Internet DRAFT - draft-ietf-idr-flow-spec-v6
draft-ietf-idr-flow-spec-v6
IDR Working Group C. Loibl, Ed.
Internet-Draft next layer Telekom GmbH
Updates: I-D.ietf-idr-rfc5575bis (if R. Raszuk, Ed.
approved) Bloomberg LP
Intended status: Standards Track S. Hares, Ed.
Expires: June 17, 2021 Huawei
December 14, 2020
Dissemination of Flow Specification Rules for IPv6
draft-ietf-idr-flow-spec-v6-22
Abstract
Dissemination of Flow Specification Rules I-D.ietf-idr-rfc5575bis
provides a Border Gateway Protocol extension for the propagation of
traffic flow information for the purpose of rate limiting or
filtering IPv4 protocol data packets.
This document extends I-D.ietf-idr-rfc5575bis with IPv6
functionality. It also updates I-D.ietf-idr-rfc5575bis by changing
the IANA Flow Spec Component Types registry.
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 June 17, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Definitions of Terms Used in This Memo . . . . . . . . . 3
2. IPv6 Flow Specification encoding in BGP . . . . . . . . . . . 3
3. IPv6 Flow Specification components . . . . . . . . . . . . . 3
3.1. Type 1 - Destination IPv6 Prefix . . . . . . . . . . . . 4
3.2. Type 2 - Source IPv6 Prefix . . . . . . . . . . . . . . . 4
3.3. Type 3 - Upper-Layer Protocol . . . . . . . . . . . . . . 5
3.4. Type 7 - ICMPv6 Type . . . . . . . . . . . . . . . . . . 5
3.5. Type 8 - ICMPv6 Code . . . . . . . . . . . . . . . . . . 5
3.6. Type 12 - Fragment . . . . . . . . . . . . . . . . . . . 6
3.7. Type 13 - Flow Label (new) . . . . . . . . . . . . . . . 7
3.8. Encoding Example . . . . . . . . . . . . . . . . . . . . 7
4. Ordering of Flow Specifications . . . . . . . . . . . . . . . 9
5. Validation Procedure . . . . . . . . . . . . . . . . . . . . 10
6. IPv6 Traffic Filtering Action changes . . . . . . . . . . . . 10
6.1. Redirect IPv6 (rt-redirect-ipv6) Type TBD . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8.1. Flow Spec IPv6 Component Types . . . . . . . . . . . . . 11
8.1.1. Registry Template . . . . . . . . . . . . . . . . . . 11
8.1.2. Registry Contents . . . . . . . . . . . . . . . . . . 11
8.2. IPv6-Address-Specific Extended Community Flow Spec IPv6
Actions . . . . . . . . . . . . . . . . . . . . . . . . . 13
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
11.1. Normative References . . . . . . . . . . . . . . . . . . 14
11.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Appendix A. Example python code: flow_rule_cmp_v6 . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
The growing amount of IPv6 traffic in private and public networks
requires the extension of tools used in IPv4-only networks to also
support IPv6 data packets.
This document analyzes the differences between describing IPv6
[RFC8200] flows and those of IPv4 packets. It specifies new Border
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Gateway Protocol [RFC4271] encoding formats to enable Dissemination
of Flow Specification Rules [I-D.ietf-idr-rfc5575bis] for IPv6.
This specification is an extension of the base
[I-D.ietf-idr-rfc5575bis]. It only defines the delta changes
required to support IPv6 while all other definitions and operation
mechanisms of Dissemination of Flow Specification Rules will remain
in the main specification and will not be repeated here.
1.1. Definitions of Terms Used in This Memo
AFI - Address Family Identifier.
AS - Autonomous System.
NLRI - Network Layer Reachability Information.
SAFI - Subsequent Address Family Identifier.
VRF - Virtual Routing and Forwarding instance.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. IPv6 Flow Specification encoding in BGP
[I-D.ietf-idr-rfc5575bis] defines SAFIs 133 (Dissemination of Flow
Specification) and 134 (L3VPN Dissemination of Flow Specification) in
order to carry the corresponding Flow Specification.
Implementations wishing to exchange IPv6 Flow Specifications MUST use
BGP's Capability Advertisement facility to exchange the Multiprotocol
Extension Capability Code (Code 1) as defined in [RFC4760]. The
(AFI, SAFI) pair carried in the Multiprotocol Extension Capability
MUST be: (AFI=2, SAFI=133) for IPv6 Flow Specification, and (AFI=2,
SAFI=134) for VPNv6 Flow Specification.
