Internet DRAFT - draft-wu-idr-flowspec-redirect-group
draft-wu-idr-flowspec-redirect-group
IDR Working Group Z. Wu
Internet-Draft H. Wang
Intended status: Standards Track L. Wang
Expires: 7 September 2023 Z. Tan
X. Ding
Huawei Technologies
6 March 2023
BGP Flowspec Redirect Load Balancing Group Community
draft-wu-idr-flowspec-redirect-group-01
Abstract
This document defines an extension to "BGP Community Container
Attribute" [draft-ietf-idr-wide-bgp-communities], which allows
flowspec redirection to multiple paths. This extended community
serves to redirect traffic to a load balancing group and supports
both equal-cost multi-path(ECMP) and unequal-cost multi-path(UCMP)
scenarios.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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 7 September 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Redirect Load Balancing Group Community . . . . . . . . . . . 3
2.1. Community Value . . . . . . . . . . . . . . . . . . . . . 4
2.2. Param TLV . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Sub-TLVs(Path-tlvs) . . . . . . . . . . . . . . . . . . . 5
2.3.1. Path-tlv Type 1: IPv4 Prefix Only . . . . . . . . . . 6
2.3.2. Path-tlv Type 2: IPv4 Prefix with Weight . . . . . . 6
2.3.3. Path-tlv Type 3: IPv4 Prefix with Color . . . . . . . 7
2.3.4. Path-tlv Type 4: IPv4 Prefix with Color and Weight . 8
2.3.5. Path-tlv Type 5: IPv6 Prefix Only . . . . . . . . . . 8
2.3.6. Path-tlv Type 6: IPv6 Prefix with Weight . . . . . . 9
2.3.7. Path-tlv Type 7: IPv6 Prefix with Color . . . . . . . 10
2.3.8. Path-tlv Type 8: IPv6 Prefix with Color and Weight . 10
3. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1. ECMP . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2. UCMP . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4. Validation Procedure . . . . . . . . . . . . . . . . . . . . 12
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. Redirect Group Wide Community Parameter TLV . . . . . . . 12
5.2. Redirect Group Wide Community Parameter Sub-TLVs . . . . 12
6. Operational Considerations . . . . . . . . . . . . . . . . . 12
6.1. Configuration Control . . . . . . . . . . . . . . . . . . 13
6.2. Parsing . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.3. Formating . . . . . . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7.1. BGP Wide Communities Community Type : Redirect Group . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. References . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
"Redirect to IP Extended Community", defined in
[I-D.ietf-idr-flowspec-redirect-ip], allows traffic to be redirected
to a specific IPv4 or IPv6 address, and
[I-D.ietf-idr-ts-flowspec-srv6-policy] defines the redirection action
to a SRv6 tunnel by additionally carrying the "Color Extended
Community" [RFC8955].
However, scenarios involving redirection load balancing are not
described in both documents. Although in some implementations,
Equal-cost multi-path(ECMP) of "Redirect to IP" action can be
achieved by encoding multiple redirect Extended Communities, the
current set of mechanisms can hardly support neither ECMP of SRv6
tunnels nor unequal-cost multi-path(UCMP) of either types.
This document defines an extension to "BGP Community Container
Attribute" [I-D.ietf-idr-wide-bgp-communities], the "Redirect Load
Balancing Group" community. It is a new type of wide community
container attribute with encoding format of multiple redirection path
TLVs. Each of these TLVs represents a different redirection action.
It allows traffic redirection to a load balancing group and supports
both ECMP and UCMP scenarios.
The "Redirect Load Balancing Group" community is intended to be used
within flowspec-v1 scenarios, the compatibility and interactions with
flowspec-v2 is outside the scope of this document.
1.1. Terminology
This document introduces the following terms:
ECMP: Equal-Cost Multi-Path
UCMP: Unequal-Cost Multi-Path
Redirect Group: Redirect Load Balancing Group Community, a new type
of BGP Community Container Attribute defined by this document
Path-tlv: Sub-tlv of the BGP Wide Community Parameter TLV, each
represents a redirection path
2. Redirect Load Balancing Group Community
This document defines a new type of "BGP Community Container
Attribute", the "Redirect Load Balancing Group" community type. The
format complies with "BGP Community Container Attribute"
[I-D.ietf-idr-wide-bgp-communities] and is shown below:
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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 | Flags |C|T| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Community Value: Redirect Load Balancing Group |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Context AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Param TLV | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| sub-TLVs |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Redirect Load Balancing Group Community Format
The Type, Flags, Reserved and Length fields comply with the "BGP
Community Container Attribute Common Header" definition.
