< draft-ali-6man-spring-srv6-oam-01.txt   draft-ali-6man-spring-srv6-oam-02.txt >
Networking Working Group Z. Ali
6man Z. Ali
Internet-Draft C. Filsfils Internet-Draft C. Filsfils
Intended status: Standards Track N. Kumar Intended status: Standards Track Cisco Systems
Expires: September 26, 2019 C. Pignataro Expires: January 9, 2020 S. Matsushima
R. Gandhi Softbank
F. Brockners
Cisco Systems, Inc.
J. Leddy
Individual
S. Matsushima
SoftBank
R. Raszuk
Bloomberg LP
D. Voyer D. Voyer
Bell Canada Bell Canada
G. Dawra
LinkedIn
B. Peirens
Proximus
M. Chen M. Chen
C. Li
Huawei Huawei
F. Iqbal July 8, 2019
Individual
March 27, 2019
Operations, Administration, and Maintenance (OAM) in Segment Operations, Administration, and Maintenance (OAM) in Segment Routing
Routing Networks with IPv6 Data plane (SRv6) Networks with IPv6 Data plane (SRv6)
draft-ali-6man-spring-srv6-oam-01.txt draft-ali-6man-spring-srv6-oam-02
Abstract Abstract
This document defines building blocks for Operations, Administration, This document defines building blocks for Operations, Administration,
and Maintenance (OAM) in Segment Routing Networks with IPv6 Dataplane and Maintenance (OAM) in Segment Routing Networks with IPv6 Dataplane
(SRv6). The document also describes some SRv6 OAM mechanisms. (SRv6). The document also describes some SRv6 OAM mechanisms.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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This Internet-Draft will expire on January 9, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction.........................................................3
2. Conventions Used in This Document..............................3
2.1. Abbreviations.............................................3
2.2. Terminology and Reference Topology........................3
3. OAM Building Blocks............................................4
3.1. O-flag in Segment Routing Header..........................4
3.1.1. O-flag Processing....................................5
3.2. OAM Segments..............................................5
3.2.1. End.OP: OAM Endpoint with Punt.......................6
3.2.2. End.OTP: OAM Endpoint with Timestamp and Punt........6
3.3. SRH TLV...................................................7
4. OAM Mechanisms.................................................7
4.1. Ping......................................................7
4.1.1. Classic Ping.........................................7
4.1.2. Pinging a SID Function...............................9
4.2. Error Reporting..........................................11
4.3. Traceroute...............................................11
4.3.1. Classic Traceroute..................................12
4.3.2. Traceroute to a SID Function........................13
4.4. OAM Data Piggybacked in Data traffic.....................17
4.4.1. IOAM Data Field Encapsulation in SRH................17
4.4.2. Procedure...........................................18
4.5. Monitoring of SRv6 Paths.................................20
5. Security Considerations.......................................20
6. IANA Considerations...........................................21
6.1. ICMPv6 type Numbers Registry.............................21
6.2. SRv6 OAM Endpoint Types..................................21
6.3. SRv6 IOAM TLV............................................21
7. References....................................................22
7.1. Normative References.....................................22
7.2. Informative References...................................23
1. Introduction
This document defines building blocks for
Operations, Administration, and Maintenance (OAM) in Segment Routing
Networks with IPv6 Dataplane (SRv6). The document also describes
some SRv6 OAM mechanisms.
2. Conventions Used in This Document
2.1. Abbreviations
ECMP: Equal Cost Multi-Path.
SID: Segment ID.
SL: Segment Left. 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Terminology and Reference Topology . . . . . . . . . . . 3
3. OAM Building Blocks . . . . . . . . . . . . . . . . . . . . . 5
3.1. O-flag in Segment Routing Header . . . . . . . . . . . . 5
3.1.1. O-flag Processing . . . . . . . . . . . . . . . . . . 6
3.2. OAM Segments . . . . . . . . . . . . . . . . . . . . . . 6
3.3. End.OP: OAM Endpoint with Punt . . . . . . . . . . . . . 6
3.4. End.OTP: OAM Endpoint with Timestamp and Punt . . . . . . 7
3.5. SRH TLV . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. OAM Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Ping . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1.1. Classic Ping . . . . . . . . . . . . . . . . . . . . 8
4.1.2. Pinging a SID Function . . . . . . . . . . . . . . . 9
4.1.3. Error Reporting . . . . . . . . . . . . . . . . . . . 12
4.2. Traceroute . . . . . . . . . . . . . . . . . . . . . . . 12
4.2.1. Classic Traceroute . . . . . . . . . . . . . . . . . 13
4.2.2. Traceroute to a SID Function . . . . . . . . . . . . 14
4.3. Monitoring of SRv6 Paths . . . . . . . . . . . . . . . . 18
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6.1. ICMPv6 type Numbers RegistrySEC . . . . . . . . . . . . . 19
6.2. SRv6 OAM Endpoint Types . . . . . . . . . . . . . . . . . 19
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.1. Normative References . . . . . . . . . . . . . . . . . . 21
9.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
SR: Segment Routing. 1. Introduction
SRH: Segment Routing Header. This document defines building blocks for Operations, Administration,
and Maintenance (OAM) in Segment Routing Networks with IPv6 Dataplane
(SRv6). The document also describes some SRv6 OAM mechanisms.
SRv6: Segment Routing with IPv6 Data plane. 2. Conventions Used in This Document
TC: Traffic Class. 2.1. Abbreviations
UCMP: Unequal Cost Multi-Path. The following abbreviations are used in this document:
ICMPv6: multi-part ICMPv6 messages [RFC4884]. SID: Segment ID.
2.2. Terminology and Reference Topology SL: Segment Left.
This document uses the terminology defined in [I-D.draft-filsfils- SR: Segment Routing.
spring-srv6-network-programming]. The readers are expected to be
familiar with the same.
Throughout the document, the following simple topology is used for SRH: Segment Routing Header.
illustration.
+--------------------------| N100 |------------------------+ SRv6: Segment Routing with IPv6 Data plane.
| |
====== link1====== link3------ link5====== link9------
||N1||======||N2||======| N3 |======||N4||======| N5 |
|| ||------|| ||------| |------|| ||------| |
====== link2====== link4------ link6======link10------
| |
| ------ |
+-------| N6 |---------+
link7 | | link8
------
Figure 1 Reference Topology TC: Traffic Class.
In the reference topology: ICMPv6: multi-part ICMPv6 messages [RFC4884].
Nodes N1, N2, and N4 are SRv6 capable nodes. 2.2. Terminology and Reference Topology
Nodes N3, N5 and N6 are classic IPv6 nodes. This document uses the terminology defined in [I-D.ietf- spring-srv6-
network-programming]. The readers are expected to be familiar with
the same.
Node N100 is a controller. Throughout the document, the following simple topology is used for
illustration.
Node k has a classic IPv6 loopback address A:k::/128. +--------------------------| N100 |------------------------+
| |
====== link1====== link3------ link5====== link9------
||N1||======||N2||======| N3 |======||N4||======| N5 |
|| ||------|| ||------| |------|| ||------| |
====== link2====== link4------ link6======link10------
| |
| ------ |
+-------| N6 |---------+
link7 | | link8
------
A SID at node k with locator block B and function F is represented Figure 1 Reference Topology
by B:k:F::
The IPv6 address of the nth Link between node X and Y at the X side In the reference topology:
is represented as 2001:DB8:X:Y:Xn::, e.g., the IPv6 address 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
link between N3 and N4) at node 3 is 2001:DB8:3:4:31::.
B:k:1:: is explicitly allocated as the END function at Node k. Nodes N1, N2, and N4 are SRv6 capable nodes.
B:k::Cij is explicitly allocated as the END.X function at node k Nodes N3, N5 and N6 are classic IPv6 nodes.
towards neighbor node i via jth Link between node i and node j.
e.g., B:2:C31 represents END.X at N2 towards N3 via link3 (the 1st
link between N2 and N3). Similarly, B:4:C52 represents the END.X at
N4 towards N5 via link10.
<S1, S2, S3> represents a SID list where S1 is the first SID and S3 Node N100 is a controller.
is the last SID. (S3, S2, S1; SL) represents the same SID list but
encoded in the SRH format where the rightmost SID (S1) in the SRH is
the first SID and the leftmost SID (S3) in the SRH is the last SID.
(SA, DA) (S3, S2, S1; SL) represents an IPv6 packet, SA is the IPv6 Node k has a classic IPv6 loopback address A:k::/128.
Source Address, DA the IPv6 Destination Address, (S3, S2, S1; SL) is
the SRH header that includes the SID list <S1, S2, S3>.
3. OAM Building Blocks A SID at node k with locator block B and function F is represented
by B:k:F::.
This section defines the various building blocks for The IPv6 address of the nth Link between node X and Y at the X
implementing OAM mechanisms in SRv6 networks. side is represented as 2001:DB8:X:Y:Xn::, e.g., the IPv6 address
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
link between N3 and N4) at node 3 is 2001:DB8:3:4:31::.
3.1. O-flag in Segment Routing Header B:k:Cij:: is explicitly allocated as the END.X function at node k
towards neighbor node i via jth Link between node i and node j.
e.g., B:2:C31:: represents END.X at N2 towards N3 via link3 (the
1st link between N2 and N3). Similarly, B:4:C52:: represents the
END.X at N4 towards N5 via link10.
[I-D. draft-ietf-6man-segment-routing-header] describes the Segment A SID list is represented as <S1, S2, S3> where S1 is the first
Routing Header (SRH) and how SR capable nodes use it. The SRH SID to visit, S2 is the second SID to visit and S3 is the last SID
contains an 8-bit "Flags" field [I-D. draft-ietf-6man-segment- to visit along the SR path.
routing-header]. This document defines the following bit in the
SRH.Flags to carry the O-flag:
0 1 2 3 4 5 6 7 (SA,DA) (S3, S2, S1; SL)(payload) represents an IPv6 packet with:
+-+-+-+-+-+-+-+-+
| |O| |
+-+-+-+-+-+-+-+-+
Where: * IPv6 header with source address SA, destination addresses DA
and SRH as next-header
- O-flag: OAM flag. When set, it indicates that this packet is an * SRH with SID list <S1, S2, S3> with SegmentsLeft = SL
operations and management (OAM) packet. This document defines
the usage of the O-flag in the SRH.Flags.
