Network Working Group L. Dunbar
Internet Draft Futurewei
Intended status: Standard K. Majumdar
Expires: May 2, 2021
CommScope
H. Wang
Huawei
November 2, 2020
BGP NLRI App Meta Data for 5G Edge Computing Service
draft-dunbar-idr-5g-edge-compute-app-meta-data-01
Abstract
This draft describes a new BGP Network Layer Reachability
Information (BGP NLRI) Path Attribute, AppMetaData, that can
distribute the 5G Edge Computing App running status and
environment, so that other routers in the 5G Local Data
Network can make intelligent decision on optimized forwarding
of flows from UEs. The goal is to improve latency and
performance for 5G Edge Computing services.
The extension enables a feature, called soft anchoring, which
makes one Edge Computing Server at one specific location to be
more preferred than others for the same application to receive
packets from a specific source (UE).
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.
xxx, et al. Expires May 2, 2021 [Page 1]
Internet-Draft AppMetaData NLRI for 5G EC Service
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
This Internet-Draft will expire on April 7, 2021.
Copyright Notice
Copyright (c) 2020 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. 5G Edge Computing Background......................... 3
1.2. Problem#1: ANYCAST in 5G EC Environment.............. 5
1.3. Problem #2: Unbalanced Anycast Distribution due to UE
Mobility.................................................. 6
Dunbar, et al. Expires May 2, 2021 [Page 2]
Internet-Draft AppMetaData NLRI for 5G EC Service
1.4. Problem 3: Application Server Relocation............. 6
2. Conventions used in this document......................... 7
3. Usage of App Meta Data for 5G Edge Computing.............. 8
3.1. Overview............................................. 8
3.2. IP Layer Metrics to Gauge Application Behavior....... 9
3.3. To Equalize among Multiple ANYCAST Locations........ 10
3.4. BGP Protocol Extension to advertise Load & Capacity. 10
4. The NLRI Path Attribute for App Meta Data................ 11
4.1. Load Measurement sub-TLV format..................... 13
4.2. Capacity Index sub-TLV format....................... 14
4.3. The Site Preference Index sub-TLV format............ 14
5. Soft Anchoring of an ANYCAST Flow........................ 15
6. Manageability Considerations............................. 17
7. Security Considerations.................................. 17
8. IANA Considerations...................................... 17
9. References............................................... 17
9.1. Normative References................................ 17
9.2. Informative References.............................. 17
10. Acknowledgments......................................... 18
1. Introduction
This document describes a new BGP Network Layer Reachability
Information (BGP NLRI) Path Attribute, AppMetaData, that can
distribute the 5G Edge Computing App running status and
environment, so that other routers in the 5G Local Data
Network can make intelligent decision on optimized forwarding
of flows from UEs. The goal is to improve latency and
performance for 5G Edge Computing services.
1.1. 5G Edge Computing Background
As described in [5G-EC-Metrics], one Application can have
multiple Application Servers hosted in different Edge
Computing data centers that are close in proximity. Those Edge
Computing (mini) data centers are usually very close to, or
co-located with, 5G base stations, with the goal to minimize
latency and optimize the user experience.
When a UE (User Equipment) initiates application packets using
the destination address from a DNS reply or from its own
cache, the packets from the UE are carried in a PDU session
through 5G Core [5GC] to the 5G UPF-PSA (User Plan Function -
Dunbar, et al. Expires May 2, 2021 [Page 3]
Internet-Draft AppMetaData NLRI for 5G EC Service
PDU Session Anchor). The UPF-PSA decapsulate 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.
When the UE moves out of coverage of its current gNB (next
generation Node B) (gNB1), handover procedures are initiated
and the 5G SMF (Session Management Function) also selects a
new UPF-PSA. The standard handover procedures described in
3GPP TS 23.501 and TS 23.502 are followed. When the handover
process is complete, the UE has a new IP address and the IP
point of attachment is to the new UPF-PSA. 5GC may maintain a
path from the old UPF to new the UPF for a short period of
time for SSC [Session and Service Continuity] mode 3 to make
the handover process more seamless.
