RTGWG                                                        D.H. Daniel
Internet-Draft                                                  B.T. Bin
Intended status: Standards Track                         ZTE Corporation
Expires: 8 September 2022                                      P.L. Peng
                                                            China Mobile
                                                            7 March 2022


                 Computing Delivery in Routing Network
          draft-huang-computing-delivery-in-routing-network-01

Abstract

   This document drafts a proposal of the architecture of Computing
   Delivery in Routing Network which incorporates both computing and
   networking metrics into the routing polices and enables the network
   sensing and scheduling computing services based upon traditional
   networking services.  A mechanism of two-class computing status
   granularity and two segment routing is illustrated for end-to-end
   networking and computing service in the cloud sites, while major
   networking and computing actors is defined in terms of functionality.
   An example work flow is demonstrated, and both control plane and data
   plane solution consideration is proposed..

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 8 September 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.






Daniel, et al.          Expires 8 September 2022                [Page 1]


Internet-Draft              Abbreviated Title                 March 2022


   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Computing delivery in routing network reference
           architecture  . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Hierarchical granularity routing scheme . . . . . . . . .   5
     3.2.  Two-segment routing and forwarding  . . . . . . . . . . .   6
     3.3.  Cross-domain computing routing and forwarding . . . . . .   6
     3.4.  CSI routing . . . . . . . . . . . . . . . . . . . . . . .   7
     3.5.  Traffic affinity  . . . . . . . . . . . . . . . . . . . .   7
   4.  Computing delivery in routing network architecture work
           flow  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Computing resource and service update work flow . . . . .   8
     4.2.  Service flow routing and forwarding work flow . . . . . .   8
   5.  Control plane . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Centralized control plane . . . . . . . . . . . . . . . .   9
     5.2.  Distributed control plane . . . . . . . . . . . . . . . .   9
     5.3.  Hybrid control plane  . . . . . . . . . . . . . . . . . .   9
   6.  Data plane  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  CSI encapsulation . . . . . . . . . . . . . . . . . . . .  10
     6.2.  CSI for GCR, CUR and LCR  . . . . . . . . . . . . . . . .  10
   7.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  11
   11. Informative References  . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Computing-related services have been provided in such a way that
   computing resources either are confined within isolated sites (data
   centers, MECs etc.) without coordination among multiple sites or they
   are coordinated and managed within specific and closed service
   systems without fine-grained networking facilitation, while the
   industry develops into an era in which the computing resources start
   migrating from centralized data centers to distributed edge nodes.



Daniel, et al.          Expires 8 September 2022                [Page 2]


Internet-Draft              Abbreviated Title                 March 2022


   Therefore substantial benefits in light of both cost and efficiency
   resulting from scale of economy, would be brought into multiple
   industries by intelligently and dynamically connecting the
   distributed computing resources and rendering the coordinated
   computing resources as a unified and virtual resource pool.  On top
   of the cost and efficiency gains, applications as well as services
   would be served in a more sophisticated way in which computing and
   networking resources could be aligned more efficiently and agilely
   than conventional way in which the two are delivered in separate
   systems.  Some impressive drafts such as
   [I-D.liu-dyncast-ps-usecases] and [I-D.li-dyncast-architecture]
   analyze the benefits of routing related solution, and give the
   reference architecture and preliminary test results.  End
   applications could be served not only by fine-grained computing
   services but also fine-grained networking services rather than the
   best-effort networking services without routing network involved
   otherwise.  The cost is the burden of maintaining and sensing
   computing resource status in the networking layer.  The architecture
   proposal is designed to be as much smoothly compatible with the
   ongoing routing architecture as possible.

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

   *  Global Computing-related Routing Node (GCR): 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 resource and service.  GCR usually
      resides at the network edge and works as ingress of the end to end
      service flow.

   *  Local Computing-related Routing Node (LCR): 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 resource and
      service instance in the specific cloud site.  LCAT usually resides
      at the network edge and works as egress of the end to end service
      flow.







Daniel, et al.          Expires 8 September 2022                [Page 3]


Internet-Draft              Abbreviated Title                 March 2022


   *  Computing Unaware Routing Node (CUR): routing node unaware of
      computing resource and service status and disregarding
      encapsulation of the identification of computing service.  CUR
      usually resides between GCR and LCR and works as ordinary routing
      nodes and stays irrelevant of computing delivery.

