BGP Flow Specification Version 2 - for Basic IP
draft-hares-idr-fsv2-ip-basic-01
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Susan Hares , Donald E. Eastlake 3rd , Chaitanya Yadlapalli , Sven Maduschke | ||
| Last updated | 2024-04-28 | ||
| Replaces | draft-hares-idr-flowspec-v2-ddos | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
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| Send notices to | (None) |
draft-hares-idr-fsv2-ip-basic-01
IDR Working Group S. Hares
Internet-Draft Hickory Hill Consulting
Intended status: Standards Track D. Eastlake
Expires: 30 October 2024 Futurewei Technologies
C. Yadlapalli
ATT
S. Maduscke
Verizon
28 April 2024
BGP Flow Specification Version 2 - for Basic IP
draft-hares-idr-fsv2-ip-basic-01
Abstract
BGP flow specification version 1 (FSv1), defined in RFC 8955, RFC
8956, and RFC 9117 describes the distribution of traffic filter
policy (traffic filters and actions) distributed via BGP. During the
deployment of BGP FSv1 a number of issues were detected, so version 2
of the BGP flow specification (FSv2) protocol addresses these
features. In order to provide a clear demarcation between FSv1 and
FSv2, a different NLRI encapsulates FSv2.
The IDR WG requires two implementation Implementers feedback on FSv2
was that FSv2 has a correct design, but that breaking FSv2 into a
progression of documents would aid deployment of the draft. The IDR
WG requires two implementation so This document is the first of the
series of documents indicating the basic FSv2 with user ordering of
filters added to FSv1 IP Filters and IP actions.
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
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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 30 October 2024.
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Copyright Notice
Copyright (c) 2024 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Why Flow Specification v2 . . . . . . . . . . . . . . . . 4
1.2. Definitions and Acronyms . . . . . . . . . . . . . . . . 5
1.3. RFC 2119 language . . . . . . . . . . . . . . . . . . . . 6
2. Flow Specification Version 2 Primer . . . . . . . . . . . . . 6
2.1. Flow Specification v1 (FSv1) Overview . . . . . . . . . . 7
2.2. FSv2 Overview . . . . . . . . . . . . . . . . . . . . . . 9
2.3. Flow Specification v2 (FSv2) Series of Specifications . . 12
3. FSv2 NLRI Formats and Actions . . . . . . . . . . . . . . . . 14
3.1. FSv2 NLRI Format . . . . . . . . . . . . . . . . . . . . 14
3.2. Basic IP Filters . . . . . . . . . . . . . . . . . . . . 16
3.2.1. IP header SubTLV (type=1(0x01)) . . . . . . . . . . . 16
3.2.2. Components for FSv2 supporting IP Basic FSV2 . . . . 19
3.3. FSv2 Actions for IP Basic . . . . . . . . . . . . . . . . 25
3.3.1. FSv2 Extended Community Actions inherited from
FSv1 . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3.2. Default Ordering for FSv2 Extended Community
Actions . . . . . . . . . . . . . . . . . . . . . . . 30
3.3.3. Action Chain Ordering FSv2 Extended Community (ACO
FSv2-EC) . . . . . . . . . . . . . . . . . . . . . . 31
4. Validation and Ordering of NLRI . . . . . . . . . . . . . . . 36
4.1. Validation of FSv2 NLRI . . . . . . . . . . . . . . . . . 37
4.1.1. Validation of FS NLRI (FSv1 or FSv2) . . . . . . . . 37
4.1.2. Validation of Flow Specification Actions . . . . . . 39
4.1.3. Error handling and Validation . . . . . . . . . . . . 40
4.2. Ordering for Flow Specification v2 (FSv2) . . . . . . . . 40
4.2.1. Ordering of FSv2 NLRI Filters . . . . . . . . . . . . 40
4.2.2. Ordering of the Actions . . . . . . . . . . . . . . . 42
4.3. Ordering of FS filters for BGP Peers support FSv1 and
FSv2 . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5. Scalability and Aspirations for FSv2 . . . . . . . . . . . . 47
6. Optional Security Additions . . . . . . . . . . . . . . . . . 48
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6.1. BGP FSv2 and BGPSEC . . . . . . . . . . . . . . . . . . . 48
6.2. BGP FSv2 with ROA . . . . . . . . . . . . . . . . . . . . 49
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49
7.1. Flow Specification V2 SAFIs . . . . . . . . . . . . . . . 49
7.2. BGP Capability Code . . . . . . . . . . . . . . . . . . . 50
7.3. Filter IP Component types . . . . . . . . . . . . . . . . 50
7.4. FSV2 NLRI TLV Types . . . . . . . . . . . . . . . . . . . 51
7.5. Community Container Type Assignments . . . . . . . . . . 52
8. Security Considerations . . . . . . . . . . . . . . . . . . . 52
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.1. Normative References . . . . . . . . . . . . . . . . . . 53
9.2. Informative References . . . . . . . . . . . . . . . . . 56
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 57
1. Introduction
Version 2 of BGP flow specification was original defined in
[I-D.ietf-idr-flowspec-v2] (BGP FSv2). In this document it will be
refered to as FSv2.
The FSv2 specification was consider technically correct, but it
contains more than the initial implementers desired. Why? The IDR
WG requires two implementations of any specification. Therefore, the
original FSv2 draft will remain a WG draft, but the content will be
split out into functions that implementers can incrementally deploy.
This draft provides the FSv2 specification for transmitting user-
ordered Basic IP filters with FSv2 actions in set of Extended
Communities. These extended communities have either the pre-defined
set of ordering and interactions, or a implementation specific set
ordering. FSv2 filters and actions are defined in setion 3.
FSv2 is an update to BGP Flow specification version 1 (BGP FSv1).
BGP FSv1 as defined in [RFC8955], [RFC8956], and [RFC9117] specified
2 SAFIs (133, 134) to be used with IPv4 AFI (AFI = 1) and IPv6 AFI
(AFI=2). In this document it will be refered to as FS
This document specifies 2 new SAFIs (TBD1, TBD2) for FSv2 to be used
with 5 AFIs (1, 2, 6, 25, and 31) to allow user-ordered lists of
traffic match filters for user-ordered traffic match actions encoded
in Communities (Wide or Extended).
FSv1 and FSv2 use different AFI/SAFIs to send flow specification
filters. Since BGP route selection is performed per AFI/SAFI, this
approach can be termed “ships in the night” based on AFI/SAFI.
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1.1. Why Flow Specification v2
Modern IP routers have the capability to forward traffic and to
classify, shape, rate limit, filter, or redirect packets based on
administratively defined policies. These traffic policy mechanisms
allow the operator to define match rules that operate on multiple
fields within header of an IP data packet. The traffic policy allows
actions to be taken upon a match to be associated with each match
rule. These rules can be more widely defined as “event-condition-
action” (ECA) rules where the event is always the reception of a
packet.
BGP ([RFC4271]) flow specification as defined by [RFC8955],
[RFC8956], [RFC9117] specifies the distribution of traffic filter
policy (traffic filters and actions) via BGP to a mesh of BGP peers
(IBGP and EBGP peers). The traffic filter policy is applied when
packets are received on a router with the flow specification function
turned on. The flow specification protocol defined in [RFC8955],
[RFC8956], and [RFC9117] will be called BGP flow specification
version 1 (BGP FSv1) in this draft.
Some modern IP routers also include the abilities of firewalls which
can match on a sequence of packet events based on administrative
policy. These firewall capabilities allow for user ordering of match
rules and user ordering of actions per match.
Multiple deployed applications currently use BGP FSv1 to distribute
traffic filter policy. These applications include: 1) mitigation of
Denial of Service (DoS), 2) traffic filtering in BGP/MPLS VPNS, and
3) centralized traffic control for networks utilizing SDN control of
router firewall functions, 4) classifiers for insertion in an SFC,
and 5) filters for SRv6 (segment routing v6).
During the deployment of BGP flow specification v1, the following
issues were detected:
* lack of consistent TLV encoding prevented extension of encodings,
* inability to allow user defined order for filtering rules,
* inability to order actions to provide deterministic interactions
or to allow users to define order for actions, and
* no clearly defined mechanisms for BGP peers which do not support
flow specification v1.
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Networks currently cope with some of these issues by limiting the
type of traffic filter policy sent in BGP. Current Networks do not
have a good workaround/solution for applications that receive but do
not understand FSv1 policies.
FSv1 is a critical component of deployed applications. Therefore,
this specification defines how FSv2 will interact with BGP peers that
support either FSv2, FSv1, FSv2 and FSv1,or neither of them. It is
expected that a transition to FSv2 will occur over time as new
applications require FSv2 extensibility and user-defined ordering for
rules and actions or network operators tire of the restrictions of
FSv1 such as error handling issues and restricted topologies.
Section 2 contains a Primer on FSv1, FSv2, and the FSv2 seriess of
specifications. Section 3 contains the encoding rules for FSv2 and
user-based encoding sent via BGP. Section 4 describes how to
validate and order FSv2 NLRI. Sections 5-8 discusses scalability,
optional security additions, security considerations, and IANA
considerations.
1.2. Definitions and Acronyms
AFI - Address Family Identifier
AS - Autonomous System
BGPSEC - secure BGP [RFC8205] updated by [RFC8206]
BGP Session ephemeral state - state which does not survive the
loss of BGP peer session.
Configuration state - state which persist across a reboot of
software module within a routing system or a reboot of a hardware
routing device.
DDOs - Distributed Denial of Service.
Ephemeral state - state which does not survive the reboot of a
software module, or a hardware reboot. Ephemeral state can be
ephemeral configuration state or operational state.
FSv1 - Flow Specification version 1 [RFC8955] [RFC8956]
FSv2 - Flow Specification version 2 (this document)
NETCONF - The Network Configuration Protocol [RFC6241].
RESTCONF - The RESTCONF configuration Protocol [RFC8040]
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RIB - Routing Information Base.
ROA - Route Origin Authentication [RFC6482]
RR - Route Reflector.
SAFI – Subsequent Address Family Identifier
1.3. RFC 2119 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 BCP 14 [RFC2119]
[RFC8174] when, and only when, they appear in all capitals as shown
here.
2. Flow Specification Version 2 Primer
A BGP Flow Specification (v1 or v2) is an n-tuple containing one or
more match criteria that can be applied to IP traffic, traffic
encapsulated in IP traffic or traffic associated with IP traffic.