The container type MUST be 1, which represents BGP Wide Community.
The Length field represents the total length of the container's
contents in octets.
2.1. Community Value
The Community Value, Source AS Number and Context AS Number fields
comply with the corresponding definition in "BGP Community Container
Attribute".
Community Value: 4 octets value that represents the "Redirect Load
Balancing Group" community type. The value is TBD and requires IANA
registration; See Section 5.1.
2.2. Param TLV
The BGP Wide Community Parameter TLV (Sub-Type 3) contains a list of
path-tlvs, comply with "BGP Wide Community Parameter(s) TLV" section
of "BGP Community Container Attribute".
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The Parameter TLV MUST present and SHOULD appear only once in a
"Redirect Load Balancing Group" community container, no or multiple
present SHOULD be considered malformed.
Sub-Type: Type 3 (BGP Wide Community Parameter TLV)
Length: Length of all the sub-TLVs in octets.
2.3. Sub-TLVs(Path-tlvs)
The list of path-tlvs that Param Tlv contains. Each path-tlv
represents a different redirection path.
The general format of the sub-TLVs comply with path-tlvs' format
defined in "BGP Community Container Attribute", as below:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Param Sub-TlV Format
The Type field is an octet from 1~254 (0 and 255 are reserved).
Supported type of the sub-TLVs includes:
Type 1: IPv4 Prefix Only
Type 2: IPv4 Prefix with Weight
Type 3: IPv4 Prefix with Color
Type 4: IPv4 Prefix with Color and Weight
Type 5: IPv6 Prefix Only
Type 6: IPv6 Prefix with Weight
Type 7: IPv6 Prefix with Color
Type 8: IPv6 Prefix with Color and Weight
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These sub-TLV types SHOULD be used exclusively within "Redirect Load
Balancing Group" community containers.
The Length represents the length of the "Value" field in octets, and
it is fixed for each specific sub-TLV.
If the length and type of a sub-TLV do not match, the "Redirect Load
Balancing Group" community container SHOULD be considered malformed.
If a sub-TLV is a total dupilication of a previous one, the latter
sub-TLV MUST be ignored.
In principle, sub-TLVs of different types may be combined in any
mode. The supported combinations depend on the specific
implementation.
2.3.1. Path-tlv Type 1: IPv4 Prefix Only
Indicating the redirection path is unweighted and to a IPv4 address.
The format is shown below:
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: 1 | Length: 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Path-tlv Type 1: IPv4 Prefix Only
Length: MUST be 6.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv4: 4-octet IPv4 address, redirection destination
2.3.2. Path-tlv Type 2: IPv4 Prefix with Weight
Indicating the redirection path is weighted and to a IPv4 address.
The format is shown below:
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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: 2 | Length: 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight(1) |
+-+-+-+-+-+-+-+-+
Figure 4: Path-tlv Type 2: IPv4 Prefix with Weight
Length: MUST be 7.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv4: 4-octet IPv4 address, redirection destination
Weight: 1 octet, values from 1~255, load balancing weight
2.3.3. Path-tlv Type 3: IPv4 Prefix with Color
Indicating the redirection path is unweighted and to a SR-TE tunnel.
The format is shown below:
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: 3 | Length: 10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Path-tlv Type 3: IPv4 Prefix with Color
Length: MUST be 10.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv4: 4-octet IPv4 address, SR-TE tunnel Endpoint for redirection
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Color: 4 octets, SR-TE tunnel Color for redirection
2.3.4. Path-tlv Type 4: IPv4 Prefix with Color and Weight
Indicating the redirection path is weighted and to a SR-TE tunnel.
The format is shown below:
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: 4 | Length: 11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight(1) |
+-+-+-+-+-+-+-+-+
Figure 6: Path-tlv Type 4: IPv4 Prefix with Color and Weight
Length: MUST be 11.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv4: 4-octet IPv4 address, SR-TE tunnel Endpoint for redirection
Color: 4 octets, SR-TE tunnel Color for redirection
Weight: 1 octet, values from 1~255, load balancing weight
2.3.5. Path-tlv Type 5: IPv6 Prefix Only
Indicating the redirection path is unweighted and to a IPv6 address.