3. IPv6 Flow Specification components
The encoding of each of the components begins with a type field (1
octet) followed by a variable length parameter. The following
sections define component types and parameter encodings for IPv6.
Types 4 (Port), 5 (Destination Port), 6 (Source Port), 9 (TCP flags),
10 (Packet length) and 11 (DSCP), as defined in
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[I-D.ietf-idr-rfc5575bis], also apply to IPv6. Note that IANA is
requested to update the "Flow Spec Component Types" registry in order
to contain both IPv4 and IPv6 Flow Specification component type
numbers in a single registry (Section 8).
3.1. Type 1 - Destination IPv6 Prefix
Encoding: <type (1 octet), length (1 octet), offset (1 octet),
pattern (variable), padding(variable) >
Defines the destination prefix to match. The offset has been defined
to allow for flexible matching to portions of an IPv6 address where
one is required to skip over the first N bits of the address (these
bits skipped are often indicated as "don't care" bits). This can be
especially useful where part of the IPv6 address consists of an
embedded IPv4 address and matching needs to happen only on the
embedded IPv4 address. The encoded pattern contains enough octets
for the bits used in matching (length minus offset bits).
length - The length field indicates the N-th most significant bit in
the address where bitwise pattern matching stops.
offset - The offset field indicates the number of most significant
address bits to skip before bitwise pattern matching starts.
pattern - Contains the matching pattern. The length of the pattern
is defined by the number of bits needed for pattern matching
(length minus offset).
padding - The minimum number of bits required to pad the component
to an octet boundary. Padding bits MUST be 0 on encoding and MUST
be ignored on decoding.
length = offset = 0 matches every address, otherwise length MUST be
in the range offset < length < 129 or the component is malformed.
Note: This Flow Specification component can be represented by the
notation ipv6address/length if offset is 0, or ipv6address/offset-
length. The ipv6address in this notation is the textual IPv6
representation of the pattern shifted to the right by the number of
offset bits. See also Section 3.8.
3.2. Type 2 - Source IPv6 Prefix
Encoding: <type (1 octet), length (1 octet), offset (1 octet),
pattern (variable), padding(variable) >
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Defines the source prefix to match. The length, offset, pattern and
padding are the same as in Section 3.1.
3.3. Type 3 - Upper-Layer Protocol
Encoding: <type (1 octet), [numeric_op, value]+>
Contains a list of {numeric_op, value} pairs that are used to match
the first Next Header value octet in IPv6 packets that is not an
extension header and thus indicates that the next item in the packet
is the corresponding upper-layer header (see [RFC8200] Section 4).
This component uses the Numeric Operator (numeric_op) described in
[I-D.ietf-idr-rfc5575bis] Section 4.2.1.1. Type 3 component values
SHOULD be encoded as single octet (numeric_op len=00).
Note: While IPv6 allows for more than one Next Header field in the
packet, the main goal of the Type 3 Flow Specification component is
to match on the first upper-layer IP protocol value. Therefore the
definition is limited to match only on this specific Next Header
field in the packet.
3.4. Type 7 - ICMPv6 Type
Encoding: <type (1 octet), [numeric_op, value]+>
Defines a list of {numeric_op, value} pairs used to match the type
field of an ICMPv6 packet (see also [RFC4443] Section 2.1).
This component uses the Numeric Operator (numeric_op) described in
[I-D.ietf-idr-rfc5575bis] Section 4.2.1.1. Type 7 component values
SHOULD be encoded as single octet (numeric_op len=00).
In case of the presence of the ICMPv6 Type component only ICMPv6
packets can match the entire Flow Specification. The ICMPv6 Type
component, if present, never matches when the packet's upper-layer IP
protocol value is not 58 (ICMPv6), if the packet is fragmented and
this is not the first fragment, or if the system is unable to locate
the transport header. Different implementations may or may not be
able to decode the transport header.
3.5. Type 8 - ICMPv6 Code
Encoding: <type (1 octet), [numeric_op, value]+>
Defines a list of {numeric_op, value} pairs used to match the code
field of an ICMPv6 packet (see also [RFC4443] Section 2.1).
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This component uses the Numeric Operator (numeric_op) described in
[I-D.ietf-idr-rfc5575bis] Section 4.2.1.1. Type 8 component values
SHOULD be encoded as single octet (numeric_op len=00).
