Network Working Group T. Graf
Internet-Draft Swisscom
Intended status: Standards Track B. Claise
Expires: 21 September 2022 Huawei
20 March 2022
Export of Segment Routing IPv6 Information in
IP Flow Information Export (IPFIX)
draft-tgraf-opsawg-ipfix-srv6-srh-03
Abstract
This document introduces new IP Flow Information Export (IPFIX)
information elements to identify the SRv6 Segment Routing Header
dimensions and SRv6 Control Plane Protocol that traffic is being
forwarded with.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IPFIX Information Elements . . . . . . . . . . . . . . . . . 2
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Operational Considerations . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. IPFIX Encoding Example . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
A new type of Routing Extension Header called Segment Routing Header
(SRH) is defined by [RFC8754] which is used for applying Segment
Routing (SR) on the IPv6 data plane.
Three routing protocol extensions, OSPFv3 Extensions
[I-D.li-lsr-ospfv3-srv6-extensions], IS-IS Extensions
[I-D.ietf-lsr-isis-srv6-extensions], BGP Prefix Segment Identifiers
(Prefix-SIDs) [I-D.ietf-bess-srv6-services] and one Path Computation
Element Communication Protocol (PCEP) Extension
[I-D.ietf-pce-segment-routing-ipv6] have been defined to propagate
Segment Identifiers (SIDs) for the IPv6 data plane.
This document defines eight new IPFIX Information Elements (IEs) and
two new subregistries within the "IPFIX Information Elements"
registry [RFC7012], respectively for the new SRH dimensions and
routing protocol and PCEP extensions.
2. IPFIX Information Elements
This section defines and describes the new IPFIX IEs.
ipv6SRHFlags
8-bit flags defined in the SRH.
ipv6SRHTag
16-bit tag field defined in the SRH that marks a packet as part of
a class or group of packets sharing the same set of properties.
ipv6SRHSegment
128-bit IPv6 address that represents an SRv6 segment.
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ipv6SRHSegmentBasicList
Ordered basicList [RFC6313] of zero or more 128-bit IPv6 addresses
in the SRH that represents the SRv6 segment list. The Segment
List is encoded starting from the active segment of the SR Policy.
ipv6SRHSegmentListSection
Exposes the SRH Segment List as defined in section 2 of [RFC8754]
as series of n octets.
ipv6SRHSegmentsLeft
8-bit unsigned integer defining the number of route segments
remaining to reach the end of the segment list.
ipv6SRHSection
Exposes the SRH and its TLV's as defined in section 2 of [RFC8754]
as series of n octets.
ipv6SRHSegmentType
Name of the routing protocol or PCEP extension from where the
active SRv6 segment has been learned from.
3. Use Cases
By using ipv6SRHSegmentBasicList(TBD4), ipv6SRHSegmentsLeft (TBD6),
ipv6SRHSegmentType(TBD8) and forwardingStatus(89) it is possible to
identify
* how many packets are forwarded or dropped
* if dropped, for which reasons,
* identify the control plane protocol which defined the active
segment,
* the SRv6 segment list and
* how many SRv6 segments are left.
4. IANA Considerations
This document requests IANA to create new IEs (see table1) and two
new subregistries called "IPFIX IPv6 SRH Flags" (table 2) and "IPFIX
IPv6 SRH Segment type" (table 3) under the "IPFIX Information
Elements" registry [RFC7012] available at [IANA-IPFIX] and assign the
following code initial points.
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+-------+---------------------------+
|Element| Name |
| ID | |
+-------+---------------------------+
| TBD1 | ipv6SRHFlags |
| | |
+-------+---------------------------+
| TBD2 | ipv6SRHTag |
| | |
+-------+---------------------------+
| TBD3 | ipv6SRHSegment |
| | |
+-------+---------------------------+
| TBD4 | ipv6SRHSegmentBasicList |
| | |
+-------+---------------------------+
| TBD5 | ipv6SRHSegmentListSection |
| | |
+-------+---------------------------+
| TBD6 | ipv6SRHSegmentsLeft |
| | |
+-------+---------------------------+
| TBD7 | ipv6SRHSection |
+-------+---------------------------+
| TBD8 | ipv6SRHSegmentType |
+-------+---------------------------+
Table 1: Creates IEs in the "IPFIX Information Elements" registry
Note to the RFC-Editor:
* Please replace TBD1 - TBD12 with the values allocated by IANA
* Please replace the [RFC-to-be] with the RFC number assigned to
this document
4.1. ipv6SRHFlags
Name: ipv6SRHFlags ElementID: TBD1 Description: This Information
Element identifies the 8-bit flags defined in the SRH. Values for
this Information Element are listed in the "IPFIX IPv6 SRH Flags"
registry, see [IANA-IPFIX]. Initial values in the registry are
defined by the table below. New assignments of values will be
administered by IANA and are subject to Expert Review Abstract Data
Type: unsigned8 Data Type Semantics: flags Reference: [RFC-to-be],
RFC8754[RFC8126]. Experts need to check definitions of new values
for completeness, accuracy, and redundancy.