The format is shown below:
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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: 5 | Length: 18 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6(16) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Path-tlv Type 5: IPv6 Prefix Only
Length: MUST be 18.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv6: 16-octet IPv6 address, redirection destination
2.3.6. Path-tlv Type 6: IPv6 Prefix with Weight
Indicating the redirection path is weighted and to a IPv6 address.
The format is shown below:
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: 6 | Length: 19 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6(16) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight(1) |
+-+-+-+-+-+-+-+-+
Figure 8: Path-tlv Type 6: IPv6 Prefix with Weight
Length: MUST be 19.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv6: 16-octet IPv6 address, redirection destination
Weight: 1 octet, values from 1~255, load balancing weight
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2.3.7. Path-tlv Type 7: IPv6 Prefix with Color
Indicating the redirection path is unweighted and to a SRv6 tunnel.
The format is shown below:
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: 7 | Length: 22 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6(16) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Path-tlv Type 7: IPv6 Prefix with Color
Length: MUST be 22.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv6: 16-octet IPv6 address, SRv6 tunnel Endpoint for redirection
Color: 4 octets, SRv6 tunnel Color for redirection
2.3.8. Path-tlv Type 8: IPv6 Prefix with Color and Weight
Indicating the redirection path is weighted and to a SRv6 tunnel.
The format is shown below:
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: 8 | Length: 23 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6(16) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight(1) |
+-+-+-+-+-+-+-+-+
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Figure 10: Path-tlv Type 8: IPv6 Prefix with Color and Weight
Length: MUST be 23.
Flags: 2 octets, reserved for future use, MUST be set to 0 upon the
sender and MUST be ignored upon the receiver.
IPv6: 16-octet IPv6 address, SRv6 tunnel Endpoint for redirection
Color: 4 octets, SRv6 tunnel Color for redirection
Weight: 1 octet, values from 1~255, load balancing weight
3. Scenarios
This section describes a few use-case scenarios when deploying
"Redirect Load Balancing Group" community type.
Weighted path-tlv types: Path-tlvs contain a Weight field, such as
Type 2, 4, 6, 8
Unweighted path-tlv types: Path-tlvs do not contain a Weight field,
such as Type 1, 3, 5, 7
3.1. ECMP
A system that originates a flowspec route with a "Redirect Load
Balancing Group" community, among which its parameter TLV contains
more than 1 path-tlvs. If not all path-tlvs are of a weighted type,
these path-tlvs will form a ECMP group.
Implementations MUST be prepared to accept a Parameter TLV with both
weighted and unweighted path-tlvs. In this case, the Weight field of
the weighted path-tlv SHOULD be ignored.
3.2. UCMP
A system that originates a flowspec route with a "Redirect Load
Balancing Group" community, among which its parameter TLV contains
more than 1 path-tlvs. If all path-tlvs are of a weighted type,
these path-tlvs will form a UCMP group.
In this case, the Weight field value of these path-tlvs SHOULD NOT be
ignored, and the values are used as the ratio of the UCMP group.
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4. Validation Procedure
In the absence of explicit configuration, a Redirect Group attribute
MUST be validated before it is used for redirection action or sent to
a BGP peer.
The validation procedure for a Redirect Group attribute follows the
following rules:
* Each Path-tlv of the Redirect Group attribute SHOULD be validated
separately. The validation of each path follows the validation
procedure of Redirect to IP Action
[I-D.ietf-idr-flowspec-redirect-ip].
* A Redirect Group attribute SHOULD be considered verified, only
after all path-tlvs in the Redirect Group attribute are verified.
* If any path-tlvs are invalid, these paths SHOULD NOT participate
in load-balance calculation and used for redirection actions.
* If any path-tlvs are invalid, the Redirect Group attribute SHOULD
NOT be sent to a BGP peer.
5. Error Handling
Comply with Error Handling Procedure in "BGP Community Container
Attribute" [I-D.ietf-idr-wide-bgp-communities].
In addition:
5.1. Redirect Group Wide Community Parameter TLV
A "Redirect Load Balancing Group" community container with no or
multiple parameter TLVs SHOULD be considered malformed, and a "treat
as withdraw" behavior is expected.
5.2. Redirect Group Wide Community Parameter Sub-TLVs
If the length and type of a sub-TLV do not match, the "Redirect Load
Balancing Group" community container SHOULD be considered malformed,
and a "treat as withdraw" behavior is expected.
