Network Working Group C. Li Internet-Draft C. Xie Intended status: Informational China Telecom Expires: November 5, 2017 R. Kumar R. Lohiya Juniper Networks J. Bi Tsinghua University W. Xu Huawei Technologies May 4, 2017 Coordinated Address Space Management architecture draft-li-casm-address-pool-management-architecture-00 Abstract This document describes an architecture for the IP address space management. It includes architectural concepts and components used in the CASM (Coordinated Address Space Management), with a focus on those interfaces to be standardized in the IETF. 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 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 November 5, 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 (http://trustee.ietf.org/license-info) in effect on the date of Li, et al. Expires November 5, 2017 [Page 1] Internet-Draft Address Pool Management May 2017 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. CASM Reference architecture . . . . . . . . . . . . . . . . . 3 4. CASM Functional and Logical Blocks . . . . . . . . . . . . . 5 4.1. CASM Application . . . . . . . . . . . . . . . . . . . . 5 4.2. CASM Coordinator . . . . . . . . . . . . . . . . . . . . 5 4.3. CASM Device . . . . . . . . . . . . . . . . . . . . . . . 6 5. CASM Interface and operation . . . . . . . . . . . . . . . . 7 5.1. CASM App-facing Interface . . . . . . . . . . . . . . . . 7 5.1.1. Functional requirements . . . . . . . . . . . . . . . 7 5.1.2. General operational . . . . . . . . . . . . . . . . . 8 5.1.3. Interface modeling requirements . . . . . . . . . . . 8 5.2. CASM device-facing Interface . . . . . . . . . . . . . . 8 5.2.1. Functional requirements . . . . . . . . . . . . . . . 8 5.2.2. Interface modeling requirements . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.1. Normative References . . . . . . . . . . . . . . . . . . 15 8.2. Informative References . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction The address space management is an integral part of any network management solution. The network architectures are rapidly changing with the migration toward private and public clouds. At the same time, application architectures are also evolving with a shift toward micro-services and multi-tiered approach. There is a pressing need to define a new address management system which can meet these diverse set of requirements. Such a system must be built with well-defined interfaces so users can easily migrate from one vendor to another without rewriting their network management systems. This document defines a reference architecture that should become the basis to develop a new address management system. We are calling Li, et al. Expires November 5, 2017 [Page 2] Internet-Draft Address Pool Management May 2017 this new system as Centralized Address Space Management (CSAM) system. A series of use cases are defined in "Use Case Draft". For example, 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. Above is one example of use case, there are other devices which may need to configure address pools as well. 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: CASM: Coordinated Address Space Management IPAM: IP Address Management DA: A device agent in device, which contact with CASM Coordinator to manipulate address pool CASM Coordinator: A management system which has a centralized database manage the overall address pools and allocate address pools to the device in the devices. 3. CASM Reference architecture The figure below shows the reference model for CASM. This figure covers the various possible scenarios that can exist in a CASM system. Li, et al. Expires November 5, 2017 [Page 3] Internet-Draft Address Pool Management May 2017 +-------------+ +-------------+ +-------------+ | CASM | | CASM | | CASM | |application 1| |application j| |application n| +------/------+ +------/------+ +------/------+ | | | | | | | | | | | | | | | +-------\---------------------\---------------------\-------+ | Coordinated Address Space Management System (CASM) | | Coordinator | | +-------------+ +-------------+ +-------------+ | | | Pool | | Address | | Address | | | | Management | | Management | | Database | | | +-------------+ +-------------+ +-------------+ | | | +---.-------------------------.--------------------------.--+ | | | | | | | | | | | | | | | +----------\--------+ +---------\---------+ +--------\----------+ | | | | | | | +-------------+ | | +-------------+ | | +-------------+ | | | Agent | | | | Agent | | | | Agent | | | +-------------+ | | +-------------+ | | +-------------+ | | | | | | | | +-------------+ | | +-------------+ | | +-------------+ | | | CASM | | | | CASM | | | | CASM | | | | Distributor | | | | Distributor | | | | Distributor | | | +-------------+ | | +-------------+ | | +-------------+ | | Device 1 | | Device 2 | | Device m | +-------------------+ +-------------------+ +-------------------+ Figure 1: CASM reference architecture 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. Li, et al. Expires November 5, 2017 [Page 4] Internet-Draft Address Pool Management May 2017 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. CASM Functional and Logical Blocks 4.1. CASM Application CASM Application is a functional entity which usually used to manage, operate, maintain the CASM Coordinator. For example, operator or external user can manage the address pool in CASM Coordinator, and access log, address allocation records, etc. 4.2. CASM Coordinator Coordinated Address Space Management System (CASM) Coordinator is a centralized address management coordinator for CASM application to maintain the overall address pools, addresses, address properties, etc. It maintains an address database including the overall address pools (OAP) and the address pool status (APS). CASM Applications can maintain its remaining address pools in the OAP. They can also reserve some address pool for special-purpose usage. The address Li, et al. Expires November 5, 2017 [Page 5] Internet-Draft Address Pool Management May 2017 pools status is to reflect the current usage of the address pools for different devices. CASM Coordinator also has the interface to maintain the address pools to different devices dynamically. 