Internet DRAFT - draft-li-casm-address-pool-management-arch

draft-li-casm-address-pool-management-arch







Network Working Group                                              C. Li
Internet-Draft                                                    C. Xie
Intended status: Informational                             China Telecom
Expires: September 7, 2017                                         J. Bi
                                                     Tsinghua University
                                                                   W. Xu
                                                     Huawei Technologies
                                                           March 6, 2017


                Interface to the Address Pool Management
             draft-li-casm-address-pool-management-arch-00

Abstract

   This document describes an mechanism for a standard, programmatic
   interface for address pool management.  With the remaining IPv4
   address becoming more and more scattered, it is complicated to
   manually configure the address pools on lots of Broadband Network
   Gateways(BNGs) for operators.  By introducing SDN/NFV in BNG, the
   address pools can be allocated in a centralized way.  It will not
   only simplify the address management for operators, but also improve
   the utilization efficiency of the address pool.

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 http://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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 7, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   3
   4.  Initial Address Pool Configuration  . . . . . . . . . . . . .   5
   5.  Address Pool Status Report  . . . . . . . . . . . . . . . . .   7
   6.  Address Pool Status Query . . . . . . . . . . . . . . . . . .   8
   7.  Address Exhaustion  . . . . . . . . . . . . . . . . . . . . .   8
   8.  Address Pool Release  . . . . . . . . . . . . . . . . . . . .   8
   9.  Compatibility of different forms of devices . . . . . . . . .  10
   10. Control Protocol consideration  . . . . . . . . . . . . . . .  10
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  11
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     13.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   The Broadband Network Gateway(BNG), which manages a routable IP
   address on behalf of each subscriber, should be configured with the
   IP address pools allocated to subscribers.  However, currently
   operators are facing with the address shortage problem, the remaining
   IPv4 address pools are usually quite scattered, no more than /24 per
   address pool in many cases.  Therefore, it is complicated to manually
   configure the address pools on lots of Broadband Network Gateway(BNG)
   for operators.  For large scale MAN, the number of BNGs can be up to
   over one hundred.  Manual configuration on all the BNGs statically
   will not only greatly increase the workload, but also decrease the
   utilization efficiency of the address pools when the number of
   subscribers changes in the future.

   Another use case which needs to configure the address pools is IPv6
   migration.  For IPv6 transition mechanisms, e.g.  DS-Lite, lw4over6,
   etc., they all need to be configured with address pools as translated
   routeable addresses.  When high availability features, e.g. active-
   active/active-standby failover mechanism, etc., are enabled for these
   IPv6 transition mechanisms, different address pools need to be



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   configured on each transition instance.  This will further increase
   the number of address pools need to be configured.  Besides, the
   occupation of the address pools may vary during different transition
   periods, (e.g. at the early stage of IPv6 transition, IPv4 traffic
   will normally occupy a great portion of the total traffic, while in
   the later stage of IPv6 transition, IPv4 traffic will decrease and
   the amount of IPv4 address pools will decrease accordingly.

   There are other devices which may need to configure address pools as
   well.  For example, the Firewall need to configure the address pool
   for acl/NAT process.  The VPN also needs to configure the address
   pools for end-users.

   When SDN/NFV is introduced in the network, these devices (e.g.  BNG,
   CGN, firewall, VPN, etc.) will run as VNFs in virtualized
   environment.  A common centralized address management server can
   interact with different VNFs and allocate address pools
   automatically.

   In this document, we propose a mechanism to manage the address pools
   centrally.  In this way, operators do not need to configure the
   address pools one by one manually and it also helps to use the
   address pools more efficiently.

2.  Terminology

   The following terms are used in this document:

      APMS A management system which has a centralized databse manage
      the overall address pools and allocate address pools to the device
      in the devices.

      DA A device agent in device, which contact with APM server to
      manipulate address pool.

3.  Architectural Overview

   In this architecture, the Address Pool Management (APM) server is a
   centralized address pool management server for operators to configure
   the overall address pools.  It maintains the address pool database
   including the overall address pools (OAP) and the address pool
   status(APS).  Operators can configure its remaining address pools in
   the OAP.  They can also reserve some address pool for special-purpose
   usage.  The address pools status is to reflects the current usage of
   the address pools for different devices.  APM also has the interface
   to configure the address pools to different devices dynamically.





