Network Working Group Z. Li
Internet-Draft S. Peng
Intended status: Standards Track Huawei Technologies
Expires: April 28, 2022 D. Voyer
Bell Canada
C. Li
China Telecom
P. Liu
China Mobile
C. Cao
China Unicom
G. Mishra
Verizon Inc.
K. Ebisawa
Toyota Motor Corporation
S. Previdi
Huawei Technologies
J. Guichard
Futurewei Technologies Ltd.
October 25, 2021
Application-aware Networking (APN) Framework
draft-li-apn-framework-04
Abstract
A multitude of applications are carried over the network, which have
varying needs for network bandwidth, latency, jitter, and packet
loss, etc. Some new emerging applications have very demanding
performance requirements. However, in current networks, the network
and applications are decoupled, that is, the network is not aware of
the applications' requirements in a fine granularity. Therefore, it
is difficult to provide truly fine-granularity traffic operations for
the applications and guarantee their SLA requirements.
This document proposes a new framework, named Application-aware
Networking (APN), where application-aware information (i.e. APN
attribute) including APN identification (ID) and/or APN parameters
(e.g. network performance requirements) is encapsulated at network
edge devices and carried in packets traversing an APN domain in order
to facilitate service provisioning, perform fine-granularity traffic
steering and network resource adjustment.
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Status of This Memo
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This Internet-Draft will expire on April 28, 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Specification of Requirements . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. APN Framework and Key Components . . . . . . . . . . . . . . 5
5. APN Requirements . . . . . . . . . . . . . . . . . . . . . . 6
5.1. APN Attribute Conveying Requirements . . . . . . . . . . 7
5.1.1. Protocol Extensions Requirements . . . . . . . . . . 8
5.2. APN attribute Handling Requirements . . . . . . . . . . . 9
5.2.1. Fine granular SLA Guarantee . . . . . . . . . . . . . 10
5.2.2. Fine granular network slicing . . . . . . . . . . . . 10
5.2.3. Fine granular deterministic networking . . . . . . . 11
5.2.4. Fine granular service function chaining . . . . . . . 11
5.2.5. Fine granular network measurement . . . . . . . . . . 12
6. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 12
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6.1. Example use case description . . . . . . . . . . . . . . 12
6.2. User Group and Application Group Design . . . . . . . . . 13
6.3. Derive the User Group and User Group at APN Edge . . . . 15
6.4. Access Right Check at the edge of the backbone network . 15
6.5. SLA Guarantee in the backbone network . . . . . . . . . . 16
6.5.1. Network Measurement . . . . . . . . . . . . . . . . . 16
6.5.2. Traffic Steering . . . . . . . . . . . . . . . . . . 17
7. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 18
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
12.1. Normative References . . . . . . . . . . . . . . . . . . 20
12.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
A multitude of applications are carried over the network, which have
varying needs for network bandwidth, latency, jitter, and packet
loss, etc. Some applications such as online gaming and live video
streaming have very demanding network requirements and therefore
require special treatment in the network. However, in current
networks, the network and applications are decoupled, that is, the
network is not aware of the applications' requirements in a fine
granularity. Therefore, it is difficult to provide truly fine-
granularity traffic operations for the applications and guarantee
their SLA requirements accordingly.
[I-D.li-apn-problem-statement-usecases] describes the challenges of
traditional differentiated service provisioning methods, such as five
tuples used for ACL/PBR causing coarse granularity as well as
orchestration and SDN-based solution causing long control loops.
This document proposes a new framework, named Application-aware
Networking (APN), where application-aware information (APN attribute)
including application-aware identification (APN ID) and application-
aware parameters (APN Parameters), is encapsulated at network edge
devices and carried along with the encapsulation of the tunnel that
is used by the packet to traverse the APN domain. The APN attribute
will facilitate service provisioning and provide fine-granularity
services in the APN domain.
The APN attribute is acquired based on the existing information in
the packet header such as 5-tuple and QinQ (S-VLAN and C-VLAN) at the
edge devices of the APN domain, added to the data packets along with
the tunnel encapsulation, delivered within the network, and removed
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when the packets leave the domain together with the tunnel
encapsulation.
