Internet-Draft New TCP and IPv6 EH IPFIX IEs July 2024
Boucadair & Claise Expires 6 January 2025 [Page]
Workgroup:
OPSAWG
Internet-Draft:
draft-ietf-opsawg-ipfix-tcpo-v6eh-17
Published:
Intended Status:
Standards Track
Expires:
Authors:
M. Boucadair
Orange
B. Claise
Huawei

Extended TCP Options and IPv6 Extension Headers IPFIX Information Elements

Abstract

This document specifies new IP Flow Information Export (IPFIX) Information Elements (IEs) to solve issues with existing ipv6ExtensionHeaders and tcpOptions IPFIX IEs, especially the ability to export any observed IPv6 extension headers or TCP options.

Discussion Venues

This note is to be removed before publishing as an RFC.

Discussion of this document takes place on the Operations and Management Area Working Group Working Group mailing list (opsawg@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/opsawg/.

Source for this draft and an issue tracker can be found at https://github.com/boucadair/ipfix-tcpoptions-and-v6eh.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 6 January 2025.

Table of Contents

1. Introduction

This document specifies new IP Flow Information Export (IPFIX) [RFC7011] Information Elements (IEs) to solve a set of issues encountered with the specifications of ipv6ExtensionHeaders (to export IPv6 extension headers) and tcpOptions (to export TCP options) IEs [IANA-IPFIX]. More details about these issues are provided in the following sub-sections.

1.1. Issues with ipv6ExtensionHeaders Information Element

The specification of the ipv6ExtensionHeaders IPFIX IE (64) does not:

  • Cover the full extension headers' range defined in the IPv6 specification (Section 4 of [RFC8200]).

  • Specify the procedure to follow when all bits are exhausted.

  • Specify a means to export the order and the number of occurrences of a given extension header.

  • Specify how to automatically update the IANA IPFIX registry ([IANA-IPFIX]) when a new value is assigned in the IPv6 Extension Header Types registry [IANA-EH]. Only a frozen set of extension headers can be exported using the ipv6ExtensionHeaders IE. For example, the ipv6ExtensionHeaders IE can't report some IPv6 EHs, specifically EHs for Host Identity Protocol (139), Shim6 Protocol (140) or extension headers for experimentation and testing.

  • Specify whether the exported values match the full enclosed values or only up to a limit imposed by hardware or software (e.g., Section 1.1 of [RFC8883]). Note that some implementations may not be able to export all observed extension headers in a Flow because of a hardware or software limit (see, e.g., [I-D.ietf-6man-eh-limits]). The specification of the ipv6ExtensionHeaders IE does not discuss whether it covers all enclosed extension headers or only up to a limit.

  • Specify how to report the length of IPv6 extension headers.

  • Optimize the encoding.

  • Explain the reasoning for reporting values which do not correspond to extension headers (e.g., "Unknown Layer 4 header" or "Payload compression header").

  • Specify how to report extension header chains or aggregate extension headers length.

Section 3 addresses these issues.

This specification deprecates the ipv6ExtensionHeaders IPFIX IE in favor of the new IEs defined in this document.

1.2. Issues with tcpOptions Information Element

The specification of the tcpOptions IPFIX IE (209) does not:

  • Describe how some observed TCP options in a Flow can be exported using IPFIX. Only TCP options having a Kind <= 63 can be exported in a tcpOptions IE.

  • Allow reporting the observed Experiment Identifiers (ExIDs) that are carried in shared Experimental TCP options (Kind=253 or 254) [RFC6994].

  • Optimize the encoding.

Section 4 addresses these issues.

This specification deprecates the tcpOptions IE in favor of the new IEs defined in this document.

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

This document uses the IPFIX-specific terminology (Information Element, Template Record, Flow, etc.) defined in Section 2 of [RFC7011]. As in the base IPFIX specification [RFC7011], these IPFIX-specific terms have the first letter of a word capitalized.

Also, the document uses the terms defined in IPv6 [RFC8200] and TCP [RFC9293] specifications.

