Skip to main content

IP Layer Metrics for Edge Services
draft-dunbar-cats-edge-service-metrics-00

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Linda Dunbar , Kausik Majumdar , Gyan Mishra , Haoyu Song
Last updated 2023-04-25
RFC stream (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-dunbar-cats-edge-service-metrics-00
Network Working Group                                   L. Dunbar
Internet Draft                                          Futurewei
Intended status: Standard                             K. Majumdar
Expires: October 25, 2023                              Microsoft
                                                       G. Mishra
                                                         Verizon
                                                         H. Song
                                                       Futurewei
                                                   April 25, 2023

                 IP Layer Metrics for Edge Services
             draft-dunbar-cats-edge-service-metrics-00

Abstract

   This draft describes the IP Layer metrics and methods to
   measure the Edge Services' running status and environment for
   IP network to dynamically optimize the forwarding of low
   latency edge services without any knowledge above the IP
   layer.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79. This document may not be
   modified, and derivative works of it may not be created,
   except to publish it as an RFC and to translate it into
   languages other than English.

   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."

xxx, et al.            Expires October 25, 2023          [Page 1]
              IP Layer Metrics for 5G Edge Services

   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

   This Internet-Draft will expire on April 7, 2021.

Copyright Notice

   Copyright (c) 2023 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..............................................3
      1.1. Use Case: 5G Edge Computing..........................3
      1.2. Problem 1: Selecting 5G Edge Service Instance
      Location..................................................4
      1.3. Problem 2: UE mobility creates unbalanced anycast
      distribution..............................................5
   2. Conventions used in this document.........................6
   3. IP-Layer Metrics Definitions for 5G Edge Services........11
      3.1. IP-Layer Service ID.................................11
      3.2. IP-Layer metric for Service Instances Load
      Measurement..............................................11
      3.3. Capacity Index in the overall cost..................14
      3.4. Site Preference Index in the overall cost...........14
      3.5. RTT to an ANYCAST Address in 5G EC..................15
   4. Algorithm in Selecting the optimal Target Location.......16
   5. Scope of IP Layer Metrics Advertisement..................17
   6. Manageability Considerations.............................17

Dunbar, et al.         Expires October 25, 2023          [Page 2]
              IP Layer Metrics for 5G Edge Services

   7. Security Considerations..................................17
   8. IANA Considerations......................................18
   9. References...............................................18
      9.1. Normative References................................18
      9.2. Informative References..............................18
   10. Acknowledgments.........................................19

1. Introduction
1.1. Use Case: 5G Edge Computing

   In the 5G Edge Computing environment [3GPP-EdgeComputing],
   one application or service can have multiple instances hosted
   in different Edge Computing data centers. Those Edge
   Computing (mini) data centers are usually very close to, or
   co-located with, 5G base stations to minimize latency and
   optimize the user experience.

   When a UE (User Equipment) initiates the packets using the
   destination address from a DNS reply or its own cache, the
   packets from the UE are carried in a PDU session through the
   5G Core [5GC] to the 5G UPF-PSA (User Plan Function - PDU
   Session Anchor). The UPF-PSA decapsulates the 5G GTP outer
   header and forwards the packets from the UEs to the Ingress
   router of the Edge Computing (EC) Local Data Network (LDN).
   The LDN for 5G EC, which is the IP Networks from 5GC
   perspective, is responsible for forwarding the packets to the
   intended destinations.

   Routers in the local IP network should be able to select the
   "best" or "closest" location out of many service instances.
   However, simply using distance alone as a metric may not be
   sufficient as there may be many locations in close proximity.
   Moreover, one of the main aims of locating the service
   instance close to the user is to provide lower latency. When
   a UE moves and attaches to another UPF, the packets from the
   UE can enter the IP network from a different ingress router.
   It is desirable if the IP network can continue forwarding the
   packets from the UE to the established service instance. As a
   user keeps moving further away, a closer service instance
   might be able to serve the UE better. Network measurements,
   including latency of various paths are provided to the
   ingress router to assist in re-selection.

Dunbar, et al.         Expires October 25, 2023          [Page 3]
              IP Layer Metrics for 5G Edge Services

1.2. Problem 1: Selecting 5G Edge Service Instance Location

   Having multiple locations closer to UEs to host one service
   can greatly improve the user experience. But selecting an
   optimal location for the service traffic from a UE may not be
   that simple.

