RTG Working Group L. Dunbar Internet Draft Futurewei Intended status: Standard track K. Majumdar Expires: October 7, 2022 CommScope U. Chunduri Intel July 7, 2021 BGP Dissemination of FlowSpec for Transport Aware Mobility draft-dmc-idr-flowspec-tn-aware-mobility-00 Abstract This document defines a BGP Flow Specification (flowSpec) extension to disseminate flows from 5G mobile networks so that the 5G mobile systems slices and Service Types (SSTs) can be mapped to optimal underlying network paths in the data network outside the 5G UPFs, or the N6 interface in 3GPP 5G Architecture [3GPP TR 23.501]. 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), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html xxx, et al. Expires January 7, 2022 [Page 1] Internet-Draft FlowSpec of TN Aware Mobility July 2021 This Internet-Draft will expire on April 23, 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://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 extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction.................................................. 2 2. Conventions used in this document............................. 3 3. TN-Aware matching conditions.................................. 4 4. Redirect a flow over underlay tunnels......................... 6 5. Indirection-id Community for IPv4 IPsec Tunnel................ 7 6. IANA Considerations........................................... 9 7. Security Considerations....................................... 9 8. Contributors.................................................. 9 9. References.................................................... 9 9.1. Normative References..................................... 9 9.2. Informative References.................................. 10 10. Acknowledgments............................................. 10 Authors' Addresses.............................................. 12 1. Introduction The [TN-AWARE-MOBILITY-EXT] describes a framework for extending the mobility aware transport network characteristics through the Data Network outside the 5G UPFs. Dunbar, et al. Expires October15, 2022 [Page 2] Internet-Draft FlowSpec of TN Aware Mobility July 2021 +-----------+ +------+ | | | | UE---| gNB-CU(UP)|------| UPF +|--------DN------- | | | C-PE | +-----------+ +------+ |- N3 OR N9 -||----N6 -------------| |------ Mobile Network ----||-- IP Network-------| Figure 1: Mobile and IP Data Network for UE The 5G UPF terminates the 5G GTP tunnels from gNB and pass the IP packets to the N6 data networks, which deliver the packets over hybrid paths, like MPLS, SR paths, Private-IP, or public Internet to reach the packets' destinations. This document focuses on using FlowSpec to disseminate rules that utilize the mobility aware transport network characteristics to forward 5G flows. Border Gateway Protocol (BGP) Flow Specification (FlowSpec) [RFC8955] and FlowSpec for IPv6 [RFC8956] leverage the BGP Control Plane to simplify the distribution of rules for the specified flows. FlowSpec filter rules can be injected to all BGP peers simultaneously without changing router configuration. 2. Conventions used in this document BSID - Binding SID DC - Data Center DN - Data Network (5G) EMBB - enhanced Mobile Broadband (5G) gNB - 5G NodeB Dunbar, et al. Expires October15, 2022 [Page 3] Internet-Draft FlowSpec of TN Aware Mobility July 2021 GTP-U - GPRS Tunneling Protocol - Userplane (3GPP) MIOT - Massive IOT (5G) PECP - Path Computation Element (PCE) Communication Protocol SD-WAN - Software-Defined Wide Area Network SID - Segment Identifier SLA - Service Layer Agreement SST - Slice and Service Types (5G) SR - Segment Routing SR-PCE - SR Path Computation Element UE - User Equipment UPF - User Plane Function (5G) URLLC - Ultra reliable and low latency communications (5G) 3. TN-Aware matching conditions [RFC8955] defines a BGP Network Layer Reachability Information (NLRI) format used to distribute traffic flow specification rules. The NLRI for (AFI=1, SAFI=133) specifies IPv4 unicast filtering. The NLRI for (AFI=1, SAFI=134) specifies IPv4 BGP/MPLS VPN filtering [RFC7432]. The Flow Specification match part defined in [RFC8955] includes L3/L4 information like IPv4 source/destination prefix, protocol, ports, and the like, so traffic flows can be filtered based on L3/L4 information. This has been extended by [RFC8956] to cover IPv6 (AFI=2) L3/L4. The NLRI