Internet DRAFT - draft-defoy-coinrg-p4-by-tenants-in-mobile-nw
draft-defoy-coinrg-p4-by-tenants-in-mobile-nw
Network Working Group X. de Foy
Internet-Draft InterDigital Communications, LLC
Intended status: Informational 27 May 2021
Expires: 28 November 2021
Use Case for P4 Programmability by Tenants of Future Mobile Virtual
Networks
draft-defoy-coinrg-p4-by-tenants-in-mobile-nw-00
Abstract
Support for multi-tenancy has been the subject of recent work on P4
switch programming. This draft further describes a potential use
case where a tenant programs a virtual network built over a mobile
network, and discusses related requirements. The use case is based
on the existing 5GLAN feature, since it is a well documented virtual
network architecture supported by 5G.
Status of This Memo
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This Internet-Draft will expire on 28 November 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. A Use Case for Programmability of 5GLANs, by Tenants . . . . 3
3. Requirements for Mobile Network Programming by Tenants . . . 6
4. Informative References . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
In the context of data centers, it has been shown that P4 programs
provided by tenants could be used to program and control virtual
network instances [Stoyanov]. This could be extended to virtual
networks provided by 5G or future mobile networks. This document
discusses such a use case, using 5GLAN as a baseline, since this
recent 5G feature has a well documented architecture. However, this
type of feature is NOT currently planned in 3GPP, it is explored here
as a possible future evolution.
As part of its improving integration with other networks, the 5G
network has now the ability to provide LAN-like connectivity between
5G devices. This "5GLAN" feature provides a virtual LAN service
between devices which are members of a configured group. Section 5.1
of [I-D.ravi-icnrg-5gc-icn] provides a description of the 5G network
functions and interfaces relevant to 5GLAN, which are otherwise
specified in [TS23.501] and [TS23.502]. From the 5GLAN service
customer standpoint, the 5G network operates as a switch.
However, today network operators do not have the option to use
network programming (such as P4) to program 5GLANs, as they could for
fixed network switches. A form of network programming would
nevertheless help to cope with the ever-increasing complexity of the
5G network and its future evolutions. It would also help further
integrating mobile networks, as a piece of infrastructure, with other
home, enterprise and data center networks.
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In this document we describe a use case for P4 programming of 5GLANs
by tenants in Section 2. An expected outcome of this work is a list
of requirements initiated in Section 3. This document is also part
of a larger effort to gather use cases related to computing in the
network, that is documented in [I-D.irtf-coinrg-use-cases].
2. A Use Case for Programmability of 5GLANs, by Tenants
In the use case depicted in Figure 1, a 5G customer operates a
network including a 5GLAN network segment (seen as a single logical
switch), as well as fixed segments. This can be in a plant or
enterprise network, using for an example a 5G Non-Public Network
(NPN). The customer uses P4 programs to determine the operation of
the fixed and 5GLAN switches. The customer provisions a 5GLAN P4
program into the mobile network, and can also operate a controller.
In Figure 1, the mobile devices (or User Equipment nodes) UE1, UE2,
UE3 and UE4 are in the same 5GLAN, as well as Device1 and Device2
(through UE4).
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..... Customer ......
P4 program : :
deployment : Operation :
V :
+-----+ air interface +----------------+ :
| UE1 +----------------+ | :
+-----+ | | :
| | :
+-----+ | | V
| UE2 +----------------+ 5GLAN | +------------+
+-----+ | Logical +------+ Controller |
| Switch | P4 +-------+----+
+-----+ | | runtime |
| UE3 +----------------+ | API |
+-----+ | | |
| | |
+-----+ | | |
+-+ UE4 +----------------+ | |
| +-----+ +----------------+ |
| |
| Fixed or wireless connection |
| P4 runtime API |
| +---------+ +-------------------------------+
+--+ Device1 | |
| +---------+ |
| |
| +---------+ +------+-----+
`--+ Device2 +----+ P4 Switch +--->(fixed network)
+---------+ +------------+
Figure 1: Use Case for P4 Programming by a 5GLAN Customer
Looking in more details in Figure 2, the 5GLAN P4 program can be
split between multiple data plane nodes (PDU Session Anchor (PSA)
User Plane Functions (UPF), other UPFs, or even mobile devices),
although in some cases the P4 program may be hosted on a single node.
In the most general case, a distributed deployment is useful to keep
traffic on optimal paths, because, except in simple cases, within a
5GLAN all traffic will not pass through a single node.
In Figure 2, P4 programs could be deployed in UPF1, UPF2, UPF3, UE3
and UE4. In this example, UE1-UE2 traffic is using a local switch on
PSA UPF1, UE1-UE3 traffic is tunneled between PSA UPF1 and PSA UPF2
through the N19 interface, and UE1-UE4 traffic is forwarded through
an external Data Network (DN). Traffic between Device1 and Device2
is forwarded through UE4.