APN aims to apply various policies in different nodes along a network
path onto a traffic flow altogether, for example, at the headend to
steer into corresponding path, at the midpoint to collect
corresponding performance measurement data, and at the service
function to execute particular policies.
APN works within a limited trusted domain. Typically, an APN domain
is defined as a Network Operator controlled limited domain (see
Figure 1), in which MPLS, VXLAN, SR/SRv6 and other tunnel
technologies are adopted to provide network services.
2. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
This document is not a protocol specification and the key words in
this document are used for clarity and emphasis of requirements
language.
3. Terminology
ACL: Access Control List
APN: Application-aware Networking
APN6: Application-aware Networking for IPv6/SRv6
LB: Load Balancing
MPLS: Multiprotocol Label Switching
PBR: Policy Based Routing
QoE: Quality of Experience
SDN: Software Defined Networking
SLA: Service Level Agreement
SR: Segment Routing
SR-MPLS: Segment Routing over MPLS dataplane
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SRv6: Segment Routing over IPv6 dataplane
4. APN Framework and Key Components
The APN framework is shown in Figure 1. The key components include
App-aware Edge Device (APN-Edge), App-aware-process Head-End (APN-
Head), App-aware-process Mid-Point (APN-Midpoint), and App-aware-
process End-Point (APN-Endpoint).
Packets carry application characteristic information (i.e. APN
attribute) which includes the following information:
o Application-aware identification (APN ID): identifies the set of
attributes, indicating that all packets belonging to the same flow
will be given the same treatment by the network. ;
o Application-aware parameters (APN parameters): The typical
application-aware parameters are the network performance
requirement parameters including bandwidth, delay, delay
variation, packet loss ratio, etc.
Client Server
+-----+ +-----+
|App x|-\ /->|App x|
+-----+ | +-----+ +-----+ +---------+ +--------+ +-----+ | +-----+
\->|APN | |APN |-A-|APN |-A-|APN | |APN |->/
User side |- |-|- |-B-|- |-B-|- |-|- |
/->|Edge | |Head |-C-|Midpoint |-C-|Endpoint| |Edge |->\
+-----+ | +-----+ +-----+ +---------+ +--------+ +-----+ | +-----+
|App y|-/ |------------------APN Domain--------------| \->|App y|
+-----+ +-----+
Figure 1: Framework and Key Components
The key components are introduced as follows.
o App-aware Edge Device (APN-Edge): this network device receives
packets from applications and obtains the APN attribute based on
the configuration on this device according to the existing
information in the packet header, such as 5-tuple, VLAN or double
VLAN tagging (C-VLAN and S-VLAN). The APN-Edge device adds the
APN attribute in the tunnel encapsulation. The packets carrying
the APN attribute will be sent to the APN-Head, and the APN
attribute will be used to apply various policies in different
nodes along the network path onto the traffic flow, e.g., at the
headend to steer into corresponding path satisfying SLAs, at the
midpoint to collect corresponding performance measurement data, at
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the service function to execute particular policies. When the
packets leave the APN domain, the APN attribute will be removed
together with the tunnel encapsulation.
o App-aware-process Head-End (APN-Head): This network device
receives packets from the APN-Edge, obtains the APN attribute, and
initiates the corresponding process. Generally, in order to
satisfy different SLA requirements, a set of paths, tunnels or SR
policies, are set up between the APN-Head and the APN-Endpoint.
These multiple parallel paths have different SLA guarantees. The
APN-Head maintains the matching relationship between the APN
attribute and the paths between the APN-Head and the APN-Endpoint.
The APN-Head determines the path between the APN-Head and the APN-
Endpoint according to the APN attribute carried in the packets and
the matching relationship with it, which satisfies the service
requirements of the applications. The APN-Head forwards the
packets along the path. The APN attribute conveyed by the packet
received from the APN-Edge can also be copied or be mapped to the
outgoing packet header.
o App-aware-process Mid-Point (APN-Midpoint): the APN-Midpoint
provides the path service and enforces various policies according
to the APN attribute carried in the packets. The APN-Midpoint may
also adjust the resource locally to guarantee the service
requirements depending on a specific policy and the APN attribute
conveyed by the packet. Policy definitions and mechanisms are out
of the scope of this document.
o App-aware-process End-Point (APN-Endpoint): the process of the
specific service path will end at the APN-Endpoint. If the outer
tunnel header for the path between the APN-Head and the APN-
Endpoint exists, it will be removed by the APN-Endpoint. If the
APN attribute is copied or mapped to the outer tunnel header by
the APN-Head, it will also be removed along with the outer tunnel
header.