In case of the presence of the ICMPv6 Code component only ICMPv6
packets can match the entire Flow Specification. The ICMPv6 code
component, if present, never matches when the packet's upper-layer IP
protocol value is not 58 (ICMPv6), if the packet is fragmented and
this is not the first fragment, or if the system is unable to locate
the transport header. Different implementations may or may not be
able to decode the transport header.
3.6. Type 12 - Fragment
Encoding: <type (1 octet), [bitmask_op, bitmask]+>
Defines a list of {bitmask_op, bitmask} pairs used to match specific
IP fragments.
This component uses the Bitmask Operator (bitmask_op) described in
[I-D.ietf-idr-rfc5575bis] Section 4.2.1.2. The Type 12 component
bitmask MUST be encoded as single octet bitmask (bitmask_op len=00).
0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| 0 | 0 | 0 | 0 |LF |FF |IsF| 0 |
+---+---+---+---+---+---+---+---+
Figure 1: Fragment Bitmask Operand
Bitmask values:
IsF - Is a fragment other than the first - match if IPv6 Fragment
Header ([RFC8200] Section 4.5) Fragment Offset is not 0
FF - First fragment - match if IPv6 Fragment Header ([RFC8200]
Section 4.5) Fragment Offset is 0 AND M flag is 1
LF - Last fragment - match if IPv6 Fragment Header ([RFC8200]
Section 4.5) Fragment Offset is not 0 AND M flag is 0
0 - MUST be set to 0 on NLRI encoding, and MUST be ignored during
decoding
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3.7. Type 13 - Flow Label (new)
Encoding: <type (1 octet), [numeric_op, value]+>
Contains a list of {numeric_op, value} pairs that are used to match
the 20-bit Flow Label IPv6 header field ([RFC8200] Section 3).
This component uses the Numeric Operator (numeric_op) described in
[I-D.ietf-idr-rfc5575bis] Section 4.2.1.1. Type 13 component values
SHOULD be encoded as 4-octet quantities (numeric_op len=10).
3.8. Encoding Example
3.8.1. Example 1
The following example demonstrates the prefix encoding for: "packets
from ::1234:5678:9a00:0/64-104 to 2001:db8::/32 and upper-layer-
protocol tcp".
+--------+----------------------+-------------------------+----------+
| length | destination | source | ul-proto |
+--------+----------------------+-------------------------+----------+
| 0x12 | 01 20 00 20 01 0D B8 | 02 68 40 12 34 56 78 9A | 03 81 06 |
+--------+----------------------+-------------------------+----------+
Decoded:
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+-------+------------+-------------------------------+
| Value | | |
+-------+------------+-------------------------------+
| 0x12 | length | 18 octets (len<240 1-octet) |
| 0x01 | type | Type 1 - Dest. IPv6 Prefix |
| 0x20 | length | 32 bit |
| 0x00 | offset | 0 bit |
| 0x20 | pattern | |
| 0x01 | pattern | |
| 0x0D | pattern | |
| 0xB8 | pattern | (no padding needed) |
| 0x02 | type | Type 2 - Source IPv6 Prefix |
| 0x68 | length | 104 bit |
| 0x40 | offset | 64 bit |
| 0x12 | pattern | |
| 0x34 | pattern | |
| 0x56 | pattern | |
| 0x78 | pattern | |
| 0x9A | pattern | (no padding needed) |
| 0x03 | type | Type 3 - upper-layer-proto |
| 0x81 | numeric_op | end-of-list, value size=1, == |
| 0x06 | value | 06 |
+-------+------------+-------------------------------+
This constitutes a NLRI with a NLRI length of 18 octets.
Padding is not needed either for the destination prefix pattern
(length - offset = 32 bit) or for the source prefix pattern (length -
offset = 40 bit), as both patterns end on an octet boundary.
3.8.2. Example 2
The following example demonstrates the prefix encoding for: "all
packets from ::1234:5678:9a00:0/65-104 to 2001:db8::/32".