   Using DNS to reply with the address of the service instance
   location closest to the requesting UE can encounter issues
   like:
     - UE can cache results indefinitely, when the UE moves to a
       5G cell site very far away, the cached address may still
       be used, which can incur large network delay.
     - The service instance at a specific location whose address
       replied by the DNS might be heavily loaded causing slow
       or no response, when there are available low utilized
       service instances, for the same service, at different
       locations very close in proximity.
     - No inherent leverage of proximity information present in
       the network (routing) layer, resulting in loss of
       performance
     - Local DNS resolver become the unit of traffic management

   Increasingly, Anycast is used extensively by various
   application providers and CDNs because ANYCAST makes it
   possible to dynamically load balance across locations that
   host the application/service instances based on network
   conditions. Service instances' location selection using
   Anycast address leverages the proximity information present
   in the network (routing) layer and eliminates the single
   point of failure and bottleneck at the DNS resolvers and
   application layer load balancers. Another benefit of using
   ANYCAST address is removing the dependency on UEs that use
   their cached destination IP addresses for extended period.

   But selection of an ANYCAST location purely based on the
   network condition can encounter issue of the location
   selected by network routing information being overutilized
   while there are available underutilized locations close by.

Dunbar, et al.         Expires October 25, 2023          [Page 4]
              IP Layer Metrics for 5G Edge Services

1.3. Problem 2: UE mobility creates unbalanced anycast
   distribution

   Another problem of using ANYCAST address for multiple
   locations of one service in 5G environment is that UEs'
   frequent moving from one 5G site to another. The frequent
   move of UEs can make it difficult to plan where the service
   instances should be hosted. When a large number of UEs using
   a particular service congregate together unpredictably, the
   ANYCAST location selected based on routing distance can be
   heavily utilized, while the instances of the same service at
   other locations close-by are underutilized.

Dunbar, et al.         Expires October 25, 2023          [Page 5]
              IP Layer Metrics for 5G Edge Services

   +--+
   |UE|---\+---------+                 +------------------+
   +--+    |  5G     |  +-----------+  |  S1: aa08::4450  |
   +--+    | Site A +----+         +----+                 |
   |UE|----|        | Ra |         | R1 | S2: aa08::4460  |
   +--+    |        +----+         +----+                 |
  +---+    |         |  |           |  |  S3: aa08::4470  |
  |UE1|---/+---------+  |           |  +------------------+
  +---+                 |IP Network |       L-DN1
                        |(3GPP N6)  |
     |                  |           |  +------------------+
     |                  |           |  |  S1: aa08::4450  |
     |                  |          +----+                 |
     |                  |          | R3 | S2: aa08::4460  |
     v                  |          +----+                 |
                        |           |  |  S3: aa08::4470  |
                        |           |  +------------------+
                        |           |      L-DN3
   +--+                 |           |
   |UE|---\+---------+  |           |  +------------------+
   +--+    |  5G     |  |           |  |  S1: aa08::4450  |
   +--+    | Site B +----+         +----+                 |
   |UE|----|        | Rb |         | R2 | S2: aa08::4460  |
   +--+    |        +----+         +----+                 |
   +--+    |         |  +-----------+  |  S3: aa08::4470  |
   |UE|---/+---------+                 +------------------+
   +--+                                     L-DN2
     Figure 1: multiple ANYCAST instances in different edge DCs

This document describes the measurements at the IP Layer that
can reflect the service instances running status and environment
at the specific locations. This document also describes the
method of incorporating those measurements with IP routing cost
to come up with a more optimal criteria in selecting the service
instance locations.

2. Conventions used in this document

   CATS:       Computing-Aware Traffic Steering takes into
               account the dynamic nature of computing resource

Dunbar, et al.         Expires October 25, 2023          [Page 6]
              IP Layer Metrics for 5G Edge Services

               metrics and network state metrics to steer
               service traffic to a service instance.

   Service:    A monolithic function. A composite service can be
               built by orchestrating monolithic services.

   Service instance: A run-time environment (e.g., a server or a
               process on a server) that makes the functionality
               of a service available. One service can have
               multiple instances running at the same or
               different network locations.

   CS-ID:      The CATS Service ID is an identifier representing
               a service, which the clients use to access said
               service. Such an identifier identifies all of the
               instances of the same service, no matter on where
               they are actually running. The CS-ID is
               independent of which service instance serves the
               service demand. Usually multiple instances
               provide a (logically) single service, and service
               demands are dispatched to the different instance
               by choosing one instance among all available
               instances.

