rfc4443>.
[RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
"Extended ICMP to Support Multi-Part Messages", RFC 4884, "Extended ICMP to Support Multi-Part Messages", RFC 4884,
DOI 10.17487/RFC4884, April 2007, DOI 10.17487/RFC4884, April 2007,
<https://www.rfc-editor.org/info/rfc4884>. <https://www.rfc-editor.org/info/rfc4884>.
skipping to change at page 22, line 15 skipping to change at page 23, line 10
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>. July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8403] Geib, R., Ed., Filsfils, C., Pignataro, C., Ed., and N. [RFC8403] Geib, R., Ed., Filsfils, C., Pignataro, C., Ed., and N.
Kumar, "A Scalable and Topology-Aware MPLS Data-Plane Kumar, "A Scalable and Topology-Aware MPLS Data-Plane
Monitoring System", RFC 8403, DOI 10.17487/RFC8403, July Monitoring System", RFC 8403, DOI 10.17487/RFC8403, July
2018, <https://www.rfc-editor.org/info/rfc8403>. 2018, <https://www.rfc-editor.org/info/rfc8403>.
[RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
IGP Traffic Engineering Performance Metric Extensions",
RFC 8571, DOI 10.17487/RFC8571, March 2019,
<https://www.rfc-editor.org/info/rfc8571>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
Authors' Addresses Authors' Addresses
Zafar Ali Zafar Ali
Cisco Systems Cisco Systems
Email: zali@cisco.com Email: zali@cisco.com
Clarence Filsfils Clarence Filsfils
Cisco Systems Cisco Systems
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