Note that in the actual implementation, the APN-Edge can co-exist
with the APN-Head or APN-Endpoint, that is, one network device can
implement the functionalities of both APN-Edge and the APN-Head/APN-
Endpoint.
5. APN Requirements
This section specifies the requirements for supporting the APN
framework, including the requirements for conveying and handling the
APN attribute.
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5.1. APN Attribute Conveying Requirements
The APN attribute consists of APN ID and APN parameters.
APN ID includes the following identifiers (IDs),
o Application Group ID: identifies an application group of the
traffic.
o User Group ID: identifies the user group of the traffic.
APN ID can be acquired through different ways. In the APN work it
MUST be acquired according to the existing available information in
the packet header without inspection into the payload.
The different combinations of the IDs can be used to provide
different granularity of the service provisioning and SLA guarantee
for the traffic.
The APN parameters are the network performance requirement
parameters. The network service requirement can include the
following parameters:
o Bandwidth: the bandwidth requirement
o Latency: the latency requirement
o Packet loss ratio: the packet loss ratio requirement
o Jitter: the jitter requirement
The different combinations of the parameters are for further
expressing the more detailed service requirements, conveyed together
with the APN ID, which can be used to match to appropriate tunnels/SR
Policies and queues that can satisfy these service requirements.
APN attribute MUST be encapsulated within tunnels in the network
layer. The tunnels include but not limit to MPLS, VxLAN, SR-MPLS,
and SRv6. It can be extended according to requirements in the
future.
[REQ 1a]. APN ID SHOULD include Application Group ID to indicate the
application group that the packet belongs to.
[REQ 1b]. APN ID SHOULD include User Group ID to indicate the user
group that the packet belongs to.
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[REQ 1c]. APN ID MUST include either Application Group ID or User
Group ID.
[REQ 1d]. APN ID MUST be acquired from the existing available
information of the packet header without interference into the
payload.
[REQ 1e]. APN parameters is OPTIONAL.
[REQ 1f]. APN attribute MUST be carried by the outer tunnel
encapsulation.
[REQ 1g]. All the nodes along the path SHOULD be able to process the
APN attribute if needed.
[REQ 1h]. The APN attribute is generated by the APN-Edge though
local policy.
[REQ 1i]. The APN attribute SHOULD be kept intact when directly
copied at the APN-Head and carried in the tunnel encapsulation.
[REQ 1j]. The APN attribute MUST be removed along with the tunnel
encapsulation by the APN-Edge when the packets leave the APN domain.
5.1.1. Protocol Extensions Requirements
The APN attribute is conveyed with the tunnel encapsulation. There
are two typical types of tunnels:
o MPLS-based tunnel: LDP tunnel, RSVP-TE tunnel, SR-MPLS tunnel or
policy, etc.
o IPv6-based tunnel: IPv6-based VxLAN tunnel, IPv6-based UDP tunnel,
IPv6-based GRE tunnel, SRv6 tunnel or policy, etc.
In order to support encapsulation of APN attribute, the MPLS data
plane and IPv6 data plane need to be extended.
In order to support acquiring the APN attribute according to the
existing available information in the packet header, YANG models
should be defined to configure the mapping between the application/
user group ID and the existing information in the packet header and
configure the corresponding APN attribute for the application/user
group. It can also be implemented with protocol extensions such as
BGP and PCEP which can advertise the information from the central
controller to the APN-Edge.
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In addition, in the APN domain, the above-mentioned mapping and
applying APN parameters may also be advertised from the APN-Edge/APN-
Head to other devices or from the network devices to the central
controller in the APN domain. IGP extensions or BGP-LS extensions
should be introduced to achieve the purposes.
[REQ 1-1a] MPLS encapsulation SHOULD be extended to be able to carry
the APN attribute for MPLS-based tunnels.