- 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.
3.1.1. O-flag Processing * Note the difference between the < > and () symbols: <S1, S2,
S3> represents a SID list where S1 is the first SID and S3 is
the last SID to traverse. (S3, S2, S1; SL) represents the same
SID list but encoded in the SRH format where the rightmost SID
in the SRH is the first SID and the leftmost SID in the SRH is
the last SID. When referring to an SR policy in a high-level
use-case, it is simpler to use the <S1, S2, S3> notation. When
referring to an illustration of the detailed packet behavior,
the (S3, S2, S1; SL) notation is more convenient.
Implementation of the O-flag is OPTIONAL. A node MAY ignore * (payload) represents the the payload of the packet.
SRH.Flags.O-flag. It is also possible that a node is capable of
supporting the O-bit but based on a local decision it MAY ignore it
during processing on some local SIDs. If a node does not support the
O-flag, then upon reception it simply ignores it. If a node supports
the O-flag, it can optionally advertise its potential via node
capability advertisement in IGP [I-D.bashandy-isis-srv6-
extensions] and BGP-LS [I-D.dawra-idr-bgpls-srv6-ext].
The SRH.Flags.O-flag implements the "punt a timestamped copy and SRH[SL] represents the SID pointed by the SL field in the first
forward" behavior. SRH. In our example, SRH[2] represents S1, SRH[1] represents S2
and SRH[0] represents S3.
When N receives a packet whose IPv6 DA is S and S is a local SID, N 3. OAM Building Blocks
executes the following the pseudo-code, before the execution of the
local SID S.
1. IF SRH.Flags.O-flag is True and SRH.Flags.O-flag is locally
supported for S THEN
a. Timestamp a local copy of the packet. ;; Ref1
b. Punt the time-stamped copy of the packet to CPU for processing
in software (slow-path). ;; Ref2
Ref1: Timestamping is done in hardware, as soon as possible during
the packet processing. As timestamping is done on a copy of the
packet which is locally punted, timestamp value can be carried in
the local packet (punt) header.
Ref1: Hardware (microcode) just punts the packet. Software (slow path)
implements the required OAM
mechanism. Timestamp is not carried in the packet forwarded to the
next hop.
3.2. OAM Segments This section defines the various building blocks for implementing OAM
mechanisms in SRv6 networks.
OAM Segment IDs (SIDs) is another component of the SRv6 OAM building 3.1. O-flag in Segment Routing Header
Blocks. This document defines a
couple of OAM SIDs. Additional SIDs will be added in the later
version of the document.
3.2.1. End.OP: OAM Endpoint with Punt [I-D.ietf-6man-segment-routing-header] describes the Segment Routing
Header (SRH) and how SR capable nodes use it. The SRH contains an
8-bit "Flags" field [I-D.draft-ietf-6man-segment- routing-header].
This document defines the following bit in the SRH.Flags to carry the
O-flag:
Many scenarios require punting of SRv6 OAM packets at the desired 0 1 2 3 4 5 6 7
nodes in the network. The "OAM Endpoint with Punt" function (End.OP +-+-+-+-+-+-+-+-+
for short) represents a particular OAM function to implement the | |O| |
punt behavior for an OAM packet. It is described using the +-+-+-+-+-+-+-+-+
pseudocode as follows:
When N receives a packet destined to S and S is a local End.OP SID, Where:
N does:
1. Punt the packet to CPU for SW processing (slow-path) ;; Ref1 O-flag: OAM flag. When set, it indicates that this packet is an
operations and management (OAM) packet. This document defines the
usage of the O-flag in the SRH.Flags.
Ref1: Hardware (microcode) punts the packet. Software (slow path) The document does not define any other flag in the SRH.Flags and
implements the required OAM mechanisms. meaning and processing of any other bit in SRH.Flags is outside of
the scope of this document.
Please note that in an SRH containing END.OP SID, it is RECOMMENDED 3.1.1. O-flag Processing
to set the SRH.Flags.O-flag = 0.
3.2.2. End.OTP: OAM Endpoint with Timestamp and Punt Implementation of the O-flag is OPTIONAL. A node MAY ignore
SRH.Flags.O-flag. It is also possible that a node is capable of
supporting the O-bit but based on a local decision it MAY ignore it
during processing on some local SIDs. If a node does not support the
O-flag, then upon reception it simply ignores it. If a node supports
the O-flag, it can optionally advertise its potential via node
capability advertisement in IGP [I-D.ietf-isis-srv6- extensions] and
BGP-LS [I-D.ietf-idr-bgpls-srv6-ext].
Scenarios demanding performance management of an SR policy/ path The SRH.Flags.O-flag implements the "punt a timestamped copy and
requires hardware timestamping before hardware punts the packet to forward" behavior.
the software for OAM processing. The "OAM Endpoint with Timestamp
and Punt" function (End.OTP for short) represents an OAM SID
function to implement the timestamp and punt behavior for an OAM
packet. It is described using the pseudocode as follows:
When N receives a packet destined to S and S is a local End.OTP SID, When N receives a packet whose IPv6 DA is S and S is a local SID, N
N does: executes the following pseudo-code, before the execution of the local
SID S.
1. Timestamp the packet ;; Ref1 1. IF SRH.Flags.O-flag is one and local configuration permits THEN
a. Make a copy of the packet.
b. Send the copied packet, along with an accurate timestamp
to the OAM process. ;; Ref1
Ref1: An implementation SHOULD copy and record the timestamp as soon as
possible during packet processing. Timestamp is not carried in the packet
forwarded to the next hop.
2. Punt the packet to CPU for SW processing (slow-path) ;; Ref2 3.2. OAM Segments
Ref1: Timestamping is done in hardware, as soon as possible OAM Segment IDs (SIDs) is another component of the SRv6 OAM building
during the packet processing. Blocks. This document defines a couple of OAM SIDs.
Ref2: Hardware (microcode) timestamps and punts the packet. 3.3. End.OP: OAM Endpoint with Punt
Software (slow path) implements the required OAM mechanisms.
Please note that in an SRH containing END.OTP SID, it is RECOMMENDED Many scenarios require punting of SRv6 OAM packets at the desired
to set the SRH.Flags.O-flag = 0. nodes in the network. The "OAM Endpoint with Punt" function (End.OP
for short) represents a particular OAM function to implement the punt
behavior for an OAM packet. It is described using the pseudocode as
follows:
3.3 SRH TLV When N receives a packet destined to S and S is a local End.OP SID, N
does:
SRH TLV plays an important role in carrying OAM and Performance 1. Send the packet to the OAM process
Management (PM) metadata. For example, when SRH TLV piggybacks OAM
information onto the data traffic (i.e., for In-situ OAM (IOAM) and
Performance Management (PM) data in SRv6.
networks).
4. OAM Mechanisms Please note that in an SRH containing END.OP SID, it is RECOMMENDED
to set the SRH.Flags.O-flag = 0.
This section describes how OAM mechanisms can be implemented using 3.4. End.OTP: OAM Endpoint with Timestamp and Punt
the OAM building blocks described in the previous section.
Additional OAM mechanisms will be added in a future revision of the
document.
[RFC4443] describes Internet Control Message Protocol for IPv6 Scenarios demanding performance management of an SR policy/ path
(ICMPv6) that is used by IPv6 devices for network diagnostic and requires hardware timestamping before hardware punts the packet to
error reporting purposes. As Segment Routing with IPv6 data plane the software for OAM processing. The "OAM Endpoint with Timestamp
(SRv6) simply adds a new type of Routing Extension Header, existing and Punt" function (End.OTP for short) represents an OAM SID function
ICMPv6 ping mechanisms can be used in an SRv6 network. This section to implement the timestamp and punt behavior for an OAM packet. It
describes the applicability of ICMPv6 in the SRv6 network and how is described using the pseudocode as follows:
the existing ICMPv6 mechanisms can be used for providing OAM
functionality.
The document does not propose any changes to the standard ICMPv6 When N receives a packet destined to S and S is a local End.OTP SID,
[RFC4443], [RFC4884] or standard ICMPv4 [RFC792]. N does:
4.1. Ping 1. Timestamp the packet ;; Ref1
There is no hardware or software change required for ping operation 2. Send the packet, along with an accurate timestamp, to the OAM process.
at the classic IPv6 nodes in an SRv6 network. That includes the
classic IPv6 node with ingress, egress or transit roles.
Furthermore, no protocol changes are required to the standard ICMPv6
[RFC4443], [RFC4884] or standard ICMPv4 [RFC792]. In other words,
existing ICMP ping mechanisms work seamlessly in the SRv6 networks.
The following subsections outline some use cases of the ICMP ping in Ref1: Timestamping SHOULD be done in hardware, as soon as possible
the SRv6 networks. during the packet processing.
4.1.1. Classic Ping Please note that in an SRH containing END.OTP SID, it is RECOMMENDED
to set the SRH.Flags.O-flag = 0.
The existing mechanism to ping a remote IP prefix, along the 3.5. SRH TLV
shortest path, continues to work without any modification. 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.
If an SRv6 capable ingress node wants to ping an IPv6 prefix via an [I-D.ietf-6man-segment-routing-header] defines TLVs of the Segment
arbitrary segment list <S1, S2, S3>, it needs to initiate ICMPv6 Routing Header.
ping with an SR header containing the SID list <S1, S2, S3>. This is
illustrated using the topology in Figure 1. Assume all the links
have IGP metric 10 except both links between node2 and node3, which
have IGP metric set to 100. User issues a ping from node N1 to a
loopback of node 5, via segment list <B:2:C31, B:4:C52>.
Figure 2 contains sample output for a ping request initiated at node SRH TLV plays an important role in carrying OAM and Performance
N1 to the loopback address of node N5 via a segment list <B:2:C31, Management (PM) metadata.
B:4:C52>.