6. Operational Considerations
The Extended Community attributes for redirection mentioned in this
section include:
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* Redirect to IP Extended Community
[I-D.ietf-idr-flowspec-redirect-ip]
* Redirect to IPv6 Extended Community
[I-D.ietf-idr-flowspec-redirect-ip]
* Redirect to SRv6 Policy [I-D.ietf-idr-ts-flowspec-srv6-policy]
6.1. Configuration Control
There SHOULD be an explicit configuration to control whether the
Redirect Group attribute is used for redirection actions. In the
absence of the explicit configuration(by default), the Redirect Group
attribute MAY NOT take precedence over Extended Community attribute.
With the explicit configuration, the Redirect Group attribute MAY
take precedence over Extended Community attribute for redirection.
For clarity, the first scenario, in which the Redirect Group
attribute does not take precedence, is called configuration situation
A. And the second scenario is called configuration situation B.
6.2. Parsing
While receiving a flowspec route with Redirect Group attribute from a
BGP peer:
* In configuration situation A, the Redirect Group attribute SHOULD
NOT be used for redirection actions. If the route carries
Extended Community attributes for redirection, these attributes
MAY be used to generate the redirection actions. The Redirect
Group attribute SHOULD still be saved locally and advertised with
the fowspec route to other appropriate peers.
* In configuration situation B, the Redirect Group attribute SHOULD
take precedence over Extended Community attribute for redirection.
If the route carries Extended Community attributes for
redirection, these attributes SHOULD NOT be used to generate the
redirection actions, but SHOULD still be saved locally and
advertised with the fowspec route to other appropriate peers.
6.3. Formating
While encoding a local-generated flowspec route:
* In configuration situation A, a Redirect Group attribute SHOULD
NOT be encoded. Appropriate Extended Community attributes MAY be
used for specifying redirection actions.
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* In configuration situation B, the Redirect Group attribute SHOULD
be encoded for specifying redirection actions, despite of there is
one or more paths. For the sake of compatibility, we MAY select
the path with the lowest IP address from the paths of the Redirect
Group attribute and encode it with appropriate Extended Community
attributes. During this selection, an IPv4 address is preferred
over an IPv6 address.
While encoding a flowspec route learned from other BGP peers:
* In configuration situation A, the Redirect Group attribute MUST be
encoded without modification.
* In configuration situation B, the Redirect Group attribute MUST
pass the validation procedure before it is encoded and sent to a
BGP peer.
7. IANA Considerations
7.1. BGP Wide Communities Community Type : Redirect Group
This document requests a new community value under "Registered Type 1
BGP Wide Community Community Types" registery. This registery is
defined and requested in "BGP Community Container Attribute"
[I-D.ietf-idr-wide-bgp-communities].
Requested value:
Name Type Value
---- ----------
Redirect Load Balancing Group TBD
8. Security Considerations
A system that originates a flowspec route with a "Redirect Load
Balancing Group" BGP wide community can cause many receivers of that
route to redirect traffic to a single next-hop, overwhelming that
next-hop and resulting in inadvertent or deliberate denial-of-
service. This is also a concern about the "redirect to IP" extended
community, therefore this document introduces no additional security
considerations than those already covered in [RFC8955].
9. References
9.1. Normative References
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[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-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-10, 2 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
wide-bgp-communities-10>.
[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>.
9.2. References
[I-D.ietf-idr-ts-flowspec-srv6-policy]
Wenying, J., Liu, Y., Zhuang, S., Mishra, G. S., and S.
Chen, "Traffic Steering using BGP FlowSpec with SRv6
Policy", Work in Progress, Internet-Draft, draft-ietf-idr-
ts-flowspec-srv6-policy-01, 9 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-ts-
flowspec-srv6-policy-01>.
[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>.
[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>.
Authors' Addresses
Wu, et al. Expires 7 September 2023 [Page 15]
Internet-Draft Flowspec Redirect Load Balancing March 2023
Zhiwen Wu
Huawei Technologies
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: wuzhiwen1@huawei.com
Haibo Wang
Huawei Technologies
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: rainsword.wang@huawei.com
Lili Wang
Huawei Technologies
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: lily.wong@huawei.com
Zhen Tan
Huawei Technologies
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: tanzhen6@huawei.com
Xiangfeng Ding
Huawei Technologies
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: dingxiangfeng@huawei.com
Wu, et al. Expires 7 September 2023 [Page 16]
