Internet DRAFT - draft-huang-service-aware-network-framework
draft-huang-service-aware-network-framework
INTAREA D.H. Daniel
Internet-Draft B.T. Bin
Intended status: Standards Track ZTE Corporation
Expires: 26 May 2023 D.Y. Dong
Beijing Jiaotong University
22 November 2022
Service Aware Network Framework
draft-huang-service-aware-network-framework-01
Abstract
Cloud has been migrating from concentrated center sites to edge nodes
with responsive and agile services to the subscribers. This
industry-wide trend would be reasonably expected to continue into the
future which would enjoy geographically ubiquitous services. Rather
than transmitting service data streams to the stable and limited
service locations such as centered cloud sites, routing and
forwarding network will have to adapt to the emerging scenarios where
the service instances would be highly dynamic and distributed, and
further more, demand more fine-grained networking policies than the
current routing and forwarding scheme unaware of service SLA
requirements. This proposal is to demonstrate a framework under
which the above-mentioned requirements would be satisfied.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. SAN framework and its chief components . . . . . . . . . . . 5
4. Layer 4 of SAN framework . . . . . . . . . . . . . . . . . . 6
5. Layer 3 of SAN framework . . . . . . . . . . . . . . . . . . 7
5.1. SAN ingress . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. SAN relay . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3. SAN egress . . . . . . . . . . . . . . . . . . . . . . . 8
5.4. SAN control plane consideration . . . . . . . . . . . . . 8
5.4.1. Centralized control plane consideration . . . . . . . 9
5.4.2. Distributed control plane consideration . . . . . . . 9
5.4.3. Hybrid control plane consideration . . . . . . . . . 9
5.5. SAN user plane consideration . . . . . . . . . . . . . . 9
5.5.1. SIL encapsulation . . . . . . . . . . . . . . . . . . 10
5.5.2. SIL in forwarding and routing network . . . . . . . . 10
5.5.3. SIL-based routing . . . . . . . . . . . . . . . . . . 10
5.6. Hierarchical service routing architecture . . . . . . . . 11
5.6.1. Routing scheme in line with multiple service-related
resources granularity . . . . . . . . . . . . . . . . 12
5.6.2. Two-segment routing and forwarding . . . . . . . . . 12
5.6.3. Cross-domain computing routing and forwarding . . . . 13
5.6.4. Service traffic affinity . . . . . . . . . . . . . . 14
5.7. Logical sub-layer of service routing in forwarding and
routing network . . . . . . . . . . . . . . . . . . . . . 14
6. Governance and life cycle of service identification label . . 15
6.1. Originality and governance of SIL . . . . . . . . . . . . 15
6.2. Life cycle of SIL . . . . . . . . . . . . . . . . . . . . 15
7. An example of end-to-end SAN work flow . . . . . . . . . . . 15
7.1. Initiation and maintenance of rendering algorithm in SAN
system . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.2. Configuration of a rendering algorithm (as SIL-RA) in SAN
forwarding and routing network . . . . . . . . . . . . . 17
7.3. Publication/Subscription of SIL-RA . . . . . . . . . . . 17
7.4. SIL-RA service data stream treatment at SAN forwarding and
routing network . . . . . . . . . . . . . . . . . . . . . 17
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7.4.1. SIL-RA service data stream treatment at SAN
ingress . . . . . . . . . . . . . . . . . . . . . . . 18
7.4.2. SIL-RA service data stream treatment at SAN relay . . 18
7.4.3. SIL-RA service data stream treatment at SAN egress . 18
7.5. SIL-RA service data stream treatment at cloud site . . . 18
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
11. Informative References . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
When it comes to user data security and service responsiveness, it's
imperative to migrate the cloud services and resources to the
locations with good proximity to the users who could reside anywhere
and launch service requests at any time in the ongoing and upcoming
industry scenarios. Therefore, the cloud services and resources has
been and would continue to be deployed in such a distributed way that
the services would be ubiquitous, and scheduled and requested
dynamically by various subscribers. Cloud and networking services
and resources operate more coherently with each other as more and
more services migrate into cloud. Network has to without gap delay
adapt as the cloud shift into a new distributed architecture. The
same service could be instantiated at multiple locations with
different networking and computing resources which would be updated
dynamically. Under this circumstance, the best service quality
should be guaranteed by both fine-grained networking and computing
policies.