> ping A:5:: via segment-list B:2:C31, B:4:C52 4. OAM Mechanisms
Sending 5, 100-byte ICMP Echos to B5::, timeout is 2 seconds: This section describes how OAM mechanisms can be implemented using
!!!!! the OAM building blocks described in the previous section.
Success rate is 100 percent (5/5), round-trip min/avg/max = 0.625 Additional OAM mechanisms will be added in a future revision of the
/0.749/0.931 ms document.
Figure 2 A sample ping output at an SRv6 capable node
All transit nodes process the echo request message like any other [RFC4443] describes Internet Control Message Protocol for IPv6
data packet carrying SR header and hence do not require any change. (ICMPv6) that is used by IPv6 devices for network diagnostic and
Similarly, the egress node (IPv6 classic or SRv6 capable) does not error reporting purposes. As Segment Routing with IPv6 data plane
require any change to process the ICMPv6 echo request. For example, (SRv6) simply adds a new type of Routing Extension Header, existing
in the ping example of Figure 2: ICMPv6 ping mechanisms can be used in an SRv6 network. This section
describes the applicability of ICMPv6 in the SRv6 network and how the
existing ICMPv6 mechanisms can be used for providing OAM
functionality.
- Node N1 initiates an ICMPv6 ping packet with SRH as follows The document does not propose any changes to the standard ICMPv6
(A:1::, B:2:C31)(A:5::, B:4:C52, B:2:C31, SL=2, NH = [RFC4443], [RFC4884] or standard ICMPv4 [RFC792].
ICMPv6)(ICMPv6 Echo Request).
- Node N2, which is an SRv6 capable node, performs the standard
SRH processing. Specifically, it executes the END.X function
(B:2:C31) and forwards the packet on link3 to N3.
- Node N3, which is a classic IPv6 node, performs the standard
IPv6 processing. Specifically, it forwards the echo request
based on DA B:4:C52 in the IPv6 header.
- Node N4, which is an SRv6 capable node, performs the standard
SRH processing. Specifically, it observes the END.X function
(B:4:C52) with PSP (Penultimate Segment POP) on the echo
request packet and removes the SRH and forwards the packet
across link10 to N5.
- The echo request packet at N5 arrives as an IPv6 packet without
an SRH. Node N5, which is a classic IPv6 node, performs the
standard IPv6/ ICMPv6 processing on the echo request and
responds, accordingly.
4.1.2. Pinging a SID Function 4.1. Ping
The classic ping described in the previous section cannot be used to There is no hardware or software change required for ping operation
ping a remote SID function, as explained using an example in the at the classic IPv6 nodes in an SRv6 network. That includes the
following. classic IPv6 node with ingress, egress or transit roles.
Furthermore, no protocol changes are required to the standard ICMPv6
[RFC4443], [RFC4884] or standard ICMPv4 [RFC792]. In other words,
existing ICMP ping mechanisms work seamlessly in the SRv6 networks.
Consider the case where the user wants to ping the remote SID The following subsections outline some use cases of the ICMP ping in
function B:4:C52, via B:2:C31, from node N1. Node N1 constructs the the SRv6 networks.
ping packet (A:1::, B:2:C31)(B:4:C52, B:2:C31, SL=1;
NH=ICMPv6)(ICMPv6 Echo Request). The ping fails because the node N4
receives the ICMPv6 echo request with DA set to B:4:C52 but the next
header is ICMPv6, instead of SRH. To solve this problem, the
initiator needs to mark the ICMPv6 echo request as an OAM packet.
The OAM packets are identified either by setting the O-flag in SRH 4.1.1. Classic Ping
or by inserting the END.OP/ END.OTP SIDs at an appropriate place in
the SRH. The following illustration uses END.OTP SID but the
procedures are equally applicable to the END.OP SID.
In an SRv6 network, the user can exercise two flavors of the ping: The existing mechanism to ping a remote IP prefix, along the shortest
end-to-end ping or segment-by-segment ping, as outlined in the path, continues to work without any modification. The initiator may
following. 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.
4.1.2.1. End-to-end ping using END.OP/ END.OTP If an SRv6 capable ingress node wants to ping an IPv6 prefix via an
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
illustrated using the topology in Figure 1. Assume all the links
have IGP metric 10 except both links between node2 and node3, which
have IGP metric set to 100. User issues a ping from node N1 to a
loopback of node 5, via segment list <B:2:C31, B:4:C52>.
The end-to-end ping illustration uses the END.OTP SID but the Figure 2 contains sample output for a ping request initiated at node
procedures are equally applicable to the END.OP SID. N1 to the loopback address of node N5 via a segment list <B:2:C31,
B:4:C52>.
Consider the same example where the user wants to ping a remote > ping A:5:: via segment-list B:2:C31, B:4:C52
SID function B:4:C52, via B:2:C31, from node N1. To force a
punt of the ICMPv6 echo request at the node N4, node N1 inserts
the END.OTP SID just before the target SID B:4:C52 in the SRH.
The ICMPv6 echo request is processed at the individual nodes
along the path as follows:
- Node N1 initiates an ICMPv6 ping packet with SRH as follows Sending 5, 100-byte ICMP Echos to B5::, timeout is 2 seconds:
(A:1::, B:2:C31)(B:4:C52, B:4:OTP, B:2:C31; SL=2; !!!!!
NH=ICMPv6)(ICMPv6 Echo Request). Success rate is 100 percent (5/5), round-trip min/avg/max = 0.625
- Node N2, which is an SRv6 capable node, performs the standard /0.749/0.931 ms
SRH processing. Specifically, it executes the END.X function
(B:2:C31) on the echo request packet.
- Node N3 receives the packet as follows (A:1::,
B:4:OTP)(B:4:C52, B:4:OTP, B:2:C31 ; SL=1; NH=ICMPv6)(ICMPv6
Echo Request). Node N3, which is a classic IPv6 node, performs
the standard IPv6 processing. Specifically, it forwards the
echo request based on DA B:4:OTP in the IPv6 header.
- When node N4 receives the packet (A:1::, B:4:OTP)(B:4:C52,
B:4:OTP, B:2:C31 ; SL=1; NH=ICMPv6)(ICMPv6 Echo Request), it
processes the END.OTP SID, as described in the pseudocode in
Section 3. The packet gets punted to the ICMPv6 process for
processing. The ICMPv6 process checks if the next SID in SRH
(the target SID B:4:C52) is locally programmed.
- If the target SID is not locally programmed, N4 responses with Figure 2 A sample ping output at an SRv6 capable node
the ICMPv6 message (Type: "SRv6 OAM (TBA)", Code: "SID not
locally implemented (TBA)"); otherwise a success is returned.
4.1.2.2. Segment-by-segment ping using O-flag (Proof of Transit) All transit nodes process the echo request message like any other
data packet carrying SR header and hence do not require any change.
Similarly, the egress node (IPv6 classic or SRv6 capable) does not
require any change to process the ICMPv6 echo request. For example,
in the ping example of Figure 2:
Consider the same example where the user wants to ping a remote SID o Node N1 initiates an ICMPv6 ping packet with SRH as follows
function B:4:C52, via B:2:C31, from node N1. However, in this ping, (A:1::, B:2:C31)(A:5::, B:4:C52, B:2:C31, SL=2, NH =
the node N1 wants to get a response from each segment node in the ICMPv6)(ICMPv6 Echo Request).
SRH as a "proof of transit". In other words, in the segment-by-segment
ping case, the node N1 expects a response from node N2 and node N4 for
their respective local SID function. When a response to O-bit is desired
from the last SID in a SID-list, it is the responsibility of the ingress
node to use USP as the last SID. E.g., in this example, the target SID
B:4:C52 is a USP SID.
To force a punt of the ICMPv6 echo request at node N2 and node N4, o Node N2, which is an SRv6 capable node, performs the standard SRH
node N1 sets the O-flag in SRH. The ICMPv6 echo request is processed processing. Specifically, it executes the END.X function
at the individual nodes along the path as follows: and (B:2:C31) and forwards the packet on link3 to N3.
- Node N1 initiates an ICMPv6 ping packet with SRH as follows o Node N3, which is a classic IPv6 node, performs the standard IPv6
(A:1::, B:2:C31)(B:4:C52, B:2:C31; SL=1, Flags.O=1; processing. Specifically, it forwards the echo request based on
NH=ICMPv6)(ICMPv6 Echo Request). DA B:4:C52 in the IPv6 header.
- When node N2 receives the packet (A:1::, B:2:C31)(B:4:C52,
B:2:C31; SL=1, Flags.O=1; NH=ICMPv6)(ICMPv6 Echo Request)
packet, it processes the O-flag in SRH, as described in the
pseudocode in Section 3. A time-stamped copy of the packet gets
punted to the ICMPv6 process for processing. Node N2 continues
to apply the B:2:C31 SID function on the original packet and
forwards it, accordingly. As B:4:C52 is a USP SID, N2 does not
remove the SRH.
The ICMPv6 process at node N2 checks if its local SID (B:2:C31) is
locally programmed or not and responds to the ICMPv6 Echo
Request.
- If the target SID is not locally programmed, N4 responses with
the ICMPv6 message (Type: "SRv6 OAM (TBA)", Code: "SID not
locally implemented (TBA)"); otherwise a success is returned.
Please note that, as mentioned in Section 3, if node N2 does
not support the O-flag, it simply ignores it and process the
local SID, B:2:C31.
- Node N3, which is a classic IPv6 node, performs the standard
IPv6 processing. Specifically, it forwards the echo request
based on DA B:4:C52 in the IPv6 header.
- When node N4 receives the packet (A:1::, B:4:C52)(B:4:C52, o Node N4, which is an SRv6 capable node, performs the standard SRH
B:2:C31; SL=0, Flags.O=1; NH=ICMPv6)(ICMPv6 Echo Request), it processing. Specifically, it observes the END.X function
processes the O-flag in SRH, as described in the pseudocode in (B:4:C52) with PSP (Penultimate Segment POP) on the echo request
Section 3. A time-stamped copy of the packet gets punted to the packet and removes the SRH and forwards the packet across link10
ICMPv6 process for processing. The ICMPv6 process at node N4 to N5.
checks if its local SID (B:2:C31) is locally programmed or not
and responds to the ICMPv6 Echo Request. If the target SID is
not locally programmed, N4 responses with the ICMPv6 message
(Type: "SRv6 OAM (TBA)", Code: "SID not locally implemented
(TBA)"); otherwise a success is returned.