+--------+----------------------+-------------------------+
| length | destination | source |
+--------+----------------------+-------------------------+
| 0x0f | 01 20 00 20 01 0D B8 | 02 68 41 24 68 ac f1 34 |
+--------+----------------------+-------------------------+
Decoded:
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+-------+-------------+-------------------------------+
| Value | | |
+-------+-------------+-------------------------------+
| 0x0f | length | 15 octets (len<240 1-octet) |
| 0x01 | type | Type 1 - Dest. IPv6 Prefix |
| 0x20 | length | 32 bit |
| 0x00 | offset | 0 bit |
| 0x20 | pattern | |
| 0x01 | pattern | |
| 0x0D | pattern | |
| 0xB8 | pattern | (no padding needed) |
| 0x02 | type | Type 2 - Source IPv6 Prefix |
| 0x68 | length | 104 bit |
| 0x41 | offset | 65 bit |
| 0x24 | pattern | |
| 0x68 | pattern | |
| 0xac | pattern | |
| 0xf1 | pattern | |
| 0x34 | pattern/pad | (contains 1 bit padding) |
+-------+-------------+-------------------------------+
This constitutes a NLRI with a NLRI length of 15 octets.
The source prefix pattern is 104 - 65 = 39 bits in length. After the
pattern one bit of padding needs to be added so that the component
ends on a octet boundary. However, only the first 39 bits are
actually used for bitwise pattern matching starting with a 65 bit
offset from the topmost bit of the address.
4. Ordering of Flow Specifications
The definition for the order of traffic filtering rules from
[I-D.ietf-idr-rfc5575bis] Section 5.1 is reused with new
consideration for the IPv6 prefix offset. As long as the offsets are
equal, the comparison is the same, retaining longest-prefix-match
semantics. If the offsets are not equal, the lowest offset has
precedence, as this Flow Specification matches the most significant
bit.
The code in Appendix A shows a Python3 implementation of the
resulting comparison algorithm. The full code was tested with Python
3.7.2 and can be obtained at https://github.com/stoffi92/draft-ietf-
idr-flow-spec-v6/tree/master/flowspec-cmp [1].
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5. Validation Procedure
The validation procedure is the same as specified in
[I-D.ietf-idr-rfc5575bis] Section 6 with the exception that item a)
of the validation procedure should now read as follows:
a) A destination prefix component with offset=0 is embedded in the
Flow Specification
6. IPv6 Traffic Filtering Action changes
Traffic Filtering Actions from [I-D.ietf-idr-rfc5575bis] Section 7
can also be applied to IPv6 Flow Specifications. To allow an IPv6-
Address-Specific Route-Target, a new Traffic Filtering Action IPv6-
Address-Specific Extended Community [RFC5701] is specified in
Section 6.1 below.
6.1. Redirect IPv6 (rt-redirect-ipv6) Type TBD
The redirect IPv6-Address-Specific Extended Community allows the
traffic to be redirected to a VRF routing instance that lists the
specified IPv6-Address-Specific Route-Target in its import policy.
If several local instances match this criteria, the choice between
them is a local matter (for example, the instance with the lowest
Route Distinguisher value can be elected).
This IPv6-Address-Specific Extended Community uses the same encoding
as the IPv6-Address-Specific Route-Target Extended Community
[RFC5701] Section 2 with the Type value always TBD.
The Local Administrator sub-field contains a number from a numbering
space that is administered by the organization to which the IP
address carried in the Global Administrator sub-field has been
assigned by an appropriate authority.
Interferes with: All BGP Flow Specification redirect Traffic
Filtering Actions (with itself and those specified in
[I-D.ietf-idr-rfc5575bis] Section 7.4).
7. Security Considerations
This document extends the functionality in [I-D.ietf-idr-rfc5575bis]
to be applicable to IPv6 data packets. The same Security
Considerations from [I-D.ietf-idr-rfc5575bis] now also apply to IPv6
networks.
[RFC7112] describes the impact of oversized IPv6 header chains when
trying to match on the transport header; [RFC8200] Section 4.5 also
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requires that the first fragment must include the upper-layer header
but there could be wrongly formatted packets not respecting
[RFC8200]. IPv6 Flow Specification component type 3 (Section 3.3)
will not be enforced for those illegal packets. Moreover, there are
hardware limitations in several routers ([RFC8883] Section 1) that
may make it impossible to enforce a policy signaled by a type 3 Flow
Specification component or Flow Specification components that match
on upper-layer properties of the packet.
8. IANA Considerations
This section complies with [RFC7153].
8.1. Flow Spec IPv6 Component Types
IANA has created and maintains a registry entitled "Flow Spec
Component Types". IANA is requested to add [this document] to the
reference for this registry. Furthermore the registry should be
rewritten to also contain the IPv6 Flow Specification Component Types
as described below. The registration procedure should remain
unchanged.
8.1.1. Registry Template
Type Value:
Contains the assigned Flow Specification component type value.