[REQ 1-1b] IPv6 encapsulation SHOULD be extended to be able to carry
the APN attribute for IPv6-based tunnels.
[REQ 1-1c] YANG models SHOULD be defined to implement the mapping
between the application/user group ID and the existing available
information in the packet header and configure the corresponding APN
parameters.
[REQ 1-1d] BGP extensions SHOULD be defined to advertise the mapping
between the application/user group ID and the existing available
information in the packet header and the corresponding APN parameters
from the central controller to the APN-Edge in the APN domain.
[REQ 1-1e] PCEP extensions SHOULD be defined to advertise the mapping
between the application/user group ID and the existing available
information in the packet header and the corresponding APN parameters
from the central controller to the APN-Edge in the APN domain.
[REQ 1-1f] IGP extensions SHOULD be defined to advertise the mapping
between the application/user group ID and the existing available
information in the packet header and the corresponding APN parameters
from the APN-Edge to the network devices in the APN domain.
[REQ 1-1g] BGP-LS extensions SHOULD be defined to advertise the
mapping between the application/user group ID and the existing
available information in the packet header and the corresponding APN
parameters from the network devices to the central controller in the
APN domain.
5.2. APN attribute Handling Requirements
The APN Head and APN-Midpoint perform matching operation against the
APN attribute, that is, to match IDs and/or service requirements to
the corresponding network resources such as tunnels/SR policies and
queues.
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5.2.1. Fine granular SLA Guarantee
In order to achieve better Quality of Experience (QoE) of end users
and engage customers, the network needs to be able to provide fine-
granularity SLA guarantee [I-D.li-apn-problem-statement-usecases].
[REQ 2-1a]. With the APN attribute, the APN-Head SHOULD be able to
steer the traffic to the tunnel/SR policy that satisfies the matching
operation.
[REQ 2-1b]. With the APN attribute, the APN-Head SHOULD be able to
trigger the setup of the tunnel/SR policy that satisfies the matching
operation.
[REQ 2-1c]. With the APN attribute, the APN-Head and APN-Midpoint
SHOULD be able to steer the traffic to the queue that satisfies the
matching operation.
[REQ 2-1d]. With the APN attribute, the APN-Head and APN-Midpoint
SHOULD be able to trigger the configuration of the queue that
satisfies the matching operation.
[REQ 2-1e]. If the tunnels are used to satisfy the performance
requirements, the APN-Head SHOULD be able to copy or map the APN
attribute conveyed by the packet received from the APN-Edge to the
outer tunnel header.
[REQ 2-1f]. If the tunnels are used to satisfy the performance
requirements and the APN attribute are conveyed along with the outer
tunnel, the APN-Endpoint MUST remove the APN attribute along with the
outer tunnel.
5.2.2. Fine granular network slicing
Network slicing provides ways to partition the network infrastructure
in either control plane or data plane into multiple network slices
that are running in parallel. The resources on each node need to be
associated to corresponding slices.
APN is to help the operator of a network to steer some of the traffic
tagged with an APN attribute to a certain network slice based on the
SLA agreement with its customer.
[REQ 2-2a]. With the APN attribute, the APN-Head SHOULD be able to
steer the traffic to the slice that satisfies the matching operation.
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[REQ 2-2b]. With the APN attribute, the APN-Midpoint SHOULD be able
to associate the traffic to the resources in the slice that satisfies
the matching operation.
5.2.3. Fine granular deterministic networking
Along the path each node needs to provide guaranteed bandwidth,
bounded latency, and other properties relevant to the transport of
time-sensitive data for the Detnet flows that coexist with the best-
effort traffic.
APN is to help the operator of a network to steer some of the traffic
tagged with an APN attribute to a certain deterministic path based on
the SLA agreement with its customer.
[REQ 2-3a]. With the APN attribute, the APN-Head SHOULD be able to
steer the traffic to the appropriate path that satisfies the matching
operation.
[REQ 2-3b]. With the APN attribute, the APN-Head SHOULD be able to
trigger the setup of the appropriate path that satisfies the matching
operation for the Detnet flows.
[REQ 2-3c]. With the APN attribute, the APN-Midpoint SHOULD be able
to associate the traffic to the resources along the path that
satisfies the performance guarantee.