   CB-ID:      The CATS Binding ID is an identifier of a single
               service instance of a given CS-ID. Different
               service instances provide the same service
               identified through a single CS-ID, but with
               different CATS Binding IDs.

   Service demand: The demand for a specific service identified
               by a specific CS-ID.

   Service request: The request for a specific service instance.

   CATS-router: A network device (usually at the edge of the
               network) that makes forwarding decisions based on
               CATS information to steer traffic belonging to
               the same service demand to the same chosen
               service instance.

Dunbar, et al.         Expires October 25, 2023          [Page 7]
              IP Layer Metrics for 5G Edge Services

   Ingress CATS-Router: A network edge router that serves as a
               service access point for CATS clients. It steers
               the service packets onto an overlay path to an
               Egress CAN-Router linked to the most suitable
               edge site to access a service instance.

   CATS-ER:    CATS-ER is an egress CATS-Router, i.e., the
               egress endpoint of an overlay path to a service
               instance. CATS-ER is used to describe the last
               router that the service instances are attached.
               In a 5G EC environment, the CATS-ER can be the
               gateway router to the Edge Computing Data Center.

   C-SMA:   The CATS Service Metric Agent responsible for
               collecting service capabilities and status, and
               for reporting them to the C-PS.

               NOTE: The above terminologies are the same as
               those used in 3GPP TR 23.758

   C-NMA:      The CATS Network Metric Agent responsible for
               collecting network capabilities and status, and
               for reporting them to the C-PS

   C-PS:       The CATS Path Selector determines the path toward
               the appropriate service location and service
               instances to meet a service demand given the
               service status and network status information.

   C-TC:       The CATS Traffic Classifier is responsible for
               determining which packets belong to a traffic
               flow for a particular service demand, and for
               steering them on the path to the service instance
               as determined by the C-PS.

   Edge DC:    Edge Data Center, which provides the Hosting
               Environment for the edge services. An Edge DC
               might host 5G core functions in addition to the
               frequently used application servers.

   gNB         next generation Node B

Dunbar, et al.         Expires October 25, 2023          [Page 8]
              IP Layer Metrics for 5G Edge Services

   PSA:        PDU Session Anchor (UPF)

   SSC:        Session and Service Continuity

   UE:         User Equipment

   UPF:        User Plane Function

   ANYCAST Instance: refer to the service instance at a specific
               location which is reachable by the ANYCAST
               address.

   Service Instance Location: Represent a cluster of servers at
               one location serving the same Service. One
               service may have a Layer 7 Load balancer, whose
               address(es) are reachable from external IP
               network, in front of a set of service instances.
               From the IP network perspective, this whole group
               of instances are considered as one service
               instance at the location.

   EC:         Edge Computing

   Edge Computing Hosting Environment: An environment, such as
               psychical or virtual machines, host the service
               instances.

               NOTE: The above terminologies are the same as
               those used in 3GPP TR 23.758

   Edge DC:    Edge Data Center, which provides the Edge Hosting
               Environment. It might be co-located with 5G Base
               Station and not only host 5G core functions, but
               also host frequently used Edge server instances.

Dunbar, et al.         Expires October 25, 2023          [Page 9]
              IP Layer Metrics for 5G Edge Services

   L-DN:       Local Data Network

   PSA:        PDU Session Anchor (UPF)

   RTT:        Round Trip Time

   RTT-ANYCAST:   A list of Round trip times to a group of
               routers that have the ANYCAST instances directly
               attached.

   SSC:        Session and Service Continuity

   UE:         User Equipment

   UPF:        User Plane Function

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
   RECOMMENDED", "MAY", and "OPTIONAL" in this document are to
   be interpreted as described in BCP 14 [RFC2119] [RFC8174]
   when, and only when, they appear in all capitals, as shown
   here.

Dunbar, et al.         Expires October 25, 2023         [Page 10]
              IP Layer Metrics for 5G Edge Services

3. IP-Layer Metrics Definitions for 5G Edge Services

 3.1. IP-Layer Service ID

   From network perspective, a service identifier, or IP Layer
   Service ID, is an ANYCAST address that can represent multiple
   service instances at different locations that host the
   service.

