| IDR Working Group | S. Hares |
| Internet-Draft | Huawei |
| Intended status: Standards Track | June 25, 2016 |
| Expires: December 27, 2016 |
BGP Flow Specification Version 2
draft-hares-idr-flowspec-v2-00.txt
BGP flow specification version 1 (RFC5575) describes the distribution of traffic filter policy (traffic filters and actions) which are distributed via BGP to BGP peers. Three applications utilize this traffic filter policy: (1) mitigation of Denial of Service (DoS), (2) enabling of traffic filtering in BGP/MPLS VPNS, and (3)centralized traffic control for networks with SDN or NFV controllers. Application of centralized traffic utilizing BGP Flow Specification traffic filters may need user-ordered filters rather than RFC5575's strict ordering of filters and defined ordering of actions.
This document proposes a new BGP Flow specification version 2 that supports user-order of filters and actions plus allowing more actions
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BGP flow specification [RFC5575] describes the distribution of filters and actions that apply when packets are received on a router with the flow specification function turned on. If one considers the reception of the packet as an event, then BGP flow specification describes a set of minimalistic Event-MatchCondition-Action (ECA) policies were the match-condition is defined in the BGP NLRI, and the action is defined either by the default condition (accept traffic) or actions defined in Extended BGP Communiites values [RFC4360].
The initial set of policy [RFC5575] and [RFC7674] for this policy includes 12 types of match filters encoded in two application specific AFI/SAFIs for the IPv4 AFI.
The popularity of these flow specification filters in deployment for DoS and SDN/NFV has led to the requirement for more BGP flow specification match filters in the NLRI and more BGP flow specification actions.
This document describes distribution of two new BGP Flow Specification NLRI (2 AFI/SAFI pairs) that allow user-ordered list of traffic match filters, and user-ordered traffic match actions encoded in BGP Wide Communities.
The rest of this section provides background on BGP Flow Specification filters interaction with I2RS Filter-Based RIBs carried by NETCONF/RESTCONF protocol. Figure 1 below is a logial description of BGP Flow Specification rules that combine filters in BGP NLRI with actions in BGP Extended communities.
+-----------------------------+
| Flow Specification (FS) |
| Policy |
+-----------------------------+
^ ^
| |
| |
+--------^-------+ +-------^-------+
| FS Rule | | FS Rule |
+----------------+ +---------------+
: :
: :
......: :.....
: :
+---------V---------+ +----V-------------+
| Rule Condition | | Rule Action |
| in BGP NLRIs | | in BGP extended |
| SAFI 133, 134 | | Communities |
+-------------------+ +------------------+
: : : : : :
.....: . :..... .....: . :.....
: : : : : :
+----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 1: BGP Flow Specification Policy
BGP Flow Specification (BGP-FS) ([RFC5575] and [I-D.raszuk-idr-rfc5575bis]) describes how to distribute the BGP Flow Specification policy as BGP routes which are locally configured on the originating BGP peer. Like BGP routes, if the BGP peer session drops then BGP Flow Specification routes are dropped. [RFC5575] and [I-D.raszuk-idr-rfc5575bis] do not indicate how the BGP Flow Specification policy is installed in the kernel.
[RFC5575] describes the dissemination of flow specification rules policy is similar to the the statically configured Filter-Based RIB described in [I-D.ietf-i2rs-fb-rib-data-model], and the I2RS Filter-Based RIB ([I-D.ietf-i2rs-fb-rib-info-model], [I-D.ietf-i2rs-fb-rib-data-model], [I-D.ietf-i2rs-pkt-eca-data-model]). These FB-RIBs start on the reception of a packet using match filters to match frames (L2) or packet data (L3/L4/Application), and perform actions as shown in figure 2.
+-----------+ +------------+
|Rule Group | | Rule Group |
+-----------+ +------------+
^ ^
| |
| |
+--------^-------+ +-------^-----------+
| Rule | | Rule |
+----------------+ +-------------------+
: : : :
:.................: : : :
: |.........: : :
+--V--+ +--V--+ : :
| name| |order| .........: :.....
+-----+ +-----+ : :
: :
+--------------V-------+ +--V------------+
| Rule Match condition | | Rule Action |
+----------------------+ +---------------+
: : : : : :
.....: . :..... .....: . :.....
: : : : : :
+----V---+ +---V----+ +--V---+ +-V------++--V-----++--V---+
| Match | | match | |match | | Action || action ||action|
|Operator| |variable| |Value | |Operator||Variable|| Value|
+--------+ +--------+ +------+ +--------++--------++------+
Figure 2: I2RS Filter-Based RIB Policy
[I-D.ietf-i2rs-fb-rib-data-model] suggests that the storage of BGP Flow Specification routes in the kernel should utilize the same format as the statically configured FB-RIB and the I2RS ephemeral FB-RIB so that these traffic filters may be compared. This draft also proposes that precedence between these three sources of filters in the kernel (statically configured, I2RS ephemeral, and BGP ephemeral routes) can either set by local policy or defaults. If it is set by defaults [I-D.ietf-i2rs-fb-rib-data-model] suggests the default precedence between static, I2RS, and BGP-FS installed filters is:
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].
The BGP Flow Specification version 2 (BGP-FS v2) uses an NRLI with the format for AFI/SAFI (SAFI = TBD) for IP flow, and AFI/SAFI for BGP/MPLS (SAFI = TBD). This NLRI information is encoded using MP_READ_NRI and MP_UNREACH_NLRI attributes defined in [RFC4760]. Whenever the corresponding application does not require Next-HOP information, this shall be encoded as zero-octet length Next Hop in the MP_REAC_NLRI and ignored upon receipt.