FlowSpec components described in RFC8955 and RFC8956 are adequate for specifying the UDP Source Port Range which is used to differentiate SLAs of flows from UPFs [EXT-TN-AWARE-Mobility]. Dunbar, et al. Expires October15, 2022 [Page 4] Internet-Draft FlowSpec of TN Aware Mobility July 2021 The Ingress PE, which is either a function inside UPF or directly connected to UFP, acting as BGP FlowSpec Receiver is assumed to have a BGP FlowSpec session with the FlowSpec Controller. The Mobility traffic destination would resolve in the BGP Peer Next Hop in the data network. The BGP FlowSpec Controller would be programmed with {5G UDP Src Port Range} to map different SSTs defined in [TN-AWARE-MOBILITY] to create internal mapping Table for {5G UDP Src Port Range} < -- > {BGP FlowSpec Generalized Indirection-ID}. The Mobility IP packets coming out of the UPF, i.e., GTP header being decapsulated, carrying specific UDP Source Port can be classified based on the matching policy carried by the FlowSpec NLRI. For example, to filter out flows with source UDP port number between [i, j], the following encoding can be used in the NLRI (SAFI=133 or SAFI 134): Encoding Numberic_Op1 is: 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | e | a | len | 0 |lt |gt |eq | | 0 | 1 | 00 | 0 | 0 | 1 | 0 | +---+---+---+---+---+---+---+---+ Numberic_Op2 is: 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | e | a | len | 0 |lt |gt |eq | | 1 | 1 | 00 | 0 | 1 | 0 | 0 | +---+---+---+---+---+---+---+---+ Where len ==0, meaning two bytes of value [i] follows the Numeric_op1 and two bytes of value [j] follows the Numberic_op2. Dunbar, et al. Expires October15, 2022 [Page 5] Internet-Draft FlowSpec of TN Aware Mobility July 2021 The "numeric_op3" and "numeric_op4" are for comparing the source and destination addresses of the UE traffic. 4. Redirect a flow over underlay tunnels For the flows matching with the filter conditions carried by the FlowSpec NLRI, the policy for redirect path can indicate a set of underlay tunnels or one underlay tunnel. The Transitive Extended Community described by [Flowspec-path- redirect] and [SRv6-flowspec-path-redirect] can be extended to steer flows to hybrid underlay paths. The below figure tries to capture the overall topology, showing the mobility traffic from UPF being redirected to different paths per the BGP FlowSpec from the Controller: +-----------+ +----+{5G UDP Src Port Range} | FlowSpec |-->| Map| <--> | Controller| | DB |{Generalized Indirection-ID} +-----------+ +----+ / / / BGP FlowSpec NLRI with 5G BGP FlowSpec / Src-Pfx, Dst-Pfx, UDP Source Port Range Session / / BGP FlowSpec Redirect / Indirection-ID Ext Comm / / /Public / MIOT / Cloud / +------/ +-------+ Ind-ID1: UDP Src Port Xx-Xy / | A1-------------------------------+ | | Ind-ID2: UDP Src Port Yx-Yy URLLC UE------| UPF + A2-------------------------------------Internet | PE1 | Ind-ID3: UDP Src Port Zx-Zy | A3-------------------------------+ | | \ +-------+ +-----+ {UE Src IP, UE Dst IP, UDP Src Port Num# <--> \ FlowSpec Ind-ID# -> Transport Hdr} EMBB \ \ Dunbar, et al. Expires October15, 2022 [Page 6] Internet-Draft FlowSpec of TN Aware Mobility July 2021 ----------> +------+----------+-------+-----+----------+ | Data | Inner IP | GTP-U | UDP | Outer IP | +------+----------+-------+-----+----------+ ----------> +------+----------+------------------+ | Data | Inner IP | Transport Header | +------+----------+------------------+ Figure 2: TN Aware Mobility Traffic Mapping to FS Redirect Path 5. Indirection-id Community for IPv4 IPsec Tunnel This section defines a new sub-type value for in "FlowSpec Redirect to indirection-id Extended Community". The format of this extended community with the new sub-type value is show below: 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 |Sub-Type (TBD) | Flags(1 octet)| ID-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec redirection ID (16 octets) | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: FlowSpec IPsec Redirection ID Sub-TLV Where Type: 1 octet, defined in [flowspec-path-redirect]. Sub-Type: 1 octet, its value (TBD) will be assigned by IANA. Flags: Same as that defined in [flowspec-path-redirect]. ID-Type: 1 octet value. Here is the new value needed for IPsec IPv4 tunnel. 