IPv4 Name:
Contains the associated IPv4 Flow Specification component name
as specified in [I-D.ietf-idr-rfc5575bis].
IPv6 Name:
Contains the associated IPv6 Flow Specification component name
as specified in this document.
Reference:
Contains referenced to the specifications.
8.1.2. Registry Contents
+ Type Value: 0
+ IPv4 Name: Reserved
+ IPv6 Name: Reserved
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 1
+ IPv4 Name: Destination Prefix
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+ IPv6 Name: Destination IPv6 Prefix
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 2
+ IPv4 Name: Source Prefix
+ IPv6 Name: Source IPv6 Prefix
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 3
+ IPv4 Name: IP Protocol
+ IPv6 Name: Upper-Layer Protocol
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 4
+ IPv4 Name: Port
+ IPv6 Name: Port
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 5
+ IPv4 Name: Destination Port
+ IPv6 Name: Destination Port
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 6
+ IPv4 Name: Source Port
+ IPv6 Name: Source Port
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 7
+ IPv4 Name: ICMP Type
+ IPv6 Name: ICMPv6 Type
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 8
+ IPv4 Name: ICMP Code
+ IPv6 Name: ICMPv6 Code
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 9
+ IPv4 Name: TCP Flags
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+ IPv6 Name: TCP Flags
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 10
+ IPv4 Name: Packet Length
+ IPv6 Name: Packet Length
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 11
+ IPv4 Name: DSCP
+ IPv6 Name: DSCP
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 12
+ IPv4 Name: Fragment
+ IPv6 Name: Fragment
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
+ Type Value: 13
+ IPv4 Name: Unassigned
+ IPv6 Name: Flow Label
+ Reference: [this document]
+ Type Value: 14-254
+ IPv4 Name: Unassigned
+ IPv6 Name: Unassigned
+ Reference:
+ Type Value: 255
+ IPv4 Name: Reserved
+ IPv6 Name: Reserved
+ Reference: [I-D.ietf-idr-rfc5575bis] [this document]
8.2. IPv6-Address-Specific Extended Community Flow Spec IPv6 Actions
IANA maintains a registry entitled "Transitive IPv6-Address-Specific
Extended Community Types". For the purpose of this work, IANA is
requested to assign a new value:
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+------------+-----------------------------------+-----------------+
| Type Value | Name | Reference |
+------------+-----------------------------------+-----------------+
| TBD | Flow spec rt-redirect-ipv6 format | [this document] |
+------------+-----------------------------------+-----------------+
Table 1: Registry: Transitive IPv6-Address-Specific Extended
Community Types
9. Acknowledgements
Authors would like to thank Pedro Marques, Hannes Gredler, Bruno
Rijsman, Brian Carpenter, and Thomas Mangin for their valuable input.
10. Contributors
Danny McPherson
Verisign, Inc.
Email: dmcpherson@verisign.com
Burjiz Pithawala
Individual
Email: burjizp@gmail.com
Andy Karch
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
USA
Email: akarch@cisco.com
11. References
11.1. Normative References
[I-D.ietf-idr-rfc5575bis]
Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
draft-ietf-idr-rfc5575bis-27 (work in progress), October
2020.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC5701] Rekhter, Y., "IPv6 Address Specific BGP Extended Community
Attribute", RFC 5701, DOI 10.17487/RFC5701, November 2009,
<https://www.rfc-editor.org/info/rfc5701>.
[RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of
Oversized IPv6 Header Chains", RFC 7112,
DOI 10.17487/RFC7112, January 2014,
<https://www.rfc-editor.org/info/rfc7112>.
[RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP
Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
March 2014, <https://www.rfc-editor.org/info/rfc7153>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8883] Herbert, T., "ICMPv6 Errors for Discarding Packets Due to
Processing Limits", RFC 8883, DOI 10.17487/RFC8883,
September 2020, <https://www.rfc-editor.org/info/rfc8883>.
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Internet-Draft IPv6 Flow Specification December 2020
11.2. URIs
[1] https://github.com/stoffi92/draft-ietf-idr-flow-spec-
v6/tree/master/flowspec-cmp
Appendix A. Example python code: flow_rule_cmp_v6
<CODE BEGINS>
"""
Copyright (c) 2020 IETF Trust and the persons identified as authors
of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, is permitted pursuant to, and subject to the license
terms contained in, the Simplified BSD License set forth in Section
4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info).