In addition, the document makes use of the following term:

Extension header chain:

Refers to the chain of extension headers that are present in an IPv6 packet.

This term should not be confused with the IPv6 header chain, which includes the IPv6 header, zero or more IPv6 extension headers, and zero or a single Upper-Layer Header.

Flow with varying extension header chain:

Refers to a Flow where distinct extension header chains are observed. Concretely, different packets in such a Flow will have a different sequence of extension header type codes.

3. Information Elements for IPv6 Extension Headers

3.1. ipv6ExtensionHeaderType Information Element

Name:

ipv6ExtensionHeaderType

ElementID:

TBD1

Description:

Type of an IPv6 extension header observed in at least one packet of this Flow.

Abstract Data Type:

unsigned8

Data Type Semantics:

identifier

Additional Information:

See the IPv6 Extension Header Types registry at [IANA-EH].

See Section 4 of [RFC8200] for the general definition of IPv6 extension headers.

Reference:

This-Document

3.2. ipv6ExtensionHeaderCount Information Element

Name:

ipv6ExtensionHeaderCount

ElementID:

TBD2

Description:

The number of consecutive occurrences of the same extension header type in a Flow.

This IE is reported, e.g., in the ipv6ExtensionHeaderTypeCountList IE.

The type of the extension header is provided in the ipv6ExtensionHeaderType IE.

Abstract Data Type:

unsigned8

Data Type Semantics:

totalCounter

Additional Information:

See the IPv6 Extension Header Types registry at [IANA-EH].

See Section 4 of [RFC8200] for the general definition of IPv6 extension headers.

Reference:

This-Document

3.3. ipv6ExtensionHeadersFull Information Element

Name:

ipv6ExtensionHeadersFull

ElementID:

TBD3

Description:

IPv6 extension headers observed in packets of this Flow. The information is encoded in a set of bit fields. For each IPv6 extension header, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow contains the corresponding IPv6 extension header. Otherwise, if no observed packet of this Flow contains the respective IPv6 extension header, the value of the corresponding bit is 0.

The IPv6 extension header associated with each bit is provided in [NEW_IPFIX_IPv6EH_SUBREGISTRY]. Bit 0 corresponds to the least-significant bit in the ipv6ExtensionHeadersFull IE while bit 255 corresponds to the most-significant bit of the IE. In doing so, few octets will be needed to encode common IPv6 extension headers when observed in a Flow.

The "No Next Header" (bit 2) value (Section 4.7 of [RFC8200]) is used if there is no upper-layer header in an IPv6 packet. Even if the value is not considered as an extension header as such, the corresponding bit is set in the ipv6ExtensionHeadersFull IE whenever that value is encountered in the Flow.

Extension headers observed in a Flow with varying extension header chain MUST NOT be grouped in the ipv6ExtensionHeadersFull IE if the ipv6ExtensionHeaderChainLengthList IE is also present.

If the ipv6ExtensionHeaderChainLengthList IE is not present, then extension headers observed in a Flow with varying extension header chain MAY be grouped in one single ipv6ExtensionHeadersFull IE or be exported in separate ipv6ExtensionHeadersFull IEs, one for each extension header chain.

The ipv6ExtensionHeadersFull IE MUST NOT be exported if ipv6ExtensionHeaderTypeCountList IE is also present because of the overlapping scopes between these two IEs.

The value of ipv6ExtensionHeadersFull IE may be encoded in fewer octets per the guidelines in Section 6.2 of [RFC7011].

Abstract Data Type:

unsigned256

Data Type Semantics:

flags

Additional Information:

See the ipv6ExtensionHeaders Bits registry at [NEW_IPFIX_IPv6EH_SUBREGISTRY].

See the IPv6 Extension Header Types registry at [IANA-EH].

See Section 4 of [RFC8200] for the general definition of IPv6 extension headers.

Reference:

This-Document

  • Note to the RFC Editor: Please replace [NEW_IPFIX_IPv6EH_SUBREGISTRY] with the link to the "ipv6ExtensionHeaders Bits" registry (Section 8.4).