 3.2. IP-Layer metric for Service Instances Load Measurement

   There are many network techniques and protocols to optimize
   forwarding and ensure QoS, such as DSCP/DiffServ, Traffic
   Engineered (TE) solutions, Segment Routing, etc. But most
   applications and services don't expose their internal logic
   to network operators. Their communications are generally
   encrypted. Most do not respond to PING or ICMP messages
   initiated by routers or network elements.

   This document specifies the IP Layer metrics and algorithms
   that enable the IP networks to dynamically optimize the
   forwarding of 5G edge computing service without any knowledge
   above the IP layer.

   Without knowledge of application internal logics, network
   layer or IP Layer can monitor the traffic patterns to/from
   the service instances at each location to gauge the running
   status of the service at the location. The proposed IP Layer
   Metrics and algorithm enable the IP networks to be more aware
   of the service behavior without dependency on getting
   information from the services themselves.

   First, the network needs to discover which router(s) has the
   service instances attached. Those routers are called CATS
   Egress Router, or CATS-ER for short. CATS-ER is usually the
   Gateway Router to an Edge Computing Data Center. To discover
   if a router is the CATS-ER for a specific edge service, the
   router can periodically send reverse ARP (IPv4) or Neighbor
   Discovery scan with the address of the Service ID to discover
   if there are the service instances hosted in its edge
   computing data center. If yes, the router or routers are
   identified as the CATS-ER for the Service ID. For one Service
   ID, there can be many CATS-ERs at different EC Data Centers.

Dunbar, et al.         Expires October 25, 2023         [Page 11]
              IP Layer Metrics for 5G Edge Services

   For a service instance at a specific location, which is
   identified by the address of the service instance at the IP
   layer, the CATS-ER can measure the amount of traffic destined
   towards the address & the amount of the traffic from the
   specific address, such as:

     - Total number of packets to the attached service instance
       (ToPackets);
     - Total number of packets from the attached service
       instance (FromPackets);
     - Total number of Bytes to the attached service instance
       (ToBytes);
     - Total number of bytes from the attached service instance
       (FromBytes);

   The actual load measurement to the service instance attached
   to an CATS-ER can be based on one of the metrics above or
   including all four metrics with different weights applied to
   each, such as:

   LoadIndex =
   w1*ToPackets+w2*FromPackes+w3*ToBytes+w4*FromBytes

          Where 0<= wi <=1 and w1+ w2+ w3+ w4 = 1.

   The weights of each metric contributing to the load index of
   the service instance attached to a CATS-ER can be configured
   or learned by self-adjusting based on user feedbacks.

   The raw measurement is useful when the CATS-ER routers cannot
   be configured with a consistent algorithm to compute the
   aggregated load index and the raw measurements are needed by
   a central analytic system.

   The CATS-ER can advertise either the aggregated Load Index or
   the raw measurements periodically, by BGP UPDATE messages
   (in-band) or BGP-LS (via controller), to a group of routers
   that have traffic destined towards the ANYCAST addresses of
   those services.

Dunbar, et al.         Expires October 25, 2023         [Page 12]
              IP Layer Metrics for 5G Edge Services

   It is better to have applications or their controllers
   directly reporting their own workload running status to the
   network. When it is not feasible to have the third-party
   application controller provide the workload information to
   the network operators, the proposed IP layer Load
   Measurements provide an intelligent estimate of the instance
   running status at a specific location.

Dunbar, et al.         Expires October 25, 2023         [Page 13]
              IP Layer Metrics for 5G Edge Services

 3.3. Capacity Index in the overall cost

     Capacity Index indicates the capacity value for a site or a
     pod where the edge services are hosted. One Edge Site can
     be in full capacity, reduced capacity, or completely out of
     service.

     Cloud Site/Pod failures and degradation include, but not
     limited to, a site capacity degradation or entire site
     going down caused by a variety of reasons, such as fiber
     cut connecting to the site or among pods within one site,
     cooling failures, insufficient backup power, cyber threats
     attacks, too many changes outside of the maintenance
     window, etc. Fiber-cut is not uncommon within a Cloud site
     or between sites.

     When those failure events happen, the Edge (egress) router
     visible to the ingress routers can be running fine.
     Therefore, the ingress routers with paths to the egress
     routers can't use BFD to detect the failures.

