Network Working Group H. Wang
Internet-Draft Huawei
Intended status: Standards Track A. Wang
Expires: January 13, 2022 China Telecom
S. Zhuang
Huawei
July 12, 2021
Destination-IP-Origin-AS Filter for BGP Flow Specification
draft-wang-idr-flowspec-dip-origin-as-filter-04
Abstract
BGP Flowspec mechanism (BGP-FS) [RFC8955] [RFC8956]propogates 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 AS-
level filtering. The match field is the origin AS number 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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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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 13, 2022.
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Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3
3. The Flow Specification Encoding for Destination-IP-Origin-AS
Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Use Case . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
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][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 AS-
level filtering. The match field is the origin AS number of the
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destination IP address that is encoded in the Flowspec NLRI. This
function is applied in a single administrative domain.
2. Definitions and Acronyms
o FS: Flow Specification
o Destination-IP-Origin-AS: The origin AS number of the destination
IP address
3. The Flow Specification Encoding for Destination-IP-Origin-AS 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.
o Destination-IP-Origin-AS
Type TBD1 - Destination-IP-Origin-AS
Encoding: <type (1 octet), [op, value]+>
Contains a set of {operator, value} pairs that are used to match the
Destination-IP-Origin-AS (i.e. the origin AS number 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 |
+---+---+---+---+---+---+---+---+
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-Origin-AS 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.
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gt - greater than comparison between data and value.
eq - equality between data and value.
The bits lt, gt, and eq can be combined to produce match the
Destination-IP-Origin-AS filter or a range of Destination-IP-Origin-
AS filter(e.g. less than AS1 and greater than AS2).
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-Origin-AS (4 octets) ~
+---------------------------------------------------------------+
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 Case
This section describes how to use this function in a simple scenario.
Considering the topology shown in Figure 1. In AS64597's R1, if the
ISP AS64597 wants to redirect all packets originating from IP Prefix
61 to AS64598, first goto to R3, then forward them to AS64598", the
ISP AS64597 can use the traditional method or the method defining in
this draft.
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+---------+
| BGP FS |
| Server |
+----|----+
|
|
/
/
************/************ IP Prefix 81
* / * IP Prefix 82
IP Prefix 61 * / AS64597 * IP Prefix 83
* / * IP Prefix 84
+-------+ * +---+/ +---+ * +-------+
+AS64596+-------+ R1+---------+ R2|------+AS64598+
+-------+ * +-+-+\ +---+ */ +-------+
* \ |\ /
* \ | \ /* IP Prefix 91
* \ | /\* IP Prefix 92
* \ | / \ IP Prefix 93
* \ |/ *\ IP Prefix 94
* \ +-+-+ * \ +-------+
* \-+ R3+------+AS64599+
* +---+ * +-------+
* *
*************************
Figure 1: 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 83 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
| IP Prefix 84 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
| More... |
+--------------+--------------+-------------------------+
Figure 2: 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 Origin AS + Source Prefix" rule in Router
R1 as following:
+--------------+--------------+-------------------------+
| Destination | Source Prefix| Redirect to IP Nexthop |
| IP Origin AS | | |
+--------------+--------------+-------------------------+
| 64598 | IP Prefix 61 | R3 |
+--------------+--------------+-------------------------+
Figure 3: Using the AS-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 an AS has, the more obvious the benefit.
5. Security Considerations
No new security issues are introduced to the BGP protocol by this
specification.
6. IANA
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-Origin-AS |
+----------------------------------------------------------+
7. Contributors
TBD
8. Acknowledgments
The authors would like to acknowledge the review and inputs from Gang
Yan, Zhenbin Li, Rainbow Wu, Jie Dong and Ziqing Cao.
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9. References
[I-D.ietf-idr-flowspec-l2vpn]
Hao, W., Eastlake, D. E., Litkowski, S., and S. Zhuang,
"BGP Dissemination of L2 Flow Specification Rules", draft-
ietf-idr-flowspec-l2vpn-16 (work in progress), November
2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[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
Haibo Wang
Huawei
156 Beiqing Road
Beijing 100095
P.R. China
Email: rainsword.wang@huawei.com
Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing 102209
P.R. China
Email: wangaj3@chinatelecom.cn
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Shunwan Zhuang
Huawei
156 Beiqing Road
Beijing 100095
P.R. China
Email: zhuangshunwan@huawei.com
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