Internet DRAFT - draft-zzl-tvr-use-case-tidal-network

draft-zzl-tvr-use-case-tidal-network







TVR                                                        L. Zhang, Ed.
Internet-Draft                                                   T. Zhou
Intended status: Standards Track                                 J. Dong
Expires: 14 September 2023                                        Huawei
                                                           13 March 2023


                       Use Case of Tidal Network
                draft-zzl-tvr-use-case-tidal-network-00

Abstract

   The tidal effect of traffic is very typical on our network, this
   document introduces the time variant routing scenario in the tidal
   network, and then describes the assumptions and routing impacts based
   on the use case.  Finally, an exempar of a network to the use case is
   provided.

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   This Internet-Draft will expire on 14 September 2023.

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   provided without warranty as described in the Revised BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Assumptions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Routing Impacts . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Exemplar  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The tidal effect of traffic is very typical on our network, and the
   traffic volume varies greatly at different times.  For example, in
   the Chinese New Year, there are 200 million people move from their
   work town to home town, and these people generate huge traffic on our
   network.  For the campus network, there are thousands of people go to
   the Teaching buildings, libraries and labs in the daytime and go to
   dormitory in the night.  Therefore, the traffic of different places
   in the campus fluctuate obviously and regularly.

   In the previous scenarios, If the network maintains all the devices
   up to guarantee the maximum throughput all the time, a lot of power
   will be wasted.  Therefore, it is an effective energy-saving method
   to shut down some devices when the traffic is low.  Thus, a scenario
   in which the network connection status can be predicted is formed in
   the tidal network.

   This document introduces the time variant routing scenario in the
   tidal network, and then describes the assumptions and routing impacts
   based on the use case.  Finally, an exemplar of a network to the use
   case is provided.

1.1.  Requirements Language

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









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2.  Assumptions

   In order to reduuce energy consumption based on the regularity of
   tidal traffic, the controller or other control device needs to know
   the rule of traffic changing.  It is assumed that there is a
   algorithm that can calculates which nodes and links should be
   disabled or enabled under different traffic scales.  Finally, it is
   assumed that there is a method to config the switching rules for each
   node.

   1.  Known the regularity of tidal traffic, It is assumed that the
       controller or other control device knows the regularity of tidal
       traffic, and the change of traffic in the future can be
       predicated.  The regularity information may come from the manual
       input or the results of computer's calculation.

   2.  An algorithm to calculate which nodes or links can be disabled or
       enabled under different traffic scales.  It is assumed that the
       controller or other control device supports a algorithm to
       calculate the minimal topology that satisfies the requirements of
       traffic at different time.  Based on that, it is known which
       nodes or link should be disabled or enabled under different
       traffic scales.

3.  Routing Impacts

   The change of link status will change the topology of the network.
   Furthermore, the data routing may be affected which may result in
   packet disorder or packet loss.  In order to solve these problems,
   the existing routing protocols may need to provide the following
   capabilities.

   1.  Data model with time-variant information.  There is a need for
       the nodes or controllers to deliver the predicated time-variant
       information by specific data model or structure.  For the tidal
       network, the change of network topology usually has a regular
       period, and the overlay of mutiple groups of time-variant
       information (For example, the regularity of traffic in campus
       network is quite differern on weekdays and weekend) also should
       be considered.

   2.  Collection and advertisement for the time-variant information of
       each node and link.  For the distributed routing protocols, each
       node needs to calculate the routing table, so it is required that
       each node advertise its own time-variant information(This step is
       not necessary when every node knows all of the time-variant
       information about the topology).  For the centralized routing
       protocols, the controller is responsible for the calculation of



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       routing path, so the controller may need to collect the time-
       variant information of all the nodes(It is also not necessary
       when the controller already knows all of the time-variant
       information about the topology).

   3.  Routing algorithm based on time-variant information.  When the
       routing calculator knows the time-variant information of each
       node, there is a need for a new algorithm to calculate the
       routing paths, it may be quite different from the existing
       algorithm.

4.  Exemplar

   One example of a network with tidal traffic is the campus network,
   the traffic in the dormitory will raise in the evening and drop in
   the morning.  In contrast, the traffic in the library will raise in
   the morning and almost drop to zero at night. the traffic of campus
   changes with a significant period.

   Consider a four nodes network, and the traffic of the network at
   different time is shown in Figure 1.

   T |
   R |    ------                   ------
   A |   /      \                 /      \
   F |  /        \               /        \
   F | /          \             /          \
   I |/            ------------/
   C +---++----++-----------------++------++---
        t1    t2                 t1+T    t2+T
                    Time

             Figure 1: Traffic of the network at different time

   The topology of network is shown in Figure 2

       N1---------L1---------N2
       |  \                / |
       |    \            /   |
       |      \        /     |
       |       L6    L5      |
       L2         \/         L3
       |         /  \        |
       |       /      \      |
       |     /          \    |
       |   /              \  |
       N3--------L4----------N4




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                 Figure 2: Topology of a four node network

   In order to reduce the power consumption, some of the links may be
   shut down during the period form t1+nT to t2+nT(n=0,1,2,...).  For
   example, link L5 and L6 can be shut down when the traffic is low, so
   the possible time-variant topology is as shown in Figure 3

       N1---------L1---------N2        N1---------L1---------N2
       |  \                / |         |                     |
       |    \            /   |         |                     |
       |      \        /     |         |                     |
       |        L6    L5     |         |                     |
      L2          \/        L3         L2                   L3
       |         /  \        |         |                     |
       |       /      \      |         |                     |
       |     /          \    |         |                     |
       |   /              \  |         |                     |
       N3---------L4--------N4         N3---------L4--------N4
    Topology1 (form t1+T to t2+T)    Topology 2(form t2+T to t1+T)

                      Figure 3: Time-variant topology

   In this example, The controller is required to deliver the time-
   variant information of link L5 and L6 to the related nodes, and then
   the controller or each node(Every node has already known the time-
   variant information of topology) needs to calculate the routing path
   with the time-variant information of L5 and L6.  It should be noted
   that if there are some packets being transmitted over link L5 or L6
   at time t1, the shutdown of L5 and L6 may cause packet loss until the
   source node computes a new routing path.  The new routing mechanism
   may need solve these problems of tidal network.

5.  Security Considerations

   TBD

6.  IANA Considerations

   TBD

7.  Normative References

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

Authors' Addresses

   Li Zhang (editor)
   Huawei
   Beiqing Road
   Beijing
   China
   Email: zhangli344@huawei.com


   Tianran Zhou
   Huawei
   Email: zhoutianran@huawei.com


   Jie Dong
   Huawei
   Email: jie.dong@huawei.com





























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