Implementatinos wishing to exchange flow specificastion rules MUST use BGP's Capability Advertisement facility to exchange the Multiprotocol Extension Capability Code (Code 1) as defined in [RFC4760].
+------------------------+ |length (2 octets) | +------------------------+ | Sub-TLVs (variable) | | +====================+ | | | order (2 octets) | | | +--------------------+ | | | type (2 octets) | | | +--------------------+ | | | length (2 octets) | | | +--------------------+ | | | value (variable) | | | |[multiples of | | | | 2 octets] | | | +====================+ | +------------------------+ Figure 16 - NRLI revision
The AFI/SAFI NLRI for BGP Flow Specification has the format
where:
Filters are process in the order specified by the user. If multiple filters exist for the same order, the strict filter ordering defined in [RFC5575] and [I-D.raszuk-idr-rfc5575bis] will be used for the filters with the same value for user order.
The BGP-FS version 2 actions are passed in a Wide Community [I-D.ietf-idr-wide-bgp-communities] atom with the following format.
+--------------------------+ | order (2 octets) | +--------------------------+ | Action type (2 octets) | +--------------------------+ | Action length (2 octets) | +--------------------------+ | Action Values (variable) | | (multiples of 2 octets) | +--------------------------+ Wide Community Atom figure 17
where:
+-----------------------------+ | Source AS Number (4 octets)| +-----------------------------+ | list of atoms (variable) | +-----------------------------+ figure 18
The BGP Flow Specification (BGP-FS) atom can be part of the Wide Community container (type 1) or the BGP Flow Specification Atom can be part of the BGP Flow Specification container (type 2) which will have:
Same as [RFC5575] and [I-D.raszuk-idr-rfc5575bis].
This section discusses the optional BGP Security additions for BGP-FS v2: BGPSEC [I-D.ietf-sidr-bgpsec-protocol], ROA [RFC6482] and revised security for flow specification distributed from a centralized server within an AS [I-D.ietf-idr-bgp-flowspec-oid]. These optional security parameters can be applied per BGP peer.
[RFC5575] does not require BGP Flow specifications to be passed BGPSEC [I-D.ietf-sidr-bgpsec-protocol]. BGP FS v2 can be passed in BGPSEC, but it is not required.
BGP-FS v2 can utilize ROAs in the validation. If BGP-FS v2 is used with BGPSEC and ROA, the first thing is to vaildate 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:
The best match is defined to be the longest-match NLRI with the highest preference.
The distribution of Flow Specifications from a centralized server supports mitigation of DoS attacks. [I-D.ietf-idr-bgp-flowspec-oid] suggests the following redefined procedure for validation for this case:
A route is valid if the following conditions holds true:
This reduced validation mechanism can be used for BGP-FS v2 within a single domain.
This section complies with [RFC7153]
This document requests:
Registry be created for BGP-FS V2 filter component types with the following ranges:
Registry be created for BGP-FS v2 action types with the following ranges:
The use of ROA improves on [RFC5575] to check the route orgination is valid can improve the validation sequence for a multiple-AS environment. The use of BGPSEC [I-D.ietf-sidr-bgpsec-protocol] 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 [I-D.ietf-idr-bgp-flowspec-oid] can provide adequate validation for distribution of flow specification within an single autonomous system for prevention of DDOS.
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.
| [I-D.ietf-i2rs-architecture] | Atlas, A., Halpern, J., Hares, S., Ward, D. and T. Nadeau, "An Architecture for the Interface to the Routing System", Internet-Draft draft-ietf-i2rs-architecture-15, April 2016. |
| [I-D.ietf-i2rs-ephemeral-state] | Haas, J. and S. Hares, "I2RS Ephemeral State Requirements", Internet-Draft draft-ietf-i2rs-ephemeral-state-09, May 2016. |
| [I-D.ietf-i2rs-fb-rib-data-model] | Hares, S., Kini, S., Dunbar, L., Krishnan, R., Bogdanovic, D. and R. White, "Filter-Based RIB Data Model", Internet-Draft draft-ietf-i2rs-fb-rib-data-model-00, June 2016. |
| [I-D.ietf-i2rs-fb-rib-info-model] | Kini, S., Hares, S., Dunbar, L., Ghanwani, A., Krishnan, R., Bogdanovic, D. and R. White, "Filter-Based RIB Information Model", Internet-Draft draft-ietf-i2rs-fb-rib-info-model-00, June 2016. |
| [I-D.ietf-i2rs-pkt-eca-data-model] | Hares, S., Wu, Q. and R. White, "Filter-Based Packet Forwarding ECA Policy", Internet-Draft draft-ietf-i2rs-pkt-eca-data-model-00, June 2016. |
| [I-D.ietf-netconf-restconf] | Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", Internet-Draft draft-ietf-netconf-restconf-13, April 2016. |
| [I-D.ietf-netmod-acl-model] | Bogdanovic, D., Koushik, K., Huang, L. and D. Blair, "Network Access Control List (ACL) YANG Data Model", Internet-Draft draft-ietf-netmod-acl-model-07, March 2016. |
| [RFC6074] | Rosen, E., Davie, B., Radoaca, V. and W. Luo, "Provisioning, Auto-Discovery, and Signaling in Layer 2 Virtual Private Networks (L2VPNs)", RFC 6074, DOI 10.17487/RFC6074, January 2011. |
| [RFC6483] | Huston, G. and G. Michaelson, "Validation of Route Origination Using the Resource Certificate Public Key Infrastructure (PKI) and Route Origin Authorizations (ROAs)", RFC 6483, DOI 10.17487/RFC6483, February 2012. |