Dunbar, et al. Expires May 2, 2021 [Page 4]
Internet-Draft AppMetaData NLRI for 5G EC Service
+--+
|UE|---\+---------+ +------------------+
+--+ | 5G | +---------+ | S1: aa08::4450 |
+--+ | Site +--++---+ +----+ |
|UE|----| A |PSA| Ra| | R1 | S2: aa08::4460 |
+--+ | +---+---+ +----+ |
+---+ | | | | | S3: aa08::4470 |
|UE1|---/+---------+ | | +------------------+
+---+ |IP Network | L-DN1
|(3GPP N6) |
| | | +------------------+
| UE1 | | | S1: aa08::4450 |
| moves to | +----+ |
| Site B | | R3 | S2: aa08::4460 |
v | +----+ |
| | | S3: aa08::4470 |
| | +------------------+
| | L-DN3
+--+ | |
|UE|---\+---------+ | | +------------------+
+--+ | 5G | | | | S1: aa08::4450 |
+--+ | Site +--++-+--+ +----+ |
|UE|----| B |PSA| Rb | | R2 | S2: aa08::4460 |
+--+ | +--++----+ +----+ |
+--+ | | +-----------+ | S3: aa08::4470 |
|UE|---/+---------+ +------------------+
+--+ L-DN2
Figure 1: App Servers in different edge DCs
1.2. Problem#1: ANYCAST in 5G EC Environment
Increasingly, Anycast is used extensively by various
application providers and CDNs because ANYCAST makes it
possible to dynamically load balance across server locations
based on network conditions.
Application Server 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
Dunbar, et al. Expires May 2, 2021 [Page 5]
Internet-Draft AppMetaData NLRI for 5G EC Service
removing the dependency on UEs. Some UEs (or clients) might
use their cached IP addresses instead of querying DNS for
extended period.
But, having multiple locations of the same ANYCAST address in
5G Edge Computing environment can be problematic because all
those edge computing Data Centers can be close in proximity.
There might be very little difference in the routing cost to
reach the Application Servers in different Edge DCs.
BGP is an integral part in the way IP Anycast usually
functions. Within BGP routing there are multiple routes for
the same IP address which are pointing to different locations.
This draft describes the BGP UPDATE extension to allow the App
Servers Running status and environment to be included in the
BGP UPDATE messages, so that other routers can select more
optimal ANYCAST location based on the combination of network
delay, the App Server load index, the location capacity index
and the location preference.
1.3. Problem #2: Unbalanced Anycast Distribution due to UE
Mobility
Another problem of using ANYCAST address for multiple
Application Servers of the same application in 5G environment
is that UEs' frequent moving from one 5G site to another,
which can make it difficult to plan where the App Server
should be hosted. When one App server is heavily utilized,
other App servers of the same address close-by can be very
underutilized. Since the condition can be short lived, it is
difficult for the application controller to anticipate the
move and adjust.
1.4. Problem 3: Application Server Relocation
When an Application Server is added to, moved, or deleted from
a 5G Edge Computing Data Center, the routing protocol needs to
propagate the changes to 5G PSA or the PSA adjacent routers.
After the change, the cost associated with the site [5G-EC-
Metrics] might change as well.
Dunbar, et al. Expires May 2, 2021 [Page 6]
Internet-Draft AppMetaData NLRI for 5G EC Service
Note: for the ease of description, the Edge Application Server
and Application Server are used interchangeably throughout
this document.
2. Conventions used in this document
A-ER: Egress Router to an Application Server, [A-ER] is
used to describe the last router that the
Application Server is attached. For 5G EC
environment, the A-ER can be the gateway router to
a (mini) Edge Computing Data Center.
Application Server: An application server is a physical or
virtual server that host the software system for
the application.
Application Server Location: Represent a cluster of servers at
one location serving the same Application. One
application may have a Layer 7 Load balancer,
whose address(es) are reachable from external IP
network, in front of a set of application servers.
From IP network perspective, this whole group of
servers are considered as the Application server
at the location.
Edge Application Server: used interchangeably with Application
Server throughout this document.
EC: Edge Computing
Edge Hosting Environment: An environment providing support
required for Edge Application Server's execution.
NOTE: The above terminologies are the same as
those used in 3GPP TR 23.758
Dunbar, et al. Expires May 2, 2021 [Page 7]
Internet-Draft AppMetaData NLRI for 5G EC Service
Edge DC: Edge Data Center, which provides the Edge
Computing 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.
gNB next generation Node B
L-DN: Local Data Network
PSA: PDU Session Anchor (UPF)
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.