This proposal introduces a light-weight service identification label
as an index in the user plane to enable the network to be highly
effectively aware of the dynamic requirements of various cloud
applications. The service identification label is designed to
purport to the fundamental and common services for which the service
qualities should be guaranteed by both fine-grained networking and
computing resources. Combined with an enhanced control plane, a
logical sub-layer of service function has been employed in this
framework to enable the network respond to the application's
networking and computing demands in a more fine-grained and
intelligent way, which would bring significant benefits to all
parties involved in the network and cloud ecosystem while ensure the
framework to be compatible with the ongoing network architecture.
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1.1. Requirements Language
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 [RFC2119].
2. Terminology
* SAN. Service Awareness Network
* SIL. Service Identification Label, a light-weight label designed
to indicate the fundamental and common service types
* SCMS. Service Control and Management System, an entity
responsible for SIL management and controlling which includes
materializing networking and computing policies in terms of SIL
and delivering them to the SAN forwarding and routing nodes.
* SAN ingress: routing node maintaining computing resource as well
as service status from remote cloud sites, and executing the
cross-site routing policies in terms of the aforementioned status
as well as the identification of computing service. SAN ingress
usually resides at the network edge and works as ingress of the
end to end service flow.
* SAN egress: routing node maintaining computing resource as well as
service status from the geographically local cloud sites and being
responsible for the last hop of the service flow towards the
computing service instance in the specific cloud site. SAN egress
usually resides at the network edge and works as egress of the end
to end service flow.
* SAN relay: routing node which is optionally aware of computing
resource and service status . SAN relay usually resides between
SAN ingress and SAN egress and works as ordinary routing nodes and
only gets involved in computing delivery when SAN ingress fails to
do so. In particular, when an end-to-end networking policy in
which SAN relay would be required to identify SIL with specific
routing and forwarding behavior is involved, SAN relay would
decapsulate and encapsulate SIL and execute the SIL-specific
policies.
* Global Service Resource and Service Status(GSRS) : General cloud
site status of the service-related resources and service which
consists of overall resource occupation and types of service
(algorithms, functions etc.) the specific cloud site provides.
GSRS is maintained at SAN ingress and expected to remain
relatively stable and change in slow frequency.
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* Local Service Resource and Service Status(LSRS) : fine-grained
cloud site status of the service-related resource and service
which consists of status of each active service instance as well
as its parameters which could impact the way the instance would be
selected and visited by SAN egress. LSRS is maintained at SAN
egress and expected to stay quite dynamic and change in high
frequency.
* Service Instance(SI): an active instance of a SIL which resides in
a host usually purporting to a server, container or virtual
machine.
3. SAN framework and its chief components
An host address is request from DNS system to indicate the user's
intention of it's service destination as well as establish a service
connection under the conventional internet servivce architecture,
while SAN framework proposes a refined architecture under which
user's intention is simply indicated by the service indentification
label regardless of the actual service destination. Therefore, the
center piece of the SAN framework is the light-weight service
identification label. SIL should be confined within a limited and
exhaustive service type space which only covers the indispensable and
fundamental networking and computing service blocks. SIL could be
component service which would be expected to be invoked by multiple
application parties, or explicitly specified sub-stream of the same
service data stream. A Service control and management system (SCMS)
which could be a standalone or an enhanced version of the existing
system. An entity with the authority of service and resource
provisioning and delivery takes control of registry, publishing,
authorization, authentication and policing of SIL within a closed
governance domain. The life cycle of SIL runs through end user
client, routing and forwarding network and cloud in terms of the end-
to-end service process, and will survive in the above-mentioned
closed governance domain permanently unless it's withdrawn or updated
with the new service identification label norms.
SIL is designed under this reference framework as a sophisticated
interface between user and service as well as between service and
network and cloud. User client requests the service through SIL
encapsulated in user data packet header with customized networking
and computing provisioning guaranteed by SAN routing and forwarding
network which would index SIL with the corresponding networking and
computing policies and resources configured from SCMS. Cloud
governance system takes SIL as a public interface between user client
and the cloud service provisioning system.