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+--------+-------------------+--------------------------------------+
| Value | Description | Reference |
+--------+-------------------+--------------------------------------+
| 0-7 | Unassigned | |
+--------+-------------------+--------------------------------------+
Table 2: "IPFIX IPv6 SRH Flags" registry
4.2. ipv6SRHTag
Name: ipv6SRHTag ElementID: TBD2 Description: This Information
Element identifies the 16-bit tag field defined in the SRH that marks
a packet as part of a class or group of packets sharing the same set
of properties. Abstract Data Type: unsigned16 Data Type Semantics:
identifier Reference: [RFC-to-be], RFC8754
4.3. ipv6SRHSegment
Name: ipv6SRHSegment ElementID: TBD3 Description: This Information
Element identifies the 128-bit IPv6 address that represents an SRv6
segment. Abstract Data Type: ipv6address Data Type Semantics:
default Reference: [RFC-to-be], RFC8754
4.4. ipv6SRHSegmentBasicList
Name: ipv6SRHSegmentBasicList ElementID: TBD4 Description: This
Information Element identifies the Ordered basicList [RFC6313] of
zero or more 128-bit IPv6 addresses in the SRH that represents the
SRv6 segment list. The Segment List is encoded starting from the
active segment of the SR Policy. Abstract Data Type: basicList Data
Type Semantics: list Reference: [RFC-to-be], RFC8754
4.5. ipv6SRHSegmentListSection
Name: ipv6SRHSegmentListSection ElementID: TBD5 Description: Exposes
the SRH Segment List as defined in section 2 of Abstract Data Type:
octetArray Data Type Semantics: default Reference: [RFC-to-be],
RFC8754[RFC8754] as series of n octets.
4.6. ipv6SRHSegmentsLeft
Name: ipv6SRHSegmentsLeft ElementID: TBD6 Description: This
Information Element identifies the 8-bit unsigned integer defining
the number of route segments remaining to reach the end of the
segment list. Abstract Data Type: unsigned8 Data Type Semantics:
quantity Reference: [RFC-to-be], RFC8754
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4.7. ipv6SRHSection
Name: ipv6SRHSection ElementID: TBD7 Description: This Information
Element exposes the SRH and its TLV's as defined in s ection 2 of
Abstract Data Type: octetArray Data Type Semantics: default
Reference: [RFC-to-be], RFC8754[RFC8754] as series of n octets.
4.8. ipv6SRHSegmentType
Name: ipv6SRHSegmentType ElementID: TBD8 Description: This
Information Element identifies the name of the routing protocol or
PCEP extension from where the active SRv6 segment has been learned
from. Values for this Information Element are listed in the "IPFIX
IPv6 SRH Segment type" registry, see [IANA-IPFIX]. Initial values in
the registry are defined by the table below. New assignments of
values will be administered by IANA and are subject to Expert Review
Abstract Data Type: unsigned8 Data Type Semantics: identifier
Reference: [RFC-to-be][RFC8126]. Experts need to check definitions
of new values for completeness, accuracy, and redundancy.
+-------+--------------------+--------------------------------------+
| Value | Description | Reference |
+-------+--------------------+--------------------------------------+
| TBD9 | Unknown | [RFC-to-be] |
| | | |
+-------+--------------------+--------------------------------------+
| TBD10 | Path Computation | [RFC-to-be], |
| | Element | draft-ietf-pce-segment-routing-ipv6 |
+-------+--------------------+--------------------------------------+
| TB11 | OSPFv3 | [RFC-to-be], |
| | Segment Routing | draft-li-ospf-ospfv3-srv6-extensions |
+-------+--------------------+--------------------------------------+
| TBD12 | IS-IS | [RFC-to-be] |
| | Segment Routing | draft-ietf-lsr-isis-srv6-extensions |
+-------+--------------------+--------------------------------------+
| TBD13 | BGP Segment | [RFC-to-be], |
| | Routing Prefix-SID | draft-ietf-bess-srv6-services |
+-------+--------------------+--------------------------------------+
Table 3: "IPFIX IPv6 SRH Segment type" subregistry
5. Operational Considerations
The zero or more 128-bit IPv6 addresses in the SRH [RFC8754] can be
exported in two different ways, with two different IPFIX IEs:
* ipv6SRHSegmentBasicList
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* ipv6SRHSegmentListSection
The ipv6SRHSegmentBasicList encodes the SID list of IPv6 addresses
with a basicList, specified in the IPFIX Structured Data [RFC6313].
This encoding offers the advantage to the data collection that the
different IPv6 addresses are already structured as a list, without
the need of post processing. However, this method requires some
extra processing on the exporter, to realize the BasicList data
mapping.
The ipv6SRHSegmentListSection, on the other hand, encodes the list of
IPv6 addresses as an octetArray. This doesn't impose any data flow
manipulation on the exporter, facilitating the immediate export.
However, the data collection must be able to decode the IPv6
addresses according the SR specifications.
It is not expected that an exporter would support both
ipv6SRHSegmentBasicList and ipv6SRHSegmentListSection at the same
time.
6. Security Considerations
There exists no significant extra security considerations regarding
the allocation of these new IPFIX IEs compared to [RFC7012].