[REQ 2-3d]. With the APN attribute, the APN-Midpoint SHOULD be able
to reserve the resources for the Detnet flows along the path that
satisfies the performance guarantee.
5.2.4. Fine granular service function chaining
The end-to-end service delivery often needs to go through various
service functions, including traditional network service functions
such as firewalls, LB as well as new application-specific functions,
both physical and virtual. SFC is applicable to both fixed and
mobile networks as well as data center networks.
APN is to help the operator of a network to steer some of the traffic
tagged with an APN attribute to a certain service function chain
based on the SLA agreement with its customer. On each service
function along the service function chain, the policy can be enforced
based on the APN attribute in the outer header.
[REQ 2-4a]. With the APN attribute, the App-aware-process devices
SHOULD be able to steer the traffic to the appropriate service
function.
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[REQ 2-4b]. The App-aware-process devices including VAS SHOULD be
able to process the APN attribute carried in the packets.
5.2.5. Fine granular network measurement
Network measurement can be used for verifying whether the network
performance requirements have been satisfied, as well as locating
silent failure and predicting QoE satisfaction, which enables real-
time SLA awareness/proactive OAM and potential resource adjustments.
APN is to help the operator of a network to trigger performance
measurement for the traffic tagged with an APN attribute based on its
customer' consent.
[REQ 2-5a]. The App-aware-process devices SHOULD be able to perform
IOAM based on the APN attribute.
[REQ 2-5b]. The network measurement results can be reported based on
the APN attribute and verify whether the performance requirements are
satisfied.
6. Illustration
In order to better clarify what APN can enable with the introduced
APN attribute compared to the existing network without APN, we
illustrate how APN works through an example use case, which is also a
typical network service being provisioned nowadays, i.e. the Cloud
Leased Line service. In order to make the tunnel description much
easier to understand, we use the recent technology in IETF, i.e.
SRv6.
6.1. Example use case description
We take the "SRv6-based Cloud Leased Line Service" as an illustrative
example to show how APN is needed and can be beneficial.
Enterprises usually buy Cloud Leased Line Service to interconnect
their local sites to Cloud. Generally, the Cloud Leased Line Service
needs to go across multiple domains which are owned by the same
operator and can be controlled by multiple controllers and an
orchestrator/super-controller.
Due to management reasons, the network information in the
intermediate domain cannot be advertised to other domains, so the
ingress node cannot set up an appropriate E2E path. In that case,
the intermediate domain is treated as a black box, and no fine grain
traffic steering and other services can be provisioned.
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The example of the network to provide the cloud leased lined service
reference diagram is shown as the following figure. The network is
composed by three network domains including the two metro networks in
the City A and City B and the backbone network which connects the two
metro networks. The cloud leased line services is provided to the
specific enterprise whose branches located in different cities need
to access the cloud-based service located in the City B.
Domain 1 Domain 2 Domain 3
/-------------\ /------------\ /-----------\
+-/-+ City A +-\-+ +-/-+ IPv6 +-\-+ +-/-+ City B +-\-+
Branch---|PE1| |CR1|---|CR2| |CR3|---|CR4| |PE2|--Cloud
+-\-+ Metro +-/-+ +-\-+ Backbone +-/-+ +-\-+ Metro +-/-+
\-------------/ \------------/ \-----------/
|<--OSPF/ISIS-->|<-EBGP->|<- IPv6/SRv6 ->|<-EBGP->|<-OSPF/ISIS->|
|<----------------------- EBGP VPNv4 Peer --------------------->|
|<----------------------- L3VPN over SRv6 --------------------->|