The following are examples of such traffic: IP packet or an IP packet
inside a L2 packet (Ethernet), an MPLS packet, and SFC flow.
A given Flow Specification NLRI may be associated with a set of path
attributes depending on the particular application, and attributes
within that set may or may not include reachability information
(e.g., NEXT_HOP). FSv1 and FSv2-DDOS use only the Extended Community
to encode a set of pre-determined actions. The full FSv2 uses either
Extended Communities or Wide Communities to encode actions.
A particular application is identified by a specific AFI/SAFI
(Address Family Identifier/Subsequent Address Family Identifier) and
corresponds to a distinct set of RIBs. Those RIBs should be treated
independently of each other in order to assure noninterference
between distinct applications.
BGP processing treats the NLRI as a key to entries in AFI/SAFI BGP
databases. Entries that are placed in the Loc-RIB are then
associated with a given set of semantics which are application
dependent. Standard BGP mechanisms such as update filtering by NLRI
or by attributes such as AS_PATH or large communities apply to the
BGP Flow Specification defined NLRI-types.
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Network operators can control the propagation of BGP routes by
enabling or disabling the exchange of routes for a particular AFI/
SAFI pair on a particular peering session. As such, the Flow
Specification may be distributed to only a portion of the BGP
infrastructure.
2.1. Flow Specification v1 (FSv1) Overview
The FSv1 NLRI defined in [RFC8955] and [RFC8956] include 13 match
conditions encoded for the following AFI/SAFIs:
* IPv4 traffic: AFI:1, SAFI:133
* IPv6 Traffic: AFI:2, SAFI:133
* BGP/MPLS IPv4 VPN: AFI:1, SAFI: 134
* BGP/MPLS IPv6 VPN: AFI:2, SAFI: 134
If one considers the reception of the packet as an event, then BGP
FSv1 describes a set of Event-MatchCondition-Action (ECA) policies
where:
* event is the reception of a packet,
* condition stands for “match conditions” defined in the BGP NLRI as
an n-tuple of component filters, and
* the action is either: the default condition (accept traffic), or a
set of actions (1 or more) defined in Extended BGP Community
values [RFC4360].
The flow specification conditions and actions combine to make up FSv1
specification rules. Each FSv1 NLRI must have a type 1 component
(destination prefix). Extended Communities with FSv1 actions can be
attached to a single NLRI or multiple NLRIs in a BGP message
Within an AFI/SAFI pair, FSv1 rules are ordered based on the
components in the packet (types 1-13) ordered from left-most to
right-most and within the component types by value of the component.
Rules are inserted in the rule list by component-based order where an
FSv1 rule with existing component type has higher precedence than one
missing a specific component type,
Since FSv1 specifications ([RFC8955], [RFC8956], and [RFC9117])
specify that the FSv1 NLRI MUST have a destination prefix (as
component type 1) embedded in the flow specification, the FSv1 rules
with destination components are ordered by IP Prefix comparison rules
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for IPv4 ([RFC8955]) and IPv6 ([RFC8956]). [RFC8955] specifies that
more specific prefixes (aka longest match) have higher precedence
than that of less specific prefixes and that for prefixes of the same
length the lower IP number is selected (lowest IP value). [RFC8955]
specifies that if the offsets within component 1 are the same, then
the longest match and lowest IP comparison rules from [RFC8955]
apply. If the offsets are different, then the lower offset has
precedence.
These rules provide a set of FSv1 rules ordered by IP Destination
Prefix by longest match and lowest IP address. [RFC8955] also states
that the requirement for a destination prefix component “MAY be
relaxed by explicit configuration” Since the rule insertions are
based on comparing component types between two rules in order, this
means the rules without destination prefixes are inserted after all
rules which contain destination prefix component.
The actions specified in FSv1 are:
* accept packet (default),
* traffic flow limitation by bytes (0x6),
* traffic-action (0x7),
* redirect traffic (0x8),
* mark traffic (0x9), and
* traffic flow limitation by packets (12, 0xC)
Figure 1 shows a diagram of the FSv1 logical data structures with 5
rules. If FSv1 rules have destination prefix components (type=1) and
FSv1 rule 5 does not have a destination prefix, then FSv1 rule 5 will
be inserted in the policy after rules 1-4.
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+--------------------------------------+
| Flow Specification (FS) |
| Policy |
+--------------------------------------+
^ ^ ^
| | |
| | |
+--------^----+ +-------^-------+ +-------------+
| FS Rule 1 | | FS Rule 2 | ... | FS rule 5 |
+-------------+ +---------------+ +-------------+
: :
: :
...: :........
: :
+---------V---------+ +----V-------------+
| Rule Condition | | Rule Action |
| in BGP NLRIs | | in BGP extended |
| AFIs: 1 and 2 | | Communities |
| SAFI 133, 134 | | |
+-------------------+ +------------------+
: : : : : :
.....: . :..... .....: . :.....
: : : : : :
+----V---+ +---V----+ +--V---+ +-V------+ +--V-----++--V---+
| Match | | match | |match | | Action | | action ||action|
|Operator| |Variable| |Value | |Operator| |variable|| Value|
|*1 | | | | | |(subtype| | || |
+--------+ +--------+ +------+ +--------+ +--------++------+
*1 match operator may be complex.
Figure 2-1: BGP Flow Specification v1 Policy
2.2. FSv2 Overview
FSv2 allows the user to order the flow specification rules and the
actions associated with a rule. Each FSv2 rule may have one or more
match conditions and one or more associated actions. The IDR WG
draft [I-D.ietf-idr-flowspec-v2] contains the complete solution for
FSv2. However, this complete solution makes implementation of these
features a large task so, please see the next section on how the
complete solution is broken into a series of solutions. This section
describres the complete solution.
The original FSv2 specification [I-D.ietf-idr-flowspec-v2] supports
the components and actions for the following:
* IPv4 (AFI=1, SAFI=TBD1) [defined in FSv2-DDOS],
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* IPv6 (AFI=2, SAFI=TBD2) [defined in FSv2-DDOS],
* L2 (AFI=6, SAFI=TDB1) [defined in FSv2-L2],
* BGP/MPLS IPv4 VPN: (AFI=1, SAFI=TBD2),
* BGP/MPLS IPv6 VPN: (AFI=2, SAFI=TBD2),
* BGP/MPLS L2VPN (AFI=25, SAFI=TDB2) [defined in FSv2-L2],
* SFC: (AFI=31, SAFI=TBD1) [defined in FSv2-SFC], and
* SFC VPN (AFI=31, SAFI=TBD2) [defined in FSv2-SFC].
An IDR specification for tunneled traffic is in
[I-D.ietf-idr-flowspec-nvo3]. This Draft was original target for
FSv1, and will be considered for FSv2. The series of FSv2 support
the same scope of functionality in a series of documents.
FSv2 operates in the ships-in-the night model with FSv1 so network
operators can manipulate which the distribution of FSv2 and FSv1
using configuration parameters. Since the lack of deterministic
ordering was an FSv1 problem, this specification provides rules and
protocol features to keep filters in a deterministic order between
FSv1 and FSv2.
The basic principles regarding ordering of flow specification filter
rules are:
1) Rule-0 (zero) is defined to be 0/0 with the “permit-all”
action.
2) FSv2 rules are ordered based on user-specified order.
- The user-specified order is carried in the FSv2 NLRI and a
numerical lower value takes precedence over a numerically
higher value. For rules received with the same order value,
the FSv1 rules apply (order by component type and then by value
of the components).
3) FSv2 rules are added starting with Rule 1 and FSv1 rules are
added after FSv2 rules
- For example, BGP Peer A has FSv2 data base with 10 FSv2 rules
(1-10). FSv1 user number is configured to start at 301 so 10
FSv1 rules are added at 301-310.
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4) An FSv2 peer may receive BGP NLRI routes from a FSv1 peer or a
BGP peer that does not support FSv1 or FSv2. The capabilities
sent by a BGP peer indicate whether the AFI/SAFI can be received
(FSv1 NLRI or FSv2 NLRI).
5) Associate a chain of actions to rules based on user-defined
action number (1-n). (optional)
- If no actions are associated with a filter rule, the default is
to drop traffic the filter rules match
- An action chain of 1-n actions can be associated with a set of
filter rules can via Extended Communities or a Community
attribute with a FSv2 type. Only the Community attribute
allows for user-defined order for the actions. If an
implementation allows for FSv2 actions with user-ordering and
Extended Community actions, the by default the Extended
Community are ordered after the user-ordered actions. This
FSv2 action order default can be changed by the Action Chain
Ordering FSv2 action.
Figure 2-2 provides a logical diagram of the FSv2 structure
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+--------------------------------+
| Rule Group |
+--------------------------------+
^ ^ ^
| |--------- |
| | ------
| | |
+--------^-------+ +-------^-----+ +---^-----+
| Rule1 | | Rule2 | ... | Rule-n |
+----------------+ +-------------+ +---------+
: : : :
:.................: : : :
: |...........: : :
+--V--+ +--V-------+ : :
|order| |identifier| .......: :
+-----+ +----------+ : :
: :
+------------------V--+ +-----V----------------+
|Rule Match condition | | Rule Action |
+---------------------+ +----------------------+
: : : : : : : : |
+--V--+ : : : +--V---+ : : : V
| Rule| : : : |action| : : : +-----------+
| name| : : : |order | : : : |action name|
+-----+ : : : +------+ : : : +-----------+
: : : : : :.............
: : : : : :
.....: . :..... ..: :...... :
: : : : : :
+----V---+ +---V----+ +--V---+ +-V------+ +--V-----+ +--V---+
| Match | | match | |match | | Action | | action | |action|
|Operator| |variable| |Value | |Operator| |Variable| | Value|
+--------+ +--------+ +------+ +--------+ +--------+ +------+
Figure 2-2: BGP FSv2 Data storage
2.3. Flow Specification v2 (FSv2) Series of Specifications
The full FSV2 information is contained in [I-D.ietf-idr-flowspec-v2].
Feedback from the implementers indicate that the Flow Specification
v2 needs to broken into drafts based on the use cases the technology
supports. These include IPv4/IPv6 IP Basic Filters for DDOS, IPv4/
IPv6 filters beyond DDOS, BGP/MPLS IPv4 VPN, BGP/MPLS IPv6 VPN, BGP/
MPLS L2VPN, Segment routing (SRMPLS, SRv6), SFC, SFC VPN, L2, L2
VPNs, and tunneled traffic (e.g., nv03 WG tunnels).