     When there is a failure occurring at an edge site (or pod),
     many instances can be impacted. In addition, the routes
     (i.e., the IP addresses) in an Edge Cloud Site might not be
     aggregated nicely. Instead of many BGP UPDATE messages for
     each instance to the impacted ingress routers, the egress
     router can send one single BGP UPDATE indicating the
     capacity of the site. The ingress routers can switch all or
     a portion of the instances that are associated with the
     site depending on how much the site is degraded.

     Site Capacity should be represented as the percentage of
     the site availability, e.g., 100%, 50%, or 0%. When a site
     goes dark, the Index is set to 0.  50 means 50% capacity
     functioning.

 3.4. Site Preference Index in the overall cost

     As described in [IPv6-StickyService] and [ISPF-EXT-EC], an
     EC sticky service needs to connect a UE to the service
     instance that has been serving the UE before the UE moves
     to a new 5G Site, unless there is failure to that location.

Dunbar, et al.         Expires October 25, 2023         [Page 14]
              IP Layer Metrics for 5G Edge Services

     To achieve the goal of sticking a flow from one specific UE
     to a specific site, a "site Preference Index" is created.
     The value of the Site Preference Index can be manipulated
     for packets of some flows to be steered towards a instance
     location farther away in routing distance. The "Site
     Preference Index" enables some sites to be more preferred
     for handling the UE traffic to a instance than others.

 3.5. RTT to an ANYCAST Address in 5G EC

     ANYCAST used in 5G Edge computing environment is slightly
     different from the typical ANYCAST address being deployed.
     Typical ANYCAST address is used to represent instances in
     vast different geographical locations, such as different
     continents. ANCAST address for "app.net" for Asia lead
     packets to a server instance of "app.net" hosted in Asia.
     Therefore, the RTT for "app.net" in Asia, is a single value
     that represent the round time trip to the server in Asia
     that host the "app.net".

     5G Edge Computing environment can have one service hosted
     in multiple Edge Computing DCs close in proximity. Routers,
     i.e. the ingress router to 5G LDN (Local Data Network), can
     forward packets for the ANYCAST address of "app.net" to
     different egress routers that have "app.net" instances
     attached.

     If "app.net" is hosted in four different 5G Edge Computing
     Data Centers. All those DCs have the same ANYCAST address
     for the "app.net". The RTT to "app.net" ANYCAST address
     need to be a group of values (instead of one RTT value to a
     unicast address). The RTT group value should include the
     CATS-ER router's specific unicast address (e.g., the
     loopback address) to which the service instance is
     attached.

     RTT to "app.net" ANYCAST Address is represented as:

         List of {Egress Router address, RTT value}

     This list is called "RTT-ANYCAST".

     In order to better optimize the ANYCAST traffic, each
     router adjacent to 5G PSA needs to periodically measure RTT
     to a list of CATS-ER routers that advertise the ANYCAST
     address. The RTT to egress router at Site-i is considered
     as the RTT to the ANYCAST instance at the Site-i.

Dunbar, et al.         Expires October 25, 2023         [Page 15]
              IP Layer Metrics for 5G Edge Services

4. Algorithm in Selecting the optimal Target Location

   The goal of the algorithm is to equalize the traffic among
   multiple locations of the same ANYCAST address.

   The main benefit of using ANYCAST is to leverage the IP-layer
   information to equalize the traffic among multiple locations
   of the same service, usually identified by one or a group of
   ANYCAST addresses.

   For 5G Edge Computing environment, the ingress router to each
   LDN needs to be notified of the Load Index and Capacity Index
   of the service instances at different EC site to make the
   intelligent decision on where to forward the traffic from UEs
   for the service.

   The Algorithm needs to take the following attributes into
   consideration:

     -              Load Measurement Index [Section 3.2],
     - capacity index [Section 3.3],
     - Preference Index [Section 3.4], and
     - network delay [Section 3.5].

   Here is an algorithm for a router, e.g., the router directly
   attached to the 5G PSA, to compare the cost to reach the
   service instances at Site-i or Site-j:

               Load-i * CP-j               Pref-j * Delay-i
Cost-i=min(w *(----------------) + (1-w) *(------------------))
              Load-j * CP-i               Pref-i * Delay-j

      Load-i: Load Index at Site-i, it is the weighted
      combination of the total packets and bytes sent to and
      received from the service instance at Site-i during a
      fixed time period.

      CP-i (Capacity-i) (higher value means higher capacity):
      capacity index at the site i.