3.4. ipv6ExtensionHeaderTypeCountList Information Element

Name:

ipv6ExtensionHeaderTypeCountList

ElementID:

TBD4

Description:

As per Section 4.1 of [RFC8200], IPv6 nodes must accept and attempt to process extension headers occurring any number of times in the same packet. This IE echoes the order of extension headers and number of consecutive occurrences of the same extension header type in a Flow.

This IE is a subTemplateList of ipv6ExtensionHeaderType and ipv6ExtensionHeaderCount IEs.

Each header chain in Flow with varying extension header chain MUST be exported in a separate IE.

The same extension header type may appear several times in an ipv6ExtensionHeaderTypeCountList IE. For example, if an IPv6 packet of a Flow includes a Hop-by-Hop Options header, a Destination Options header, a Fragment header, and Destination Options header, the ipv6ExtensionHeaderTypeCountList IE will report:

  • the count of Hop-by-Hop Options headers,

  • the occurrences of the Destination Options headers that are observed before a Fragment header,

  • the occurrences of the Fragment headers, and

  • the occurrences of the Destination Options headers that are observed right after a Fragment header.

If an implementation determines that an observed packet of a Flow includes an extension header (including an extension header that it does not support), then the exact observed code of that extension header MUST be echoed in the ipv6ExtensionHeaderTypeCountList IE. How an implementation disambiguates between unknown upper-layer protocols vs. extension headers is not IPFIX-specific. Refer, for example, to Section 2.2 of [RFC8883] for a behavior of an intermediate node that encounters an unknown Next Header type.

Abstract Data Type:

subTemplateList

Data Type Semantics:

list

Additional Information:

See the IPv6 Extension Header Types registry at [IANA-EH].

See [RFC8200] for the general definition of IPv6 extension headers.

Reference:

This-Document

3.5. ipv6ExtensionHeadersLimit Information Element

Name:

ipv6ExtensionHeadersLimit

ElementID:

TBD5

Description:

When set to "false", this IE indicates that the exported extension headers information (e.g., ipv6ExtensionHeadersFull or ipv6ExtensionHeaderTypeCountList) does not match the full enclosed extension headers, but only up to a limit that is typically set by hardware or software.

When set to "true", this IE indicates that the exported extension header information matches the full enclosed extension headers.

Abstract Data Type:

boolean

Data Type Semantics:

default

Additional Information:

See Section 4 of [RFC8200] for the general definition of IPv6 extension headers.

See [RFC8883] for an example of IPv6 packet processing due to limits on extension headers.

Reference:

This-Document

3.6. ipv6ExtensionHeadersChainLength Information Element

Name:

ipv6ExtensionHeadersChainLength

ElementID:

TBD6

Description:

In theory, there are no limits on the number of IPv6 extension headers that may be present in a packet other than the path MTU. However, it was regularly reported that IPv6 packets with extension headers are often dropped in the Internet.

As discussed in Section 1.2 of [RFC8883], some hardware devices implement a parsing buffer of a fixed size to process packets, including all the headers. When the aggregate length of headers of an IPv6 packet exceeds that size, the packet will be discarded or deferred to a slow path.

The ipv6ExtensionHeadersChainLength IE is used to report, in octets, the length of an extension header chain observed in a Flow. The length is the sum of the length of all extension headers of the chain. Exporting such information might help identifying root causes of performance degradation, including packet drops.

Each header chain length of a Flow with varying extension header chain MUST be exported in a separate ipv6ExtensionHeadersChainLength IE.

Abstract Data Type:

unsigned32

Data Type Semantics:

identifier

Units:

octets

Additional Information:

See Section 4 of [RFC8200] for the general definition of IPv6 extension headers.

See [RFC9098] for an overview of operational implications of IPv6 packets with extension headers.

Reference:

This-Document

3.7. ipv6ExtensionHeaderChainLengthList Information Element

Name:

ipv6ExtensionHeaderChainLengthList

ElementID:

TBD7

Description:

This IE is used to report the chains and their length as observed in a Flow with varying extension header chain.