The following is the list of planned drafts:
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FSv2 IP Basic: The first draft will support IP filter functions
(Type 1) and Extended Community actions supported by [RFC8955] and
[RFC8956] with additions to provide the following:
* user ordering of IP filters
* no support for user ordering of actions
* a new FSv2 Actions (FSv2 AO) in an Extended Community that
deals with and interaction of other Extended Community Actions
for FSv2.
This draft provides the basic functions all other FSv2 drafts will
extend.
FSv2 More IP Filters:(draft-ietf-hares-idr-fsv2-more-IP-filters)
This draft is the describes additional IP packet filters for FSv2.
Drafts may be proposed to be included in this draft or extend this
draft.
FSv2 More IP Actions (draft-ietf-hares-idr-fsv2-more-IP-actions): Th
is draft is the describes describes how FSv2 actions can be
described as either:
FSv2 Extended Community Actions for generic, IPv4, or IPv6 (v4
and v6) with no user ordering. Each Extended Community actions
will be required to provide interactions with other Actions and
abide by the Basic ordering. Basic ordering will provide a
choice of defined ordering or implementation specific knobs.
FSv2 Wide Community Actions in Type 2 Community Container This
draft provides Wide Community actions in the type 2 format of
the Community attribute.
This draft will also define FSv2 Wide community actions for
existing Extended Community actions.
FSv2 Non-IP Filters(draft-hares-idr-fsv2-non-IP-Filters): This draft
defines FSv2 non-IP filters in data packets passed by MPLS
packets, Segment Routing packets (SR-MPLS or SRv6), SFC, L2, and
tunnels. Previous work in this area includes:
FSV2 work on MPLS filters: MPLS filters to match labels.
Original IDR work is found in [I-D.ietf-idr-flowspec-v2] from
[I-D.ietf-idr-flowspec-mpls-match]
FSv2 Work for SRv6: Filters for SRv6 service identifers and
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functions. Original work was found in
[I-D.ietf-idr-flowspec-v2] from [I-D.ietf-idr-flowspec-srv6].
FSV2 actions for SFC direction: Network Service Header (NSH) is
defined in [RFC8300]. Flow specification filters were not
defined in [RFC9015], but filters could be defined for this
header.
FSv2 L2 filters: ([I-D.ietf-idr-flowspec-l2vpn]) This document
provides user ordered filters for L2VPNs. Other drafts have
suggested extending this to cover the reduced latency L2 use
case (detnet).
Tunnels Defined by nv03 group ([I-D.ietf-idr-flowspec-nvo3]).
FSv2 Non-IP Actions (draft-hares-idr-fsv2-non-IP-Filters): This
draft defines FSv2 non-IP actions in data packets passed by L2,
MPLS packets, Segment Routing packets (SR-MPLS or SRv6), SFC and
tunnels. The potential work in this area includes:
FSV2 actions on MPLS filters: MPLS actions to push, pop, swap
labels. Original IDR work is found in
[I-D.ietf-idr-flowspec-v2] from
[I-D.ietf-idr-bgp-flowspec-label]
FSv2 Work for SRv6: While the original work does not have FSv2
actions, some individual drafts have suggested actions for SRv6
headers. One such action could be compression of SRv6.
FSV2 actions for SFC direction: SFC classifier actions based on
Action with Service Path identifier (SPI), Service Index (SI),
and Service function type (SFT). The original description of
the action is in [RFC9015] in section 7.4.
FSv2 L2VPN: ([I-D.ietf-idr-flowspec-l2vpn]) The L2 filters for
packets in L2 or L2VPN.
Tunnels Defined by nv03 group ([I-D.ietf-idr-flowspec-nvo3]).
3. FSv2 NLRI Formats and Actions
3.1. FSv2 NLRI Format
The BGP FSv2 uses an NRLI with the format for AFIs for IPv4 (AFI =
1), IPv6 (AFI = 2), L2 (AFI = 6), L2VPN (AFI=25), and SFC (AFI=31)
with SAFIs TBD1 and TBD2 to support transmission of the flow
specification which supports user ordering of traffic filters and
actions for IP traffic and IP VPN traffic.
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This NLRI information is encoded using MP_REACH_NLRI and
MP_UNREACH_NLRI attributes defined in [RFC4760]. When advertising
FSv2 NLRI, the length of the Next-Hop Network Address MUST be set to
0. Upon reception, the Network Address in the Next-Hop field MUST be
ignored.
Implementations wishing to exchange flow specification rules MUST use
BGP's Capability Advertisement facility to exchange the Multiprotocol
Extension Capability Code (Code 1) as defined in [RFC4760], and
indicate a capability for FSv1, FSv2 (Code TBD3), or both.
The AFI/SAFI NLRI for BGP Flow Specification version 2 (FSv2) has the
format:
+--------------------------------+
| NLRI length (2 octets) |
+--------------------------------+
| TLVs+ |
| +============================+ |
| | order (4 octets) | |
| +----------------------------+ |
| | identifier (4 octets) | |
| +----------------------------+ |
| + FSv2 Filter type (2 octet) + |
| +----------------------------+ |
| + length TLVs (2 octet) + |
| + ---------------------------+ |
| + value (variable) + |
| +----------------------------+ |
+-------------------------------+
Figure 3-1 - NLRI format for fFSv2
where:
* TLV+ - indicates the repetition of the TLV field
* NLRI length: length of field including all SubTLVs in octets.
* order: flow-specification global rule order number (4 octets).
* identifier: identifier for the rule (used for NM/Logging) (4
octets)
* FSv2 Filter type: contains a type for FSv2 TLV format of the NRLI
(2 octets) which can be:
- 0 - reserved,
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- 1 - IP Basic Filter Rules
- 2 - Extended IP Filter rules
- 3- L2 traffic rules
- 4- SFC Traffic rules
- 5- SFC VPN Traffic rules
- 6 - BGP/MPLS VPN IP Traffic Rules
- 7 - BGP/MPLS VPN L2 Traffic Rules
- 8 - Tunneled traffic
* length-TLV: is the length of the value part of the Sub-TLV,
* value: value depends on the type of FSv2 Filter type. For
example, the IP Traffic Rules defines the
All FSv2 function must recognize valid Filter Types, even if the
handling of the Filter types are not supported by the implementation.
The TLV allows all FSv2 Filter types to be passed, even if the Filter
rules cannot be installed.
Note: This specification only defines the IP Basic Filter Rules that
all FSv2 must support.
3.2. Basic IP Filters
3.2.1. IP header SubTLV (type=1(0x01))
The format of the IP header TLV value field is shown in figure 3-2.
The IP header for the VPN case is specified in section 3.5.
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+-------------------------------+
| NLRI length (2 octets) |
+-------------------------------+
| TLVs+ |
| +===========================+ |
| | order (4 octets) | |
| +---------------------------+ |
| | identifier (4 octets) | |
| +---------------------------+ |
| + FSv2 Filter type = 1 + |
| +---------------------------+ |
| + length TLVs (2 octet) + |
| + --------------------------+ |
| + value (variable) + |
| +---------------------------+ |
+-------------------------------+
Figure 3-2 NLRI format for FSv2 IP Filter Type
Where: Each value field has the format:
+--------------------------------+
| + ---------------------------+ |
| + Components TLVs (variable) + |
| +----------------------------+ |
+--------------------------------+
Where the Component TLVs are:
+----------------------------+
| Component Type (1 octet) |
+----------------------------+
| length (1 octet) |
+ ---------------------------+
| value (variable) |
+----------------------------+
Figure 3-3 – IP header Component TLVs
Where:
Component type: component values are defined in the “Flow
Specification Component types” registry for IPv4 and IPv6 by
[RFC8955], [RFC8956], and [I-D.ietf-idr-flowspec-srv6]
length: length of SubTLV (varies depending on the component type)>
value: dependent on component type.
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- For descriptions of value portions for components 1-13 see
[RFC8955] and [RFC8956]. For component 14 see
[I-D.ietf-idr-flowspec-v2].
Many of the components use the operators [numeric_op] and
[bitmask_op] defined in [RFC8955]
The list of valid SubTLV types appears in Table 2.
Table 3-1 IP SubTLV Types for IP filters
for IP Basic FSv2
SubTLV
-type Definition
====== ============
1 - IP Destination prefix
2 - IP Source prefix
3 – IPv4 Protocol /
IPv6 Upper Layer Protocol
4 – Port
5 – Destination Port
6 – Source Port
7 – ICMPv4 type / ICMPv6 type
8 – ICMPv4 code / ICPv6 code
9 – TCP Flags
10 – Packet length
11 – DSCP
12 – Fragment
13 – Flow Label
14 - TTL
15-63 reserved for IP Extensions
(standards action)
64-127 Reserved for Non-IP Filters
128-191 Reserved for Standard Action
192-249 FCFS
250-255 Reserved
Current Non-IP Filters for short term reference.
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Table 3-2 IP SubTLV types for non-IP Filters
SubTLV IP SubTLV types
-type Definition
====== ===========
64 Parts of SID
65 MPLS LAbel Match-1
66 MPLS Label Match-2
67-127 Match reserved for Non-IP
128-191 reserved (standards action)
192-249 FCFS
250- FSv2 Filter Error handling
251-255 Reserved
Ordering within the TLV in FSv2: The transmission of SubTLVs within a
flow specification rule MUST be sent ascending order by SubTLV type.
If the SubTLV types are the same, then the value fields are compared
using mechanisms defined in [RFC8955] and [RFC8956] and MUST be in
ascending order. NLRIs having TLVs which do not follow the above
ordering rules MUST be considered as malformed by a BGP FSv2
propagator. This rule prevents any ambiguities that arise from the
multiple copies of the same NLRI from multiple BGP FSv2 propagators.
A BGP implementation SHOULD treat such malformed NLRIs as "Treat-as-
withdraw" [RFC7606].
See [RFC8955], [RFC8956], and [I-D.ietf-idr-flowspec-srv6]. for
specific details.
3.2.2. Components for FSv2 supporting IP Basic FSV2
3.2.2.1. IP Destination Prefix (type = 1)
IPv4 Name: IP Destination Prefix (reference: [RFC8955])
IPv6 Name: IPv6 Destination Prefix (reference: [RFC8956])
IPv4 length: Prefix length in bits
IPv4 value: IPv4 Prefix (variable length)
IPv6 length: length of value
IPv6 value: [offset (1 octet)] [pattern (variable)]
[padding(variable)]
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If IPv6 length = 0 and offset = 0, then component matches every
address. Otherwise, length must be offset "less than" length "less
than" 129 or component is malformed.
