Internet DRAFT - draft-wu-idr-flowspec-dip-community-filter
draft-wu-idr-flowspec-dip-community-filter
Network Working Group T. Wu
Internet-Draft J. Ge
Intended status: Standards Track X. Ding
Expires: 31 August 2024 H. Wang
Huawei
28 February 2024
Destination-IP-Community Filter for BGP Flow Specification
draft-wu-idr-flowspec-dip-community-filter-00
Abstract
BGP Flowspec mechanism (BGP-FS) propagates both traffic Flow
Specifications and Traffic Filtering Actions by making use of the BGP
NLRI and the BGP Extended Community encoding formats. This document
specifies a new BGP-FS component type to support community-level
filtering. The match field is the community of the destination IP
address that is encoded in the Flowspec NLRI. This function is
applied in a single administrative domain.
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 [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
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 31 August 2024.
Copyright Notice
Copyright (c) 2024 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 2
3. The Flow Specification Encoding for Destination-IP-Community
Filter . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
BGP Flow Specification (BGP-FS) [RFC8955] [RFC8956] defines a new BGP
NLRI to distribute traffic flow specification rules via BGP
([RFC4271]). BGP-FS policies have a match condition that may be
n-tuple match in a policy, and an action that modifies the packet and
forwards/drops the packet. Via BGP, new filter rules can be sent to
all BGP peers simultaneously without changing router configuration,
and the BGP peer can install these routes in the forwarding table.
BGP-FS defines Network Layer Reachability Information (NLRI) format
used to distribute traffic flow specification rules. NLRI (AFI=1,
SAFI=133) is for IPv4 unicast filtering. NLRI (AFI=1, SAFI=134) is
for BGP/MPLS VPN filtering.[I-D.ietf-idr-flowspec-l2vpn] extends the
flow-spec rules for layer 2 Ethernet packets.
This document specifies a new BGP-FS component type to support
community-level filtering. The match field is the community of the
destination IP address that is encoded in the Flowspec NLRI. This
function is applied in a single administrative domain.
2. Definitions and Acronyms
* FS: Flow Specification
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* Destination-IP-Community: The community of the destination IP
address
3. The Flow Specification Encoding for Destination-IP-Community Filter
This document proposes a new flow specification component type that
is encoded in the BGP Flowspec NLRI. The following new component
type is defined.
* Destination-IP-Community
Type TBD1 - Destination-IP-Community
Encoding: <type (1 octet), [op, value]+>
Contains a set of {operator, value} pairs that are used to match the
Destination-IP-Community (i.e. the community of the destination IP
address).
The operator byte is encoded as:
0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| e | a | len | 0 |lt |gt |eq |
+---+---+---+---+---+---+---+---+
Figure 1: Numeric Operator (numeric_op)
Where:
e - end-of-list bit. Set in the last {op, value} pair in the list.
a - AND bit. If unset, the previous term is logically ORed with the
current one. If set, the operation is a logical AND. It MUST be
unset in the Destination-IP-Community filter.
len - The length of the value field for this operator given as (1 <<
len). This encodes 1 (len=00), 2 (len=01), 4 (len=10), and 8
(len=11) octets.
lt - less than comparison between data and value.
gt - greater than comparison between data and value.
eq - equality between data and value.
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The bits lt, gt, and eq can be combined to produce match the
Destination-IP-Community filter or a range of Destination-IP-
Community filter(e.g. less than community 1 and greater than
community 2).
The value field is encoded as:
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
+---------------------------------------------------------------+
~ Destination-IP-Community (4 octets) ~
+---------------------------------------------------------------+
Figure 2: Destination-IP-Community
Per section 10 of [RFC8955] , If a receiving BGP speaker cannot
support this new Flow Specification component type, it MUST discard
the NLRI value field that contains such unknown components. Since
the NLRI field encoding (Section 4 of [RFC8955]) is defined in the
form of a 2-tuple <length, NLRI value>, message decoding can skip
over the unknown NLRI value and continue with subsequent remaining
NLRI.
4. Use Cases
This section describes how to use this function in a simple scenario.
Considering the topology shown in Figure 3 ("Comm" is short for
"Community"). In AS64597's R1, if the ISP AS64597 wants to redirect
all packets originating from IP Prefix 61 to AS64598 and AS64599:
"first go to R3", the ISP AS64597 can use the traditional method or
the method defining in this draft.
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+---------+
| BGP FS |
| Server |
+----|----+
|
|
/
/
************/************
* / *
IP Prefix 61 * / AS64597 * IP Prefix 81 with Comm 1:1
* / * IP Prefix 82 with Comm 1:1
+-------+ * +---+/ +---+ * +-------+
+AS64596+-------+ R1+---------+ R2|------+AS64598+
+-------+ * +-+-+\ +---+ */ +-------+
* \ |\ /
* \ | \ /*
* \ | /\*
* \ | / \ IP Prefix 91 with Comm 1:1
* \ |/ *\ IP Prefix 92 with Comm 1:1
* \ +-+-+ * \ +-------+
* \-+ R3+------+AS64599+
* +---+ * +-------+
* *
*************************
Figure 3: Redirect the traffic using Flowspec
Using the traditional method, the ISP AS64597 needs to setup multiple
"Destination Prefix + Source Prefix" rules in Router R1 as following:
+--------------+--------------+-------------------------+
| Destination | Source Prefix| Redirect to IP Nexthop |
| Prefix | | |
+--------------+--------------+-------------------------+
| IP Prefix 81 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
| IP Prefix 82 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
| IP Prefix 91 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
| IP Prefix 92 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
| More ... |
+--------------+--------------+-------------------------+
Figure 4: Using the traditional method to redirect the traffic
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Using the method defining in this draft, the ISP AS64597 needs to
setup only one "Destination Community + Source Prefix" rule in Router
R1 as following:
+--------------+--------------+-------------------------+
| Destination | Source Prefix| Redirect to IP Nexthop |
| Community | | |
+--------------+--------------+-------------------------+
| 1::1 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
Figure 5: Using the community-level filtering method to redirect the traffic
Obviously, the new method defining in this draft saves a lot of entry
spaces on the control plane and forwarding plane, and it would
greatly simplify the operation of the control plane, and the more
destination prefixes with the same community has, the more obvious
the benefit.
5. IANA Considerations
IANA is requested to a new entry in "Flow Spec component types
registry" with the following values:
+---------+--------------+---------------------------------+
| Type | RFC or Draft | Description |
+---------+--------------+---------------------------------+
| TBD1 | This Draft | Destination-IP-Community |
+---------+--------------+---------------------------------+
6. Security Considerations
No new security issues are introduced to the BGP protocol by this
specification.
7. References
7.1. Normative References
[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>.
7.2. Informative References
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[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-22, 16 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-l2vpn-22>.
[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>.
[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
Tianhao Wu
Huawei
Email: wutianhao10@huawei.com
Jun Ge
Huawei
Email: jack.gejun@huawei.com
Xiangfeng Ding
Huawei
Email: dingxiangfeng@huawei.com
Haibo Wang
Huawei
Email: rainsword.wang@huawei.com
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