This IE is a subTemplateList of ipv6ExtensionHeadersFull and ipv6ExtensionHeadersChainLength IEs.

If several extension header chains are observed in a Flow, each header chain MUST be exported in a separate ipv6ExtensionHeaderChainLengthList IE.

Abstract Data Type:

subTemplateList

Data Type Semantics:

list

Additional Information:

See the IPv6 Extension Header Types registry at [IANA-EH].

See [RFC8200] for the general definition of IPv6 extension headers.

Reference:

This-Document

4. Information Elements for TCP Options

4.1. tcpOptionsFull Information Element

This section specifies a new IE to cover the full TCP options range.

Name:

tcpOptionsFull

ElementID:

TBD8

Description:

TCP options in packets of this Flow. The information is encoded in a set of bit fields. For each TCP option, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow contains the corresponding TCP option. Otherwise, if no observed packet of this Flow contains the respective TCP option, the value of the corresponding bit is 0.

Options are mapped to bits according to their option numbers. TCP option Kind 0 corresponds to the least-significant bit in the tcpOptionsFull IE while Kind 255 corresponds to the most-significant bit of the IE. This approach allows an observer to export any observed TCP option even if it does support that option and without requiring updating a mapping table.

The value of tcpOptionsFull IE may be encoded in fewer octets per the guidelines in Section 6.2 of [RFC7011].

The presence of tcpSharedOptionExID16List or tcpSharedOptionExID32List IEs is an indication that a shared TCP option (Kind=253 or 254) is observed in a Flow. The presence of tcpSharedOptionExID16List or tcpSharedOptionExID32List IEs takes precedence over setting the corresponding bits in the tcpOptionsFull IE for the same Flow. In order to optimize the use of the reduced-size encoding in the presence of tcpSharedOptionExID16List or tcpSharedOptionExID32List IEs, the Exporter MUST NOT set to 1 the shared TCP options (Kind=253 or 254) flags of the tcpOptionsFull IE that is reported for the same Flow.

Abstract Data Type:

unsigned256

Data Type Semantics:

flags

Additional Information:

See the TCP Option Kind Numbers registry at [IANA-TCP].

See [RFC9293] for the general definition of TCP options.

Reference:

This-Document

4.2. tcpSharedOptionExID16 Information Element

Name:

tcpSharedOptionExID16

ElementID:

TBD9

Description:

Reports an observed 2-byte ExID in a shared TCP option (Kind=253 or 254) in a Flow.

A basicList of tcpSharedOptionExID16 is used to report tcpSharedOptionExID16List values.

Abstract Data Type:

unsigned16

Data Type Semantics:

identifier

Additional Information:

See the TCP Experimental Option Experiment Identifiers (TCP ExIDs) registry at [IANA-TCP-EXIDs].

See [RFC9293] for the general definition of TCP options.

See [RFC6994] for the shared use of experimental TCP Options.

Reference:

This-Document

4.3. tcpSharedOptionExID32 Information Element

Name:

tcpSharedOptionExID32

ElementID:

TBD10

Description:

Reports an observed 4-byte ExID in a shared TCP option (Kind=253 or 254) in a Flow.

A basicList of tcpSharedOptionExID32 is used to report tcpSharedOptionExID32List values.

Abstract Data Type:

unsigned32

Data Type Semantics:

identifier

Additional Information:

See the TCP Experimental Option Experiment Identifiers (TCP ExIDs) registry at [IANA-TCP-EXIDs].

See [RFC9293] for the general definition of TCP options.

See [RFC6994] for the shared use of experimental TCP Options.

Reference:

This-Document

4.4. tcpSharedOptionExID16List Information Element

Name:

tcpSharedOptionExID16List

ElementID:

TBD11

Description:

Reports observed 2-byte ExIDs in shared TCP options (Kind=253 or 254) in a Flow.