3.2.2.2. IP Source Prefix (type = 2)
IPv4 Name: IP Source Prefix (reference: [RFC8955])
IPv6 Name: IPv6 Source Prefix (reference: [RFC8956])
IPv4 length: Prefix length in bits
IPv4 value: Source IPv4 Prefix (variable length)
IPv6 length: length of value
IPv6 value: [offset (1 octet)] [pattern
(variable)][padding(variable)]
If IPv6 length = 0 and offset = 0, then component matches every
address. Otherwise, length must be offset < length < 129 or
component is malformed.
3.2.2.3. IP Protocol (type = 3)
IPv4 Name: IP Protocol IP Source Prefix (reference: [RFC8955])
IPv6 Name: IPv6 Upper-Layer Protocol: (reference: [RFC8956])
IPv4 length: variable
IPv4 value: [numeric_op, value]+
IPv6 length: variable
IPv6 value: [numeric_op, value}+
where the value following each numeric_op is a single octet.
3.2.2.4. Port (type = 4)
IPv4/IPv6 Name: Port (reference: [RFC8955]), [RFC8956])
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Filter defines: a set of port values to match either destination port
or source port.
IPv4 length: variable
IPv4 value: [numeric_op, value]+
IPv6 length: variable
IPv6 value: [numeric_op, value]+
where the value following each numeric_op is a single octet.
Note-1: (from FSV1) In the presence of the port component
(destination or source port), only a TCP (port 6) or UDP (port 17)
packet can match the entire flow specification. If the packet is
fragmented and this is not the first fragment, then the system may
not be able to find the header. At this point, the FSv2 filter may
fail to detect the correct flow. Similarly, if other IP options or
the encapsulating security payload (ESP) is present, then the node
may not be able to describe the transport header and the FSv2 filter
may fail to detect the flow.
The restriction in note-1 comes from the inheritance of the FSv1
filter component for port. If better resolution is desired, a new
FSv2 filter should be defined.
Note-2: FSv2 component only matches the first upper layer protocol
value.
3.2.2.5. Destination Port (type = 5)
IPv4/IPv6 Name: Destination Port (reference: [RFC8955]), [RFC8956])
Filter defines: a list of match filters for destination port for TCP
or UDP within a received packet
Length: variable
Component Value format: [numeric_op, value]+
3.2.2.6. Source Port (type = 6)
IPv4/IPv6 Name: Source Port (reference: [RFC8955]), [RFC8956])
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Filter defines: a list of match filters for source port for TCP or
UDP within a received packet
IPv4/IPv6 length: variable
IPv4/Ipv6 value: [numeric_op, value]+
3.2.2.7. ICMP Type (type = 7)
IPv4: ICMP Type (reference: [RFC8955])
Filter defines: Defines: a list of match criteria for ICMPv4 type
IPv6: ICMPv6 Type (reference: [RFC8956])
Filter defines: a list of match criteria for ICMPv6 type.
IPv4/IPv6 length: variable
IPv4/IPv6 value: [numeric_op, value]+
3.2.2.8. ICMP Code (type = 8)
IPv4: ICMP Type (reference: [RFC8955])
Filter defines: a list of match criteria for ICMPv4 code.
IPv6: ICMPv6 Type (reference: [RFC8956])
Filter defines: a list of match criteria for ICMPv6 code.
IPv4/IPv6 length: variable
IPv4/IPv6 value: [numeric_op, value]+
3.2.2.9. TCP Flags (type = 9)
IPv4/IPv6: TCP Flags Code (reference: [RFC8955])
Filter defines: a list of match criteria for TCP Control bits
IPv4/IPv6 length: variable
IPv4/IPv6 value: [bitmask_op, value]+
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Note: a 2 octets bitmask match is always used for TCP-Flags
3.2.2.10. Packet length (type = 10 (0x0A))
IPv4/IPv6: Packet Length (reference: [RFC8955], [RFC8956])
Filter defines: a list of match criteria for length of packet
(excluding L2 header but including IP header).
IPv4/IPv6 length: variable
IPv4/IPv6 value: [numeric_op, value]+
Note:[RFC8955] uses either 1 or 2 octet values.
3.2.2.11. DSCP (Differentiaed Services Code Point)(type = 11 (0x0B))
IPv4/IPv6: DSCP Code (reference: [RFC8955], [RFC8956])
Filter defines: a list of match criteria for DSCP code values to
match the 6-bit DSCP field.
IPv4/IPv6 length: variable
IPv4/IPv6 value: [numeric_op, value]+
Note: This component uses the Numeric Operator (numeric_op) described
in [RFC8955] in section 4.2.1.1. Type 11 component values MUST be
encoded as single octet (numeric_op len=00).
The six least significant bits contain the DSCP value. All other
bits SHOULD be treated as 0.
3.2.2.12. Fragment (type = 12 (0x0C))
IPv4/IPv6: Fragment (reference: [RFC8955], [RFC8956])
Filter defines: a list of match criteria for specific IP fragments.
Length: variable
Component Value format: [bitmask_op, value]+
Bitmask values are:
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0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| 0 | 0 | 0 | 0 |LF |FF |IsF| DF|
+---+---+---+---+---+---+---+---+
Figure 3-4
Where:
DF (don’t fragment): match If IP header flags bit 1 (DF) is 1.
IsF(is a fragment other than first: match if IP header fragment
offset is not 0.
FF (First Fragment): Match if [RFC0791] IP Header Fragment offset
is zero and Flags Bit-2 (MF) is 1.
LF (last Fragment): Match if [RFC7091] IP header Fragment is not 0
And Flags bit-2 (MF) is 0
0: MUST be sent in NLRI encoding as 0, and MUST be ignored during
reception.
3.2.2.13. Flow Label(type = 13 (0xOD))
IPv4/IPv6: Fragment (reference: [RFC8956])
Filter defines: a list of match criteria for 20-bit Flow Label in the
IPv6 header field.
Length: variable
Component Value format: [numeric_op, value]+
3.2.2.14. TTL (type=14 (0x0E))
TTL: Defines matches for 8-bit TTL field in IP header
Encoding: <[numeric_op, value]+>
where: value is a 1 octet value for TTL.
ordering: by full value of number_op concatenated with value
conflict: none
reference: draft-bergeon-flowspec-ttl-match-00.txt
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3.3. FSv2 Actions for IP Basic
The full FSV2 [I-D.ietf-idr-flowspec-v2] specifies that FSv2 actions
can be sent in Extended Communities or a Community attribute with the
FSv2 community type. The IP Basic FSv2 only allows FSv2 actions to
be sent in an Extended Community (FSv2-EC)
The Extended Community encodes the Flow Specification actions in the
Extended IPv4 Community format [RFC4360] or in the extended IPv6
Community format [RFC5701]. The FSv2-EC actions cannot be ordered by
the user and some FSv2-EC interact. . This section defines the
FSv2-EC actions for FSv2 IP Basic by defining existing FSv2-EC action
formats, the interaction between actions, and the default order of
actions.
The FSv2 Action Chain Ordering Extended Community (AO-EC) signals if
the defaults for the FSv2 Extended Community action ordering and
interactions are being ignored, and an implementation specific
ordering being used instead. This Action Chain Ordering Extended
Community aids the transition between FSv1 actions which are ordered
uniquely by each implementation, and the FSv2 actions which use a
global default.
The implementer and the operator deploying need to be aware of
default order of actions and the interactions between any set of FSv2
actions.
The Community attribute [I-D.ietf-idr-wide-bgp-communities] describes
an attribute with flexible format for specifying community
information. The flexible format defines a short common header
followed by type-specific community. FSv2 [I-D.ietf-idr-flowspec-v2]
defines a new type of Community denoted as a FSv2 Action for the
Community Attribute (FSv2-CA) This FSv2 More IP Actions (draft-hares-
fsv2-more-ip-actions) defines the format of the FSv2-CA.
3.3.1. FSv2 Extended Community Actions inherited from FSv1
This section reviews FSv1 actions in Extended Communities (IPv4 and
IPv6) and conflicts FSv1 actions. The FSv2 IP Basic uses these basic
FSv1 with one addition Action Ordering Extended Community.
This section first describes the following Information elated to FSv2
Actions in Extended Communities:
* Generic Transitive Extended Communities for FSv2 Actions (FS-TG-
EC) [RFC8955]
* Transitive Extended Communities for redirect. This includes:
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- (Generalized redirection ID with Sequencing and copy)
[I-D.ietf-idr-flowspec-path-redirect]
- Redirect plus Copy bit [I-D.ietf-idr-flowspec-redirect-ip]
- Transitive IPv6-Address Extended Community formats for FSv2
actions [RFC8956]
3.3.1.1. Encoding FSv2 Actions in Generic Transitive Communities
The FSv2 actions encoded in Generic Transitive communities inherit
the FSv1 actions in Generic Transitive communities.
The Extended Community encodes the Flow Specification actions in the
Extended Community format as generic transitive extended communities
per [RFC4360] per [RFC8955], [RFC9117], and [RFC9184].
The format of the these actions can be:
Generic Transitive Extended Community (0x80): where the Sub-Types
are defined in the Generic Transitive Extended Community Sub-Types
registry.
Generic Transitive Extended Community Part 2(0x81): where the Sub-
Types are defined in the Generic Transitive Extended Community
Part 2 Sub-Types registry.
Transitive Four-Octet AS-Specific Extended Communit(0x82): where the
Sub-Types defined in the Generic Transitive Extended Community
Part 3 Sub-Types registry.