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   In each device, there is an device agent (DA) to contact with APM
   server.  It initiates the address pools allocation requests, passes
   the address pools to local instances, report the status of local
   address pool usage and update the address pools requests, etc.  For
   some devices, e.g. v6transition, VPN, etc., additional routing
   modules needs to update the routing table accordingly.


                           +*********************+
                           |     APM server      |
                           |   +------------+    |
                           |   | Address DB |    |
                           |   +------------+    |
                           +***^*****^******^*^**+
                               |     |      |
                               |     |      |
                  +------------+     |      +------------+
                  |                  |                   |
                  |                  |                   |
           +------v------+    +------v------+     +------v------+
           | +--------+  |    | +--------+  |     | +--------+  |
           | | agent  |  |    | | agent  |  |     | | agent  |  |
           | +----+---+  |    | +----+---+  |     | +----+---+  |
           |      |      |    |      |      |     |      |      |
           |      v      |    |      v      |     |      v      |
           | +--------+  |    | +---------+ |     | +---------+ |
           | | Local  |  |    | | v6tra   | |     | | VPN     | |
           | | Conf   |  |    | | instance| |     | |instance | |
           | +--------+  |    | +----+----+ |     | +---------+ |
           +-------------+    |      |      |     |      |      |
           |      v      |    |      v      |     |      v      |
           | +---------+ |    | +---------+ |     | +---------+ |
           | | routing | |    | | routing | |     | | routing | |
           | +---------+ |    | +---------+ |     | +---------+ |
           +-------------+    +-------------+     +-------------+
              BNG/vBNG            v6tra/fw             VPN

           Figure 1: Interface to Address Pool Management (APM)

   The overall procedure is as follows:

   o  Operators will configure remaining address pools centrally in the
      Address Pool Management System (APMS).  There are multiple address
      pools which can be configured centrally.  The APMS server will
      then divide the address pools into addressing unit (AU) which will
      be allocated to the agent in devices by default.





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   o  The agent will initiate Address Pool request to the APMS.  It can
      carry its desired size of address pool the request, or just use a
      default value.  The address pool size in the request is only used
      as a hint.  The actual size of the address pool is totally
      determined by APMS.  It will also carry the DA's identification
      and the type of address pool.

   o  APMS looks up the remaining address pool in its local database.
      It will then allocate a set of address pools to the DA.  Each
      address pool has a related lifetime.

   o  DA receives the AddressPool reply and use them for their purpose.

   o  If the lifetime of the address pool is going to expire, the DA
      should issue an AddressPoolRenew request to extend the
      lifetime,including the IPv4, IPv6, Ports, etc.

   o  The AddressPoolReport module keeps monitoring and reports the
      current usage of all current address pools for each transition
      mechanism. if it is running out of address pools, it can renew the
      AddressPoolRequest for a newly allocated one.  It can also release
      and recycle an existing address pool if the that address pool has
      not been used for a specific and configurable time.

   o  When the connection of APMS is lost or the APMS needs the status
      information of certain applications, the APMS may pre-actively
      query the DA for the status information.

4.  Initial Address Pool Configuration






















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        +--------------+                           +-----------------+
        |   Device     |                           |AddrPoolMangement|
        |   Agent      |                           |   Server        |
        +------+-------+                           +--------+--------+
               |                                            |
      +--------+-------+                                    |
      |1.DA start-up   |                                    |
      +---------+------+                                    |
                |            2.Address Pool Request         |
                |------------------------------------------>|
                |                                           |
                |                                  +--------+-------+
                |                                  |  3. Check      |
                |                                  |   address pool |
                |                                  +--------+-------+
                |          4.Address Pool Reply             |
                |<------------------------------------------|
                |                                           |
                |                                           |

               Figure 2: Initial Address Pool Configuration

   Figure 2 illustrates the initial address pool configuration
   procedure:

   1.  The DA checks whether there is already address pool configured in
       the local site when it starts up. if no, it means the initial
       start-up or the address pool has been released. if yes, the
       address pool could be used directly.