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End user subscribes the service from SCMS and service client carries
on materializing the service by instantiating an SIL into the service
packet. Upon arriving at networking edge, SIL is identified and
further enables the fine-grained networking service and computing-
based routing and scheduling. Along the routing path the service
data stream gets customized treatment in terms of SIL which is
inherently defined to bo domain independent. Figure 1 is the
reference framework of SAN. SAN domain reaches beyond conventional
forwarding and routing network with SIL presence in both service
client and server at end user devices and cloud sites respectively
which includes layer 4 and layer 3 from a network architecture
perspective. Nevertheless, SAN forwarding and routing domain would
be a predominant part of the entire reference framework.
+--------------------------------------------------------------+
| Service Control and Management System |
+----------------------------|---------------------------------+
|
Service Client | Service Server
+--+ Service connection upon SIL +--+
| |<------------------------|----------------------------->| |
| | | | |
| | +-------------------|------------------------+ | |
| |<----| Service Identification Label |---->| |
| | +---|---------------|------------------|-----+ | |
| | | | | | |
| | | | | | |
| | +----V------+ +----V------+ +-----V------+ | |
| |--->|SAN Ingress|-->| SAN Relay |---->| SAN Egress |--->| |
+--+ +-----------+ +-----------+ +------------+ +--+
| | SAN forwarding and routing domain | |
| |<--------------------------------->| |
| Service Identification domain |
|<-------------------------------------------------------->|
Figure 1
4. Layer 4 of SAN framework
From perspective of layer 4 which builds and maintains the service
connection for the application, end user quality of experience would
be significantly increased with a host-address irrelevant connection
that remains stable regardless of whether or not the application
server host shifts. It's achieved by establishing the layer 4
connection with SIL which indicates only the service type without
semantics of server host location.
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In particular, SIL could be encapsulated in layer 4 protocol-intact
way and layer 4 protocol-updated way. The former entails informing
the app client of an SIL when it comes to the process of informing it
of a destination address such as DNS inquiry process. Therefore,
layer 4 protocol remains intact by taking SIL as destination address
and proceeds as usual. SIL would be identified and treated with
fine-grained networking and computing policies of which an
addressable server host address would be selected and encapsulated in
the out layer routing header by SAN ingress. A mapping between SIL
and server host address could be made either by SAN egress or app
client and server. So far as the latter is concerned, a dedicated
sub-layer between layer 4 and layer 3 should be employed to
encapsulate SIL which is to be used by layer 4 protocol to establish
the service connection. The dedicated SIL sub-layer survives through
end user, SAN network and the cloud, and SAN nodes would index the
SIL from this sub-layer to execute the fine-grained service treatment
in terms of both networking and computing policies.
SIL structure designing as well as the dedicated sub-layer protocol
specification are out of scope of this proposal.
5. Layer 3 of SAN framework
Layer 3 SAN domain is responsible for the fine-grained treatment of
service flow referenced by SIL in terms of both networking and
computing requirements.
5.1. SAN ingress
SAN ingress extracts SIL from either the destination address field to
be encapsulated with SIL or the dedicated SIL sub-layer as
illustrated in section 4, and determines its fine-grained networking
policy as well as its next hop in light of which cloud site hosts the
satisfying service node. Under this particular circumstance, the
next hop could be either an SAN egress which connects directly to the
selected remote cloud site or the selected service server within the
local cloud site.
Meanwhile, SCMS delivers both fine-grained networking and computing
policies in terms of SIL to SAN ingress which maps the extracted SIL
to the corresponding policies and executes them upon the forwarding
plane. SCMS could be the combination of computing and networking
orchestrator and controller which logically should be two standalone
entities. The orchestrator part is responsible for the general
scheduling policies of computing and networking resources, such as at
which threshold a policy is triggered, while the controller generates
and delivers the SIL-indexed policies according to the scheduling
policies from the orchestrator. Under distributed routing scheme,
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the computing and networking policies generated by the protocols
(such as BGP) within the SAN forwarding and routing node could also
be part of SCMS logically.
5.2. SAN relay
SAN relay is optionally designed to identify SIL and execute the
according service routing as well as networking policies when SAN
ingress alone could not do this. Particularly, SIL-indexed routing
status would not necessarily be maintained by SAN ingress once and
all, so SAN relay could play the role of recursive routing table
query. Also, SAN relay could coordinate with SAN ingress to execute
the networking policy in terms of SIL when necessary. Nevertheless,
SAN relay could be reduced to an ordinary forwarding and routing node
without knowledge of SIL when SAN ingress completes the service and
networking service policies.