6 - IPsec SA ID (Assuming the IPsec SA is pre-established, its Security Association (SA) ID is within a single administrative Dunbar, et al. Expires October15, 2022 [Page 7] Internet-Draft FlowSpec of TN Aware Mobility July 2021 domain a globally unique identifier. The allocation and establishment of the IPsec SA among peers is outside scope of the document). The IPsec-SA-ID sub-TLV specified by [SDWAN-Edge-Discovery] can be placed in the IPsec Indirection ID field in Figure 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= IPsec-SA-ID subTLV | Length (2 Octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA Identifier #1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPsec SA Identifier #2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This draft continues using the Context Types specified by [Flowspec-RedirectSRv6]: 0 - Localised ID (The flowspec client uses the received indirection-id to lookup forwarding information within the localised indirection-id table. The allocation and programming of the localised indirection-id table is outside scope of the document) 1 - Node ID with SID/index in MPLS-based Segment Routing (This means the indirection-id is mapped to an MPLS label using the index as a global offset in the SID/label space) 2 - Node ID with SID/label in MPLS-based Segment Routing (This means the indirection-id is mapped to an MPLS label using the indirection-id as global label) 3 - Binding Segment ID with SID/index in MPLS-based Segment Routing (This means the indirection-id is mapped to an MPLS binding label using the indirection-id as index for global offset in the SID/label space). 4 - Binding Segment ID with SID/label in MPLS-based Segment Dunbar, et al. Expires October15, 2022 [Page 8] Internet-Draft FlowSpec of TN Aware Mobility July 2021 Routing (This means indirection-id is mapped to an MPLS binding label using the indirection-id as global label). 5 - Tunnel ID (Tunnel ID is within a single administrative domain a globally unique tunnel identifier. The allocation and programming of the Tunnel ID within the localized indirection-id table is outside scope of the document) 6. IANA Considerations This draft needs an IANA code point allocation for Sub-Type: IPsec SA. A request for any IANA code point allocation would be submitted. 7. Security Considerations TBD. 8. Contributors The following people have contributed to this document. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC8955] C. Loibl, et al, "Dissemination of Flow specification Rules", Dec 2020. Dunbar, et al. Expires October15, 2022 [Page 9] Internet-Draft FlowSpec of TN Aware Mobility July 2021 [RFC8956] C. Loibl, et, al, "Dissemination of Flow Specification Rules for IPv6". Dec 2020. 9.2. Informative References [RFC5440] JP. Vasseur, Ed., JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", March 2009 [Flowspec-path-redirect] G. Van De Velde, et al, "Flowspec Indirection-id Redirect", draft-ietf-idr-flowspec-path-redirect- 11, March 2020 [SRv6-Flowspec-path-redirect] G. Van De Velde, et al, "Flowspec Indirection-id Redirect for SRv6], draft-ietf0-idr-srv6-flowspec- path-redirect-05, Jan. 2021 [TN-AWARE-MOBILITY] U. Chunduri, et al, "Transport Network aware Mobility for 5G", draft-clt-dmm-tn-aware-mobility-07, April 2021 [TN-AWARE-MOBILITY-EXT] K. majumdar, et al, "Extension of Transport Aware Mobility in Data Network", draft-mcd-rtgwg- extension-tn-aware-mobility-01, May 2021 [BGP-SR-TE-POLICY] S. Previdi, et al, "Advertising Segment Routing Policies in BGP", draft-ietf-idr-segment-routing-te-policy-09, November 2020 [SDWAN-BGP-USAGE] L. Dunber, et al, "BGP Usage for SDWAN Overlay Networks", draft-dunbar-bess-bgp-sdwan-usage-08, January 2021 [SDWAN-Edge-Discover] L. Dunber, et al, "BGP UPDATE for SDWAN Edge Discovery", draft-dunbar-idr-sdwan-edge-discovery-04, April 2021 10. Acknowledgments TBD. This document was prepared using 2-Word-v2.0.template.dot. Dunbar, et al. Expires October15, 2022 [Page 10] Internet-Draft FlowSpec of TN Aware Mobility July 2021 Dunbar, et al. Expires October15, 2022 [Page 11] Internet-Draft FlowSpec of TN Aware Mobility July 2021 Authors' Addresses Linda Dunbar Futurewei 2330 Central Expressway Santa Clara, CA 95050 Email: linda.dunbar@futurewei.com Kausik Majumdar CommScope 350 W Java Drive, Sunnyvale, CA 94089 Email: kausik.majumdar@commscope.com Uma Chunduri Intel 2200 Mission College Blvd Santa Clara, CA 95052 Email: umac.ietf@gmail.com Dunbar, et al. Expires October15, 2022 [Page 12]