A basicList of tcpSharedOptionExID16 IEs in which each tcpSharedOptionExID16 IE carries an observed 2-byte ExID in a shared option.

Abstract Data Type:

basicList

Data Type Semantics:

list

Additional Information:

See the TCP Experimental Option Experiment Identifiers (TCP ExIDs) registry at [IANA-TCP-EXIDs].

See [RFC9293] for the general definition of TCP options.

See [RFC6994] for the shared use of experimental TCP Options.

Reference:

This-Document

4.5. tcpSharedOptionExID32List Information Element

Name:

tcpSharedOptionExID32List

ElementID:

TBD12

Description:

Reports observed 4-byte ExIDs in shared TCP options (Kind=253 or 254) in a Flow.

A basicList of tcpSharedOptionExID32 IEs in which each tcpSharedOptionExID32 IE carries an observed 4-byte ExID in a shared option.

Abstract Data Type:

basicList

Data Type Semantics:

list

Additional Information:

See the TCP Experimental Option Experiment Identifiers (TCP ExIDs) registry at [IANA-TCP-EXIDs].

See [RFC9293] for the general definition of TCP options.

See [RFC6994] for the shared use of experimental TCP Options.

Reference:

This-Document

5. Implementation and Operational Considerations

Implementations of tcpSharedOptionExID16, tcpSharedOptionExID32, tcpSharedOptionExID16List, and tcpSharedOptionExID32List IEs are assumed to be provided with a list of valid ExIDs [IANA-TCP-EXIDs]. How that list is maintained is implementation-specific. Absent that list, an implementation can't autonomously determine whether an ExID is present and, if so, whether it is 2- or 4-byte length.

If a TCP Flow contains packets with a mix of 2-byte and 4-byte ExIDs, the same Template Record is used with both tcpSharedOptionExID16 and tcpSharedOptionExID32 IEs.

6. Examples

This section provides a few examples to illustrate the use of some IEs defined in this document.

6.1. IPv6 Extension Headers

Figure 1 provides an example of EH/bit mappings in an ipv6ExtensionHeadersFull IE for an IPv6 Flow in which only the IPv6 Destination Options (0) header is observed. The bits are set following the table provided in Section 8.4.1.

MSB                                                      LSB
                     1                          25
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ... 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|   |0|0|0|0|0|0|0|1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
Figure 1: A First Example of EH/Bit Mappings in the ipv6ExtensionHeadersFull IE

The leading zeros are dropped per the reduced-size encoding guidance. One octet is thus sufficient to send these observed options on the wire. Concretely, the ipv6ExtensionHeadersFull IE will be set to 0x01 (Figure 2).

MSB           LSB
 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|0|0|0|0|0|0|0|1|
+-+-+-+-+-+-+-+-+
Figure 2: A First Example of ipv6ExtensionHeadersFull IE with Reduced-size Encoding

Figure 3 provides another example of reported values in an ipv6ExtensionHeadersFull IE for an IPv6 Flow in which the Destination Options (0), IPv6 Hop-by-Hop Options (1), and Routing (5) headers are observed. One octet is sufficient to report these observed options. Concretely, the ipv6ExtensionHeadersFull IE will be set to 0x23.

MSB           LSB
 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|0|0|1|0|0|0|1|1|
+-+-+-+-+-+-+-+-+
Figure 3: A Second Example of ipv6ExtensionHeadersFull IE with Reduced-size Encoding

Let us now consider an IPv6 Flow in which the following EH chain is observed: Routing (5), Mobility (7), and Authentication (9) header. Figure 4 shows the ipv6ExtensionHeadersFull IE (0x02A0) to reprot this individual chain.

MSB                          LSB
                     1
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0|0|0|0|0|1|0|1|0|1|0|0|0|0|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: An Example of ipv6ExtensionHeadersFull IE Reported for an Extension Header Chain

6.2. TCP Options

6.2.1. Reduced-size Encoding

Given TCP Kind allocation practices and the option mapping defined in Section 4.1, fewer octets are likely to be used for Flows with common TCP options.

