Internet DRAFT - draft-dmc-idr-flowspec-tn-aware-mobility
draft-dmc-idr-flowspec-tn-aware-mobility
RTG Working Group L. Dunbar
Internet Draft Futurewei
Intended status: Standard track K. Majumdar
Expires: January 24, 2024 Microsoft
U. Chunduri
Intel
July 24, 2023
BGP Dissemination of FlowSpec for Transport Aware Mobility
draft-dmc-idr-flowspec-tn-aware-mobility-04
Abstract
This document defines a BGP Flow Specification (FlowSpec)
extension to disseminate the policies 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 which is the
N6 interface in 3GPP 5G Architecture [3GPP TR 23.501].
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Table of Contents
1. Introduction............................................ 2
2. Conventions used in this document....................... 3
3. TN-Aware matching conditions............................ 4
4. Redirect a flow over an underlay tunnel................. 6
5. FlowSpec Redirect to Indirection-ID Non-Transitive Extended Community......................................... 8
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.
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+-----------+ +------+
| | | |
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 passes
the IP packets to the N6 Interface [3GPP] 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 specifies how to use FlowSpec to disseminate
the policies 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 which is the N6 interface in 3GPP 5G
Architecture [3GPP TR 23.501].
Border Gateway Protocol (BGP) Flow Specification (FlowSpec)
[RFC8955] and FlowSpec for IPv6 [RFC8956] leverage the BGP
Control Plane to simplify the distribution of rules &
policies for the specified flows. FlowSpec filter rules can
be injected into all BGP peers simultaneously without
changing router configuration.
2. Conventions used in this document
BSID - Binding SID
DC - Data Center
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DN - Data Network (5G)
EMBB - enhanced Mobile Broadband (5G)
gNB - 5G NodeB
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 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]
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includes L3/L4 information like IPv4 source/destination
prefix, protocol, ports, etc., so traffic flows can be
filtered based on L3/L4 information. [RFC8956] specifies the
filtering 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].
The ingress PE, which can be a function integrated with a
UPF or an edge router directly connected to a 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 an 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., the GTP header being
decapsulated, carrying a specific UDP Source Port, can be
classified based on the matching policies 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
<Type = 6, [numeric_op1, i][numberic_op2, j]>
<Type = 2, [numeric_op3, Src-Prefix]>
<Type = 1, [numeric_op4, Dest-prefix]>
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 |
+---+---+---+---+---+---+---+---+
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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, which indicates two bytes of value [i] follow
the Numeric_op1 and two bytes of value [j] follow the
Numberic_op2.
The "numeric_op3" and "numeric_op4" are for comparing the
source and destination addresses of the UE traffic.
4. Redirect a flow over an underlay tunnel
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.
As the BGP FlowSpec Receiver, i.e., the ingress PE, takes
the action of redirecting traffic to specific underlay
tunnels, a non-transitive Extended Community for Path
Redirect [Flowspec-path-redirect] and [SRv6-flowspec-path-
redirect] should be used.
[IANA Action: need a new type:
0x49 FlowSpec Redirect to Indirection-id Non-transitive
Extended Community.
]
For hierarchical RR deployments where the FlowSpec rules
need to be propagated via the RRs to the ingress PE, the
Transitive Path Redirect Extended Community [FlowSpec-path-
redirect] can be used.
The figure below depicts the overall topology, showing the
mobility traffic from UPF being redirected to different
paths per the BGP FlowSpec from the Controller:
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+-----------+ +----+{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
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 \
\
---------->
+------+----------+-------+-----+----------+
| Data | Inner IP | GTP-U | UDP | Outer IP |
+------+----------+-------+-----+----------+
---------->
+------+----------+------------------+
| Data | Inner IP | Transport Header |
+------+----------+------------------+
Figure 2: Mobility Traffic Mapping to Redirect Path
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5. FlowSpec Redirect to Indirection-ID Non-Transitive Extended
Community
This section defines "FlowSpec Redirect to Indirection-ID
Non-Transitive Extended Community for IPSec Tunnel ID". The
format of this extended community is shown 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 |IPSecSA SubType| Flags(1 octet)|IPSecSA ID-Type|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPsec Tunnel ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Redirect to Ind-ID Ext Community for IPSec Tunnel
Where
Type = 0x49 (to be assigned by IANA): Non-Transitive
FlowSpec Redirect to Indirection-ID Extended Community for
IPSec Tunnel ID.
[Note: Type = 0x09 for Transitive FlowSpec Redirect to
Indirection-ID Extended Community can also be used for
Hierarchical deployment, where the FlowSpec Update needs to
be propagated]
IPSec SA Sub-Type: 1 octet, its value (TBD) will be assigned
by IANA to indicate the ID carried by the Extended Community
is IPsec SA ID. Assuming the IPsec SA is pre-established,
its Security Association (SA) ID is within a single
administrative domain a globally unique identifier. The
allocation and establishment of the IPsec SA among peers is
outside scope of the document.
Flags: Same as that defined in [Flowspec-path-redirect].
IPSec SA ID-Type: 1 octet value. Here are the new values
needed for IPsec IPv4 tunnel (to be assigned by IANA)
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v1 - Inner Encap type = IPSec+GRE
v2 - Inner Encap type = IPSec+Vxlan
6. IANA Considerations
This draft needs an IANA code point allocation for the Non-
Transitive FlowSpec Redirect to Indirection-ID Extended
Community.
Type: Non-Transitive FlowSpec Redirect to Indirection-ID
Extended Community for IPSec Tunnel ID.
IPsec SA Sub-Type:
IPSec SA ID-Type:
v1 - Inner encap type = IPSec+GRE
v2 - Inner encap type = IPSec+Vxlan
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.
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[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, "Mobility aware
Transport Network Slicing for 5G", draft-ietf-dmm-tn-aware-
mobility-07, July 2023
[TN-AWARE-MOBILITY-EXT] K. majumdar, et al, "Extension of
Transport Aware Mobility in Data Network", draft-mcd-rtgwg-
extension-tn-aware-mobility-06, July 2023
[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-ietf-bess-bgp-sdwan-usage-14, July
2023
[SDWAN-Edge-Discover] L. Dunber, et al, "BGP UPDATE for
SDWAN Edge Discovery", draft-ietf-idr-sdwan-edge-discovery-
10, June 2023
10. Acknowledgments
TBD.
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Linda Dunbar
Futurewei
2330 Central Expressway
Santa Clara, CA 95050
Email: linda.dunbar@futurewei.com
Kausik Majumdar
Microsoft
Email: kmajumdar@microsoft.com
Uma Chunduri
Intel
2200 Mission College Blvd
Santa Clara, CA 95052
Email: umac.ietf@gmail.com
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