5.3. SAN egress
When it comes to SAN egress, SIL could be extracted from the
destination address field when there is a tunnel encapsulation as an
outside header such as SRH (SRv6 Header), or from the dedicated SIL
header when the original SIL in the destination address field has
been replaced with a selected SAN egress address by SAN ingress. SAN
egress maps the SIL with the networking and computing policies from
SCMS and executes them upon the forwarding plane, the next hop would
be selected through the computing policy as a server hosting the
service or a proxy of the service. SAN egress always removes the
outside tunnel header and terminates the networking policy.
The networking and computing policy exchange with SCMS follows the
same process of SAN ingress other than the difference of
particularity of the policies generated and delivered.
5.4. SAN control plane consideration
As the conventional IP routing control plane scheme in place, SAN
control plane could also be deployed by centralized and distributed
scheme or combination of both with additional service status as well
as the polices. Service-related control plane only has impacts upon
SAN ingress and egress, and could logically be decoupled from the
conventional IP control plane.
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5.4.1. Centralized control plane consideration
SIL-centered networking and computing resource and policy generation
and maintenance is the key feature of SAN control plane. Networking
resource and policy generally aligns with the existing scheme other
than the SIL-centered networking policy is differentiated in a fine-
grained granularity. As far as computing resource and policy is
concerned, LSRS's volatility makes it infeasible to be maintained and
controlled in a centralized entity, GSRS is the chief computing
resource and service status information to be collected and managed
in the controller with regard to service stream delivery in routing
network architecture. Routing and forwarding policies from GSRS
calculated in the centralized controller apply only to the segment
between SAN ingress and egress, while the second segment routing
policy from SAN egress to the selected service instance in the cloud
site is determined by LSRS at SAN egress.
Hierarchically centralized control plane architecture would be
strongly recommended under the circumstances of nationwide networking
and computing management and scheduling.
5.4.2. Distributed control plane consideration
Networking resource is notified and updated through existing
distributed protocols (BGP/IGP etc.) and the SIL-centered networking
policy would be formulated as well. When it comes to computing
resource, GSRS is updated among the SAN edge routers which have been
connected in a mesh way that each pair of edge routers could exchange
GSRS to each other, while LSRS will be unidirectionally updated from
cloud site to the associated SAN edge router in which LSRS is
maintained and its update process is terminated.
Protocol consideration upon which GSRS and LSRS is updated is out of
the scope of this proposal and will be illustrated in forthcoming
draft.
5.4.3. Hybrid control plane consideration
In terms of the particularity of service-related resource updating
and notification, it would be more efficient to update the GSRS by a
distributed way than a centralized way in terms of routing request
and response in a limited network and cloud domain, but would be the
opposite case in a nationwide circumstance. This is how hybrid
control plane could be deployed in such a scheme that overall
optimization could be achieved.
5.5. SAN user plane consideration
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5.5.1. SIL encapsulation
Service identification label is the predominant index across the
entire SAN framework ranging through user terminal, forwarding and
routing network and cloud with SIL working as the virtual
destination. Data plane determines the routing and forwarding
orientation with SIL by inquiring GSRS and LSRS at SAN ingress and
SAN egress respectively. SIL encapsulation could be achieved by
extending the existing packet header and also achieved by designing a
dedicated SIL sub-layer, which along with the specific structure of
SIL are out of the scope of this proposal and will be illustrated in
forthcoming draft.
5.5.2. SIL in forwarding and routing network
SAN ingress obtains SIL from either the destination address field or
the dedicated SIL sub-layer of the user packet header explicitly or
mapping from the traditional 5 tuples implicitly. Either way SIL
starts being indexed for networking and computing policies until it
arrives at SAN egress. SIL in the dedicated sub-layer would remain
intact in the user packet header, while SIL in the destination
address field would remain intact if SAN ingress employs a tunnel
header or could be replaced with a selected SAN egress address with a
dedicated SIL encapsulation in extension headers such as DoH, SRH,
HBH. In the case of absence of SIL in user packet header, SAN
ingress would generate and encapsulate SIL in extension headers by
combination of existing parameters from user packet header such as 5
tuples etc. Apart from the networking and computing policy execution
at SAN ingress and egress, SIL could be ignored by SAN relay and
without computing state maintenance unless the mapping between SIL
and GSRS fails or SIL fine-grained networking policy is involved.