Figure 5 shows an example of Kind/bit mappings in a tcpOptionsFull IE for a TCP Flow in which End of Option List (0), Maximum Segment Size (2), and Window Scale (3) options are observed.

MSB                                                      LSB
                     1                          25
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ... 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|   |0|0|0|0|1|1|0|1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+
Figure 5: An Example of TCP Options / Bit Mappings in a tcpOptionsFull IE

One octet is sufficient to report these observed options. Concretely, the tcpOptionsFull IE will be set to 0x0D (Figure 6).

MSB           LSB
 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|0|0|0|0|1|1|0|1|
+-+-+-+-+-+-+-+-+
Figure 6: An Example of tcpOptionsFull IE with Reduced-size Encdoing

6.2.2. Shared Options

Let us consider a TCP Flow in which shared options with ExIDs 0x0348 (HOST_ID) [RFC7974], 0x454E (TCP-ENO) [RFC8547], and 0xE2D4C3D9 (Shared Memory communications over RMDA protocol) [RFC7609] are observed. Figure 7 shows an excerpt of the Data Set encoding with a focus on the tcpSharedOptionExID16 and tcpSharedOptionExID32 IEs. The meaning of the fields is defined in [RFC6313].

 MSB                                                          LSB
 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
:                           ...                                 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      255      |        List Length = 9        |semantic=allof |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|tcpSharedOptionExID16 = TBD9   |         Field Length = 2      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|              0x0348           |             0x454E            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      255      |        List Length = 9        |semantic=allof |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|tcpSharedOptionExID32 = TBD10  |         Field Length = 4      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           0xE2D4C3D9                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:                           ...                                 :
Figure 7: Example of TCP Shared IEs

7. Security Considerations

IPFIX security considerations are discussed in Section 11 of [RFC7011].

ipv6ExtensionHeadersChainLength and ipv6ExtensionHeadersLimit IEs can be exploited by an unauthorized observer as a means to deduce the processing capabilities of nodes. Section 8 of [RFC7012] discusses the required measures to guarantee the integrity and confidentiality of the exported information.

This document does not add new security considerations for exporting IEs other than those already discussed in Section 8 of [RFC7012].

8. IANA Considerations

8.1. Deprecate ipv6ExtensionHeaders and tcpOptions Information Elements

This document requests IANA to update the "IPFIX Information Elements" registry under the "IP Flow Information Export (IPFIX) Entities" registry group [IANA-IPFIX] as follows:

  • Update the ipv6ExtensionHeaders IE (64) entry by marking it as deprecated in favor of the ipv6ExtensionHeadersFull IE defined in this document. This note should also be echoed in the "Additional Information" of the ipv6ExtensionHeaders IE.

  • Update the tcpOptions IE (209) entry by marking it as deprecated in favor of the tcpOptionsFull IE defined in this document. This note should also be echoed in the "Additional Information" of the tcpOptions IE.

IANA is also requested to update the reference of ipv6ExtensionHeaders IE (64) and tcpOptions IE (209) to point to this document.

8.2. IPFIX Information Elements

This document requests IANA to add the following new IPFIX IEs to the "IPFIX Information Elements" registry under the "IP Flow Information Export (IPFIX) Entities" registry group [IANA-IPFIX]:

Table 1: New IPFIX Information Elements
Value Name Reference
TBD1 ipv6ExtensionHeader Section 3.1 of This-Document
TBD2 ipv6ExtensionHeaderCount Section 3.2 of This-Document
TBD3 ipv6ExtensionHeadersFull Section 3.3 of This-Document
TBD4 ipv6ExtensionHeaderTypeCountList Section 3.4 of This-Document
TBD5 ipv6ExtensionHeadersLimit Section 3.5 of This-Document
TBD6 ipv6ExtensionHeadersChainLength Section 3.6 of This-Document
TBD7 ipv6ExtensionHeaderChainLengthList Section 3.7 of This-Document
TBD8 tcpOptionsFull Section 4.1 of This-Document
TBD9 tcpSharedOptionExID16 Section 4.2 of This-Document
TBD10 tcpSharedOptionExID32 Section 4.3 of This-Document
TBD11 tcpSharedOptionExID16List Section 4.4 of This-Document
TBD12 tcpSharedOptionExID32List Section 4.5 of This-Document