   *  Global Computing Resource and Service Status (GCRS): General cloud
      site status of the computing resource and service which consists
      of overall resource occupation and types of computing service
      (algorithms, functions etc.) the specific cloud site provides.
      GCRS is maintained at GCR and expected to remain relatively stable
      and change in slow frequency.

   *  Local Computing Resource and Service Status (LCRS): fine-grained
      cloud site status of the computing resource and service which
      consists of status of each active computing service instance as
      well as its parameters which impact the way the instance would be
      selected and visited by LCR.  LCRS is maintained at LCR and
      expected to stay quite active and change in high frequency.

   *  Computing Service Identification (CSI): a globally unique
      identification of a computing service with optional parameters,
      and it could be an IPv6-like address or specifically designed
      identification structure.

   *  Instantiated Computing Service (ICS): an active instance of a
      computing service identification which resides in a host usually
      purporting to a server, container or virtual machine.

3.  Computing delivery in routing network reference architecture

   Routing network is enabled sensing the computing resource and service
   from the cloud sites and routing the service flow according to both
   network and computing metrics by a computing delivery in routing
   network architecture as illustrated in figure 1.  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 GCRS 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 ingress
   and egress, while PE2 maintains LCRS 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 computing service type (CSI).
   On top of the role of LCR which maintains LCRS, PE2 and PE3 also
   fulfill the role GCR which maintains GCRS from neighboring cloud
   sites.  P provides traditional routing and forwarding functionality
   for computing service flow, and remains unaware of any computing-



Daniel, et al.          Expires 8 September 2022                [Page 4]


Internet-Draft              Abbreviated Title                 March 2022


   related status as well as CSI encapsulations.



                                                  +--------+        +--------+
                                          +------>|LCR/GCR |------->|   ICS  |
                                          |       +--------+        +--------+
                +--------+    +--------+  |          PE2                S1
                |  GCR   |--->|  CUR   |--+
                +--------+    +--------+  |          PE3                S2
                   PE1            P       |       +--------+        +--------+
                                          +------>|LCR/GCR |------->|   ICS  |
                                                  +--------+        +--------+
                |<------------ Network domain --------------->|<--Computing->|
                                                                   domain



                               Figure 1

3.1.  Hierarchical granularity routing scheme

   Status updates of computing 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 instance.  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 computing
   resource and services into different categories with differentiated
   characteristics from routing perspective.  GCRS and LCRS correspond
   to cross-site domain and local site domain respectively, and GCRS
   aggregates the computing resource and service status with low update
   frequency from multiple cloud sites while LCRS focuses only upon the
   status with high frequency in the local sites.  Under this two-
   granularity scheme, computing-related routing table of GCRS in the
   GCR remains in a position roughly as stable as the traditional
   routing table, and the LCRS in the LCR maintains a near synchronized
   state table of the highly dynamic updates of computing service
   instances in the local cloud site.  Nonetheless, LCRS focusing upon a
   single and local cloud site is the normal case while upon multiple
   sites should be exemption if not impossible.








Daniel, et al.          Expires 8 September 2022                [Page 5]


Internet-Draft              Abbreviated Title                 March 2022


3.2.  Two-segment routing and forwarding

   When it comes to end to end service flow routing and forwarding,
   there is an status information gap between GCRS and LCRS, therefore a
   two-segment mechanism has to be in place in line with the two-
   granularity routing scheme demonstrated in 3.1.  As is illustrated in
   figure 2, R1as ingress determines the specific service flow's egress
   which turns out to be R2 according to policy calculation from GCRS.
   In particular, the CSI from both in-band (user plane) and out-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
   Service Agreement Level.  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 GCR aware of the two SLA
   is out of scope of this proposal.


                   +--------+    +--------+    +--------+    +--------+
                   |  GCRS  |--->|        |--->|  LCRS  |--->|   ICS  |
                   +--------+    +--------+    +--------+    +--------+
                       R1            R
                   |<---------- GCRS segment ---------->|<-   LCRS  ->|
                                                             segment


                                  Figure 2

   When the service flow arrives at R2 which terminates the GCRS segment
   routing and determines S1 which is the service instance selected
   according to LCRS maintained at R2.  Again CSI is the only index for
   LCRS segment routing process.