Support for O-flag is part of node capability advertisement. That o The echo request packet at N5 arrives as an IPv6 packet without an
enables node N1 to know which segment nodes are capable of SRH. Node N5, which is a classic IPv6 node, performs the standard
responding to the ICMPv6 echo request. Node N1 processes the echo IPv6/ ICMPv6 processing on the echo request and responds,
responses and presents data to the user, accordingly. accordingly.
Please note that segment-by-segment ping can be used to address 4.1.2. Pinging a SID Function
proof of transit use-case.
4.2. Error Reporting The classic ping described in the previous section cannot be used to
ping a remote SID function, as explained using an example in the
following.
Any IPv6 node can use ICMPv6 control messages to report packet Consider the case where the user wants to ping the remote SID
processing errors to the host that originated the datagram packet. function B:4:C52, via B:2:C31, from node N1. Node N1 constructs the
To name a few such scenarios: ping packet (A:1::, B:2:C31)(B:4:C52, B:2:C31, SL=1;
NH=ICMPv6)(ICMPv6 Echo Request). The ping fails because the node N4
receives the ICMPv6 echo request with DA set to B:4:C52 but the next
header is ICMPv6, instead of SRH. To solve this problem, the
initiator needs to mark the ICMPv6 echo request as an OAM packet.
- If the router receives an undeliverable IP datagram, or The OAM packets are identified either by setting the O-flag in SRH or
- If the router receives a packet with a Hop Limit of zero, or by inserting the END.OP/ END.OTP SIDs at an appropriate place in the
- If the router receives a packet such that if the router SRH. The following illustration uses END.OTP SID but the procedures
decrements the packet's Hop Limit it becomes zero, or are equally applicable to the END.OP SID.
- If the router receives a packet with problem with a field in
the IPv6 header or the extension headers such that it cannot
complete processing the packet, or
- If the router cannot forward a packet because the packet is
larger than the MTU of the outgoing link.
In the scenarios listed above, the ICMPv6 response also contains the In an SRv6 network, the user can exercise two flavors of the ping:
IP header, IP extension headers and leading payload octets of the end-to-end ping or segment-by-segment ping, as outlined in the
"original datagram" to which the ICMPv6 message is a response. following subsection.
Specifically, the "Destination Unreachable Message", "Time Exceeded
Message", "Packet Too Big Message" and "Parameter Problem Message"
ICMPV6 messages can contain as much of the invoking packet as
possible without the ICMPv6 packet exceeding the minimum IPv6 MTU
[RFC4443], [RFC4884]. In an SRv6 network, the copy of the invoking
packet contains the SR header. The packet originator can use this
information for diagnostic purposes. For example, traceroute can use
this information as detailed in the following.
4.3. Traceroute 4.1.2.1. End-to-end ping using END.OP/ END.OTP
There is no hardware or software change required for traceroute
operation at the classic IPv6 nodes in an SRv6 network. That
includes the classic IPv6 node with ingress, egress or transit
roles. Furthermore, no protocol changes are required to the standard
traceroute operations. In other words, existing traceroute
mechanisms work seamlessly in the SRv6 networks.
The following subsections outline some use cases of the traceroute The end-to-end ping illustration uses the END.OTP SID but the
in the SRv6 networks. procedures are equally applicable to the END.OP SID.
4.3.1. Classic Traceroute Consider the same example where the user wants to ping a remote SID
function B:4:C52, via B:2:C31, from node N1. To force a punt of the
ICMPv6 echo request at the node N4, node N1 inserts the END.OTP SID
just before the target SID B:4:C52 in the SRH. The ICMPv6 echo
request is processed at the individual nodes along the path as
follows:
The existing mechanism to traceroute a remote IP prefix, along the o Node N1 initiates an ICMPv6 ping packet with SRH as follows
shortest path, continues to work without any modification. The (A:1::, B:2:C31)(B:4:C52, B:4:OTP, B:2:C31; SL=2;
initiator may be an SRv6 node or a classic IPv6 node. Similarly, the NH=ICMPv6)(ICMPv6 Echo Request).
egress or transit may be an SRv6 node or a classic IPv6 node.
If an SRv6 capable ingress node wants to traceroute to IPv6 prefix o Node N2, which is an SRv6 capable node, performs the standard SRH
via an arbitrary segment list <S1, S2, S3>, it needs to initiate processing. Specifically, it executes the END.X function
traceroute probe with an SR header containing the SID list <S1, S2, (B:2:C31) on the echo request packet.
S3>. That is illustrated using the topology in Figure 1. Assume all
the links have IGP metric 10 except both links between node2 and
node3, which have IGP metric set to 100. User issues a traceroute
from node N1 to a loopback of node 5, via segment list <B:2:C31,
B:4:C52>. Figure 3 contains sample output for the traceroute
request.
> traceroute A:5:: via segment-list B:2:C31, B:4:C52 o Node N3 receives the packet as follows (A:1::, B:4:OTP)(B:4:C52,
B:4:OTP, B:2:C31 ; SL=1; NH=ICMPv6)(ICMPv6 Echo Request). Node
N3, which is a classic IPv6 node, performs the standard IPv6
processing. Specifically, it forwards the echo request based on
DA B:4:OTP in the IPv6 header.
Tracing the route to B5:: o When node N4 receives the packet (A:1::, B:4:OTP)(B:4:C52,
B:4:OTP, B:2:C31 ; SL=1; NH=ICMPv6)(ICMPv6 Echo Request), it
processes the END.OTP SID, as described in the pseudocode in
Section 3. The packet gets punted to the ICMPv6 process for
processing. The ICMPv6 process checks if the next SID in SRH (the
target SID B:4:C52) is locally programmed.
1 2001:DB8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec o If the target SID is not locally programmed, N4 responses with the
SRH: (A:5::, B:4:C52, B:2:C31, SL=2) ICMPv6 message (Type: "SRv6 OAM (TBA)", Code: "SID not locally
implemented (TBA)"); otherwise a success is returned.
2 2001:DB8:2:3:31:: 0.721 msec 0.810 msec 0.795 msec 4.1.2.2. Segment-by-segment ping using O-flag (Proof of Transit)
SRH: (A:5::, B:4:C52, B:2:C31, SL=1)
3 2001:DB8:3:4::41:: 0.921 msec 0.816 msec 0.759 msec Consider the same example where the user wants to ping a remote SID
SRH: (A:5::, B:4:C52, B:2:C31, SL=1) function B:4:C52, via B:2:C31, from node N1. However, in this ping,
the node N1 wants to get a response from each segment node in the SRH
as a "proof of transit". In other words, in the segment-by-segment
ping case, the node N1 expects a response from node N2 and node N4
for their respective local SID function. When a response to O-bit is
desired from the last SID in a SID-list, it is the responsibility of
the ingress node to use USP as the last SID. E.g., in this example,
the target SID B:4:C52 is a USP SID.
4 2001:DB8:4:5::52:: 0.879 msec 0.916 msec 1.024 msec To force a punt of the ICMPv6 echo request at node N2 and node N4,
node N1 sets the O-flag in SRH. The ICMPv6 echo request is processed
at the individual nodes along the path as follows:
Figure 3 A sample traceroute output at an SRv6 capable node o Node N1 initiates an ICMPv6 ping packet with SRH as follows
(A:1::, B:2:C31)(B:4:C52, B:2:C31; SL=1, Flags.O=1;
NH=ICMPv6)(ICMPv6 Echo Request).
Please note that information for hop2 is returned by N3, which is a o When node N2 receives the packet (A:1::, B:2:C31)(B:4:C52,
classic IPv6 node. Nonetheless, the ingress node is able to display B:2:C31; SL=1, Flags.O=1; NH=ICMPv6)(ICMPv6 Echo Request) packet,
SR header contents as the packet travels through the IPv6 classic it processes the O-flag in SRH, as described in the pseudocode in
node. This is because the "Time Exceeded Message" ICMPv6 message can Section 3. A time-stamped copy of the packet gets punted to the
contain as much of the invoking packet as possible without the ICMPv6 process for processing. Node N2 continues to apply the
ICMPv6 packet exceeding the minimum IPv6 MTU [RFC4443]. The SR B:2:C31 SID function on the original packet and forwards it,
header is also included in these ICMPv6 messages initiated by the accordingly. As B:4:C52 is a USP SID, N2 does not remove the SRH.
classic IPv6 transit nodes that are not running SRv6 software. The ICMPv6 process at node N2 checks if its local SID (B:2:C31) is
Specifically, a node generating ICMPv6 message containing a copy of locally programmed or not and responds to the ICMPv6 Echo Request.
the invoking packet does not need to understand the extension
header(s) in the invoking packet.
The segment list information returned for hop1 is returned by N2, o If the target SID is not locally programmed, N4 responses with the
which is an SRv6 capable node. Just like for hop2, the ingress node ICMPv6 message (Type: "SRv6 OAM (TBA)", Code: "SID not locally
is able to display SR header contents for hop1. implemented (TBA)"); otherwise a success is returned. Please note
that, as mentioned in Section 3, if node N2 does not support the
O-flag, it simply ignores it and process the local SID, B:2:C31.
There is no difference in processing of the traceroute probe at an o Node N3, which is a classic IPv6 node, performs the standard IPv6
IPv6 classic node and an SRv6 capable node. Similarly, both IPv6 processing. Specifically, it forwards the echo request based on
classic and SRv6 capable nodes may use the address of the interface on DA B:4:C52 in the IPv6 header.
which probe was received as the source address in the ICMPv6
response. ICMP extensions defined in [RFC5837] can be used to also
display information about the IP interface through which the
datagram would have been forwarded had it been forwardable, and the
IP next hop to which the datagram would have been forwarded, the IP
interface upon which a datagram arrived, the sub-IP component of an
IP interface upon which a datagram arrived.