   2.  The DA will initiate Address Pool request to the APMS.  It can
       carry its desired size of address pool in the request, or just
       use a default value.  The address pool size in the DA's request
       is only used as a hint.  The actual size of the address pool is
       totally determined by APMS.  It will also carry the DA's
       identification, the type of transition mechanism and the
       indication of port allocation support.

   3.  The APMS determines the address pool allocated for the DA based
       on the parameters received.

   4.  The APMS sends the Address Pool Reply to the DA.  It will also
       distribute the routing entry of the address pool automatically.
       In particular, if the newly received address pool can be
       aggregated to an existing one, the routing should be aggregated
       accordingly.





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5.  Address Pool Status Report


        +--------------+                             +-----------------+
        |   Device     |                             |AddrPoolMangement|
        |   Agent      |                             |   Server        |
        +------+-------+                             +--------+--------+
               |                                              |
      +--------+-------+                                      |
      |1.Monitor and   |                                      |
      |count the status|                                      |
      +--------+-------+                                      |
               |        2.Address Pool Status Report          |
               |--------------------------------------------->|
               |                                     +--------+-------+
               |                                     |  3. Record     |
               |                                     |   address pool |
               |                                     +--------+-------+
               |       4.Address Pool Report Confirm          |
               |<---------------------------------------------|
               |                                              |
               |                                              |


                   Figure 3: Address Pool Status Report

   Figure 3 illustrates the active address pool status report procedure:

   1.  The DA will monitor and count the usage status of the local
       address pool.  The DA counts the address usage status in one
       month, one week and one day, which includes the local address,
       address usage ratio (peak and average values), and the port usage
       ratio (peak and average values).

   2.  The DA reports the address pool usage status to the APMS. for
       example, it will report the address usage status in one day,
       which contains the IP address, NAT44, address list:
       30.14.44.0/28, peak address value 14, average address usage ratio
       90%, TCP port usage ratio 20%, UDP port usage ratio 30% and etc.

   3.  The APMS records the status and compares with the existing
       address information to determine whether additional address pool
       is needed.

   4.  The APMS will confirm the address pool status report request to
       the DA.  It will keep sending the address pool status report
       request to the APMS if no confirm message is received.




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6.  Address Pool Status Query

   When the status of APMS is lost or the AMS needs the status
   information of the DAs, the APMS may actively query the TD for the
   status information, as shown in step 1 of Figure 4.  The following
   steps 2,3,4,5 are the same as the Address Pool Status Report
   procedure.


        +--------------+                             +-----------------+
        |   Device     |                             |AddrPoolMangement|
        |   Agent      |                             |   Server        |
        +------+-------+                             +--------+--------+
               |                                              |
               |                                              |
               |         1.Address Pool Status Query          |
               |<---------------------------------------------|
               |                                              |
      +--------+-------+                                      |
      |2.Monitor and   |                                      |
      |count the status|                                      |
      +--------+-------+                                      |
               |        3.Address Pool Status Report          |
               |--------------------------------------------->|
               |                                     +--------+-------+
               |                                     |  4. Record     |
               |                                     |   address pool |
               |                                     +--------+-------+
               |       5.Address Pool Report Confirm          |
               |<---------------------------------------------|
               |                                              |
               |                                              |


                    Figure 4: Address Pool Status Query

7.  Address Exhaustion

   When the DA uses up the addresses allocated, it will renew the
   address pool request to the APMS for an additional address pool.  The
   procedure is the same as the initial address pool request.

8.  Address Pool Release








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        +--------------+                             +-----------------+
        |   Device     |                             |AddrPoolMangement|
        |   Agent      |                             |   Server        |
        +------+-------+                             +--------+--------+
               |                                              |
      +--------+-------+                                      |
      |1.Address pools |                                      |
      |  not used for a|                                      |
      |   long time    |                                      |
      +--------+-------+                                      |
               |        2.Address Pool Release Request        |
               |--------------------------------------------->|
               |                                     +--------+-------+
               |                                     |3. Update       |
               |                                     |   address pool |
               |                                     |   database     |
               |                                     +--------+-------+
               |       4.Address Pool Release Notification    |
               |<---------------------------------------------|
      +--------+-------+                                      |
      |5. Reduce       |                                      |
      |  address pool  |                                      |
      +--------+-------+                                      |
               |         6.Address Pool Release Confirm       |
               |--------------------------------------------->|
               |                                              |
               |                                              |