3. Usage of App Meta Data for 5G Edge Computing
3.1. Overview
From IP Layer, the Application Servers are identified by their
IP (ANYCAST) addresses. The 5G Edge Computing controller or
management system is aware of the ANYCAST addresses of the
Applications that need optimized forwarding in 5G EC
environment. The 5G Edge Computing controller or management
system can configure the ACLs to filter out those applications
on the routers adjacent to the 5G PSA and the routers to which
the Application Servers are directly attached.
The proposed solution is for the routers, i.e. A-ER, that have
direct links to the Application Servers to collect various
measurements about the Servers' running status [5G-EC-Metrics]
and advertise the metrics to other routers in 5G EC LDN (Local
Data Network).
Dunbar, et al. Expires May 2, 2021 [Page 8]
Internet-Draft AppMetaData NLRI for 5G EC Service
3.2. IP Layer Metrics to Gauge Application Behavior
[5G-EC-Metrics] describes the IP Layer Metrics that can gauge
the application servers running status and environment:
- IP-Layer Metric for App Server Load Measurement:
The Load Measurement to an App Server is a weighted
combination of the number of packets/bites to the App Server
and the number of packets/bytes from the App Server which
are collected by the A-ER to which the App Server is
directly attached.
The A-ER is configured with an ACL that can filter out the
packets for the Application Server.
- Capacity Index
Capacity Index is used to differentiate the running
environment of the application server. Some data centers can
have hundreds, or thousands, of servers behind an
Application Server's App Layer Load Balancer that is
reachable from external world. Other data centers can have
very small number of servers for the application server.
"Capacity Index", which is a numeric number, is used to
represent the capacity of the application server in a
specific location.
- Site preference index:
[IPv6-StickyService] describes a scenario that some sites
are more preferred for handling an application server than
others for flows from a specific UE.
In this document, the term "Application Server Egress Router"
[A-ER] is used to describe the last router that an Application
Server is attached. For 5G EC environment, the A-ER can be the
gateway router to the EC DC where multiple Application
servers' instance are hosted.
From IP Layer, an Application Server is identified by its IP
(ANYCAST) Address. Those IP addresses are called the
Application Server IDs throughout this document.
Dunbar, et al. Expires May 2, 2021 [Page 9]
Internet-Draft AppMetaData NLRI for 5G EC Service
3.3. To Equalize among Multiple ANYCAST Locations
The main benefit of using ANYCAST is to leverage the network
layer information to equalize the traffic among multiple
Application Server locations of the same Application, which is
identified by its ANYCAST addresses.
For 5G Edge Computing environment, the ingress routers to the
LDN needs to be notified of the Load Index and Capacity Index
of the App Servers at different EC data centers to make the
intelligent decision on where to forward the traffic for the
application from UEs.
[5G-EC-Metrics] describes the algorithms that can be used by
the routers directly attached to the 5G PSA to compare the
cost to reach the App Servers between the 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 or/and bytes sent to and
received from the Application Server at Site-i during a
fixed time period.
CP-i: capacity index at the site I, higher value means
higher capacity.
Delay-i: Network latency measurement (RTT) to the A-ER that
has the Application Server attached at the site-i.
Pref-i: Preference index for the site-i, higher value means
higher preference.
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.
3.4. BGP Protocol Extension to advertise Load & Capacity
Goal of the protocol extension:
Dunbar, et al. Expires May 2, 2021 [Page 10]
Internet-Draft AppMetaData NLRI for 5G EC Service
- Propagate the Load Measurement Index for the attached App
Servers to other routers in the LDN.
- Propagate the Capacity Index &
- Propagate Site Preference Index.
The BGP extension is to add the Load Index Sub-TLV, Capacity
Sub-TLV, and the Site Preference Sub-TLV in the NLRI
associated with the routes.
4. The NLRI Path Attribute for App Meta Data
The App Meta Data attribute is an optional transitive BGP Path
attribute to carry application specific data, such as running
status, capacity and site preference. Will need IANA to
assign a value as the type code of the attribute. The
attribute is composed of a set of Type-Length-Value (TLV)
encodings. Each TLV contains information corresponding to
metrics to a specific Application Server. An App Meta Data
TLV, is structured as shown in Figure 1:
0 1 2 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AppMetaData Type (2 Octets) | Length (2 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Value |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: App Meta Data TLV Value Field
AppMetaData Type (2 octets): identifies a type of Application
related metadata. The field contains values from the IANA
Registry "BGP AppMetaData Types". To be added.
o Length (2 octets): the total number of octets of the
value field.
o Value (variable): comprised of multiple sub-TLVs.