3.3.  Cross-domain computing routing and forwarding

   Co-ordinated computing resource scheduling among multiple regions
   which are usually connected by multiple network domains, as
   illustrated in section 1, 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 in 3.2 is a typical use case of cross-domain computing
   routing and forwarding and a good building block for the full-domain
   scenario solution.  Computing metric 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 CSI across terminal, network (multiple domains)



Daniel, et al.          Expires 8 September 2022                [Page 6]


Internet-Draft              Abbreviated Title                 March 2022


   and cloud along with hierarchical CSI-associated computing resource
   and service status which corresponds with different network domains,
   is the enhanced full-domain routing and forwarding solution.  Each
   domain maintains a corresponding computing resource and service
   status at its edge node and makes the computing-based routing for the
   domain-related segment which should be connected by the neighboring
   segments.

3.4.  CSI routing

   CSI encapsulated in the headers and maintained in LCRS and GCRS
   indicates an abstract service type rather than a geographically
   explicit destination label, thus the routing scheme based upon CSI is
   actually a two-part and two-layer process in which CSI only indicates
   the routing intention of user's requested computing service type
   where routing does not actually materialize in forwarding plane and
   the explicit routing destination would be determined by LCRS and
   GCRS.  Therefore the actual routing falls within the traditional
   routing scheme which remains intact.

   Apart from the indication of computing service routing intention, CSI
   could also indicates a specific network serivice requirements by
   associating the networking service policy in GCRS which would
   therefore schedule the network resources such as an SR tunnel,
   guaranteed bandwidth etc. at egress.

   Therefore, GCRS and LCRS in control plane along with CSI
   encapsulation in user plane enables an logical computing routing sub-
   layer which is able to be aware of the computing from cloud sites and
   forward the service flow in terms of computing services as well as
   computing resources.  Nevertheless, this logical sub-layer remains
   only relevant at ingress and egress nodes and is simply about
   computing nodes selection rather than executing the real forwarding
   and routing actions.

3.5.  Traffic affinity

   CSI holds the only semantics of the service type that could be
   deployed as multiple instances within specific cloud site or across
   multiple cloud sites, CSI in the destination field is not explicit
   enough for all of the service flow packets to be forwarded to a
   specific destination.  Traffic affinity has to be guaranteed at both
   GCR and LCR.  Once the egress is determined at GCR, 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 LCR maintains the binding relationship
   between the service flow identification and the selected service



Daniel, et al.          Expires 8 September 2022                [Page 7]


Internet-Draft              Abbreviated Title                 March 2022


   instance.

   Traffic affinity could be guaranteed by mechanisms beyond routing
   layer, but they will not be in the scope of this proposal.

4.  Computing delivery in routing network architecture work flow

4.1.  Computing resource and service update work flow

   The full range of computing resource and service status from a
   specific cloud site is registered at LCR which maintains LCRS in
   itself and notifies the part of GCRS to remote GCRs where GCRS would
   be thus maintained and updated.  As is illustrated in figure 3,GCR in
   R1 from site1 and site 2 is updated by R2 and R3, while LCRS of site
   1 in R2 is updated by S1 and LCRS of site 2 in R3 is updated by S2.
   GCRS in R2 and R3 is updated by each other.  Edge routers associating
   with local cloud site establish a mesh fabric to update the according
   GCRS among the whole network domain, the computing resource and
   services in distributed cloud sites thus are connected and could be
   utilized as a single pool for the applications rather than the
   isolated islands.

                                                  +--------+        +--------+
                      +---------------------------|LCR/GCR |<-------|   ICS  |
                      |                           +--------+        +--------+
                +-----V--+    +--------+            A R2 |              S1
                |  GCR   |    |  CUR   |            |    |
                +-----A--+    +--------+            | R3 V              S2
                  R1  |           R               +--------+        +--------+
                      +---------------------------|LCR/GCR |<-------|   ICS  |
                                                  +--------+        +--------+
                |<--------- GCRS update domain ----------->|<-----LCRS------>|
                                                                 domain


                               Figure 3

4.2.  Service flow routing and forwarding work flow

   From perspective of the service work flow, more details have actually
   been demonstrated in 3.2 and 3.3.  Rather than the traditional
   destination-oriented routing mechanism and the segment routing in
   which the ingress router is explicitly aware of a specific
   destination, CSI as an abstract label without semantics of physical
   address works as the required destination from viewpoint of the user
   in computing delivery in routing network architecture.  Therefore the
   service flow has to be routed and forwarded segment by segment in
   which the two segment destinations are determined by GCRS and LCRS



Daniel, et al.          Expires 8 September 2022                [Page 8]


Internet-Draft              Abbreviated Title                 March 2022


   respectively.