The information about the IP address of the incoming interface on o When node N4 receives the packet (A:1::, B:4:C52)(B:4:C52,
which the traceroute probe was received by the reporting node is B:2:C31; SL=0, Flags.O=1; NH=ICMPv6)(ICMPv6 Echo Request), it
very useful. This information can also be used to verify if SID processes the O-flag in SRH, as described in the pseudocode in
functions B:2:C31 and B:4:C52 are executed correctly by N2 and N4, Section 3. A time-stamped copy of the packet gets punted to the
respectively. Specifically, the information displayed for hop2 ICMPv6 process for processing. The ICMPv6 process at node N4
contains the incoming interface address 2001:DB8:2:3:31:: at N3. checks if its local SID (B:2:C31) is locally programmed or not and
This matches with the expected interface bound to END.X function responds to the ICMPv6 Echo Request. If the target SID is not
B:2:C31 (link3). Similarly, the information displayed for hop5 locally programmed, N4 responses with the ICMPv6 message (Type:
contains the incoming interface address 2001:DB8:4:5::52:: at N5. "SRv6 OAM (TBA)", Code: "SID not locally implemented (TBA)");
This matches with the expected interface bound to the END.X function otherwise a success is returned.
B:4:C52 (link10).
4.3.2. Traceroute to a SID Function Support for O-flag is part of node capability advertisement. That
enables node N1 to know which segment nodes are capable of responding
to the ICMPv6 echo request. Node N1 processes the echo responses and
presents data to the user, accordingly.
The classic traceroute described in the previous section cannot be Please note that segment-by-segment ping can be used to address proof
used to traceroute a remote SID function, as explained using an of transit use-case.
example in the following.
Consider the case where the user wants to traceroute the remote SID 4.1.3. Error Reporting
function B:4:C52, via B:2:C31, from node N1. The trace route fails at N4.
This is because the node N4 trace route probe where next header is
UDP or ICMPv6, instead of SRH (even though the hop limit is set to 1).
To solve this problem, the
initiator needs to mark the ICMPv6 echo request as an OAM packet.
The OAM packets are identified either by setting the O-flag in SRH Any IPv6 node can use ICMPv6 control messages to report packet
or by inserting the END.OP or END.OTP SID at an appropriate place in the processing errors to the host that originated the datagram packet.
SRH. To name a few such scenarios:
In an SRv6 network, the user can exercise two flavors of the o If the router receives an undeliverable IP datagram, or
traceroute: hop-by-hop traceroute or overlay traceroute.
- In hop-by-hop traceroute, user gets responses from all nodes o If the router receives a packet with a Hop Limit of zero, or
including classic IPv6 transit nodes, SRv6 capable transit
nodes as well as SRv6 capable segment endpoints. E.g., consider
the example where the user wants to traceroute to a remote SID
function B:4:C52, via B:2:C31, from node N1. The traceroute
output will also display information about node3, which is a
transit (underlay) node.
- The overlay traceroute, on the other hand, does not trace the
underlay nodes. In other words, the overlay traceroute only
displays the nodes that acts as SRv6 segments along the route.
I.e., in the example where the user wants to traceroute to a
remote SID function B:4:C52, via B:2:C31, from node N1, the
overlay traceroute would only display the traceroute
information from node N2 and node N4; it will not display
information from node 3.
4.3.2.1. Hop-by-hop traceroute using END.OP/ END.OTP o If the router receives a packet such that if the router decrements
the packet's Hop Limit it becomes zero, or
In this section, hop-by-hop traceroute to a SID function is o If the router receives a packet with problem with a field in the
exemplified using UDP probes. However, the procedure is equally IPv6 header or the extension headers such that it cannot complete
applicable to other implementation of traceroute mechanism. processing the packet, or
Furthermore, the illustration uses the END.OTP SID but the
procedures are equally applicable to the END.OP SID
Consider the same example where the user wants to traceroute to a o If the router cannot forward a packet because the packet is larger
remote SID function B:4:C52, via B:2:C31, from node N1. To force a than the MTU of the outgoing link.
punt of the traceroute probe only at the node N4, node N1 inserts
the END.OTP SID just before the target SID B:4:C52 in the SRH. The
traceroute probe is processed at the individual nodes along the path
as follows.
- Node N1 initiates a traceroute probe packet with a In the scenarios listed above, the ICMPv6 response also contains the
monotonically increasing value of hop count and SRH as follows IP header, IP extension headers and leading payload octets of the
(A:1::, B:2:C31)(B:4:C52, B:4:OTP, B:2:C31; SL=2; "original datagram" to which the ICMPv6 message is a response.
NH=UDP)(Traceroute probe). Specifically, the "Destination Unreachable Message", "Time Exceeded
- When node N2 receives the packet with hop-count = 1, it Message", "Packet Too Big Message" and "Parameter Problem Message"
processes the hop count expiry. Specifically, the node N2 ICMPV6 messages can contain as much of the invoking packet as
responses with the ICMPv6 message (Type: "Time Exceeded", Code: possible without the ICMPv6 packet exceeding the minimum IPv6 MTU
"Time to Live exceeded in Transit"). [RFC4443], [RFC4884]. In an SRv6 network, the copy of the invoking
- When Node N2 receives the packet with hop-count > 1, it packet contains the SR header. The packet originator can use this
performs the standard SRH processing. Specifically, it executes information for diagnostic purposes. For example, traceroute can use
the END.X function (B:2:C31) on the traceroute probe. this information as detailed in the following subsection.
- When node N3, which is a classic IPv6 node, receives the packet 4.2. Traceroute
(A:1::, B:4:OTP)(B:4:C52, B:4:OTP, B:2:C31 ; HC=1, SL=1;
NH=UDP)(Traceroute probe) with hop-count = 1, it processes the
hop count expiry. Specifically, the node N3 responses with the
ICMPv6 message (Type: "Time Exceeded", Code: "Time to Live
exceeded in Transit").
- When node N3, which is a classic IPv6 node, receives the packet
with hop-count > 1, it performs the standard IPv6 processing.
Specifically, it forwards the traceroute probe based on DA
B:4:OTP in the IPv6 header.
- When node N4 receives the packet (A:1::, B:4:OTP)(B:4:C52,
B:4:OTP, B:2:C31 ; SL=1; HC=1, NH=UDP)(Traceroute probe), it
processes the END.OTP SID, as described in the pseudocode in
Section 3. The packet gets punted to the traceroute process for
processing. The traceroute process checks if the next SID in
SRH (the target SID B:4:C52) is locally programmed. If the
target SID B:4:C52 is locally programmed, node N4 responses
with the ICMPv6 message (Type: Destination unreachable, Code:
Port Unreachable). If the target SID B:4:C52 is not a local
SID, node N4 silently drops the traceroute probe.
Figure 4 displays a sample traceroute output for this example. There is no hardware or software change required for traceroute
operation at the classic IPv6 nodes in an SRv6 network. That
includes the classic IPv6 node with ingress, egress or transit roles.
Furthermore, no protocol changes are required to the standard
traceroute operations. In other words, existing traceroute
mechanisms work seamlessly in the SRv6 networks.
> traceroute srv6 B:4:C52 via segment-list B:2:C31 The following subsections outline some use cases of the traceroute in
the SRv6 networks.
Tracing the route to SID function B:4:C52 4.2.1. Classic Traceroute
1 2001:DB8:1:2:21 0.512 msec 0.425 msec 0.374 msec The existing mechanism to traceroute a remote IP prefix, along the
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=2) shortest path, continues to work without any modification. 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.
2 2001:DB8:2:3:31 0.721 msec 0.810 msec 0.795 msec If an SRv6 capable ingress node wants to traceroute to IPv6 prefix
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=1) via an arbitrary segment list <S1, S2, S3>, it needs to initiate
traceroute probe with an SR header containing the SID list <S1, S2,
S3>. That is illustrated using the topology in Figure 1. Assume all
the links have IGP metric 10 except both links between node2 and
node3, which have IGP metric set to 100. User issues a traceroute
from node N1 to a loopback of node 5, via segment list <B:2:C31,
B:4:C52>. Figure 3 contains sample output for the traceroute
request.
3 2001:DB8:3:4::41 0.921 msec 0.816 msec 0.759 msec > traceroute A:5:: via segment-list B:2:C31, B:4:C52
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=1)
Figure 4 A sample output for hop-by-hop traceroute to a SID Tracing the route to B5::
function 1 2001:DB8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec
SRH: (A:5::, B:4:C52, B:2:C31, SL=2)
2 2001:DB8:2:3:31:: 0.721 msec 0.810 msec 0.795 msec
SRH: (A:5::, B:4:C52, B:2:C31, SL=1)
3 2001:DB8:3:4::41:: 0.921 msec 0.816 msec 0.759 msec
SRH: (A:5::, B:4:C52, B:2:C31, SL=1)
4 2001:DB8:4:5::52:: 0.879 msec 0.916 msec 1.024 msec
4.3.2.2. Tracing SRv6 Overlay Figure 3 A sample traceroute output at an SRv6 capable node
The overlay traceroute does not trace the underlay nodes, i.e., only Please note that information for hop2 is returned by N3, which is a
displays the nodes that acts as SRv6 segments along the path. This classic IPv6 node. Nonetheless, the ingress node is able to display
is achieved by setting the SRH.Flags.O bit. SR header contents as the packet travels through the IPv6 classic
node. This is because the "Time Exceeded Message" ICMPv6 message can
contain as much of the invoking packet as possible without the ICMPv6
packet exceeding the minimum IPv6 MTU [RFC4443]. The SR header is
also included in these ICMPv6 messages initiated by the classic IPv6
transit nodes that are not running SRv6 software. Specifically, a
node generating ICMPv6 message containing a copy of the invoking
packet does not need to understand the extension header(s) in the
invoking packet.
In this section, overlay traceroute to a SID function is exemplified The segment list information returned for hop1 is returned by N2,
using UDP probes. However, the procedure is equally applicable to which is an SRv6 capable node. Just like for hop2, the ingress node
other implementation of traceroute mechanism. is able to display SR header contents for hop1.