8.3. IPFIX Information Element Data Type

This document requests IANA to add the following new abstract data type to the "IPFIX Information Element Data Types" registry under the "IP Flow Information Export (IPFIX) Entities" registry group [IANA-IPFIX]:

Table 2: New IPFIX Information Element Data Type
Value Description Reference
TBD10 unsigned256 This-Document

8.3.1. unsigned256

The type "unsigned256" represents a non-negative integer value in the range of '0' to '2^256 - 1'. Similar to Section 6.1.1 of [RFC7011], this type MUST be encoded using the default canonical format in network byte order.

Reduced-Size encoding (Section 6.2 of [RFC7011]) applies to this data type. The reduction in size can be to any number of octets smaller than the unsigned256 type if the data value still fits, i.e., so that only leading zeroes are dropped.

8.4. IPFIX Subregistry for IPv6 Extension Headers

This document requests IANA to create a new registry entitled "ipv6ExtensionHeaders Bits" under the IANA IPFIX registry group [IANA-IPFIX].

When a new code is assigned to an IPv6 EH in [IANA-EH], the next available free bit is selected by IANA for this EH from "ipv6ExtensionHeaders Bits" registry and the registry is updated with the details that mirror the assigned EH. The "Label" mirrors the "keyword" of an EH as indicated in [IANA-Protocols], while the "Protocol Number" mirrors the "Protocol Number" in [IANA-EH]. IANA is requested to add the following note to [IANA-EH]:

  • Note:

    When a new code is assigned to an IPv6 Extension Header, the next available free bit in [NEW_IPFIX_IPv6EH_SUBREGISTRY] is selected for this new Extension Header. [NEW_IPFIX_IPv6EH_SUBREGISTRY] is updated accordingly. Modifications to existing registrations must be mirrored in [NEW_IPFIX_IPv6EH_SUBREGISTRY].

  • Note to the RFC Editor: Please replace [NEW_IPFIX_IPv6EH_SUBREGISTRY] with the link used by IANA for this new registry.

Otherwise, the registration policy for the registry is Expert Review (Section 4.5 of [RFC8126]). See more details in Section 8.4.2.

8.4.1. Initial Values

The initial values of this registry are provided in Table 3.

Table 3: Initial Values of the IPv6 Extension Headers IPFIX Subregistry
Bit Label Protocol Number Description Reference
0 DST 60 Destination Options for IPv6 This-Document
1 HOP 0 IPv6 Hop-by-Hop Options This-Document
2 NoNxt 59 No Next Header for IPv6 This-Document
3 UNK   Unknown extension or transport header This-Document
4 FRA0 44 Fragment header - first fragment This-Document
5 RH 43 Routing header This-Document
6 FRA1 44 Fragmentation header - not first fragment This-Document
7 MOB 135 Mobility Header This-Document
8 ESP 50 Encapsulating Security Payload This-Document
9 AH 51 Authentication Header This-Document
10 HIP 139 Host Identity Protocol This-Document
11 SHIM6 140 Shim6 Protocol This-Document
12   253 Use for experimentation and testing This-Document
13   254 Use for experimentation and testing This-Document
14 to 255     Unassigned  

8.4.2. Guidelines for the Designated Experts

It is suggested that multiple designated experts be appointed for registry change requests.

Designated experts are solicited only for changes that are not covered by the automatic mirroring described above. For example, a registration may request two bits for a new EH to cover specific behaviors or uses of that EH.

Criteria that should be applied by the designated experts include determining whether the proposed registration duplicates existing entries, whether the exception to the automatic mirroring procedure is justified, and whether the registration description is clear and fits the purpose of this registry.

Within the review period, the designated experts will either approve or deny the registration request, communicating this decision to the IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful.