Figure 2. Reference diagram for the example use case illustration
6.2. User Group and Application Group Design
The user groups can be designed as follows:
User Group
Enterprise A/Branch 1/Office Users 001001001
Enterprise A/Branch 1/R&D Users 001001002
Enterprise A/Branch 1/IT Users 001001003
Enterprise A/Branch 1/VIP Users 001001004
Enterprise A/Branch 2/Office Users 001002001
Enterprise A/Branch 2/R&D Users 001002002
Enterprise A/Branch 2/IT Users 001002003
Enterprise A/Branch 2/VIP Users 001002004
Enterprise A/Branch 3/Office Users 001003001
Enterprise A/Branch 3/R&D Users 001003002
Enterprise A/Branch 3/IT Users 001003003
Enterprise A/Branch 3/VIP Users 001003004
In the IP address design, the IPv6 address blocks allocated to the
branches are as follows :
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IPv6 Address
Enterprise A/Branch 1/Office Users 2001:DB8:A:11::/56
Enterprise A/Branch 1/R&D Users 2001:DB8:A:12::/56
Enterprise A/Branch 1/IT Users 2001:DB8:A:13::/56
Enterprise A/Branch 1/VIP Users 2001:DB8:A:1D::/56
Enterprise A/Branch 2/Office Users 2001:DB8:A:21::/56
Enterprise A/Branch 2/R&D Users 2001:DB8:A:22::/56
Enterprise A/Branch 2/IT Users 2001:DB8:A:23::/56
Enterprise A/Branch 2/VIP Users 2001:DB8:A:2D::/56
Enterprise A/Branch 3/Office Users 2001:DB8:A:31::/ 56
Enterprise A/Branch 3/R&D Users 2001:DB8:A:32::/56
Enterprise A/Branch 3/IT Users 2001:DB8:A:33::/56
Enterprise A/Branch 3/VIP Users 2001:DB8:A:3D::/56
The application groups provided by the cloud can be designed as
follows:
Application Group
Enterprise A/Office Audio Applications 101001001
Enterprise A/Office Video Applications 101001002
Enterprise A/Office Data Applications 101001003
Enterprise A/R&D Audio Applications 101002001
Enterprise A/R&D Video Applications 101002002
Enterprise A/R&D Data Applications 101002003
Enterprise A/IT Audio Applications 101003001
Enterprise A/IT Video Applications 101003002
Enterprise A/IT Data Applications 101003003
In the address design, the IPv6 address blocks allocated to the
applications of Enterprise A in the cloud is
2001:DB8:A1::/48A1::A:/16. The port number can be used to identify
different applications.
IPv6 Address Port Number
Enterprise A/Office Audio Applications 2001:DB8:A1:A1::/64 1718, 1719
Enterprise A/Office Video Applications 2001:DB8:A1:A1::/64 5060, 5061
Enterprise A/Office Data Applications 2001:DB8:A1:A1::/64 21, 80
Enterprise A/R&D Audio Applications 2001:DB8:A1:A2::/64 1718, 1719
Enterprise A/R&D Video Applications 2001:DB8:A1:A2::/64 5060, 5061
Enterprise A/R&D Data Applications 2001:DB8:A1:A2::/64 21, 80
Enterprise A/IT Audio Applications 2001:DB8:A1:A3::/64 1718, 1719
Enterprise A/IT Video Applications 2001:DB8:A1:A3::/64 5060, 5061
Enterprise A/IT Data Applications 2001:DB8:A1:A3::/64 21, 80
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6.3. Derive the User Group and User Group at APN Edge
The cloud leased line service adopts the SRv6-based L3VPN to traverse
the network. The following policy can be applied at the APN edges of
the City A1:
Match:
VPN1
Source Address 2001:DB8:A:11::/56
Action
Set user-group 001001001
Match:
VPN1
destination Address 2001:DB8:A1:A1::/64
destination port 1718,1719
Action
Set app-group 101001001
6.4. Access Right Check at the edge of the backbone network
The following check can be applied at the edge of the IP backbone
network:
Match:
user-group 001001001
app-group 101002001, 101002002, 101002003, 101003001, 101003002, 101003003
Action
Deny
Match:
user-group 001001001
app-group 101001001, 101001002, 101001003
Action
Permit
The policy means that the office users of the branch 1 can only
access the office applications.
If the address allocation is changed. For example, one office user
of the branch1's IPv6 address is changed to 2001:DB8:A:15::/56
because of the mobile office.
We only need to add the following policy at the APN edge:
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Match:
VPN1
Source Address 2001:DB8:A:15::/56
Action
Set user-group 001001001
The policy in the backbone network which is based on the user group
and the application group is not necessary to change.