"""
import itertools
import collections
import ipaddress
EQUAL = 0
A_HAS_PRECEDENCE = 1
B_HAS_PRECEDENCE = 2
IP_DESTINATION = 1
IP_SOURCE = 2
FS_component = collections.namedtuple('FS_component',
'component_type value')
class FS_IPv6_prefix_component:
def __init__(self, prefix, offset=0,
component_type=IP_DESTINATION):
self.offset = offset
self.component_type = component_type
# make sure if offset != 0 that none of the
# first offset bits are set in the prefix
self.value = prefix
if offset != 0:
i = ipaddress.IPv6Interface(
(self.value.network_address, offset))
if i.network.network_address != \
ipaddress.ip_address('0::0'):
raise ValueError('Bits set in the offset')
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class FS_nlri(object):
"""
FS_nlri class implementation that allows sorting.
By calling .sort() on an array of FS_nlri objects these
will be sorted according to the flow_rule_cmp algorithm.
Example:
nlri = [ FS_nlri(components=[
FS_component(component_type=4,
value=bytearray([0,1,2,3,4,5,6])),
]),
FS_nlri(components=[
FS_component(component_type=5,
value=bytearray([0,1,2,3,4,5,6])),
FS_component(component_type=6,
value=bytearray([0,1,2,3,4,5,6])),
]),
]
nlri.sort() # sorts the array according to the algorithm
"""
def __init__(self, components = None):
"""
components: list of type FS_component
"""
self.components = components
def __lt__(self, other):
# use the below algorithm for sorting
result = flow_rule_cmp_v6(self, other)
if result == B_HAS_PRECEDENCE:
return True
else:
return False
def flow_rule_cmp_v6(a, b):
"""
Implementation of the flowspec sorting algorithm in
draft-ietf-idr-flow-spec-v6.
"""
for comp_a, comp_b in itertools.zip_longest(a.components,
b.components):
# If a component type does not exist in one rule
# this rule has lower precedence
if not comp_a:
return B_HAS_PRECEDENCE
if not comp_b:
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return A_HAS_PRECEDENCE
# Higher precedence for lower component type
if comp_a.component_type < comp_b.component_type:
return A_HAS_PRECEDENCE
if comp_a.component_type > comp_b.component_type:
return B_HAS_PRECEDENCE
# component types are equal -> type specific comparison
if comp_a.component_type in (IP_DESTINATION, IP_SOURCE):
if comp_a.offset < comp_b.offset:
return A_HAS_PRECEDENCE
if comp_a.offset > comp_b.offset:
return B_HAS_PRECEDENCE
# both components have the same offset
# assuming comp_a.value, comp_b.value of type
# ipaddress.IPv6Network
# and the offset bits are reset to 0 (since they are
# not represented in the NLRI)
if comp_a.value.overlaps(comp_b.value):
# longest prefixlen has precedence
if comp_a.value.prefixlen > \
comp_b.value.prefixlen:
return A_HAS_PRECEDENCE
if comp_a.value.prefixlen < \
comp_b.value.prefixlen:
return B_HAS_PRECEDENCE
# components equal -> continue with next
# component
elif comp_a.value > comp_b.value:
return B_HAS_PRECEDENCE
elif comp_a.value < comp_b.value:
return A_HAS_PRECEDENCE
else:
# assuming comp_a.value, comp_b.value of type
# bytearray
if len(comp_a.value) == len(comp_b.value):
if comp_a.value > comp_b.value:
return B_HAS_PRECEDENCE
if comp_a.value < comp_b.value:
return A_HAS_PRECEDENCE
# components equal -> continue with next
# component
else:
common = min(len(comp_a.value),
len(comp_b.value))
if comp_a.value[:common] > \
comp_b.value[:common]:
return B_HAS_PRECEDENCE
elif comp_a.value[:common] < \
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comp_b.value[:common]:
return A_HAS_PRECEDENCE
# the first common bytes match
elif len(comp_a.value) > len(comp_b.value):
return A_HAS_PRECEDENCE
else:
return B_HAS_PRECEDENCE
return EQUAL
<CODE ENDS>
Authors' Addresses
Christoph Loibl (editor)
next layer Telekom GmbH
Mariahilfer Guertel 37/7
Vienna 1150
AT
Phone: +43 664 1176414
Email: cl@tix.at
Robert Raszuk (editor)
Bloomberg LP
731 Lexington Ave
New York City, NY 10022
USA
Email: robert@raszuk.net
Susan Hares (editor)
Huawei
7453 Hickory Hill
Saline, MI 48176
USA
Email: shares@ndzh.com
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