                      Figure 5: Address Pool Release

   Figure 5 illustrates the address pool release procedure:

   1.  The counting module in the DA checks that there are addresses not
       used for a long time;

   2.  The DA sends the address pool release request to the APMS to ask
       the release of those addresses;

   3.  The APMS updates the local address pool information to add the
       new addressed released.

   4.  The APMS notifies the TD that the addresses have been release
       successfully;

   5.  The DA will update the local address pool. if no Address Pool
       Release Notification is received, the DA will repeat step 2;




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   6.  The DA confirms with the APMS that the addres pool has been
       released successfully.

9.  Compatibility of different forms of devices

   As described in section 3, each device has its address pools, the
   Address Pool Management (APM) server act as a centralized address
   pool management server for operators to configure the overall address
   pools of each devices.  In this form of device, the user plane and
   the control plane are integrated in the box.  There are another form
   of device, the control plane is separated from the box and one or
   more devices share centralized control plane.  In this device form,
   the control plane will manage multiple user plane devices.  A number
   of devices that are subordinate to a control plane will jointly share
   the address pools.  The control plane device, together with the
   dependent multiple user plane devices, forms a "big" device.  This
   bigger device contacts with the APM server to manipulate IP address
   pool.  For example, the device acts as a server side when running the
   NETCONF protocol between the device and the APM.  It determines
   whether the usage status of the IP address pool resource in device is
   satisfies the condition.  For example, the address pool resource of
   device is not enough or excessive.  It sends address pools resource
   request to the APM server, and receives response with address pools
   resource for this device allocated from APM server.  Then it passes
   the address pools resource to local instances.  In addition, it
   report the status of local address pool resource usage and update the
   address pools requests, etc.

10.  Control Protocol consideration

   The I2APM architecture consists of two major distinct entities: APM
   Server and network equipment with an APM Agent.  In order to provide
   address pool manipulations between these two entities, the I2APM
   architecture calls for well-defined protocols for interfacing between
   them.  For compatibility with legacy network equipment, the
   architecture reuse legacy protocol such as radius.  While the IETF
   may also choose to define one or more specific approaches to
   manipulate address pool, such as NETCONF or RESTCONF with address
   pool YANG data model.In modern network management system, the NETCONF
   or RESTCONF is used widely, the device implements as the NETCONF or
   RESTCONF server, and the network management system implements as the
   NETCONF or RESTCONF client, that achieving more automated network
   management.








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11.  Security Considerations

12.  Acknowledgements

   N/A.

13.  References

13.1.  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,
              <http://www.rfc-editor.org/info/rfc2119>.

13.2.  Informative References

   [RFC6674]  Brockners, F., Gundavelli, S., Speicher, S., and D. Ward,
              "Gateway-Initiated Dual-Stack Lite Deployment", RFC 6674,
              DOI 10.17487/RFC6674, July 2012,
              <http://www.rfc-editor.org/info/rfc6674>.

   [RFC6888]  Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa,
              A., and H. Ashida, "Common Requirements for Carrier-Grade
              NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888,
              April 2013, <http://www.rfc-editor.org/info/rfc6888>.

Authors' Addresses

   Chen Li
   China Telecom
   No.118 Xizhimennei street, Xicheng District
   Beijing  100035
   P.R. China

   Email: lichen.bri@chinatelecom.cn


   Chongfeng Xie
   China Telecom
   No.118 Xizhimennei street, Xicheng District
   Beijing  100035
   P.R. China

   Email: xiechf.bri@chinatelecom.cn






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   Jun Bi
   Tsinghua University
   3-212, FIT Building, Tsinghua University, Haidian District
   Beijing  100084
   P.R. China

   Email: junbi@tsinghua.edu.cn


   Weiping Xu
   Huawei Technologies
   Bantian, Longgang District
   shenzhen  518129
   P.R. China

   Email: xuweiping@huawei.com



































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