5.5.3. SIL-based routing
As illustrated in section 3, SIL encapsulated in the headers and
maintained in GSRS and LSRS indicates an abstract service type rather
than a geographically explicit destination label, thus the routing
scheme based upon SIL is actually a two-part and two-layer process in
which SIL only indicates the routing intention of user's requested
service type while routing does not actually materialize in
forwarding plane and the explicit routing destination of the two
segments would be determined by GSRS and LSRS respectively.
Therefore the actual routing falls within the traditional routing
scheme which remains as they are.
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Apart from the indication of service routing intention, SIL could
also indicates a specific network serivice requirements by
associating the networking service policy in GSRS which would
therefore schedule the network resources such as an SR tunnel,
guaranteed bandwidth etc. at SAN ingress.
Therefore, GSRS and LSRS in control plane along with SIL
encapsulation in user plane enables an logical service routing sub-
layer which is able to be aware of the computing status from cloud
sites and forward the service flow in terms of networking services as
well as computing resources. Nevertheless, this logical sub-layer
remains predominantly at SAN ingress and egress nodes. There're
drafts such as [I-D.liu-dyncast-ps-usecases] and
[I-D.li-dyncast-architecture] which analyze the benefits of
computing-based routing and demonstrate an anycast-as-service-
identification solution.
5.6. Hierarchical service routing architecture
In addition to the existing networking resource and status sensing
scheme, SAN routing and forwarding network is designed specifically
to enable sensing the service-related resource and service status
from the cloud sites and routing the service flow according to both
network and computing metrics as illustrated in figure 2. The
architecture is a horizontal convergence of cloud and network, while
the latter maintains the converged resource status and thus is able
to achieve an end to end routing and forwarding policy from a
perspective of cloud and network resource. PE1 maintains GSRS with a
whole picture of the multiple cloud sites, and executes the routing
policy for the network segment between PE1 and PE2 or PE3, namely
between SAN ingress and egress, while PE2 maintains LSRS with a focus
picture of the cloud site where S1 resides, and establishes a
connection towards S1. S1 is an active instance of a specific
service type. On top of the role of SAN egress which maintains LSRS,
PE2 and PE3 also fulfill the role of SAN ingress which maintains GSRS
from neighboring cloud sites. P provides traditional routing and
forwarding functionality for computing service flow, and optionally
remains unaware of service-related status.
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+----------+ +-------+
+------>|SAN egress|----->| SI |
| +----------+ +-------+
+-----------+ +-----------+ PE2 S1
|SAN ingress|--->| SAN relay|
+-----------+ +-----------+ PE3 S2
PE1 P | +----------+ +-------+
+------>|SAN egress|----->| SI |
+----------+ +-------+
|<--------- Networking domain --------->|<-Computing domain->|
Figure 2
5.6.1. Routing scheme in line with multiple service-related resources
granularity
Status updates of service-related resource and service in the cloud
sites extend in a quite broad range from relatively stable service
types and overall resource occupation to extremely dynamic capacity
changes as well as busy and idle cycle of service instances. It
would be a disaster to build all of the status updates in the network
layer which would bring overburdened and volatile routing tables.
It should be reasonable to divide the wide range of service-related
resource and services into different categories with differentiated
characteristics from routing perspective. GSRS and LSRS correspond
to cross-site domain and local site domain respectively, and GSRS
aggregates the service-related resource and service status with low
update frequency from multiple cloud sites while LSRS focuses only
upon the status with high frequency in the local sites. Under this
two-granularity scheme, service-related routing table of GSRS in the
SAN ingress remains in a position roughly as stable as the
traditional routing table, and the LSRS in the SAN egress maintains a
near synchronized state table of the highly dynamic updates of
service instances in the local cloud site. Nonetheless, LSRS
focusing upon a single and local cloud site is the normal case while
upon multiple sites should be exception if not impossible.