6.5. SLA Guarantee in the backbone network
Due to management reasons, the network information in the
intermediate domain cannot be advertised to other domains, so the
ingress node cannot set up an appropriate TE path, the intermediate
domain is treated as a black box and no fine grain traffic steering
can be performed.
In this case, we consider fine grain traffic steering in Domain 2 on
top of the SRv6-based Cloud Leased Line Service for the purpose of
SLA Guarantee.
6.5.1. Network Measurement
In order to guarantee SLA for the VIP users, the following network
measurement policy can be applied in the backbone network:
Match:
User-group 001001004 application group 101001002
User-group 001002004 application group 101002002
User-group 001003004 application group 101003002
Action
Apply IOAM
The policy is to apply the IOAM as the network measurement for the
VIP users of the branches to access the video applications.From the
above illustration, there is the following observation:
When there is no APN deployed, at CR2, the 5 tuples of the original
packets will need to be resolved since they have been encapsulated,
and then IOAM can be triggered based on the 5 tuples. This
resolution process is costly and consumes a lot of hardware
resources. If Domain 3 needs to trigger IOAM, the same resolution
process will have to be done at CR4.
When there is APN deployed, at CR1, the APN attribute is tagged.
When these packets arrive at CR2, only the APN attribute in the outer
header will be read out, based on which the IOAM can be triggered in
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Domain 2. That is, no 5-tuple resolution process is needed at CR2
but only checking the APN attribute in the outer header.
6.5.2. Traffic Steering
If the SLA guarantee of the VIP users accessing the video
applications does not satisfy the requirements through the network
measurement based on the IOAM, the SRv6 policy can be setup. For
example, the SRv6 policy 1 which can satisfy the SLA requirement is
set up. Then the following policy can be downloaded to the edge:
Match:
User-group 001001004 application group 101001002
User-group 001002004 application group 101002002
User-group 001003004 application group 101003002
Action
Redirect SRv6 Policy 1
The policy is to steer the traffic of the VIP users to the SRv6
policy in the backbone to satisfy the requirement .
From the above illustration, there is the similar observation as the
network measurement:
When there is no APN deployed, at CR2, the 5 tuples of the original
packets will need to be resolved since they have been encapsulated,
and then the traffic can be steered into SRv6 policy 2 based on the 5
tuples. This resolution process is costly and consumes a lot of
hardware resources.
When there is APN deployed, at CR1, the APN attribute is tagged When
these packets arrive at CR2, only the APN attribute in the outer
header will be read out, based on which the traffic can be steered
into SRv6 policy 2 in Domain 2.
7. Benefits
The APN attribute allows the network devices to only look at one
easily-accessible field in the outer header, without having to
resolve the 5 tuples of the original packets that are deeply
encapsulated in the tunnel encapsulation.
The APN attribute allows to simplify the policy control at every
policy enforcement point within the network. The APN attribute
allows to reducing each matching entry of policy filter since it is
only one field and hardware resources are saved. Since APN attribute
is relatively stable, it introduces the possibilities of eliminating
the "stale" policy filter entries. In most cases, the APN attribute
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is centralized configured and distributed to all the policy
enforcement points, which saves the policy filter configurations per
node and simplifies the OM.
The structured APN attribute allows to express fine granular service
requirements, e.g. MKT-user-group/app-group, RD-user-group/app-
group, latency.
The structured APN attribute allows to match to the evolving fine
granular differentiated network capabilities, e.g. SR policy with
low latency and high reliability guaranteed.
In a tunnel across multiple domains of the same operator using the
APN attribute in the outer header the operator can easily support
multiple services not just a single one in a particular domain as
illustrated in the usecase illustration section.
When there is no APN, to achieve the same, now the operator may have
two options: 1. Add all the policy identifiers at the tunnel headend
with various further encapsulations and enforce the policies based on
them at the intermediate policy enforcement nodes along the tunnel,
2. Resolve the original 5 tuples being encapsulated inside the
tunnel which will be very costly and sometimes impossible.
Moreover, the policy enforcement table in the intermediate policy
enforcement nodes is significantly reduced. Because before operator
needs to resolve the 5 tuple but now with APN, operator only needs to
read the APN attribute in one field of the outer header.