Generic Transitive Extended Community Part 3 (0x83): where the Sub-
Types defined in the Transitive Opaque Extended Community Sub-
Types" registry.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type high | Type low(*) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (6 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3-5
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Table 3-3 Generic Transitive Extended Community
Part 1 - (0x80)
IPv4 Extended Communities (Type 0x80)
Value Description Name Reference
===== ======================= ===== ==========
0x01 FSv2 Action Chain Ordering ACO [This document]
0x06 FSv2 traffic-rate-byte TRB [RFC8955]
0x07 Flow spec traffic-action TAIS [RFC8955]
0x08 Flow spec rt-redirect RDIP [RFC8955]
AS-2 octet format
0x09 Flow spec Remark DSCP TMDS [RFC8955]
0x0C Flow Spec Traffic-rate-packets TRP [RFC8955]
0xOD Flow Spec for SFC classifiers SFCC [RFC9015]
Table 3-4 Generic Transitive Extended Community
Part 2 (0x81)
IPv4 Extended Communities FSv2 action (Type 0x81)
Value Description Name Reference
===== ======================= ===== ==========
0x08 Flow spec rt-redirect RDIP [RFC8955]
Table 3-5 Generic Transitive Extended Community
Part 3 (Type 0x82)
Value Description Name Reference
===== ======================= ==== ==========
0x08 Flow spec rt-redirect RDIP [RFC8955]
AS-4 octet format
Table 3-6: Traffic Action bits
Bit Name Name Reference
===== =============== ==== ==========
47 Terminal Action TAct [RFC8955]
46 Sample Samp [RFC8955]
45 Copy Copy [this document]
44 Drop drop [this document]
Figure 3-13
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3.3.1.2. Encoding Path Forwarding in IPv4 Transitive Extended
Communities
FSv2 needs to refine the following Transitive Extended Communities
that are not "Transitive Generic Communities" to a specific set of
functions. These features provide overlapping functions. While some
of these features are implemented, these actions should be be
reviewed.
There are three types of functions:
* Active filters on interfaces in group for inbound or outbound data
traffic
* Redirect to an IP address. Optionally perform a traffic action
(copy)
* Redirect to an Indirection ID of a specific type. Optionally
perform a traffic action (copy).
Table 3-7 Transitive Extended Community types (T-EC-types)
sub-type FSv1 Description Name
======== ================== ====
0x07 FS Interface set Ifset
0x08 FS Redirect/Mirror RIPv4
0x09 FS Redirect to Indirection ID RGID
References:
ifset - [I-D.ietf-idr-flowspec-interfaceset]
RIPv4 - [I-D.ietf-idr-flowspec-redirect-ip]
RGID - [I-D.ietf-idr-flowspec-path-redirect]
3.3.1.3. Encoding FSv2 Actions in IPv6 Extended Community
The IPv6 Extended Community encodes the Flow Specification actions in
the Extended Community format [RFC5701] per [RFC8956], [RFC9117], and
[RFC9184] in the transitive opaque format.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Sub-type | Global Administrator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Global Administrator (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Administrator (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Administrator (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Administrator (cont.) | Local Administrator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3-6
The 20 octets of value are given in the following format:
Global Administrator: IPv6 address assigned by Internet Registry
Local Administrator: 2 bytes of Local Administrator
Table 3-8 transitive IPv6-Address-Specific Actions
Value Description Name
===== ======================= =====
0x01 Flow Spec Action Chain ACO
0x0C Flow Spec redirect-v6-flag RD6F
0x0D Flow Spec rt-redirect IPv6 format RDv6
IPv6 format
References:
ACO - This document
RD6F - [I-D.ietf-idr-flowspec-redirect-ip]
RDv6 - [RFC8956]
3.3.1.4. Conflicts between FSv2 actions inherited from FSv1 Actions
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Table 3-9: Conflicts between FSv2 Transitive Generic IPv4 actions
IPv4 Extended Communities (Type 0x80)
Value Name Conflicts with
===== ===== ========================
0x01 ACO none
0x06 TRB TRP
0x07 TAIS duplication also done in
RDIP, RIPv4, RGID
0x08 RDIP redirection done in
RIPv4, RGID
copy done in TAIS
0x09 TMDS none
0x0C TRP TRB
0xOD SFCC none
Table 3-10 Transitive IPv6-Address-Specific Actions
Value Name Conflicts with
===== ====== =================
0x01 ACO none
0x0C RD6F RDv6
0x0D RDv6 RD6F
3.3.2. Default Ordering for FSv2 Extended Community Actions
One of the issue that started the FSv2 work was the fact that actions
interacted. These interactions might occur when both actions
performed their duties which caused conflicting results. One example
of a potentially unexpected interaction is when the FSv2 for rate
limiting by packet (TRP) combines with the FSv2-EC action for rate
limiting by byte (TRB).
The default order is the numerical order of the action type as shown
in table x-x for IPv4 and table x-x for IPv6.
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Table 3-11 Default Order of FSv2-EC IPv4 Actions
IPv4 Extended Communities (Type 0x80)
Value Description Name
===== ======================= =====
0x01 FSv2 Action Chain Ordering ACO
0x06 FSv2 traffic-rate-byte TRB
0x07 Flow spec traffic-action TAIS
0x07 FS Interface set
0x08 Flow spec rt-redirect RDIP
0x08 FS Redirect/Mirror RDIPv4
0x08 FS Redirect/Mirror RDIPv4
0x09 FS Redirect to Path ID RD
0x09 Flow spec Remark DSCP TMDS
0x0C Flow Spec Traffic-rate-packets TRP
0xOD Flow Spec for SFC classifiers SFCC
Note: If FS Interface is widely deployed
it would be good to move it to another
type.
Table 3-12 default order for FSv2-EC IPv6 actions
Value Name Conflicts with
===== ====== =================
0x01 ACO none
0x0C RD6F RDv6
0x0D RDv6 RD6F
3.3.3. Action Chain Ordering FSv2 Extended Community (ACO FSv2-EC)
One of the issues with FSv1 is the lack of a clear definition on what
happens if multiple actions interact. One way a FSv2 action can
interact is if two actions try to do different things with the
packet. A second way an FSv2 action can interact is if the first
action fails. For example, if the first action was copy (via a
mirror action) and the second action is the packet. If the first
action fails, should the second action still occur? The correct
answer depends on the FSv2 application. If the order of the two
actions is drop the packet and then mirror, the mirror function would
not copy any packets.
The default ordering of the FSv2-EC actions makes a default action
chain for the FSv2 actions supported by the IP Basic. The addition
of the FSv2-EC action For Action Chain ordering provides a
deterministic way of determining what happens if an action fails.
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The orginal specification FSv2 [I-D.ietf-idr-flowspec-v2] first
defined the concept of an action chain to address the issues of
interaction between user-order actions. A FSv2-CA action will be
defined for FSv2 Action Chain Ordering (ACO). An implementation
which implements both the the FSv2-CA ACO action the FSv2-EC ACO
action, MUST give precedence to the ACO action AND provide a logging
entry regarding any conflict between the two actions.
The FSv2-EC also provides a flag for "Implementation specific
ordering." This flag is useful to aid transition between the FSv1
implementations and FSv2 implementations of IP Basic. In FSv1
implementations configurations or implementation defaults set the
order for actions. In FSv2 there is a default order for actions and
interactions. New FSv2-Action need to define
The AC-Failure types are:
* 0x00 – default – stop on failure
* 0x01 – continue on failure (best effort on actions)
* 0x02 – conditional stop on failure (depends on AC-Failure-value/
policy)
* 0x03 – rollback do all or nothing (depends on AC-Failure-value/
policy)
Editors note: The following options for encoding ACO exist.
Option 1: redefine bits in Traffic Action subtype
Option 2: create a new Extended Community
3.3.3.1. FSV2 Basic DDOS Actions
3.3.3.1.1. New Actions for FSv2 DDOS
There are two options for encoding the Action chain.
3.3.3.1.1.1. Option 1: Action Chain operation IPv4 Extended (ACO)(1,
0x01)
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type high | Type low(01) |ACO-dependency | AC-Failure |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AC-Failure-value (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3-7
where:
ACO Dependency - The order dependency within the Action chain.
- 0 = default order and interaction. For FSv2-EC this means a
pre-defined order and inter-dependency.
- 1 = Implementation specific order and interaction.
AC-failure-type – 1 octet byte that determines the action on
failure
- Actions may succeed or fail and an Action chain must deal with
it. The default value stored for an action chain that does not
have this action chain is “stop on failure”.
- where:
o AC-Failure types are:
+ 0x00 – default – stop on failure
+ 0x01 – continue on failure (best effort on actions)
+ 0x02 – conditional stop on failure – depending on AC-
Failure-value
+ 0x03 – rollback – do all or nothing - depending in AC-
Failure-value
AC-Failure values: TBD
3.3.3.1.1.2. Option 2: Action Chain operation encoded in IPv4 Traffic
Action (0x07)
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type high | Type low(07) |traffic action field (zero) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AC-Failure-value (cont.) |ACF|I|S|T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3-8
Where
ACO - is the Action Chain failure types (0x00 to 0x03)
00 - stop on failure
01 - continue on failure
02 - conditional stop on failure (by policy)
03 - rollback on failure (with policy)
I - Implementation ordering and interaction
0 - Default FSv2 ordering and interation
1 - Implementation defined user
S - Sample flag
T - Terminal action
3.3.3.1.2. Interactions between FSv2 DDOS actions
Table 3-13 - All FSv2 IPv4 Action types for IP DDOS
Action Name Description May Interacts
====== ==== ====================== ===============
01 ACO Action Chain Operation none
06 TRB Traffic Rate limited TRP
by Bytes
07 TA Traffic Action none
(terminal/sample/ACO)
08 RDIP Redirect IPv4 none
09 TM Mark DSCP value none
12 TRP Traffic Rate limited TRB
by Packets
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Table 3-14 – All FSv2 IPv6 Action types for IP DDOS
Action Name Description May Interacts
====== ==== ====================== ===============
01 ACO Action Chain Operation none
06 TRB Traffic Rate limited TRP
by Bytes
07 TA Traffic Action none
(terminal/sample/ACO)
08 RDIP Redirect IPv4 none
09 TM Mark DSCP value none
12 TRP Traffic Rate limited TRB
by Packets
3.3.3.2. Summary of all FSv2 Actions (informative only)
This table is informative only. It will moved to an appendix.