Consider the same example where the user wants to traceroute to a There is no difference in processing of the traceroute probe at an
remote SID function B:4:C52, via B:2:C31, from node N1. IPv6 classic node and an SRv6 capable node. Similarly, both IPv6
classic and SRv6 capable nodes may use the address of the interface
on which probe was received as the source address in the ICMPv6
response. ICMP extensions defined in [RFC5837] can be used to also
display information about the IP interface through which the datagram
would have been forwarded had it been forwardable, and the IP next
hop to which the datagram would have been forwarded, the IP interface
upon which a datagram arrived, the sub-IP component of an IP
interface upon which a datagram arrived.
- Node N1 initiates a traceroute probe with SRH as follows The information about the IP address of the incoming interface on
(A:1::, B:2:C31)(B:4:C52, B:2:C31; HC=64, SL=1, Flags.O=1; which the traceroute probe was received by the reporting node is very
NH=UDP)(Traceroute Probe). Please note that the hop-count is useful. This information can also be used to verify if SID functions
set to 64 to skip the underlay nodes from tracing. The O-flag B:2:C31 and B:4:C52 are executed correctly by N2 and N4,
in SRH is set to make the overlay nodes (nodes processing the respectively. Specifically, the information displayed for hop2
SRH) respond. contains the incoming interface address 2001:DB8:2:3:31:: at N3.
- When node N2 receives the packet (A:1::, B:2:C31)(B:4:C52, This matches with the expected interface bound to END.X function
B:2:C31; SL=1, HC=64, Flags.O=1; NH=UDP)(Traceroute Probe), it B:2:C31 (link3). Similarly, the information displayed for hop5
processes the O-flag in SRH, as described in the pseudocode in contains the incoming interface address 2001:DB8:4:5::52:: at N5.
Section 3. A time-stamped copy of the packet gets punted to the This matches with the expected interface bound to the END.X function
traceroute process for processing. Node N2 continues to apply B:4:C52 (link10).
the B:2:C31 SID function on the original packet and forwards
it, accordingly. The traceroute
process at node N2 checks if its local SID (B:2:C31) is locally
programmed. If the SID is not locally programmed, it silently
drops the packet. Otherwise, it performs the egress check by
looking at the SL value in SRH.
- As SL is not equal to zero (i.e., it's not egress node), node
N2 responses with the ICMPv6 message (Type: "SRv6 OAM (TBA)",
Code: "O-flag punt at Transit (TBA)"). Please note that, as
mentioned in Section 3, if node N2 does not support the O-flag,
it simply ignores it and processes the local SID, B:2:C31.
- When node N3 receives the packet (A:1::, B:4:C52)(B:4:C52,
B:2:C31; SL=0, HC=63, Flags.O=1; NH=UDP)(Traceroute Probe),
performs the standard IPv6 processing. Specifically, it
forwards the traceroute probe based on DA B:4:C52 in the IPv6
header. Please note that there is no hop-count expiration at
the transit nodes.
- When node N4 receives the packet (A:1::, B:4:C52)(B:4:C52,
B:2:C31; SL=0, HC=62, Flags.O=1; NH=UDP)(Traceroute Probe), it
processes the O-flag in SRH, as described in the pseudocode in
Section 3. A time-stamped copy of the packet gets punted to the
traceroute process for processing. The traceroute process at
node N4 checks if its local SID (B:2:C31) is locally
programmed. If the SID is not locally programmed, it silently
drops the packet. Otherwise, it performs the egress check by
looking at the SL value in SRH. As SL is equal to zero (i.e.,
N4 is the egress node), node N4 tries to consume the UDP probe.
As UDP probe is set to access an invalid port, the node N4
responses with the ICMPv6 message (Type: Destination
unreachable, Code: Port Unreachable).
Figure 5 displays a sample overlay traceroute output for this 4.2.2. Traceroute to a SID Function
example. Please note that the underlay node N3 does not appear in
the output.
> traceroute srv6 B:4:C52 via segment-list B:2:C31 The classic traceroute described in the previous section cannot be
used to traceroute a remote SID function, as explained using an
example in the following.
Tracing the route to SID function B:4:C52 Consider the case where the user wants to traceroute the remote SID
function B:4:C52, via B:2:C31, from node N1. The trace route fails
at N4. This is because the node N4 trace route probe where next
header is UDP or ICMPv6, instead of SRH (even though the hop limit is
set to 1). To solve this problem, the initiator needs to mark the
ICMPv6 echo request as an OAM packet.
1 2001:DB8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec The OAM packets are identified either by setting the O-flag in SRH or
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=2) by inserting the END.OP or END.OTP SID at an appropriate place in the
SRH.
2 2001:DB8:3:4::41:: 0.921 msec 0.816 msec 0.759 msec In an SRv6 network, the user can exercise two flavors of the
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=1) traceroute: hop-by-hop traceroute or overlay traceroute.
Figure 5 A sample output for overlay traceroute to a SID function o In hop-by-hop traceroute, user gets responses from all nodes
including classic IPv6 transit nodes, SRv6 capable transit nodes
as well as SRv6 capable segment endpoints. E.g., consider the
example where the user wants to traceroute to a remote SID
function B:4:C52, via B:2:C31, from node N1. The traceroute
output will also display information about node3, which is a
transit (underlay) node.
4.4 OAM Data Piggybacked in Data traffic o The overlay traceroute, on the other hand, does not trace the
underlay nodes. In other words, the overlay traceroute only
displays the nodes that acts as SRv6 segments along the route.
I.e., in the example where the user wants to traceroute to a
remote SID function B:4:C52, via B:2:C31, from node N1, the
overlay traceroute would only display the traceroute information
from node N2 and node N4; it will not display information from
node 3.
OAM and PM information from the intermediate SR endpoints can be piggybacked 4.2.2.1. Hop-by-hop traceroute using END.OP/ END.OTP
in the data packet. The OAM and PM information piggybacking in the data packets
is also known as In-situ OAM (IOAM). This section describes iOAM functionality
in SRv6 network.
The IOAM data is carried in SRH.TLV. This enables the IOAM mechanism to build In this section, hop-by-hop traceroute to a SID function is
on the network programmability capability of SRv6. The ability for an exemplified using UDP probes. However, the procedure is equally
intermediate SRv6 endpoint to determine whether to process or ignore some applicable to other implementation of traceroute mechanism.
specific SRH TLVs is based on the SID function. This enables collection of Furthermore, the illustration uses the END.OTP SID but the procedures
the IOAM information from the intermediate endpoint nodes of choice. The nodes are equally applicable to the END.OP SID.
that are not capable of supporting the IOAM functionality does not have to look
or process SRH TLV (i.e., such nodes can simply ignore the SRH IOAM TLV).
4.4.1 IOAM Data Field Encapsulation in SRH Consider the same example where the user wants to traceroute to a
remote SID function B:4:C52, via B:2:C31, from node N1. To force a
punt of the traceroute probe only at the node N4, node N1 inserts the
END.OTP SID just before the target SID B:4:C52 in the SRH. The
traceroute probe is processed at the individual nodes along the path
as follows:
The SRv6 encapsulation header (SRH) is defined in o Node N1 initiates a traceroute probe packet with a monotonically
[I-D.6man-segment-routing-header]. IOAM data fields are carried in increasing value of hop count and SRH as follows (A:1::,
the SRH, using a single pre-allocated SRH TLV. The different IOAM data B:2:C31)(B:4:C52, B:4:OTP, B:2:C31; SL=2; NH=UDP)(Traceroute
fields defined in [I-D.ietf-ippm-ioam-data] are added as sub-TLVs. probe).
0 1 2 3 o When node N2 receives the packet with hop-count = 1, it processes
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 the hop count expiry. Specifically, the node N2 responses with
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ the ICMPv6 message (Type: "Time Exceeded", Code: "Time to Live
| SRH-TLV-Type | LEN | RESERVED | exceeded in Transit").
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| IOAM-Type | IOAM HDR LEN | RESERVED | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I
! | O
! | A
~ IOAM Option and Data Space ~ M
| | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| |
| |
| Payload + Padding (L2/L3/...) |
| |
| | o When Node N2 receives the packet with hop-count > 1, it performs
| | the standard SRH processing. Specifically, it executes the END.X
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ function (B:2:C31) on the traceroute probe.
Figure 1: IOAM data encapsulation in SRH o When node N3, which is a classic IPv6 node, receives the packet
(A:1::, B:4:OTP)(B:4:C52, B:4:OTP, B:2:C31 ; HC=1, SL=1;
NH=UDP)(Traceroute probe) with hop-count = 1, it processes the hop
count expiry. Specifically, the node N3 responses with the ICMPv6
message (Type: "Time Exceeded", Code: "Time to Live exceeded in
Transit").
SRH-TLV-Type: IOAM TLV Type for SRH is defined as TBA1. o When node N3, which is a classic IPv6 node, receives the packet
with hop-count > 1, it performs the standard IPv6 processing.
Specifically, it forwards the traceroute probe based on DA B:4:OTP
in the IPv6 header.
The fields related to the encapsulation of IOAM data fields in the o When node N4 receives the packet (A:1::, B:4:OTP)(B:4:C52,
SRH are defined as follows: B:4:OTP, B:2:C31 ; SL=1; HC=1, NH=UDP)(Traceroute probe), it
processes the END.OTP SID, as described in the pseudocode in
Section 3. The packet gets punted to the traceroute process for
processing. The traceroute process checks if the next SID in SRH
(the target SID B:4:C52) is locally programmed. If the target SID
B:4:C52 is locally programmed, node N4 responses with the ICMPv6
message (Type: Destination unreachable, Code: Port Unreachable).
If the target SID B:4:C52 is not a local SID, node N4 silently
drops the traceroute probe.
IOAM-Type: 8-bit field defining the IOAM Option type, as defined in Figure 4 displays a sample traceroute output for this example.
Section 7.2 of [I-D.ietf-ippm-ioam-data].
IOAM HDR LEN: 8-bit unsigned integer. Length of the IOAM HDR in > traceroute srv6 B:4:C52 via segment-list B:2:C31
4-octet units.
