Computing-Aware 5G Edge Enhancement
draft-jiang-cats-usecase-5gedge-00
This document is an Internet-Draft (I-D).
Anyone may submit an I-D to the IETF.
This I-D is not endorsed by the IETF and has no formal standing in the
IETF standards process.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Tianji Jiang | ||
| Last updated | 2024-10-09 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-jiang-cats-usecase-5gedge-00
CATS Working Group T. Jiang
Internet-Draft China Mobile
Intended status: Informational 9 October 2024
Expires: 12 April 2025
Computing-Aware 5G Edge Enhancement
draft-jiang-cats-usecase-5gedge-00
Abstract
This draft illustrates a computing-aware use case that is based on
the study conclusion of the 3GPP 5G enhanced Edge Computing (eEdge).
This use case takes into acount both network and computing metrics
upon selecting edge application server (EAS) and user plane function
(UPF).
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). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on 12 April 2025.
Copyright Notice
Copyright (c) 2024 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 (https://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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Jiang Expires 12 April 2025 [Page 1]
Internet-Draft CATS 5G Edge Enhance October 2024
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. 5G Enhanced Edge Architecture . . . . . . . . . . . . . . 2
1.2. Definitions of Terms . . . . . . . . . . . . . . . . . . 3
2. Computing-aware 5G Enhanced Edge (eEdge) . . . . . . . . . . 3
2.1. EAS & Local-UPF Optimized Selection in 5G eEdge . . . . . 4
2.2. Integrating 5G eEdge w/ CATS . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Normative References . . . . . . . . . . . . . . . . . . 6
5.2. Informative References . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
3GPP 5G Edge Computing & its successive enhancements, i.e., eEdge,
standardize reference architectures, connectivity models along with
edge hosting envivorments (or EHE), etc., so as to enable operator
and/or 3rd party services to be hosted close to an end device's
(i.e., end user or UE) access point of attachment
[TS.23.501][TS.23.548]. The eEdge service achieves an efficient
service delivery through the reduced end-to-end latency and load on
the transport network. Edge application servers, or EAS'es, are
deployed in corresponding (edge) domain networks (DNs) that are
connected via the N6 interface of a (PSA) UPF. A DN may be under the
control of either the operator or 3rd parties.
1.1. 5G Enhanced Edge Architecture
A 5GC can select either a UPF according to provided traffic steering
rules, or an EAS based on 'holistic better metrics', etc., and then
forward traffic to enable the optimal access to the DN via a N6
interface. This may be based on the UE's local settings, the
measured or collected EAS (or edge application server) runtime
information, network policy or other related traffic rules. As shown
in the Figure 1, either the C-PSA UPF or the L-PSA UPF could be
optimally selected to foward the UE (uplink) traffic to an EAS with
the better (or even the best) 'holistic' metrics.
Jiang Expires 12 April 2025 [Page 2]
Internet-Draft CATS 5G Edge Enhance October 2024
C-PSA: Central PSA UPF L-PSA: Local PSA UPF
DL: Downlink direction UL: Uplink direction
ULCL/BP: Uplink Classifier/Branch Point
EAS: Edge App Server in Data Domain (DN)
.....................................
: [-- 5G Core --] :
: / | | :
: N1 N2 N4 :
: / | | <== DL
: / | +-------+ +-----+ :
+----+ +-----+ | UPF | | UPF | : /---------\
| UE |--| gNB |--|ULCL/BP|--|C-PSA+(N6)-/ DN or \
+----+ +-----+ +-------+ +-----+ : |DN:local-part|
: | : | |
: | UL==> | EAS |
: +-----+ : | (1 or More) |
: | UPF | : \ /
: |L-PSA|(N6)-------:----\---------/
: +-----+ :
.....................................
Figure 1: 5G Edge-Computing Architecture
1.2. Definitions of Terms
* EAS: Edge Application Server, a server offering application
services and residing in an edge DN.
* EHE: Edge Hosting Environment, an environment providing support
required for EAS's execution.
* UPF: User Plane Function, supporting routing functionalities
(similar to an IP-domain router).
2. Computing-aware 5G Enhanced Edge (eEdge)
Recently, the 3GPP 5G Rel-19 [TR.23.700-49] studied how to
effectively and optimally select (local) UPFs in 5G CN (Core Network)
and EAS'es residing in DN (or edge hosting environment) with the
consideration of the N6 (transport) delay between (local) PSA UPFs
and EAS'es, and, possibly, the computing capabilities, e.g., compute
power, memory, runtime load, storage, etc., of EAS'es.
Jiang Expires 12 April 2025 [Page 3]
Internet-Draft CATS 5G Edge Enhance October 2024
2.1. EAS & Local-UPF Optimized Selection in 5G eEdge
The 5G enhanced Edge (or eEdge) explores to discover one suitable EAS
to handle an edge application that can be served by multiple EAS'es
deployed in different sites (i.e., DNs or local DNs). The
suitability of an EAS is dependant on both of the following:
1. network metrics, such as bandwidth, latency, etc.
2. compute metrics or computing capabilities, such as processing
power, storage capacity, AS load, etc.
Evidently, the integration of both network & compute metrics conform
to the scope of the CATS charter.