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Table 3-15 - All IP Actions in Extended Communities
Action Name: Description
====== ===========
00 reserved
01 ACO: action chain operation
02 reserved
03 TAIS: traffic actions per interface group
04 LkBW: Link bandwidth
(draft-ietf-idr-linkbandwidth-07) [non-transitive]
[juniper link bandwidth] [transitive]
06 TRB: traffic rate limited by bytes
07 TA: traffic action (terminal/sample)
08 RDIP: Redirect IPv4
09 TM: mark DSCP value
10 TBA (to be assigned)
11 TBA (to be assigned)
12 TRP: traffic rate limited by packets
13 TISFC: SFC Classifier
14 RDIID: redirect to Indirection-id (move from 0x00)
31 TISFC: SFC classifier II (this document)
32 MPLSLA: MPLS label action
33 VLAN: VLAN-Action (0x16)[draft-ietf-idr-flowspec-l2vpn-17]
34 TPID: TPID-Action (0x17)[draft-ietf-idr-flowspec-l2vpn-17]
24-254 TBA (to be assigned)
255 reserved
Table 3-16 IPv6 Extended Communities (Type 1)
Value Description Name Reference
===== ======================= ===== ==========
0x01 Flow Spec Action Chain ACO [This document]
0x0C Flow Spec redirect-v6-flag RD6F [ID-redirect-IP]
0x0D Flow Spec rt-redirect RD6 [RFC8956]
IPv6 format
4. Validation and Ordering of NLRI
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4.1. Validation of FSv2 NLRI
The validation of FSv2 NLRI adheres to the combination of rules for
general BGP FSv1 NLRI found in [RFC8955], [RFC8956], [RFC9117], and
the specific additions made for SFC NLRI [RFC9015], and L2VPN NLRI
[I-D.ietf-idr-flowspec-l2vpn].
To provide clarity, the full validation process for flow
specification routes (FSv1 or FSv2) is described in this section
rather than simply referring to the relevant portions of these RFCs.
Validation only occurs after BGP UPDATE message reception and the
FSv2 NLRI and the path attributes relating to FSv2 (Extended
community and Wide Community) have been determined to be well-formed.
Any MALFORMED FSv2 NRLI is handled as a “TREAT as WITHDRAW”
[RFC7606].
4.1.1. Validation of FS NLRI (FSv1 or FSv2)
Flow specifications received from a BGP peer that are accepted in the
respective Adj-RIB-In are used as input to the route selection
process. Although the forwarding attributes of the two routes for
tbe same prefix may be the same, BGP is still required to perform its
path selection algorithm in order to select the correct set of
attributes to advertise.
The first step of the BGP Route selection procedure (section 9.1.2 of
[RFC4271] is to exclude from the selection procedure routes that are
considered unfeasible. In the context of IP routing information,
this is used to validate that the NEXT_HOP Attribute of a given route
is resolvable.
The concept can be extended in the case of the Flow Specification
NLRI to allow other validation procedures.
The FSv2 validation process validates the FSv2 NLRI with following
unicast routes received over the same AFI (1 or 2) but different
SAFIs:
* Flow specification routes (FSv1 or FSv2) received over SAFI=133
will be validated against SAFI=1,
* Flow Specification routes (FSv1 or FSv2) received over SAFI=134
will be validated against SAFI=128, and
* Flow Specification routes (FSv1 or FSv2) [AFI =1, 2] received over
SAFI=77 will be validated using only the Outer Flow Spec against
SAFI = 133.
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The FSv2 validates L2 FSv2 NLRI with the following L2 routes received
over the same AFI (25), but a different SAFI:
* Flow specification routes (FSv1 or FSv2)received over SAFI=135 are
validated against SAFI=128.
In the absence of explicit configuration, a Flow specification NLRI
(FSv1 or FSv2) MUST be validated such that it is considered feasible
if and only if all of the conditions are true:
a) A destination prefix component is embedded in the Flow
Specification,
b) One of the following conditions holds true:
- 1. The originator of the Flow Specification matches the
originator of the best-math unicast route for the destination
prefix embedded in the flow specification (this is the unicast
route with the longest possible prefix length covering the
destination prefix embedded in the flow specification).
- 2. The AS_PATH attribute of the flow specification is empty or
contains only an AS_CONFED_SEQUENCE segment [RFC5065].
o 2a.This condition should be enabled by default.
o 2b.This condition may be disabled by explicit configuration
on a BGP Speaker,
o 2c.As an extension to this rule, a given non-empty AS_PATH
(besides AS_CONFED_SEQUENCE segments) MAY be permitted by
policy].
c) There are no “more-specific” unicast routes when compared with
the flow destination prefix that have been received from a
different neighbor AS than the best-match unicast route, which has
been determined in rule b.
However, part of rule a may be relaxed by explicit configuration,
permitting Flow Specifications that include no destination prefix
component. If such is the case, rules b and c are moot and MUST be
disregarded.
By “originator” of a BGP route, we mean either the address of the
originator in the ORIGINATOR_ID Attribute [RFC4456] or the source
address of the BGP peer, if this path attribute is not present.
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A BGP implementation MUST enforce that the AS in the left-most
position of the AS_PATH attribute of a Flow Specification Route (FSv1
or FSv2) received via the Exterior Border Gateway Protocol (eBGP)
matches the AS in the left-most position of the AS_PATH attribute of
the best-match unicast route for the destination prefix embedded in
the Flow Specification (FSv1 or FSv2) NLRI.
The best-match unicast route may change over time independently of
the Flow Specification NLRI (FSv1 or FSv2). Therefore, a
revalidation of the Flow Specification MUST be performed whenever
unicast routes change. Revalidation is defined as retesting rules a
to c as described above.
4.1.2. Validation of Flow Specification Actions
Flow Specifications may be mapped to actions using Extended
Communities or a Wide Communities. The FSv2 actions in Extended
Communities and Wide communities can be associated with large number
of NLRIs.
The ordering of precedence for these actions in the case when the
user-defined order is the same follows the precedence of the FSv2
NLRI action TLV values (lowest to highest). User-defined order is
the same when the order value for action is the same. All Extended
Community actions MUST be translated to the user-defined order data
format for internal comparison. By default, all Extended Community
actions SHOULD be translated to a single value.
Actions may conflict, duplicate, or complement other actions. An
example of conflict is the packet rate limiting by byte and by
packet. An example of a duplicate is the request to copy or sample a
packet under one of the redirect functions (RDIPv4, RDIPv6, RDIID, )
Each FSv2 actions in this document defines the potential conflicts or
duplications. Specifications for new FSv2 actions outside of this
specification MUST specify interactions or conflicts with any FSv2
actions (that appear in this specification or subsequent
specifications).
Well-formed syntactically correct actions should be linked to a
filtering rule in the order the actions should be taken. If one
action in the ordered list fails, the default procedure is for the
action process for this rule to stop and flag the error via system
management. By explicit configuration, the action processing may
continue after errors.
Implementations MAY wish to log the actions taken by FS actions (FSv1
or FSv2).
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4.1.3. Error handling and Validation
The following two error handling rules must be followed by all BGP
speakers which support FSv2:
* FSv2 NLRI having TLVs which do not have the correct lengths or
syntax must be considered MALFORMED.
* FSv2 NLRIs having TLVs which do not follow the above ordering
rules described in section 4.1 MUST be considered as malformed by
a BGP FSv2 propagator.
The above two rules prevent any ambiguity that arises from the
multiple copies of the same NLRI from multiple BGP FSv2 propagators.
A BGP implementation SHOULD treat such malformed NLRIs as ‘Treat-as-
withdraw’ [RFC7606]
An implementation for a BGP speaker supporting both FSv1 and FSv2
MUST support the error handling for both FSv1 and FSv2.
4.2. Ordering for Flow Specification v2 (FSv2)
Flow Specification v2 allows the user to order flow specification
rules and the actions associated with a rule. Each FSv2 rule has one
or more match conditions and one or more actions associated with that
match condition.
This section describes how to order FSv2 filters received from a peer
prior to transmission to another peer. The same ordering should be
used for the ordering of forwarding filtering installed based on only
FSv2 filters.
Section 7.0 describes how a BGP peer that supports FSv1 and FSv2
should order the flow specification filters during the installation
of these flow specification filters into FIBs or firewall engines in
routers.
The BGP distribution of FSv1 NLRI and FSv2 NLRI and their associated
path attributes for actions (Wide Communities and Extended
Communities) is “ships-in-the-night” forwarding of different AFI/SAFI
information. This recommended ordering provides for deterministic
ordering of filters sent by the BGP distribution.
4.2.1. Ordering of FSv2 NLRI Filters
The basic principles regarding ordering of rules are simple:
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1) Rule-0 (zero) is defined to be 0/0 with the “permit-all” action
- BGP peers which do not support flow specification permit
traffic for routes received. Rule-0 is defined to be “permit-
all” for 0/0 which is the normal case for filtering for routes
received by BGP.
- By configuration option, the “permit-all” may be set to “deny-
all” if traffic rules on routers used as BGP must have a
“route” AND a firewall filter to allow traffic flow.
2) FSv2 rules are ordered based on the user-defined order numbers
specified in the FSv2 NLRI (rules 1-n).
3) If multiple FSv2 NLRI have the same user-defined order, then
the filters are ordered by type of FSv2 NRLI filters (see Table 1,
section 4) with lowest numerical number have the best precedence.
- For the same user-defined order and the same value for the FSv2
filters type, then the filters are ordered by FSv2 the
component type for that FSv2 filter type (see Tables 3-6) with
the lowest number having the best precedence.
- For the same user-defined order, the same value of FSv2 Filter
Type, and the same value for the component type, then the
filters are ordered by value within the component type. Each
component type defines value ordering.
- For component types inherited from the FSv1 component types,
there are the following two types of comparisons:
o FSv1 component value comparison for the IP prefix values,
compares the length of the two prefixes. If the length is
different, the longer prefix has precedence. If the length
is the same, the lower IP number has precedence.
o For all other FSv1 component types, unless specified, the
component data is compared using the memcmp() function
defined by [ISO_IEC_9899]. For strings with the same
length, the lowest string memcmp() value has precedence.
For strings of different lengths, the common prefix is
compared. If the common string prefix is not equal, then
the string with the lowest string prefix has higher
precedence. If the common prefix is equal, the longest
string is considered to have higher precedence
Notes:
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* Since the user can define rules that re-order these value
comparisons, this order is arbitrary and set to provide a
deterministic default.
4.2.2. Ordering of the Actions
The FSv2 specification allows for actions to be associated by:
a) a Wide Community path attribute, or
b) an Extended Community path attribute.
Actions may be ordered by user-defined action order number from 1-n
(where n is 2**16-2 and the value 2**16-1 is reserved.
Byy default, extended community actions are associated with default
order number 32768 [0x8000] or a specific configured value for the
FSv2 domain.
Action user-order number zero is defined to have an Action type of
“Set Action Chain operation” (ACO) (value 0x01) that defines the
default action chain process. For details on “set action chain
operation” see section 3.2.1 or section 5.2.1 below.
If the user-defined action number for two actions are the same, then
the actions are ordered by FSv2 action types (see Table 3 for a list
of action types). If the user-defined action number and the FSv2
action types are the same, then the order must be defined by the FSv2
action.