5.  Control plane

5.1.  Centralized control plane

   LCRS's volatility makes it infeasible to be maintained and controlled
   in a centralized entity, GCRS is the chief computing resource and
   service status information to be collected and managed in the
   controller when it comes to centralized control plane with regard to
   computing delivery in routing network architecture.  Routing and
   forwarding policies from GCRS calculated in the centralized
   controller, as is demonstrated in 3.2, apply only to the segment from
   ingress and egress, while the second segment routing policy from
   egress to the selected service instance in the cloud site is
   determined by LCRS at egress.

   Hierarchically centralized control plane architecture would be
   strongly recommended under the circumstances of nationwide network
   and cloud management.

5.2.  Distributed control plane

   GCRS is updated among the edge routers which have been connected in a
   mesh way that each pair of edge routers could exchange GCRS to each
   other, while LCRS will be unidirectionally updated from cloud site to
   the associated edge router in which LCRS is maintained and its update
   process is terminated.

   Protocol consideration upon which GCRS and LCRS is updated is out of
   the scope of this proposal and will be illustrated in another draft.

5.3.  Hybrid control plane

   It should be more efficient to update the GCRS by a distributed way
   than a centralized way in terms of routing request and response in a
   limited network and cloud domain, but be the opposite case in a
   nationwide circumstance.  This is how hybrid control plane could be
   deployed in such a scheme that overall optimization is achieved.

6.  Data plane










Daniel, et al.          Expires 8 September 2022                [Page 9]


Internet-Draft              Abbreviated Title                 March 2022


6.1.  CSI encapsulation

   Computing service identification is the predominant index across the
   entire computing delivery in routing network architecture under which
   a new virtual routing sub-layer is employed with CSI working as the
   virtual destination.  Data plane indicates the routing and forwarding
   orientation with CSI by inquiring GCRS and LCRS at GCR and LCR
   respectively.  CSI encapsulation could be achieved by extending the
   existing packet header and also achieved by designing a dedicated
   shim layer, which along with the specific structure of CSI are out of
   the scope of this proposal and will be illustrated in another draft.

6.2.  CSI for GCR, CUR and LCR

   GCR encapsulates CSI in a designated header format as a proxy by
   translating the user-originated CSI format, and makes the first
   segment routing policy and starts routing and forwarding the service
   traffic.  CUR ignores CSI and simply forwards the traffic as usual.
   LCR decapsulates CSI and makes the second segment routing policy and
   completes the last hop routing and forwarding.

7.  Summary

   It would significantly benefit the industry by connecting and
   coordinating the distributed computing resources and services and
   more so by further converging networking and computing resource.
   Uncertainty and the potential impacts over the ongoing network
   architecture is the main reason for the community to think twice.  By
   classifying the end to end routing and forwarding path into two
   segments, the impacts from computing status and metrics are to be
   reduced to a degree they would be as acceptable and comfortable
   enough as they are as networking status and metrics.  In particular,
   employment of CSI in computing delivery in routing network
   architecture enables a new service routing possibility perfectly
   compatible with the ongoing routing architecture.

8.  Acknowledgements

   To be added upon contributions, comments and suggestions.

9.  IANA Considerations

   This memo includes no request to IANA.








Daniel, et al.          Expires 8 September 2022               [Page 10]


Internet-Draft              Abbreviated Title                 March 2022


10.  Security Considerations

   As information originated from the third party (cloud sites), both
   GCRS and LCRS would be frequently updated in the network domain, both
   security threats against the routing mechanisms and credibility and
   security issues of the computing services should be taken into
   account by architecture designing.  The detailed analysis as well as
   solution consideration will be proposed in the updated version of the
   draft.

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


   Bin Tan
   ZTE Corporation
   Nanjing
   Phone: +86 13918622159
   Email: tan.bin@zte.com.cn


   Peng Liu
   China Mobile
   Beijing
   Phone: +86 13810146105



Daniel, et al.          Expires 8 September 2022               [Page 11]


Internet-Draft              Abbreviated Title                 March 2022


   Email: liupengyjy@chinamobile.com


















































Daniel, et al.          Expires 8 September 2022               [Page 12]