The 3GPP 5G eEdge document [TR.23.700-49] provides a couple of 5G
specific scenarios to justify the requirement. For example, when
some of the available transport links in DNs get congested, a UE
moves aways from the original location (very common in mobile
network), or excessive load builds up on EAS(es), then a previously
'better-optimized' EAS may become less preferable, and thus a new EAS
and/or local-PSA UPF need to be selected based on the weighted
optimization of nework and compute metrics. The 5G eEdge emphasizes
particularly on considering the EAS load and the end-to-end delay off
the N6 interface between a local PSA and a candidate EAS residing in
a (local) DN.
In the Figure 2, the UPF-1 to UPF-m indicate 'm' local PSA UPFs, all
of which could fulfill an applicaiton service (AppService) to the UE
(on the left side of the figure). The AppService is provisioned in
multiple EAS'es that reside in remote DN(s) or local DN(s), denoted
as EAS-1 to EAS-n. The selection of UPF and EAS may depend on both
the N6 delay and EAS load.
Jiang Expires 12 April 2025 [Page 4]
Internet-Draft CATS 5G Edge Enhance October 2024
C-PSA: Central PSA UPF
UPF-x(L-PSA): the x-th Local PSA UPF, x=1...m
EAS-y: the y-th Edge App Server in DN, y=1...n
DL: Downlink direction UL: Uplink direction
.....................................
: [-- 5G Core --] :
: / | | :
: N1 N2 N4 :
: / | | :
: / | +-------+ +-----+ :
+----+ +-----+ | UPF | | UPF | : /---------\
| UE |--| gNB |--|ULCL/BP|--|C-PSA+(N6)-/ DN or \
+----+ +-----+ +-------+ +-----+ : |DN:local-part|
: | : | -------- |
: | : | [EAS-1] |
: +------------+ : | |
: |UPF-1(L-PSA)|(N6)-----| [EAS-2] |
: +------------+ : | . |
: ...... : | . |
: +------------+ : | . |
: |UPF-m(L-PSA)|(N6)-----| [EAS-n] |
: +------------+ : \ /
....................................: \---------/
Figure 2: CATS-aware 5G eEdge Use Case
2.2. Integrating 5G eEdge w/ CATS
This subsection shows how to implement the computing-aware 5G eEdge
via mappings to CATS functional componenents, e.g., C-PS, C-NMA,
C-SMA, etc.[CATS.Framework]
* Network Metric: The 5G eEdge [TR.23.700-49] has concluded to
integrate into the UPF/EAS optimized selection the end-to-end N6
delay over the transport network between (local) PSA UPFs and
EAS'es.
* Compute Metric: Load of EAS(es) located in (local) DNs. While it
has been explored during the study phase of the 5G eEDGE, the
conclusion is to leave it for further integration (e.g., in 6G).
* SMF => C-PS: As of now, the 5G eEdge [TR.23.700-49] has designated
a SMF to manage the selection of the optimal UPF (from all
candidate UPFs, e.g., UPF-1, …, UPF-m as in Figure 2) and the best
EAS (from all instances, e.g., EAS-1, …, EAS-n as in Figure 2)
based on the network metric (i.e., the end-to-end N6-delay).
Jiang Expires 12 April 2025 [Page 5]
Internet-Draft CATS 5G Edge Enhance October 2024
Please note that the 5G eEdge conclusion leaves the normative
extension for a SMF helping (UPF) select the best EAS potentially
based on EAS-load to a future release (e.g., Rel-20 or beyond).
* C-NMA, C-SMA: The combined functionalies of AF & SMF make it a
C-NMA (according to both [TR.23.700-49] and the AF-influenced
procedure as in the clause 4.3.6 of [TS.23.502]). However, thanks
to the non-inclusion of the EAS-load metric, how to map C-SMA is
un-determined now, which is probably for future extension.
* Delay-measuring off N6 interface: The 5G eEdge proposes to
leverage the existing IETF protocols & mechanisms, e.g.,
ICMP[RFC792], OWAMP[RFC4656], OWAMP[RFC5357], etc.
3. Security Considerations
There is no security concern.
4. IANA Considerations
There is no IANA requirement.
5. References
5.1. Normative References
[CATS.Framework]
Li, C., et al., "A Framework for Computing-Aware Traffic
Steering (CATS)", draft-ietf-cats-framework, September
2024.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<https://www.rfc-editor.org/info/rfc4656>.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<https://www.rfc-editor.org/info/rfc5357>.
[RFC792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981,
<https://www.rfc-editor.org/info/rfc792>.
Jiang Expires 12 April 2025 [Page 6]
Internet-Draft CATS 5G Edge Enhance October 2024
[TR.23.700-49]
"3GPP TR 23.700-49 v19.0.0: Study on Enhancement of
support for Edge Computing in 5G Core network; Phase
3", 3GPP TR 23.700-49, September 2024.
[TS.23.501]
"3GPP TS 23.501 (V19.0.0): System Architecture for 5G
System; Stage 2", 3GPP TS 23.501, June 2024.
[TS.23.502]
"3GPP TS 23.502 (V19.0.0): Procedures for the 5G System;
Stage 2", 3GPP TS 23.501, June 2024.
[TS.23.548]
"3GPP TS 23.548: 5G System Enhancements for Edge
Computing; Stage 2", 3GPP TS 23.548, September 2024.
5.2. Informative References
Author's Address
Tianji Jiang
China Mobile
Email: tianjijiang@chinamobile.com
Jiang Expires 12 April 2025 [Page 7]