4.2.2.1. Action Chain Operation (ACO)
The “Action Chain Operation” (ACO) changes the way the actions after
the current action in an action chain are handled after a failure.
If no action chain operations are set, then the default action of
“stop upon failure” (value 0x00) will be used for the chain.
4.2.2.1.1. Example 1 - Default ACO
Use Case 1: Rate limit to 600 packets per second
Description: The provider will support 600 packets per second All
Packets sampled for reporting purposes and packet streams over 600
packets per second will be dropped.
Suppose BGP Peer A has a
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* a Wide Community action with user-defined order 10 with Traffic
Sampling
* a Wide Community action with user-defined order 11 from AS 2020
that limits packet-based rate limit of 600 packets per second.
* an Extended Community from AS 2020 that does limits packet-based
rate limit of 50 packets per second.
The FSv2 data base would store the following action chain:
* at user-defined action order 10
- A user action of type 7 (traffic action) with values of
Sampling and logging.
* at user-defined action order 11
- a user action type of 12 (packet-based rate limit) with values
of AS 2020 and float value for 600 packets per second (pps)
* at user-defined action order 32768 (0x8000) with type 12 and
values of A user action of type 12 with values of AS 2020 and
float value of 50 packets/second.
Normal action:
The match on the traffic would cause a sample of the traffic
(probably with packet rate saved in logging) followed by a rate
limit to 600 pps. The Extended community action would further
limit the rate to 50 packets per second.
When does the action chain stop?
The default process for the action chain is to stop on failure.
If there is no failure, then all three actions would occur. This
is probably not what the user wants.
If there is failure at action 10 (sample and log), then there
would be no rate limiting per packet (actions 11 and action
32768).
If there is failure at action 11 (rate limit to packet 600), then
there would be no rate limiting per packet (action 32768).
The different options for Action chain ordering (ACO) have been
worked on with NETCONF/RESTCONF configuration and actions.
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4.2.2.1.2. Example 2: Redirect traffic over limit to processing via SFC
Use case 2: Redirect traffic over limit to processing via SFC.
Description: The normal function is for traffic over the limit to be
forwarded for offline processing and reporting to a customer.
Suppose we have the following 4 actions defined for a match:
* Sent Redirect to indirection ID (0x01) with user-defined match 2
attached in wide community,
* Traffic rate limit by bytes (0x07) with user-defined match 1
attached in wide community,
* Traffic sample (0x07) sent in extended community, and
* SF classifier Info (0x0E) sent in extended community.
These 4 filters rate limit a potential DDoS attack by: a) redirect
the packet to indirection ID (for slower speed processing), sample to
local hardware, and forward the attack traffic via a SFC to a data
collection box.
The FSv2 action list for the match would look like this
Action 0: Operation of action chain (0x01) (stop upon failure)
Action 1: Traffic Rate limit by byte (0x07)
Action 2: Redirect to Redirection ID (0x0F)
Action 32768 (0x8000) Traffic Action (0x07) Sample
Action 32768 (0x8000) SFC Classifier: (0xE)
If the redirect to a redirection ID fails, then Traffic Sample and
sending the data to an SFC classifier for forwarding via SFC will not
happen. The traffic is limited, but not redirect away from the
network and a sample sent to DDOS processing via a SFC classifier.
Suppose the following 5 actions were defined for a FSV2 filter:
* Set Action Chain Operation (ACO) (0x01) to continue on failure
(ox01) at user-order 2 attached in wide community,
* redirect to indirection ID (0x0F) at user-order 2 attached in wide
community,
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* traffic rate limit by bytes (0x07)with user-order 1 attached in
wide community,
* Traffic sample (0x07) attached via extended community, and
* SFC classifier Info (0x0E) attached in extended community.
The FSv2 action list for the match would look like this:
Action 00: Operation of action chain (0x01) (stop upon failure)
Action 01:Traffic Rate limit by byte (0x07)
Action 02:Set Action Chain Operation (ACO) (0x01) (continue on
failure)
Action 02: Redirect to Redirection ID (0F)
Action 32768 (0x8000): Traffic Action (0x07) Sample
Action 32768 (0x8000): SFC classifier (0x0E) forward via SFC [to
DDoS classifier]
If the redirect to a redirection ID fails, the action chain will
continue on to sample the data and enact SFC classifier actions.
4.3. Ordering of FS filters for BGP Peers support FSv1 and FSv2
FSv2 allows the user to order flow specification rules and the
actions associated with a rule. Each FSv2 rule has one or more match
conditions and one or more actions associated with each rule.
FSv1 and FSv2 filters are sent as different AFI/SAFI pairs so FSv1
and FSv2 operate as ships-in-the-night. Some BGP peers in an AS may
support both FSv1 and FSv2. Other BGP peers may support FSv1 or
FSv2. Some BGP will not support FSv1 or FSV2. A coherent flow
specification technology must have consistent best practices for
ordering the FSv1 and FSv2 filter rules.
One simple rule captures the best practice: Order the FSv1 filters
after the FSv2 filter by placing the FSv1 filters after the FSv2
filters.
To operationally make this work, all flow specification filters
should be included the same data base with the FSv1 filters being
assigned a user- defined order beyond the normal size of FSv2 user-
ordered values. A few examples, may help to illustrate this best
practice.
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Example 1: User ordered numbering - Suppose you might have 1,000
rules for the FSv2 filters. Assign all the FSv1 user defined rules
to 1,001 (or better yet 2,000). The FSv1 rules will be ordered by
the components and component values.
Example 2: Storage of actions - All FSv1 actions are defined ordered
actions in FSv2. Translate your FSv1 actions into FSv2 ordered
actions for storing in a common FSv1-FSv2 flow specification data
base.
Example 3: Mixed Flow Specification Support -
Suppose an FSv2 peer (BGP Peer A) has the capability to send
either FSv1 or FSv2. BGP Peer A peers with BGP Peers B, C, D and
E.
BGP Peer B can only send FSv1 routes (NLRI + Extended Community).
BGP Peer C can send FSv2 routes (NLRI + path attributes (wide
community or extended community or none)). BGP Peer D cannot send
any FS routes. BGP E can send FSv2 and FSv1 routes
BGP Peer A sends FSv1 routes in its databases to BGP B. Since the
FSv2 NLRI cannot be sent to the FSv1 peer, only the FSv1 NLRI is
sent. BGP Peer A sends to BGP C the FSv2 routes in its database
(configured or received).
BGP peer A would not send the FSv1 NLRI or FSv2 NLRI to BGP Peer
D. The BGP Peer D does not support for these NLRI.
BGP Peer A sends the NLRI for both FSv1 and FSv2 to BGP Peer E.
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+---------+ +---------+
| A |=======================| C |
|FSv1+FSv2|. . .| FSv2 |
+---------+ . . +---------+
|| | \ . . . ||
|| | \ . . . . . . . . . . ||
|| | \ . . . ||
|| | \-----\ . . . ||
|| | \ . . . ||
+---------+ +------+ +-----+ ||
| E |-------| B |. . . .| D | ||
|FSv1+FSv2| | FSv1 | |no FS| ||
+---------+ +------+ +-----+ ||
|| . . ||
|| . . . . . . . . . . . . . . ||
|| ||
|========================================|
Double line = FSv2
Single line = FSv1
Dotted line = BGP peering with no FlowSpec
Figure 4-1: FSv1 and FVs2 Peering
5. Scalability and Aspirations for FSv2
Operational issues drive the deployment of BGP flow specification as
a quick and scalable way to distribute filters. The early operations
accepted the fact validation of the distribution of filter needed to
be done outside of the BGP distribution mechanism. Other mechanisms
(NETCONF/RESTCONF or PCEP) have reply-request protocols.
These features within BGP have not changed. BGP still does not have
an action-reply feature.
NETCONF/RESTCONF latest enhancements provide action/response features
which scale. The combination of a quick distribution of filters via
BGP and a long-term action in NETCONF/RESTCONF that ask for reporting
of the installation of FSv2 filters may provide the best scalability.
The combination of NETCONF/RESTCONF network management protocols and
BGP focuses each protocol on the strengths of scalability.
FSv2 will be deployed in webs of BGP peers which have some BGP peers
passing FSv1, some BGP peers passing FSv2, some BGP peers passing
FSv1 and FSv2, and some BGP peers not passing any routes.
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The TLV encoding and deterministic behaviors of FSv2 will not
deprecate the need for careful design of the distribution of flow
specification filters in this mixed environment. The needs of
networks for flow specification are different depending on the
network topology and the deployment technology for BGP peers sending
flow specification.
Suppose we have a centralized RR connected to DDoS processing sending
out flow specification to a second tier of RR who distribute the
information to targeted nodes. This type of distribution has one set
of needs for FSv2 and the transition from FSv1 to FSv2
Suppose we have Data Center with a 3-tier backbone trying to
distribute DDoS or other filters from the spine to combinational
nodes, to the leaf BGP nodes. The BGP peers may use RR or normal BGP
distribution. This deployment has another set of needs for FSv2 and
the transition from FSv1 to FSV2.
Suppose we have a corporate network with a few AS sending DDoS
filters using basic BGP from a variety of sites. Perhaps the
corporate network will be satisfied with FSv1 for a long time.
These examples are given to indicate that BGP FSv2, like so many BGP
protocols, needs to be carefully tuned to aid the mitigation services
within the network. This protocol suite starts the migration toward
better tools using FSv2, but it does not end it. With FSv2 TLVs and
deterministic actions, new operational mechanisms can start to be
understood and utilized.
This FSv2 specification is merely the start of a revolution of work –
not the end.
6. Optional Security Additions
This section discusses the optional BGP Security additions for BGP-FS
v2 relating to BGPSEC [RFC8205] and ROA [RFC6482].
6.1. BGP FSv2 and BGPSEC
Flow specification v1 ([RFC8955] and [RFC8956]) do not comment on how
BGP Flow specifications to be passed BGPSEC [RFC8205] BGP Flow
Specification v2 can be passed in BGPSEC, but it is not required.
FSv1 and FSv2 may be sent via BGPSEC.
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6.2. BGP FSv2 with ROA
BGP FSv2 can utilize ROAs in the validation. If BGP FSv2 is used
with BGPSEC and ROA, the first thing is to validate the route within
BGPSEC and second to utilize BGP ROA to validate the route origin.