RESERVED: 8-bit reserved field MUST be set to zero upon transmission Tracing the route to SID function B:4:C52
and ignored upon receipt. 1 2001:DB8:1:2:21 0.512 msec 0.425 msec 0.374 msec
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=2)
2 2001:DB8:2:3:31 0.721 msec 0.810 msec 0.795 msec
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=1)
3 2001:DB8:3:4::41 0.921 msec 0.816 msec 0.759 msec
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=1)
IOAM Option and Data Space: IOAM option header and data is present Figure 4 A sample output for hop-by-hop traceroute to a SID function
as defined by the IOAM-Type field, and is defined in Section 4 of
[I-D.ietf-ippm-ioam-data].
4.4.2. Procedure 4.2.2.2. Tracing SRv6 Overlay
This section summarizes the procedure for IOAM data encapsulation in The overlay traceroute does not trace the underlay nodes, i.e., only
SRv6 networks. displays the nodes that acts as SRv6 segments along the path. This
is achieved by setting the SRH.Flags.O bit.
4.4.2.1 Ingress Node In this section, overlay traceroute to a SID function is exemplified
using UDP probes. However, the procedure is equally applicable to
other implementation of traceroute mechanism.
As part of the SRH encapsulation, the ingress node of an SR domain Consider the same example where the user wants to traceroute to a
or an SR Policy [I-D.spring-segment-routing-policy] MAY add the remote SID function B:4:C52, via B:2:C31, from node N1.
IOAM TLV in the SRH of the data packet. If an ingress node supports
IOAM functionality and, based on a local configuration, wants to
collect IOAM data, it adds IOAM TLV in the SRH. Based on the size of
the segment list (SL), the ingress node preallocates space in the
IOAM TLV.
When IOAM data from the last node in the segment-list o Node N1 initiates a traceroute probe with SRH as follows (A:1::,
(Egress node) is desired, the ingress uses an Ultimate Segment Pop B:2:C31)(B:4:C52, B:2:C31; HC=64, SL=1, Flags.O=1;
(USP) SID at the Egress node. NH=UDP)(Traceroute Probe). Please note that the hop-count is set
to 64 to skip the underlay nodes from tracing. The O-flag in SRH
is set to make the overlay nodes (nodes processing the SRH)
respond.
The ingress node may also insert the IOAM o When node N2 receives the packet (A:1::, B:2:C31)(B:4:C52,
data about the local information in the IOAM TLV in the SRH at index 0 B:2:C31; SL=1, HC=64, Flags.O=1; NH=UDP)(Traceroute Probe), it
of the preallocated IOAM TLV. processes the O-flag in SRH, as described in the pseudocode in
Section 3. A time-stamped copy of the packet gets punted to the
traceroute process for processing. Node N2 continues to apply the
B:2:C31 SID function on the original packet and forwards it,
accordingly. The traceroute process at node N2 checks if its
local SID (B:2:C31) is locally programmed. If the SID is not
locally programmed, it silently drops the packet. Otherwise, it
performs the egress check by looking at the SL value in SRH.
4.4.2.2 Intermediate SR Segment Endpoint Node o As SL is not equal to zero (i.e., it's not egress node), node N2
responses with the ICMPv6 message (Type: "SRv6 OAM (TBA)", Code:
"O-flag punt at Transit (TBA)"). Please note that, as mentioned
in Section 3, if node N2 does not support the O-flag, it simply
ignores it and processes the local SID, B:2:C31.
The SR segment endpoint node is any node receiving an IPv6 packet o When node N3 receives the packet (A:1::, B:4:C52)(B:4:C52,
where the destination address of that packet is a local SID or a B:2:C31; SL=0, HC=63, Flags.O=1; NH=UDP)(Traceroute Probe),
local interface address. As part of the SR Header processing as performs the standard IPv6 processing. Specifically, it forwards
described in [I-D.6man-segment-routing-header] and the traceroute probe based on DA B:4:C52 in the IPv6 header.
[I-D.spring-srv6-network-programming], the SR Segment Endpoint node Please note that there is no hop-count expiration at the transit
performs the following IOAM operations. nodes.
If an intermediate SR segment endpoint node is not capable of processing o When node N4 receives the packet (A:1::, B:4:C52)(B:4:C52,
IOAM TLV, it simply ignores it. I.e., it does not have to look B:2:C31; SL=0, HC=62, Flags.O=1; NH=UDP)(Traceroute Probe), it
or process SRH TLV. processes the O-flag in SRH, as described in the pseudocode in
Section 3. A time-stamped copy of the packet gets punted to the
traceroute process for processing. The traceroute process at node
N4 checks if its local SID (B:2:C31) is locally programmed. If
the SID is not locally programmed, it silently drops the packet.
Otherwise, it performs the egress check by looking at the SL value
in SRH. As SL is equal to zero (i.e., N4 is the egress node),
node N4 tries to consume the UDP probe. As UDP probe is set to
access an invalid port, the node N4 responses with the ICMPv6
message (Type: Destination unreachable, Code: Port Unreachable)
If an intermediate SR segment endpoint node is capable of processing Figure 5 displays a sample overlay traceroute output for this
IOAM TLV and the local SID supports IOAM data recording, example. Please note that the underlay node N3 does not appear in
it checks if any SRH TLV is present in the packet using the output.
procedures defined in [I-D.6man-segment-routing-header].
If the node finds IOAM TLV in the SRH, based on Segment Left (SL), it
finds the local index at which it is expected to record the IOAM data.
The node records the IOAM data at the desired preallocated space.
4.4.2.3 Egress Node Tracing the route to SID function B:4:C52
1 2001:DB8:1:2:21:: 0.512 msec 0.425 msec 0.374 msec
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=2)
2 2001:DB8:3:4::41:: 0.921 msec 0.816 msec 0.759 msec
SRH: (B:4:C52, B:4:OTP, B:2:C31; SL=1)
The Egress node is the last node in the segment-list of the SRH. When Figure 5 A sample output for overlay traceroute to a SID function
IOAM data from the Egress node is desired, a USP SID advertised by
the Egress node is used.
The processing of IOAM TLV at the Egress node is similar to the 4.3. Monitoring of SRv6 Paths
processing of IOAM TLV at the SR Segment Endpoint Node. The only
difference is that the Egress node may telemeter the IOAM data to
an external entity.
4.6. Monitoring of SRv6 Paths In the recent past, network operators are interested in performing
network OAM functions in a centralized manner. Various data models
like YANG are available to collect data from the network and manage
it from a centralized entity.
In the recent past, network operators are interested in performing SR technology enables a centralized OAM entity to perform path
network OAM functions in a centralized manner. Various data models monitoring from centralized OAM entity without control plane
like YANG are available to collect data from the network and manage intervention on monitored nodes. [RFC 8403] describes such a
it from a centralized entity. centralized OAM mechanism. Specifically, the draft describes a
procedure that can be used to perform path continuity check between
any nodes within an SR domain from a centralized monitoring system,
with minimal or no control plane intervene on the nodes. However,
the draft focuses on SR networks with MPLS data plane. The same
concept applies to the SRv6 networks. This document describes how
the concept can be used to perform path monitoring in an SRv6
network. This document describes how the concept can be used to
perform path monitoring in an SRv6 network as follows.
SR technology enables a centralized OAM entity to perform path In the above reference topology, N100 is the centralized monitoring
monitoring from centralized OAM entity without control plane system implementing an END function B:100:1::. In order to verify a
intervention on monitored nodes. [I.D-draft-ietf-spring-oam-usecase] segment list <B:2:C31, B:4:C52>, N100 generates a probe packet with
describes such a centralized OAM mechanism. Specifically, the draft SRH set to (B:100:1::, B:4:C52, B:2:C31, SL=2). The controller
describes a procedure that can be used to perform path continuity routes the probe packet towards the first segment, which is B:2:C31.
check between any nodes within an SR domain from a centralized N2 performs the standard SRH processing and forward it over link3
monitoring system, with minimal or no control plane intervene on the with the DA of IPv6 packet set to B:4:C52. N4 also performs the
nodes. However, the draft focuses on SR networks with MPLS data normal SRH processing and forward it over link10 with the DA of IPv6
plane. The same concept applies to the SRv6 networks. This document packet set to B:100:1::. This makes the probe loops back to the
describes how the concept can be used to perform path monitoring in centralized monitoring system.
an SRv6 network. This document describes how the concept can be used
to perform path monitoring in an SRv6 network as follows.
In the above reference topology, N100 is the centralized monitoring In the reference topology in Figure 1, N100 uses an IGP protocol like
system implementing an END function B:100:1::. In order to verify a OSPF or ISIS to get the topology view within the IGP domain. N100
segment list <B:2:C31, B:4:C52>, N100 generates a probe packet with can also use BGP-LS to get the complete view of an inter-domain
SRH set to (B:100:1::, B:4:C52, B:2:C31, SL=2). The controller routes topology. In other words, the controller leverages the visibility of
the probe packet towards the first segment, which is B:2:C31. N2 the topology to monitor the paths between the various endpoints
performs the standard SRH processing and forward it over link3 with without control plane intervention required at the monitored nodes.
the DA of IPv6 packet set to B:4:C52. N4 also performs the normal
SRH processing and forward it over link10 with the DA of IPv6 packet
set to B:100:1::. This makes the probe loops back to the centralized
monitoring system.
In the reference topology in Figure 1, N100 uses an IGP protocol 5. Security Considerations
like 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
topology. In other words, the controller leverages the visibility of
the topology to monitor the paths between the various endpoints
without control plane intervention required at the monitored nodes.
5. Security Considerations This document does not define any new protocol extensions and relies
on existing procedures defined for ICMP. This document does not
impose any additional security challenges to be considered beyond
security considerations described in [RFC4884], [RFC4443], [RFC792],
RFCs that updates these RFCs, [I-D.ietf-6man-segment-routing-header]
and [I-D.ietf-spring-srv6-network-programming].
This document does not define any new protocol extensions and relies 6. IANA Considerations
on existing procedures defined for ICMP. This document does not
impose any additional security challenges to be considered beyond
security considerations described in [RFC4884], [RFC4443], [RFC792]
and RFCs that updates these RFCs.