5.6.2. Two-segment routing and forwarding
When it comes to end to end service flow routing and forwarding,
there is an status information gap between GSRS and LSRS, therefore a
two-segment mechanism has to be in place in line with the two-
granularity routing scheme demonstrated in 5.6.1. As is illustrated
in figure 3, R1 as ingress determines the specific service flow's
egress which turns out to be R2 according to policy calculation from
GSRS. In particular, the SIL from both in-band (user plane) and out-
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band (control plane) is the only index for R1 to calculate and
determine the egress, it's highly possible to make this egress
calculation in terms of both networking (bandwidth, latency etc) and
computing requirements. Nevertheless, the two SLA routing
optimization could be decoupled to such a degree that the traditional
routing algorithms could remain as they are. The convergence of the
SLA policies as well as the methods to make SAN ingress aware of the
two SLA would be illustrated by the example work flow of section 7.
Nevertheless, the specific solution is out of scope of this proposal.
+--------+ +--------+ +--------+ +--------+
| GSRS |--->| |--->| LSRS |--->| SI |
+--------+ +--------+ +--------+ +--------+
R1 R R2 S1
|<---------- GSRS segment ----->|<-LSRS segment--->|
Figure 3
When the service flow arrives at R2 which terminates the GSRS segment
routing and determines S1 which is the service instance selected
according to LSRS maintained at R2. Again SIL is the only index for
LSRS segment routing process.
5.6.3. Cross-domain computing routing and forwarding
Co-ordinated computing resource scheduling among multiple regions
which are usually connected by multiple network domains, is an
important part of intended scenarios with regard to why computing-
based scheduling and routing is proposed in the first place. The
two-segment routing and forwarding scheme illustrated in5.6.2 is a
typical use case of cross-domain service routing and forwarding and a
good building block for the full-domain scenario solution. Service
status information is brought into network domain to enable the
latter scheduling routing policies beyond network. However, a
particular scheme has to be put in place to ensure mild and
acceptable impacts upon the ongoing IP routing scheme. A consistent
SIL across terminal, network (multiple domains) and cloud along with
hierarchical SIL-indexed service-related resource and service status
which corresponds with different network domains, is the enhanced
full-domain routing and forwarding solution. Each domain maintains a
corresponding ervice-related resource and service status at its edge
node and makes the service-based routing for the domain-specific
segment which should be connected by the neighboring segments.
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5.6.4. Service traffic affinity
SIL holds the only semantics of the service type that could be
deployed as multiple instances within specific cloud site or across
multiple cloud sites, SIL in the destination field is not explicit
enough for all of the service flow packets to be forwarded to a
specific host. Traffic affinity has to be guaranteed at both ingress
and egress. Once the egress is determined at SAN ingress, the
binding relationship between the egress and the service flow's unique
identification (5-tuple or other specifically designed labels) is
maintained and the subsequent flow could be forwarded upon this
binding table. Likewise SAN egress maintains the binding
relationship between the service flow identification and the selected
service instance.
Traffic affinity could be guaranteed by mechanisms beyond routing
layer, but they will not be in the scope of this proposal.
5.7. Logical sub-layer of service routing in forwarding and routing
network
A SIL-indexed networking and computing policy state from SCMS is
maintained at the control plane in SAN forwarding and routing
network. The policy state regulates and guides the forwarding and
routing behaviors of SAN nodes on the basis of SIL as well as the
identification of the service stream. Namely, the fine-grained
networking and computing policies bring new abilities for forwarding
and routing network to be highly efficiently aware of the service
from perspectives of both networking and computing requirements.
Either SIL is originated from user client or SAN ingress, SIL's
presence in the data plane is guaranteed by various encapsulation
solutions and could be extracted and indexed by any node for
execution of either networking policy, computing policy or both.
As for the networking connection services for which only network-
domain resources would be involved, SIL provides a fine-grained
interface between network and application which would be unavailable
otherwise. Under this particular circumstance, SIL-indexed
networking policy state maintenance actually aligns perfectly with
the existing scheme.
When it comes to the computing services for which both networking and
computing resources would be involved, SIL is a light-weight index
for the fine-grained policies, and the particular computing policies
are clearly decoupled with that of networking policies .
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Therefore, a logical SIL sub-layer with both control and data plane
has been conceptually employed within SAN forwarding and routing
architecture. The sub-layer simply delivers the SIL specific
policies but would leave them for the existing routing layer to
execute the policies on a basis of service stream and packet.