The BGP-FS peers using both ROA and BGP-FS validation determine that
a BGP Flow specification is valid if and only if one of the following
cases:
* If the BGP Flow Specification NLRI has a IPv4 or IPv6 address in
destination address match filter and the following is true:
- A BGP ROA has been received to validate the originator, and
- The route is the best-match unicast route for the destination
prefix embedded in the match filter; or
* If a BGP ROA has not been received that matches the IPv4 or IPv6
destination address in the destination filter, the match filter
must abide by the [RFC8955] and [RFC8956] validation rules as
follows:
- The originator match of the flow specification matches the
originator of the best-match unicast route for the destination
prefix filter embedded in the flow specification", and
- No more specific unicast routes exist when compared with the
flow destination prefix that have been received from a
different neighboring AS than the best-match unicast route,
which has been determined in step A.
The best match is defined to be the longest-match NLRI with the
highest preference.
7. IANA Considerations
This section complies with [RFC7153].
7.1. Flow Specification V2 SAFIs
IANA is requested to assign two SAFI Values in the registry at
https://www.iana.org/assignments/safi-namespace from the Standard
Action Range as follows:
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Table 7-1 SAFIs
Value Description Reference
----- ------------- ---------------
TBD1 BGP FSv2 [this document]
TBD2 BGP FSv2 VPN [this document]
7.2. BGP Capability Code
IANA is requested to assign a Capability Code from the registry at
https://www.iana.org/assignments/capability-codes/ from the IETF
Review range as follows:
Table 7-2 - Capability Code
Value Description Reference Controller
----- --------------------- --------------- ----------
TBD3 Flow Specification V2 [this document] IETF
7.3. Filter IP Component types
IANA is requested to create a FSv2 Component Types registry and
indicate [this draft] as a reference. The following assignments in
the FSv2 Component Types Registry shold be made.
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Table 7-3 - Flow Specification
Registry Name: BGP FSv2 TLV types
Reference: [this document]
Registration Procedures: 0x01-0x3FFF Standards Action.
Value Description Reference
----- ------------------- ------------------------
1 Destination filter [RFC8955][RFC8956][this document]
2 Source Prefix [RFC8955][RFC8956][this document]
3 IP Protocol [RFC8955][RFC8956][this document]
4 Port [RFC8955][RFC8956][this document]
5 Destination Port [RFC8955][RFC8956][this document]
6 Source Port [RFC8955][RFC8956][this document]
7 ICMP Type [v4 or v6][RFC8955][RFC8956][this document]
8 ICMP Code [v4 or v6][RFC8955][RFC8956][this document]
9 TCP Flags [v4] [RFC8955][RFC8956][this document]
10 Packet Length [RFC8955][RFC8956][this document]
11 DSCP marking [RFC8955][RFC8956][this document]
12 Fragment [RFC8955][RFC8956][this document]
13 Flow Label [RFC8956][this document]
14 TTL [this document]
7.4. FSV2 NLRI TLV Types
IANA is requested to create the a new registries on a new "Flow
Specification v2 TLV Types” web page.
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Table 7-4 FSv2 TLV types
Registry Name: BGP FSv2 TLV types
Reference: [this document]
Registration Procedures: 0x01-0x3FFF Standards Action.
Type Description Reference
----- ----------------------- -------------
0x00 Reserved [this document]
0x01 IP traffic rules [this document]
0x02 Extended IP Rules [this document]
0x03 L2 traffic rules [this document]
0x04 SFC AFI traffic rules [this document]
0x05 SFC VPN traffic rules [this document]
0x06 BGP/MPLS IP VPN traffic rules [this document]
0x07 BGP/MPLS L2 VPN traffic rules [this document]
0x08-
0x3FFF Unassigned [this document]
0x4000-
0x7FFF Vendor specific [this document]
0x8000-
0xFFFF Reserved [this document]
7.5. Community Container Type Assignments
IANA is requested to assign values from the BGP Community Container
Types registry:
Tab;e 5 -
Name type Value
------ -----------
FSv2 Actions TBD4
8. Security Considerations
The use of ROA improves on [RFC8955] by checking to see of the route
origination. This check can improve the validation sequence for a
multiple-AS environment.
>The use of BGPSEC [RFC8205] to secure the packet can increase
security of BGP flow specification information sent in the packet.
The use of the reduced validation within an AS [RFC9117] can provide
adequate validation for distribution of flow specification within a
single autonomous system for prevention of DDoS.
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Distribution of flow filters may provide insight into traffic being
sent within an AS, but this information should be composite
information that does not reveal the traffic patterns of individuals.
9. References
9.1. Normative References
[I-D.ietf-idr-bgp-flowspec-label]
liangqiandeng, Hares, S., You, J., Raszuk, R., and D. Ma,
"Carrying Label Information for BGP FlowSpec", Work in
Progress, Internet-Draft, draft-ietf-idr-bgp-flowspec-
label-02, 20 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
flowspec-label-02>.
[I-D.ietf-idr-flowspec-interfaceset]
Litkowski, S., Simpson, A., Patel, K., Haas, J., and L.
Yong, "Applying BGP flowspec rules on a specific interface
set", Work in Progress, Internet-Draft, draft-ietf-idr-
flowspec-interfaceset-05, 18 November 2019,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-interfaceset-05>.
[I-D.ietf-idr-flowspec-l2vpn]
Weiguo, H., Eastlake, D. E., Litkowski, S., and S. Zhuang,
"BGP Dissemination of L2 Flow Specification Rules", Work
in Progress, Internet-Draft, draft-ietf-idr-flowspec-
l2vpn-23, 15 April 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-l2vpn-23>.
[I-D.ietf-idr-flowspec-mpls-match]
Yong, L., Hares, S., liangqiandeng, and J. You, "BGP Flow
Specification Filter for MPLS Label", Work in Progress,
Internet-Draft, draft-ietf-idr-flowspec-mpls-match-02, 20
October 2022, <https://datatracker.ietf.org/doc/html/
draft-ietf-idr-flowspec-mpls-match-02>.
[I-D.ietf-idr-flowspec-nvo3]
Eastlake, D. E., Weiguo, H., Zhuang, S., Li, Z., and R.
Gu, "BGP Dissemination of Flow Specification Rules for
Tunneled Traffic", Work in Progress, Internet-Draft,
draft-ietf-idr-flowspec-nvo3-19, 26 December 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-nvo3-19>.
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[I-D.ietf-idr-flowspec-path-redirect]
Van de Velde, G., Patel, K., and Z. Li, "Flowspec
Indirection-id Redirect", Work in Progress, Internet-
Draft, draft-ietf-idr-flowspec-path-redirect-12, 24
November 2022, <https://datatracker.ietf.org/doc/html/
draft-ietf-idr-flowspec-path-redirect-12>.
[I-D.ietf-idr-flowspec-redirect-ip]
Uttaro, J., Haas, J., Texier, M., akarch@cisco.com, Ray,
S., Simpson, A., and W. Henderickx, "BGP Flow-Spec
Redirect to IP Action", Work in Progress, Internet-Draft,
draft-ietf-idr-flowspec-redirect-ip-02, 5 February 2015,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-redirect-ip-02>.
[I-D.ietf-idr-flowspec-srv6]
Li, Z., Li, L., Chen, H., Loibl, C., Mishra, G. S., Fan,
Y., Zhu, Y., Liu, L., and X. Liu, "BGP Flow Specification
for SRv6", Work in Progress, Internet-Draft, draft-ietf-
idr-flowspec-srv6-05, 29 March 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-srv6-05>.
[I-D.ietf-idr-wide-bgp-communities]
Raszuk, R., Haas, J., Lange, A., Decraene, B., Amante, S.,
and P. Jakma, "BGP Community Container Attribute", Work in
Progress, Internet-Draft, draft-ietf-idr-wide-bgp-
communities-11, 9 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
wide-bgp-communities-11>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[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>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
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[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>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <https://www.rfc-editor.org/info/rfc4360>.
[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>.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065,
DOI 10.17487/RFC5065, August 2007,
<https://www.rfc-editor.org/info/rfc5065>.
[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>.
[RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)", RFC 6482,
DOI 10.17487/RFC6482, February 2012,
<https://www.rfc-editor.org/info/rfc6482>.
[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>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<https://www.rfc-editor.org/info/rfc7606>.
[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>.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
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[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/info/rfc8956>.
[RFC9015] Farrel, A., Drake, J., Rosen, E., Uttaro, J., and L.
Jalil, "BGP Control Plane for the Network Service Header
in Service Function Chaining", RFC 9015,
DOI 10.17487/RFC9015, June 2021,
<https://www.rfc-editor.org/info/rfc9015>.
[RFC9117] Uttaro, J., Alcaide, J., Filsfils, C., Smith, D., and P.
Mohapatra, "Revised Validation Procedure for BGP Flow
Specifications", RFC 9117, DOI 10.17487/RFC9117, August
2021, <https://www.rfc-editor.org/info/rfc9117>.
[RFC9184] Loibl, C., "BGP Extended Community Registries Update",
RFC 9184, DOI 10.17487/RFC9184, January 2022,
<https://www.rfc-editor.org/info/rfc9184>.
9.2. Informative References
[I-D.ietf-idr-flowspec-v2]
Hares, S., Eastlake, D., Yadlapalli, C., and S. Maduschke,
"BGP Flow Specification Version 2", Work in Progress,
Internet-Draft, draft-ietf-idr-flowspec-v2-04, 28 April
2024, <https://datatracker.ietf.org/api/v1/doc/document/
draft-ietf-idr-flowspec-v2/>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
Specification", RFC 8205, DOI 10.17487/RFC8205, September
2017, <https://www.rfc-editor.org/info/rfc8205>.
[RFC8206] George, W. and S. Murphy, "BGPsec Considerations for
Autonomous System (AS) Migration", RFC 8206,
DOI 10.17487/RFC8206, September 2017,
<https://www.rfc-editor.org/info/rfc8206>.
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[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
"Network Service Header (NSH)", RFC 8300,
DOI 10.17487/RFC8300, January 2018,
<https://www.rfc-editor.org/info/rfc8300>.
Authors' Addresses
Susan Hares
Hickory Hill Consulting
7453 Hickory Hill
Saline, MI 48176
United States of America
Phone: +1-734-604-0332
Email: shares@ndzh.com
Donald Eastlake
Futurewei Technologies
2386 Panoramic Circle
Apopka, FL 32703
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Chaitanya Yadlapalli
ATT
United States of America
Email: cy098d@att.com
Sven Maduschke
Verizon
Germany
Email: sven.maduschke@de.verizon.com
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