6. IANA Considerations 6.1. ICMPv6 type Numbers RegistrySEC
6.1. ICMPv6 type Numbers Registry This document defines one ICMPv6 Message, a type that has been
allocated from the "ICMPv6 'type' Numbers" registry of [RFC4443].
Specifically, it requests to add the following to the "ICMPv6 Type
Numbers" registry:
This document defines one ICMPv6 Message, a type that has been TBA (suggested value: 162) SRv6 OAM Message.
allocated from the "ICMPv6 'type' Numbers" registry of [RFC4443].
Specifically, it requests to add the following to the "ICMPv6 Type
Numbers" registry:
TBA (suggested value: 162) SRv6 OAM Message. The document also requests the creation of a new IANA registry to the
"ICMPv6 'Code' Fields" against the "ICMPv6 Type Numbers TBA - SRv6
OAM Message" with the following codes:
The document also requests the creation of a new IANA registry to Code Name Reference
the --------------------------------------------------------
0 No Error This document
1 SID is not locally implemented This document
2 O-flag punt at Transit This document
"ICMPv6 'Code' Fields" against the "ICMPv6 Type Numbers TBA - SRv6 6.2. SRv6 OAM Endpoint Types
OAM Message" with the following codes:
Code Name Reference This I-D requests to IANA to allocate, within the "SRv6 Endpoint
------------------------------------------------------- Behaviors Registry" sub-registry belonging to the top-level "Segment-
0 No Error This document routing with IPv6 dataplane (SRv6) Parameters" registry [I-D.ietf-
1 SID is not locally implemented This document spring- srv6-network-programming], the following allocations:
2 O-flag punt at Transit This document
6.2. SRv6 OAM Endpoint Types +------------------+-------------------+-----------+
| Value (Suggested | Endpoint Behavior | Reference |
| Value) | | |
+------------------+-------------------+-----------+
| TBA (40) | End.OP | [This.ID] |
| TBA (41) | End.OTP | [This.ID] |
+------------------+-------------------+-----------+
This I-D requests to IANA to allocate, within the "SRv6 Endpoint 7. Acknowledgements
Behaviors Registry" sub-registry belonging to the top-level
"Segment-routing with
IPv6 dataplane (SRv6) Parameters" registry [I-D.filsfils-spring-
srv6-network-programming], the following allocations:
+-------------+-----+-------------------+-----------+ The authors would like to thank Gaurav Naik for his review comments.
| Value (Suggested | Endpoint Behavior | Reference |
| Value) | | |
+------------------+-------------------+-----------+
| TBA (40) | End.OP | [This.ID] |
| TBA (41) | End.OTP | [This.ID] |
+------------------+-------------------+-----------+
6.3. SRv6 IOAM TLV 8. Contributors
IANA is requested to allocate SRH TLV Type for IOAM TLV data fields The following people have contributed to this document:
under registry name "Segment Routing Header TLVs" requested by [I-
D.6man-segment-routing-header].
+--------------+--------------------------+---------------+ Robert Raszuk
Bloomberg LP
Email: robert@raszuk.net
| SRH TLV Type | Description | Reference | John Leddy
+--------------+--------------------------+---------------+ Individual
| TBA1 | TLV for IOAM Data Fields | This document | Email: john@leddy.net
+--------------+--------------------------+---------------+
7. References Gaurav Dawra
LinkedIn
Email: gdawra.ietf@gmail.com
7.1. Normative References Bart Peirens
Proximus
Email: bart.peirens@proximus.com
[RFC792] J. Postel, "Internet Control Message Protocol", RFC 792, Nagendra Kumar
September 1981. Cisco Systems, Inc.
Email: naikumar@cisco.com
[RFC4443] A. Conta, S. Deering, M. Gupta, Ed., "Internet Control Carlos Pignataro
Message Protocol (ICMPv6) for the Internet Protocol Cisco Systems, Inc.
Version 6 (IPv6) Specification", RFC 4443, March 2006. Email: cpignata@cisco.com
[RFC4884] R. Bonica, D. Gan, D. Tappan, C. Pignataro, "Extended ICMP Rakesh Gandhi
to Support Multi-Part Messages", RFC 4884, April 2007. Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Frank Brockners
Cisco Systems, Inc.
Germany
Email: fbrockne@cisco.com
[RFC5837] A. Atlas, Ed., R. Bonica, Ed., C. Pignataro, Ed., N. Shen, Darren Dukes
JR. Rivers, "Extending ICMP for Interface and Next-Hop Cisco Systems, Inc.
Identification", RFC 5837, April 2010. Email: ddukes@cisco.com
[I-D.filsfils-spring-srv6-network-programming] C. Filsfils, et al., Cheng Li
"SRv6 Network Programming", Huawei
draft-filsfils-spring-srv6-network-programming, work in Email: chengli13@huawei.com
progress.
[I-D.6man-segment-routing-header] Previdi, S., Filsfils, et al, Faisal Iqbal
"IPv6 Segment Routing Header (SRH)", Individual
draft-ietf-6man-segment-routing-header, work in progress. Email: faisal.ietf@gmail.com
[I-D.ietf-ippm-ioam-data] Brockners, F., Bhandari, S., Pignataro, 9. References
C., Gredler, H., Leddy, J., Youell, S., Mizrahi, T.,
Mozes, D., Lapukhov, P., Chang, R., and Bernier, D., "Data
Fields for In-situ OAM", draft-ietf-ippm-ioam-data, work
in progress.
7.2. Informative References 9.1. Normative References
[I-D.bashandy-isis-srv6-extensions] IS-IS Extensions to Support Routing [I-D.ietf-6man-segment-routing-header]
over IPv6 Dataplane. L. Ginsberg, P. Psenak, C. Filsfils, Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
A. Bashandy, B. Decraene, Z. Hu, Matsushima, S., and d. daniel.voyer@bell.ca, "IPv6 Segment
draft-bashandy-isis-srv6-extensions, work in progress. Routing Header (SRH)", draft-ietf-6man-segment-routing-
header-21 (work in progress), June 2019.
[I-D.dawra-idr-bgpls-srv6-ext] G. Dawra, C. Filsfils, K. Talaulikar, [I-D.ietf-spring-srv6-network-programming]
et al., BGP Link State extensions for IPv6 Segment Routing Filsfils, C., Camarillo, P., Leddy, J.,
(SRv6), draft-dawra-idr-bgpls-srv6-ext, work in progress. daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
Network Programming", draft-ietf-spring-srv6-network-
programming-01 (work in progress), July 2019.
[I-D.ietf-spring-oam-usecase] A Scalable and Topology-Aware MPLS [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Dataplane Monitoring System. R. Geib, C. Filsfils, C. Requirement Levels", BCP 14, RFC 2119,
Pignataro, N. Kumar, draft-ietf-spring-oam-usecase, work DOI 10.17487/RFC2119, March 1997,
in progress. <https://www.rfc-editor.org/info/rfc2119>.
[I-D.brockners-inband-oam-data] F. Brockners, et al., "Data Formats 9.2. Informative References
for In-situ OAM", draft-brockners-inband-oam-data, work in
progress.
[I-D.brockners-inband-oam-transport] F.Brockners, at al., [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
"Encapsulations for In-situ OAM Data", RFC 792, DOI 10.17487/RFC0792, September 1981,
draft-brockners-inband-oam-transport, work in progress. <https://www.rfc-editor.org/info/rfc792>.
[I-D.brockners-inband-oam-requirements] F.Brockners, et al., [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
"Requirements for In-situ OAM", Control Message Protocol (ICMPv6) for the Internet
draft-brockners-inband-oam-requirements, work in progress. Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
Routing Policy for Traffic Engineering", "Extended ICMP to Support Multi-Part Messages", RFC 4884,
draft-filsfils-spring-segment-routing-policy, work in DOI 10.17487/RFC4884, April 2007,
progress. <https://www.rfc-editor.org/info/rfc4884>.
8. Acknowledgments [RFC5837] Atlas, A., Ed., Bonica, R., Ed., Pignataro, C., Ed., Shen,
N., and JR. Rivers, "Extending ICMP for Interface and
Next-Hop Identification", RFC 5837, DOI 10.17487/RFC5837,
April 2010, <https://www.rfc-editor.org/info/rfc5837>.
The authors would like to thank Gaurav Naik for his review comments. [RFC8403] Geib, R., Ed., Filsfils, C., Pignataro, C., Ed., and N.
Kumar, "A Scalable and Topology-Aware MPLS Data-Plane
Monitoring System", RFC 8403, DOI 10.17487/RFC8403, July
2018, <https://www.rfc-editor.org/info/rfc8403>.
Authors' Addresses Authors' Addresses
Clarence Filsfils
Cisco Systems, Inc.
Email: cfilsfil@cisco.com
Zafar Ali Zafar Ali
Cisco Systems, Inc. Cisco Systems
Email: zali@cisco.com
Nagendra Kumar
Cisco Systems, Inc.
Email: naikumar@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
Email: cpignata@cisco.com
Rakesh Gandhi
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Frank Brockners Email: zali@cisco.com
Cisco Systems, Inc.
Germany
Email: fbrockne@cisco.com
John Leddy Clarence Filsfils
Comcast Cisco Systems
Email: John_Leddy@cable.comcast.com
Robert Raszuk Email: cfilsfil@cisco.com
Bloomberg LP
731 Lexington Ave
New York City, NY10022, USA
Email: robert@raszuk.net
Satoru Matsushima Satoru Matsushima
SoftBank Softbank
Japan
Email: satoru.matsushima@g.softbank.co.jp Email: satoru.matsushima@g.softbank.co.jp
Daniel Voyer Daniel Voyer
Bell Canada Bell Canada
Email: daniel.voyer@bell.ca
Gaurav Dawra
LinkedIn
Email: gdawra.ietf@gmail.com
Bart Peirens Email: daniel.voyer@bell.ca
Proximus
Email: bart.peirens@proximus.com
Mach Chen Mach Chen
Huawei Huawei
Email: mach.chen@huawei.com
Cheng Li
Huawei
Email: chengli13@huawei.com
Faisal Iqbal Email: mach.chen@huawei.com
Individual
Email: faisal.ietf@gmail.com
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