Since the 5 tuples of the traffic are changing frequently due to
service deployment or management issues the policy enforcement table
in the policy enforcement nodes is not stable and there is always a
lot of stale entries in the table. But now since the APN attribute
is a mapping of the 5 tuples operator will have a relatively stable
policy enforcement table on their nodes.
8. IANA Considerations
This document does not include an IANA request.
9. Security Considerations
In the APN work, in order to reduce the privacy and security issues,
the following specifications are defined:
[S1]. The APN attribute MUST be conveyed along with the tunnel
information in the APN domain. The APN attribute is encapsulated and
removed at the APN-Edge.
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[S2]. The APN ID (including the Application Group ID and the User
Group ID) MUST be acquired from the existing available information in
the packet header without interference into the payload.
According to the above specifications, the APN attribute is only
produced and used locally within the APN domain without the
involvement of the host/application side.
In order to prevent the malicious attack through the APN attribute,
the following policies can be configured at the network devices of
the APN domain:
[P1]. If the APN attribute is conveyed without the tunnel
information, the packet MUST be dropped.
[P2]. If the APN attribute is not known to the APN domain, it should
trigger the alarm information. The packet can be forwarded without
being processed or dropped depending on the local policy.
[P3]. If the network service requirements exceed the specification
for the specific Application Group ID and/or User Group ID, it should
trigger the alarm information. The packet should be discarded to
prevent abusing of the resources.
[P4]. There should be rate-limiting policy at the APN-Edge to
prevent the traffic belonging to a specific Application Group ID and/
or User Group ID from exceeding the preset limit.
10. Acknowledgements
The authors would like to acknowledge Robert Raszuk (Bloomberg LP),
and Yukito Ueno (NTT Communications Corporation) for their valuable
reviews and comments.
11. Contributors
Daniel Bernier
Bell Canada
Email: daniel.bernier@bell.ca
Chongfeng Xie
China Telecom
Email: xiechf@chinatelecom.cn
Feng Yang
China Mobile
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Email: yangfeng@chinamobile.com
Zhuangzhuang Qin
China Unicom
Email: qinzhuangzhuang@chinaunicom.cn
Chang Liu
China Unicom
Email: liuc131@chinaunicom.cn
Gyan Mishra
Verizon
Email: hayabusagsm@gmail.com
Luis M. Contreras
Telefonica
Email: contreras.ietf@gmail.com
Luc-Fabrice Ndifor Ngwa
MTN
Email: Luc-Fabrice.Ndifor@mtn.com
12. References
12.1. Normative References
[I-D.li-apn-problem-statement-usecases]
Li, Z., Peng, S., Voyer, D., Xie, C., Liu, P., Qin, Z.,
Mishra, G., Ebisawa, K., Previdi, S., and J. N. Guichard,
"Problem Statement and Use Cases of Application-aware
Networking (APN)", draft-li-apn-problem-statement-
usecases-04 (work in progress), June 2021.
[I-D.peng-apn-security-privacy-consideration]
Peng, S., Li, Z., Voyer, D., Li, C., Liu, P., and C. Cao,
"APN Security and Privacy Considerations", draft-peng-apn-
security-privacy-consideration-02 (work in progress), June
2021.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>.
12.2. Informative References
[RFC3272] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X.
Xiao, "Overview and Principles of Internet Traffic
Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002,
<https://www.rfc-editor.org/info/rfc3272>.
Authors' Addresses
Zhenbin Li
Huawei Technologies
China
Email: lizhenbin@huawei.com
Shuping Peng
Huawei Technologies
China
Email: pengshuping@huawei.com
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
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Cong Li
China Telecom
China
Email: licong@chinatelecom.cn
Peng Liu
China Mobile
China
Email: liupengyjy@chinamobile.com
Chang Cao
China Unicom
China
Email: caoc15@chinaunicom.cn
Gyan Mishra
Verizon Inc.
USA
Email: gyan.s.mishra@verizon.com
Kentaro Ebisawa
Toyota Motor Corporation
Japan
Email: ebisawa@toyota-tokyo.tech
Stefano Previdi
Huawei Technologies
Italy
Email: stefano@previdi.net
James N Guichard
Futurewei Technologies Ltd.
USA
Email: jguichar@futurewei.com
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