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+-----+ +-----+ +------------+
| AMF | | SMF | | Controller |
+-+-+-+ +--+--+ +-----+------+
/ | | P4|
+---------+ | N4| Runtime|
N1 / |N2 | V
+------+ | | (all P4 programs*)
/ | |
+--+--+ air interface +---+-----+ N3 +-+--+----------+ N6 +----+
| UE1 +----------------+ (R)AN +----+ PSA UPF1* +----->+ |
+-----+ +---------+ +-+-------+-----+ | |
| | | | | | |
+--+--+ +---+-----+ | | | | |
| UE2 +----------------+ (R)AN +------' | | N19 | DN |
+-----+ +---------+ | | | |
| | | | | |
+--+--+ +---+-----+ +----+----+-----+ | |
| UE3*+----------------+ (R)AN +----+ PSA UPF2* + | |
+-----+ +---------+ +---------+-----+ | |
| | | | N19 | |
+--+--+ +---+-----+ +----+----+-----+ N6 | |
+-+ UE4*+----------------+ (R)AN +----+ PSA UPF3* +----->+ |
| +-----+ +---------+ +---------------+ +----+
|
| Fixed or wireless connection
|
| +---------+
+--+ Device1 | (* indicates the presence of a P4 program)
| +---------+
|
| +---------+ +------------+
`--+ Device2 +----+ P4 Switch* +--->(fixed network)
+---------+ +------------+
Figure 2: Use Case Details
Rationale for using P4 programming by 5GLAN tenants include:
* A unified programming model can facilitate replacing between fixed
and 5G technologies, as well as sharing controller, code and
expertise.
* Making P4 (or equivalent) programming available to 5G customers
can increase the level of customization available to them, when
compared with typical configuration capabilities.
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* If P4 programs can influence the 5G service (e.g., request
specific QoS for some flows), this increases the level of in-depth
customization available to 5G customers.
For example, a P4 5GLAN program could perform the following:
* Allow or block flows, and request rules from an SDN controller for
each new flow, or for flows to/from specific hosts that needs
enhanced security.
* Forward a copy of some flows towards a node for storage and
analysis.
* Update counters based on specific sources/destinations or
protocols, for detailed analytics.
* Associate traffic between specific endpoints, using specific
protocols, or originated from a given application, to a given
slice, while other traffic use a default slice.
* Experiment with a new routing protocol (e.g., ICN), using a P4
implementation of a router for this protocol. (This could use
unstructured PDU sessions.)
In the following section we discuss major requirements identified in
this use case.
3. Requirements for Mobile Network Programming by Tenants
* Splitting/Distribution: program logic can be applied exactly once
or at least once per packet, while allowing optimal forwarding
path by the 5G network.
- A 5GLAN P4 program may run on a single UPF on a simple setup,
but will need to be split in larger setups.
- It could be possible to split the program manually (i.e., by
the programmer based on a model), or automatically (which is
studied in [I-D.hsingh-coinrg-reqs-p4comp] and [Sultana]).
* Multi-Tenancy Support: multiple P4 instances can run on the same
5G network nodes.
- In [Stoyanov], tenant P4 programs can run within the control of
a host P4 program.
* 5G Network Awareness: a P4 program can be able to influence, and
be influenced by, the 5G network service.
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- For example, a P4 program may be aware of the slice used by a
flow, and possibly influence slice selection.
- Additionally, some information and actions may be available on
some nodes and not others. This can impose additional
constraints on distributed P4 programs location.
* Mobility Support: program logic should be applied on all packets
of a flow even if the source or destination(s) of the flow is
relocated to another attachment point.
* Security: programs and networks should be protected against
security risks, that include overuse or misuse of network
resources, injection of traffic, access to unauthorized traffic.
4. Informative References
[I-D.hsingh-coinrg-reqs-p4comp]
Singh, H. and M. Montpetit, "Requirements for P4 Program
Splitting for Heterogeneous Network Nodes", Work in
Progress, Internet-Draft, draft-hsingh-coinrg-reqs-p4comp-
03, 18 February 2021, <https://www.ietf.org/archive/id/
draft-hsingh-coinrg-reqs-p4comp-03.txt>.
[I-D.irtf-coinrg-use-cases]
Kunze, I., Wehrle, K., Trossen, D., and M. Montpetit, "Use
Cases for In-Network Computing", Work in Progress,
Internet-Draft, draft-irtf-coinrg-use-cases-00, 17
February 2021, <https://www.ietf.org/archive/id/draft-
irtf-coinrg-use-cases-00.txt>.
[I-D.ravi-icnrg-5gc-icn]
Ravindran, R., Suthar, P., Trossen, D., Wang, C., and G.
White, "Enabling ICN in 3GPP's 5G NextGen Core
Architecture", Work in Progress, Internet-Draft, draft-
ravi-icnrg-5gc-icn-04, 31 May 2019,
<https://www.ietf.org/archive/id/draft-ravi-icnrg-5gc-icn-
04.txt>.
[Stoyanov] Stoyanov, R. and N. Zilberman, "MTPSA: Multi-Tenant
Programmable Switches", ACM P4 Workshop in Europe
(EuroP4'20) , 2020,
<https://eng.ox.ac.uk/media/6354/stoyanov2020mtpsa.pdf>.
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[Sultana] Sultana, N., Sonchack, J., Giesen, H., Pedisich, I., Han,
Z., Shyamkumar, N., Burad, S., DeHon, A., and B.T. Loo,
"Flightplan: Dataplane Disaggregation and Placement for P4
Programs", 2020,
<https://flightplan.cis.upenn.edu/flightplan.pdf>.
[TS23.501] 501, 3gpp-23., "Technical Specification Group Services and
System Aspects; System Architecture for the 5G System;
Stage 2 (Rel.17)", 3GPP , 2021,
<https://www.3gpp.org/DynaReport/23501.htm>.
[TS23.502] 502, 3gpp-23., "Technical Specification Group Services and
System Aspects; Procedures for the 5G System; Stage 2
(Rel.17)", 3GPP , 2021,
<https://www.3gpp.org/DynaReport/23502.htm>.
Author's Address
Xavier de Foy
InterDigital Communications, LLC
1000 Sherbrooke West
Montreal H3A 3G4
Canada
Email: xavier.defoy@interdigital.com
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