6. Governance and life cycle of service identification label
6.1. Originality and governance of SIL
SIL is designated to indicate the fundamental and common service
types, and could be registered from both networking and computing
domain with regard to networking connection services and
comprehensive computing services respectively. The SIL templates
should be specified by the entity which is both technically able to
coordinate the SIL-indexed networking and computing resources and
services, or by public standardization organizations. SCMS publishes
the SIL which has been authenticated, authorized and configured with
networking and computing policies.
Application developer and operator subscribes SIL from SCMS and
integrates it into its application system, and the service client
initiates the service by encapsulating SIL into its IP protocol
headers. SIL template specification is out of scope of this
proposal.
6.2. Life cycle of SIL
Upon the registration and publication of the service, SIL is active
and available through the ecosystem of terminal, network and cloud
until it's withdrawn and terminated by SCMS. Life cycle of SIL would
not terminate with a specific end of user service, and the same SIL
could be instantiated by multiple users simultaneously. SIL renders
the services as an effective interface between service and network
which is inherently absent in the decoupled internet protocol system.
7. An example of end-to-end SAN work flow
SIL is controlled and managed by SCMS as illustrated in section 6.1,
therefore SIL subscription and service agreement process between
service client and SCMS should be finished before the service client
initiates a service request and starts sending service data stream
while SIL would be encapsulated in layer 3 header and lives on
through the service terminal, SAN routing and forwarding network, and
service server in the cloud site. An example work flow of cloud game
application will be demonstrated under SAN reference framework. From
networking and computing resource perspectives, rendering algorithm
of real-time game situation data should be the dominant sub-service
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of cloud game application. The work flow instantiates the mechanism
under which the rendering algorithm would be materialized by SAN.
7.1. Initiation and maintenance of rendering algorithm in SAN system
Rendering algorithm is identified as a fundamental and common service
which could be invoked by multiple parties, and at least one provider
has registered to SCMS and has been authenticated and verified by
SCMS for the service availability. An SIL might be allocated or
activated as SIL-RA which should be structured service identification
specifically and uniquely allocated for the rendering algorithm.
When it comes to the networking requirements of rendering algorithm,
SCMS verifies the corresponding networking resource availability as
well as capability and establishes a comprehensive SLA state for
rendering algorithm indexed by SIL-RA.
When a rendering algorithm provider registers/withdraws the rendering
algorithm service and the corresponding networking resources update
to a degree the service would not be able to be rendered as promised,
the computing and networking SLA state of SIL-RA should be updated
accordingly. The signal as well as data stream of SIL-RA is
illustrated as an example work flow in figure 4.
+--+ L4:SIL(rendering algorithm)-based service connection +--+
| |<-------------------------------------------------------->| |
| | +-------------------------------------------+ | |
| |<=====| SCMS |======>| |
| | +-#------------------#--------------------#-+ | |
| | # # # | |
| | # # # | |
| | +-v---------+ +--V------+ +------V---+ | |
| |----->|SAN Ingress|---->|SAN Relay|----->|SAN Egress|---->| |
+--+ +-----------+ +---------+ +----------+ +--+
Service Client Service Server
-------------> ===============> ###############>
service flow SIL management flow SIL policy config flow
Figure 4
The service client launches a cloud game application request to the
designated server in a centered cloud site, and a cloud game service
connection thus would be established, while the rendering algorithm
might be deployed in the edge cloud nodes for the sake of
responsiveness of the game service.
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7.2. Configuration of a rendering algorithm (as SIL-RA) in SAN
forwarding and routing network
End-to-end latency determines both the user experience and the
feasibility of the service deployed in the cloud site. The latency
resulting from the service server and the network path depends on the
rendering algorithm capability along with the computing resources and
the networking delay respectively. Therefore, SCMS maps a networking
connection policy with 10 mini-seconds of latency and computing
policy with GPU to SIL-RA, and makes the networking and computing
policies configuration to the SAN forwarding and routing nodes such
as SAN ingress, SAN relay and SAN egress through network management
and control interfaces.
7.3. Publication/Subscription of SIL-RA
Upon completion of SIL-RA initiation and configuration, SIL-RA is
ready to be published to and subscribed by all of the interested
parties. The SIL-RA publish/subscribe process is more of a
commercial agreement than a technical exchange process. The
rendering algorithm service client initiates the service by sending
the service requests as well as data stream with SIL-RA encapsulated
in layer 3 header. The rendering algorithm service connection would
be based soly upon SIL-RA which could be indexed and mapped to a
computing node located in other edge cloud site, and thus the actual
service connection could be different from that of cloud game
application connection as illustrated in section 7.1.
