Internet-Draft | FlowSpec MPLS Match | October 2022 |
Yong, et al. | Expires 23 April 2023 | [Page] |
This draft proposes BGP flow specification rules that are used to filter MPLS labeled packets.¶
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BGP Flow Specification (BGP-FS) [RFC5575] is an extension to that allows for the dissemination of 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. The typical application of BGP-FS is to automate the distribution of traffic filter lists to routers for DDOS mitigation.¶
[RFC5575] defines a new BGP 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-flow-spec-v6] defines flow-spec extension for IPv6 data packets. [I-D.ietf-idr-flowspec-l2vpn] extends the flow-spec rules for layer 2 Ethernet packets (AFI=25, SAFI=133, SAFI=134). All these flow specifications match parts only reflect single layer IP (source/destination IP prefix, protocol type, ports, etc.) and Ethernet information with matches for source/destination MAC¶
[I-D.hr-idr-rfc5575bis] provides updates to [RFC5575] to resolve unclear sections in text and conflicts with interactions of filtering actions.¶
MPLS technologies [RFC3031] have been widely deployed in WAN networks. MPLS label stack [RFC3032] is the foundation for label switched data plane. A label on a label stack may represent a label switch path (LSP), application identification such as Pseudo Wire (PW), a reserved label that triggers a specific data plane action, or etc. The data plane label switching operations includes pop, push, or swap label on the label stack.¶
For value added services, it is valuable for a MPLS network to have BGP-FS policy filter that matches on the MPLS portion of a packet and an action to modify the MPLS packet header and/or monitor the packets that match the policy. This document specifies an MPLS match filter. [I-D.ietf-idr-bgp-flowspec-label] specifies a BGP action to modify the MPLS label.¶
[I-D.hares-idr-flowspec-v2] describes the following two options for extending [RFC5575]: creating a version 2 of BGP Flow Specification which can run in parallel to the original BGP Flow specification. Version 2 may also include improved security features (ROAs or [I-D.ietf-idr-bgp-flowspec-oid])¶
This MPLS match option can be used for RFC5575 ([RFC5575], [I-D.hr-idr-rfc5575bis]) or version 2 of the flow specification.¶
This document proposes new flow specifications rules that is encoded in NLRI.¶
The operator byte is encoded as:¶
0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | e | a | i | pos | Resv | +---+---+---+---+---+---+---+---+¶
where:¶
where:¶
The value field is encoded as:¶
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+¶
Encoding: <type (1 octet), [op, value]+>¶
In this example, 5 local policy rules in the filter-based RIBs (FB-RB, aka Policy Routing) will match n-tuples (destination IP address, Destination Port, source IP address, Source IP Address, protocols (ICMP and STCP). These policy rules can be created by standard yang modules for filter-based RIBS (configuration, and ephemeral configuration) or ACLs, or vendor based policy. These policies will put the DDoS attack data onto one LSP (LSP1) in order to send the DDoS traffic to the IDS/IPS processing attached to PE2.¶
The MPLS Filter allows the BGP Flow specification to match on the LSP label rather than the IP address so that PE2 (with the FB-RIBs on PE2) can forward the traffic to a set of IDS/IPS machines. The BGP Flow Specification (BGP-FS) can forward this simple match policy along with an action policy that constraints the traffic on this Flow to a certain rate (bytes/second).¶
|<---------------- AS1 ----------------->| +---------+ +-----+ +-----+ +-----+ ===| PE1 |---|IBGP |----|IBGP |----| PE2 |--IDS-1/IPS | Filters | | | | | | |--IDS-2/IPS +---------+ +-----+ +-----+ +-----+ |-------------------------------| MPLS travel on LSP-1 with label-1 BGP Flow Specification Filter 1 BGP Flow Specification Match Policy Destination IP address (0/0) [Required by RFC5575] MPLS Label match (label-1) Action Policy Traffic-rate (n bytes)¶
The validation of BGP Flow Specification policy relies on the security of the BGP protocol and RFC 5575 checks ([RFC5575], [I-D.hr-idr-rfc5575bis]) for BGP Flow specification version 1 and BGP Flow specification version 2 ([I-D.hares-idr-flowspec-v2]). For Option 1, the MPLS Match can be one of the match filtes, and and the final match is an "AND" of all the filters. Match filters are tested in the order specified in [I-D.hares-idr-flowspec-v2] and/or an RFC5575bis document.¶
This section complies with [RFC7153]¶
IANA is requested to a new entry in "Flow Spec component types registry" with the following values:¶
Value Name: Value Reference =========== ===== ========= MPLS-Match1 TBD1 [This Document] MPLS-Match2 TBD2 [This Document]¶