      Delay-i: Network latency measurement (RTT) to the CATS-ER
      that has the service instances attached at the site-i.

Dunbar, et al.         Expires October 25, 2023         [Page 16]
              IP Layer Metrics for 5G Edge Services

      Pref-i (Preference Index: higher value means higher
      preference): Network Preference index for the site-I.

      w: Weight for load and site information, which is a value
      between 0 and 1. If smaller than 0.5, Network latency and
      the site Preference have more influence; otherwise, Server
      load and its capacity have more influence.

5. Scope of IP Layer Metrics Advertisement

   Each service might be used by a small group of UEs.
   Therefore, it is not necessary for CATS-ER router to
   advertise the IP layer metrics to all other routers in the 5G
   LDN. Likewise, each EC Data Center may only host a small
   number of low latency services.

   "Service ID Bound Group Routers" is used to refer a group of
   routers that are interested in a group of specific ANYCAST
   addresses. The IP Layer Metrics for a specific service ID
   should be advertised among the routers in the "Service ID
   bound Group Routers".

   BGP RT Constrained Distribution [RFC4684] can be used to form
   the "Service ID Bound Group Routers".

   Since there are much more Service IDs than the number of
   routers in 5G LDN, a more practical way to form the "Service
   ID Bound Group of Routers" is for each ingress router to
   query a network controller upon receiving the first packet to
   a specific ANYCAST address to be included in the "Service ID
   Bound Group Routers". There should be a timer associated with
   Ingress router, as the UE that uses the service ID might move
   away. Upon timer expires, the Ingress Router is removed from
   the "Service ID Bound Group of Routers".

6. Manageability Considerations

     To be added.

7. Security Considerations

   To be added.

Dunbar, et al.         Expires October 25, 2023         [Page 17]
              IP Layer Metrics for 5G Edge Services

8. IANA Considerations

       To be added.

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.

   [RFC4364] E. rosen, Y. Rekhter, "BGP/MPLS IP Virtual Private
             networks (VPNs)", Feb 2006.

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in
             RFC 2119 Key Words", BCP 14, RFC 8174, DOI
             10.17487/RFC8174, May 2017, <https://www.rfc-
             editor.org/info/rfc8174>.

   [RFC8200] s. Deering R. Hinden, "Internet Protocol, Version 6
             (IPv6) Specification", July 2017

9.2. Informative References

   [3GPP-EdgeComputing] 3GPP TS 23.548 V18.1.1, "3rd Generation
             Partnership Project; Technical Specification Group
             Services and System Aspects; 5G System Enhancements
             for Edge Computing; Stage 2", Release 18, April
             2023.

   [RFC5521] P. Mohapatra, E. Rosen, "The BGP Encapsulation
             Subsequent Address Family Identifier (SAFI) and the
             BGP Tunnel Encapsulation Attribute", April 2009.

   [BGP-SDWAN-Port] L. Dunbar, H. Wang, W. Hao, "BGP Extension
             for SDWAN Overlay Networks", draft-dunbar-idr-bgp-
             sdwan-overlay-ext-03, work-in-progress, Nov 2018.

Dunbar, et al.         Expires October 25, 2023         [Page 18]
              IP Layer Metrics for 5G Edge Services

   [SDWAN-EDGE-Discovery] L. Dunbar, S. Hares, R. Raszuk, K.
             Majumdar, "BGP UPDATE for SDWAN Edge Discovery",
             draft-dunbar-idr-sdwan-edge-discovery-00, work-in-
             progress, July 2020.

   [Tunnel-Encap] E. Rosen, et al "The BGP Tunnel Encapsulation
             Attribute", draft-ietf-idr-tunnel-encaps-10, Aug
             2018.

10. Acknowledgments

   Acknowledgements to XXX for their review and contributions.

   This document was prepared using 2-Word-v2.0.template.dot.

Dunbar, et al.         Expires October 25, 2023         [Page 19]
              IP Layer Metrics for 5G Edge Services

Authors' Addresses

   Linda Dunbar
   Futurewei
   Email: ldunbar@futurewei.com

   Kausik Majumdar
   Microsoft
   Email: kmajumdar@microsoft.com

   Gyan Mishra
   Verizon
   Email: gyan.s.mishra@verizon.com

   HaoYu Song
   Futurewei
   Email: haoyu.song@futurewei.com

Dunbar, et al.         Expires October 25, 2023         [Page 20]