7.4. SIL-RA service data stream treatment at SAN forwarding and routing
network
In the ongoing process of the real-time cloud game service, the
rendering algorithm service would be invoked simultaneously during
the entire life-cycle of the game service. Therefore, the rendering
algorithm would not be invoked as the initiation of the game service
and would also not reside in a same cloud site of the master game
service. The rendering algorithm service should be specifically
guaranteed by SAN with comprehensive networking and computing
policies configured for it. The game service client would initiate
an independent rendering algorithm service by encapsulating SIL-RA in
the data packet headers.
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7.4.1. SIL-RA service data stream treatment at SAN ingress
Upon arrival of SIL-RA service data stream, SAN ingress extracts SIL-
RA from the designated field of layer 3 header and identifies the
type of the SIL-RA. SIL-RA availability as well as the supporting
computing resources among multiple servers has been maintained in the
service routing table, the SAN egress connecting to a proper SIL-RA
server would be selected.
As configured in 7.3, SIL-RA service stream should be transmitted by
a forwarding and routing policy with 10 mini-seconds latency between
SAN ingress and the selected SAN egress. The SIL-RA service data
stream would be guided into a designated networking path. As far as
bounded latency of routing network is concerned, a path-specific flow
label could be employed in line with the underling networking
technologies such as Detnet.
7.4.2. SIL-RA service data stream treatment at SAN relay
SIL-RA service data stream treatment with SIL-RA involved is actually
optional, it's only necessary when SAN ingress relays the SIL-RA
service routing request to a SAN relay where the SIL-RA indexed
service routing table is homed or one or more SAN relay nodes has to
be involved to provide SIL-RA specific networking connection service.
7.4.3. SIL-RA service data stream treatment at SAN egress
As illustrated in section 5.5, SIL-RA indexed service routing table
would be aggregated with two class granularity at SAN ingress and SAN
egress respectively. So SIL-RA would be extracted from the
designated field and mapped with the LSRS table. The final hop
purporting to the selected rendering algorithm service server would
be determined by SAN egress and the service data stream would be
forwarded to the server or the server's proxy accordingly.
SAN egress should be the terminating node of the networking
connection path and the the associated path header would be removed.
7.5. SIL-RA service data stream treatment at cloud site
SIL-RA encapsulation in layer 3 header would remain intact until the
data packet arrives at the cloud site. SIL-RA would be identified
and treated as both a service connection ID by the rendering
algorithm server and a rendering algorithm to be guided and scheduled
by the cloud system respectively .
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8. Acknowledgements
To be added upon contributions, comments and suggestions.
9. IANA Considerations
This memo includes no request to IANA.
10. Security Considerations
SIL employment in SAN framework would bring security challenges for
user and application in the cloud sites as well as SAN forwarding and
routing network. SCMS is responsible for registry, authorization and
authentication of SIL and acts as the first check point for SIL. The
detailed specification of the security process of SCMS is out of
scope of this proposal. When it comes to SAN forwarding and routing
network, it's imperative for the service gateway to execute security
policies with regard to SIL and the specific security solution would
be illustrated in a dedicated proposal.
11. Informative References
[I-D.li-dyncast-architecture]
Li, Y., "Dynamic-Anycast Architecture", February 2021,
<https://datatracker.ietf.org/doc/draft-li-dyncast-
architecture/>.
[I-D.liu-dyncast-ps-usecases]
Liu, Peng., "Dynamic-Anycast (Dyncast) Use Cases and
Problem Statement", February 2021,
<https://datatracker.ietf.org/doc/draft-liu-dyncast-ps-
usecases/>.
[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>.
Authors' Addresses
Daniel Huang
ZTE Corporation
Nanjing
Phone: +86 13770311052
Email: huang.guangping@zte.com.cn
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Bin Tan
ZTE Corporation
Nanjing
Phone: +86 13918622159
Email: tan.bin@zte.com.cn
Dong Yang
Beijing Jiaotong University
Beijing
Email: dyang@bjtu.edu.cn
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