9. References

9.1. Normative References

[IANA-EH]
IANA, "Internet Protocol Version 6 (IPv6) Parameters, IPv6 Extension Header Types", <https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#extension-header>.
[IANA-IPFIX]
IANA, "IP Flow Information Export (IPFIX) Entities", <https://www.iana.org/assignments/ipfix/ipfix.xhtml>.
[IANA-Protocols]
IANA, "Protocol Numbers", <https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml>.
[IANA-TCP]
IANA, "Transmission Control Protocol (TCP) Parameters, TCP Option Kind Numbers", <https://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml#tcp-parameters-1>.
[IANA-TCP-EXIDs]
IANA, "Transmission Control Protocol (TCP) Parameters, TCP Experimental Option Experiment Identifiers (TCP ExIDs)", <https://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml#tcp-exids>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[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, , <https://www.rfc-editor.org/rfc/rfc6313>.
[RFC6994]
Touch, J., "Shared Use of Experimental TCP Options", RFC 6994, DOI 10.17487/RFC6994, , <https://www.rfc-editor.org/rfc/rfc6994>.
[RFC7011]
Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, , <https://www.rfc-editor.org/rfc/rfc7011>.
[RFC7012]
Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, , <https://www.rfc-editor.org/rfc/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, , <https://www.rfc-editor.org/rfc/rfc8126>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8200]
Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, , <https://www.rfc-editor.org/rfc/rfc8200>.
[RFC9293]
Eddy, W., Ed., "Transmission Control Protocol (TCP)", STD 7, RFC 9293, DOI 10.17487/RFC9293, , <https://www.rfc-editor.org/rfc/rfc9293>.

9.2. Informative References

[I-D.ietf-6man-eh-limits]
Herbert, T., "Limits on Sending and Processing IPv6 Extension Headers", Work in Progress, Internet-Draft, draft-ietf-6man-eh-limits-13, , <https://datatracker.ietf.org/doc/html/draft-ietf-6man-eh-limits-13>.
[RFC7609]
Fox, M., Kassimis, C., and J. Stevens, "IBM's Shared Memory Communications over RDMA (SMC-R) Protocol", RFC 7609, DOI 10.17487/RFC7609, , <https://www.rfc-editor.org/rfc/rfc7609>.
[RFC7974]
Williams, B., Boucadair, M., and D. Wing, "An Experimental TCP Option for Host Identification", RFC 7974, DOI 10.17487/RFC7974, , <https://www.rfc-editor.org/rfc/rfc7974>.
[RFC8547]
Bittau, A., Giffin, D., Handley, M., Mazieres, D., and E. Smith, "TCP-ENO: Encryption Negotiation Option", RFC 8547, DOI 10.17487/RFC8547, , <https://www.rfc-editor.org/rfc/rfc8547>.
[RFC8883]
Herbert, T., "ICMPv6 Errors for Discarding Packets Due to Processing Limits", RFC 8883, DOI 10.17487/RFC8883, , <https://www.rfc-editor.org/rfc/rfc8883>.
[RFC9098]
Gont, F., Hilliard, N., Doering, G., Kumari, W., Huston, G., and W. Liu, "Operational Implications of IPv6 Packets with Extension Headers", RFC 9098, DOI 10.17487/RFC9098, , <https://www.rfc-editor.org/rfc/rfc9098>.

Acknowledgments

Thanks to Paul Aitken, Éric Vyncke, and Joe Touch for the reviews and comments. Special thanks to Andrew Feren for sharing data about scans of IPFIX data he collected.

Thanks to Wesley Eddy for the tsvart review, Yingzhen Qu for the opsdir review, Dirk Von Hugo for intdir review, Joel Halpern for the genart review, and Tero Kivinen for the secdir review.

Thanks to Thomas Graf for the Shepherd review.

Thanks to Mahesh Jethanandani for the AD review.

Thanks to Éric Vyncke for the IESG review.

Authors' Addresses

Mohamed Boucadair
Orange
Benoit Claise
Huawei