7. Acknowledgements
I would like to thank Pierre Francois, Yao Liu and Paolo Lucente for
their review and valuable comments.
8. References
8.1. Normative References
[RFC6313] Claise, B., Dhandapani, G., Aitken, P., and S. Yates,
"Export of Structured Data in IP Flow Information Export
(IPFIX)", RFC 6313, DOI 10.17487/RFC6313, July 2011,
<https://www.rfc-editor.org/info/rfc6313>.
[RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model
for IP Flow Information Export (IPFIX)", RFC 7012,
DOI 10.17487/RFC7012, September 2013,
<https://www.rfc-editor.org/info/rfc7012>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
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8.2. Informative References
[I-D.ietf-bess-srv6-services]
Dawra, G., Filsfils, C., Talaulikar, K., Raszuk, R.,
Decraene, B., Zhuang, S., and J. Rabadan, "SRv6 BGP based
Overlay Services", Work in Progress, Internet-Draft,
draft-ietf-bess-srv6-services-13, 19 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-bess-srv6-
services-13.txt>.
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extensions to Support Segment Routing over
IPv6 Dataplane", Work in Progress, Internet-Draft, draft-
ietf-lsr-isis-srv6-extensions-18, 20 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsr-isis-srv6-
extensions-18.txt>.
[I-D.ietf-pce-segment-routing-ipv6]
Li, C., Negi, M., Sivabalan, S., Koldychev, M.,
Kaladharan, P., and Y. Zhu, "PCEP Extensions for Segment
Routing leveraging the IPv6 data plane", Work in Progress,
Internet-Draft, draft-ietf-pce-segment-routing-ipv6-12, 6
March 2022, <https://www.ietf.org/internet-drafts/draft-
ietf-pce-segment-routing-ipv6-12.txt>.
[I-D.li-lsr-ospfv3-srv6-extensions]
Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak,
"OSPFv3 Extensions for SRv6", Work in Progress, Internet-
Draft, draft-li-lsr-ospfv3-srv6-extensions-00, 15 January
2020, <https://www.ietf.org/archive/id/draft-li-lsr-
ospfv3-srv6-extensions-00.txt>.
[IANA-IPFIX]
"IANA, "IP Flow Information Export (IPFIX) Entities"",
<https://www.iana.org/assignments/ipfix/ipfix.xhtml>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
Appendix A. IPFIX Encoding Example
In this section an example is provided to show the encoding format
for the newly introduced IEs.
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+-----+------+-----+--------+---------------------------------------|
| SRH | SRH | SRH | Segment| Segment List |
| Nr | Flags| Tag | Type | |
+-----+------+-----+--------+---------------------------------------+
| 1 | 0 | 123 | IS-IS | 2001:db8::1, 2001:db8::2, 2001:db8::3 |
+-----+------+-----+--------+---------------------------------------+
| 2 | 0 | 456 | IS-IS | 2001:db8::4, 2001:db8::5 |
+-----+------+-----+--------+---------------------------------------+
| 3 | 0 | 789 | IS-IS | 2001:db8::6 |
+-----+------+-----+--------+---------------------------------------+
Table 4: 3 observed SRH headers and their routing protocol
A.1. Template Record
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 2 | Length = 41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 256 | Field Count = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| ipv6SRHFlags = TBD1 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| ipv6SRHTag = TBD2 | Field Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| ipv6SRHSegmentType = TBD8 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| ipv6SRHSegment = TBD3 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|ipv6SRHSegmentBasicList= TBD4| Field Length = 0xFFFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Table 4: Template Record Encoding Format
In this example, the Template ID is 256, which will be used in the
Data Record. The field length for ipv6SRHSegmentBasicList is 0xFFFF,
which means the length of this IE is variable, and the actual length
of this IE is indicated by the List Length field in the basicList
format as per [RFC6313].
A.2. Data Set
The data set is represented as follows:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 256 | Length = 136 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ipv6SRHFlags | ipv6SRHTag = 123 | ipv6SRHSegment|
| = 0 | | Type = TBD12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | List Length = 53 |semantic= |
| | |ordered |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ipv6SRHSegment = TBD4 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] = 2001:db8::1 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[1] = 2001:db8::2 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[2] = 2001:db8::3 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ipv6SRHFlags | ipv6SRHTag = 456 | ipv6SRHSegment|
| = 0 | | Type = TBD12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | List Length = 37 |semantic= |
| | |ordered |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ipv6SRHSegment = TBD4 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] = 2001:db8::4 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[1] = 2001:db8::5 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ipv6SRHFlags | ipv6SRHTag = 789 | ipv6SRHSegment|
| = 0 | | Type = TBD12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | List Length = 21 |semantic= |
| | |ordered |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ipv6SRHSegment = TBD4 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] = 2001:db8::6 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Table 5: Data Set Encoding Format
Authors' Addresses
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Thomas Graf
Swisscom
Binzring 17
CH-8045 Zurich
Switzerland
Email: thomas.graf@swisscom.com
Benoit Claise
Huawei
Email: benoit.claise@huawei.com
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