Dunbar, et al. Expires May 2, 2021 [Page 11]
Internet-Draft AppMetaData NLRI for 5G EC Service
Each sub-TLV consists of three fields: a 1-octet type, a 1-
octet or 2-octet length field (depending on the type), and
zero or more octets of value. A sub-TLV is structured as
shown in Figure 2:
+--------------------------------+
| Sub-TLV Type (1 Octet) |
+--------------------------------+
| Sub-TLV Length (1 or 2 Octets) |
+--------------------------------+
| Sub-TLV Value (Variable) |
+--------------------------------+
Figure 3: App Metadata Sub-TLV Value Field
o Sub-TLV Type (1 octet): each sub-TLV type defines a
certain property about the AppMetaData TLV that contains
this sub-TLV. The field contains values from the IANA
Registry "BGP AppMetaData Attribute Sub-TLVs".
o Sub-TLV Length (1 or 2 octets): the total number of
octets of the sub-TLV value field. The Sub-TLV Length field
contains 1 octet if the Sub-TLV Type field contains a value
in the range from 0-127. The Sub-TLV Length field contains
two octets if the Sub-TLV Type field contains a value in the
range from 128-255.
o Sub-TLV Value (variable): encodings of the value field
depend on the sub-TLV type as enumerated above. The
following sub-sections define the encoding in detail.
Dunbar, et al. Expires May 2, 2021 [Page 12]
Internet-Draft AppMetaData NLRI for 5G EC Service
4.1. Load Measurement sub-TLV format
Two types of Load Measurement Sub-TLVs are specified. One is
to carry the aggregated cost Index based on weighted
combination of the collected measurements; another one is to
carry the raw measurements of packets/bytes to/from the App
Server address. The raw measurement is useful when the egress
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.
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 (TBD2) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Period |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Aggregated Load Index to reach the App Server |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Aggregated Load Index Sub-TLV
Load Measurement sub-TLV has the following format:
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 (TBD3) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Period |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| total number of packets to the AppServer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| total number of packets from the AppServer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| total number of bytes to the AppServer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| total number of bytes from the AppServer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Raw Load Measurement Sub-TLV
Type =TBD2: Aggregated Load Measurement Index derived from
the Weighted combination of bytes/packets sent to/received
from the App server:
Index=w1*ToPackets+w2*FromPackes+w3*ToBytes+w4*FromBytes
Where w1+ w2+ w3+ w4 = 1 and 0< wi <1;
Dunbar, et al. Expires May 2, 2021 [Page 13]
Internet-Draft AppMetaData NLRI for 5G EC Service
Type= TBD3: Raw measurements of packets/bytes to/from the
App Server address;
Measure Period: BGP Update period or user specified period
4.2. Capacity Index sub-TLV format
The Capacity Index sub-TLV has the following format:
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 (TBD4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Capacity Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: "Capacity Index" can be more stable for each site. If
those values are configured to nodes, they might not need to
be included in every BGP UPDATE.
4.3. The Site Preference Index sub-TLV format
The site Preference Index is used to achieve Soft Anchoring
[Section 5] an application flow from a UE to a specific
location when the UE moves from one 5G site to another.
The Preference Index sub-TLV has the following format:
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 (TBD5) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: "Site Preference Index" can be more stable for each
site. If those values are configured to nodes, they might not
need to be included in every BGP UPDATE.
Dunbar, et al. Expires May 2, 2021 [Page 14]
Internet-Draft AppMetaData NLRI for 5G EC Service
5. Soft Anchoring of an ANYCAST Flow
"Sticky Service" in the 3GPP Edge Computing specification
(3GPP TR 23.748) requires a UE to a specific ANYCAST location
when the UE moves from one 5G Site to another.
"Soft Anchoring" is referring to forwarding the Application
flow from the UE to the a preferred location for the ANYCAST
address, when the preferred location is in good condition.
But if there is any failure at the preferred location, the
Application flow from the UE need to be forwarded to another
location that host the same application.
This section describes a solution that can softly anchor an
application flow from a UE to a preferred location.
Lets' assume one application "App.net" is instantiated on
four servers that are attached to four different routers R1,
R2, R3, and R4 respectively. It is desired for packets to the
"App.net" from UE-1 to stick with one server, say the App
Server attached to R1, even when the UE moves from one 5G
site to another. When there is failure at R1 or the
Application Server attached to R1, the packets of the flow
"App.net" from UE-1 need to be forwarded to the Application
Server attached to R2, R3, or R4.
We call this kind of sticky service "Soft Anchoring", meaning
that anchoring to the site of R1 is preferred, but other
sites can be chosen when the preferred site encounters
failure.
Here is details of this solution:
- Assign a group of ANYCAST addresses to one application.
For example, "App.net" is assigned with 4 ANYCAST
addresses, L1, L2, L3, and L4. L1/L2/L3/L4 represents
the location preferred ANYCAST addresses.
- For the App.net Server attached to a router, the router
has four Stub links to the same Server, L1, L2, L3, and
L4 respectively. The cost to L1, L2, L3 and L4 is
assigned differently for different routers. For example,
o When attached to R1, the L1 has the lowest cost,
say 10, when attached to R2, R3, and R4, the L1 can
have higher cost, say 30.
Dunbar, et al. Expires May 2, 2021 [Page 15]
Internet-Draft AppMetaData NLRI for 5G EC Service
o ANYCAST L2 has the lowest cost when attached to R2,
higher cost when attached to R1, R3, R4
respectively.
o ANYCAST L3 has the lowest cost when attached to R3,
higher cost when attached to R1, R2, R4
respectively, and
o ANYCAST L4 has the lowest cost when attached to R4,
higher cost when attached to R1, R2, R3
respectively
- When a UE queries for the "App.net" for the first time,
the DNS replies the location preferred ANYCAST address,
say L1, based on where the query is initiated.
- When the UE moves from one 5G site-A to Site-B, UE
continues sending packets of the "App.net" to ANYCAST
address L1. The routers will continue sending packets to
R1 because the total cost for the App.net instance for
ANYCAST L1 is lowest at R1. If any failure occurs making
R1 not reachable, the packets of the "App.net" from UE-1
will be sent to R2, R3, or R4 (depending on the total
cost to reach each of them).
If the Application Server supports the HTTP redirect, more
optimal forwarding can be achieved.
- When a UE queries for the "App.net" for the first time,
the global DNS replies the ANYCAST address G1, which has
the same cost regardless where the Application Servers
are attached.
- When the UE initiates the communication to G1, the
packets from the UE will be sent to the Application
Server that has the lowest cost, say the Server attached
to R1. The Application server is instructed with HTTPs
Redirect to respond back a location specific URL, say
App.net-Loc1. The client on the UE will query the DNS
for App.net-Loc1 and get the response of ANYCAST L1. The
subsequent packets from the UE-1 for App.net are sent to
L1.
Dunbar, et al. Expires May 2, 2021 [Page 16]
Internet-Draft AppMetaData NLRI for 5G EC Service
6. Manageability Considerations
To be added.
7. Security Considerations
To be added.
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 TR 23.748, "3rd Generation
Partnership Project; Technical Specification Group
Services and System Aspects; Study on enhancement of
support for Edge Computing in 5G Core network
(5GC)", Release 17 work in progress, Aug 2020.
Dunbar, et al. Expires May 2, 2021 [Page 17]
Internet-Draft AppMetaData NLRI for 5G EC Service
[5G-EC-Metrics] L. Dunbar, H. Song, J. Kaippallimalil, "IP
Layer Metrics for 5G Edge Computing Service", draft-
dunbar-ippm-5g-edge-compute-ip-layer-metrics-00,
work-in-progress, Oct 2020.
[5G-StickyService] L. Dunbar, J. Kaippallimalil, "IPv6
Solution for 5G Edge Computing Sticky Service",
draft-dunbar-6man-5g-ec-sticky-service-00, work-in-
progress, Oct 2020.
[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.
[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 Donald Eastlake for their review and
contributions.
This document was prepared using 2-Word-v2.0.template.dot.
Dunbar, et al. Expires May 2, 2021 [Page 18]
Internet-Draft AppMetaData NLRI for 5G EC Service
Authors' Addresses
Linda Dunbar
Futurewei
Email: ldunbar@futurewei.com
Kausik Majumdar
CommScope
350 W Java Drive, Sunnyvale, CA 94089
Email: kausik.majumdar@commscope.com
Haibo Wang
Huawei
Email: rainsword.wang@huawei.com
Dunbar, et al. Expires May 2, 2021 [Page 19]