4.3. CASM Device A CASM Device is responsible for distribute or allocate address from local address pools received from CASM Coordinator. Device agent (DA) is a component in a CASM device through which contact with CASM Coordinator. 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. CASM Distributor is another component in a CASM device, DHCP Server is a typical distributor which can assign IP addresses to client computer, DHCP protocol is usually used for this assignment. The address assignment procedure between the CASM Distributor and computer is out of scope of this draft. The device determines whether the usage status of the IP address pool in device is satisfies the condition. The address pool is a sharable resource, when the resource in device is insufficient or excessive, the device sends address pools request to the CASM Coordinator, and receives response with address pools allocated for this device from CASM COORDINATOR server. Then it can use this address pools for assignment. In addition, it reports usage status of local address pool and update the address pools requests, etc. The typical CASM devices such as BNG, BRAS, CGN, DHCP Server, NAT, V6Transition, DNS Server, etc., are described in use cases of "draft- xie-ps-centralized-address-management-02" and "draft-kumar-casm- problem-and-use-cases-00". The form of device is diverse, it can be physical or virtualized, and it can be a box integrated with control plane and user plane, or separated control plane remote from 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 to make the utilization more high. Li, et al. Expires November 5, 2017 [Page 6] Internet-Draft Address Pool Management May 2017 5. CASM Interface and operation 5.1. CASM App-facing Interface 5.1.1. Functional requirements The CASM should support following functionality for it to be adopted for wide variety of use cases. 5.1.1.1. Address pools A CASM system should allow ability to manage different kind of address pools. The following pools should be considered for implementation; this is not mandatory or exhaustive by any means but given here as most commonly used in networks. The CASM system should allow user-defined pools with any address objects. Unicast address pool: o Private IPv4 addresses o Public IPv4 addresses o IPv6 addresses o MAC Addresses Multicast address pool: o IPv4 address o IPv6 address 5.1.1.2. Pool management There should be a rich set of functionality as defined in this section for operation of a given pool. Address management: o Address allocation either as single or block o Address reservation o Allocation logic such as mapping schemes or algorithm per pool o Li, et al. Expires November 5, 2017 [Page 7] Internet-Draft Address Pool Management May 2017 General management: o Pool initializing, resizing, threshold markings for resource monitoring o Pool attributes such as used to automatically create DNS record o Pool priority for searching across different pools o Pool fragmentation rules, such as how pool can be sub-divided o Pool lease rules for allocation requests 5.1.2. General operational The CASM architecture consists of three major distinct entities: CASM Application, CASM Coordinator and network device with a device Agent. In order to provide address space and pools resource that CASM Coordinator can centrally maintaining, there is an interface between CASM Applications and CASM Coordinator. The CASM Application can manage the address space and pool in the CASM Coordinator, and the get address allocation records, logs from CASM Coordinator. 5.1.3. Interface modeling requirements There are three broad categories for CASM interface definition: Pool management interface: Interface to external user or applications such as SDN controller to manage addresses Log interface: Interface to access log and records such as DHCP, DNS, NAT Integration interface: Interface to address services such as DHCP, DNS, NAT 5.2. CASM device-facing Interface 5.2.1. Functional requirements In order to build a complete address management system, it is important that CASM should be able to integrate with other address services. This will provide a complete solution to network operators without requiring any manual or proprietary workflows. DHCP server: o Interface to initialize address pools on DHCP server o Notification interface whenever an address lease is modified Li, et al. Expires November 5, 2017 [Page 8] Internet-Draft Address Pool Management May 2017 o Interface to access address lease records from DHCP server o Ability to store lease records and play back to DHCP server on reboot DNS server: o Interface to initialize NAT pools o Interface to access NAT records from NAT device o Ability to store NAT records and play back to NAT device on reboot 5.2.1.1. General operational The CASM architecture consists of three major distinct entities: CASM Application, CASM Coordinator and network device with a device Agent. In order to provide address pool manipulations between CASM Coordinator and device, the CASM architecture calls for well-defined protocols for interfacing between them. For example, legacy protocol such as radius to compatible with legacy network equipment. In modern network management system, device acts as NETCONF/RESTCONF server side. It sends address pool request to the CASM Coordinator which is protocol client, the centralized CASM Coordinator responses with allocated address pool, the device receives the response message and retrieve the allocated address pool information carried in the response message. The overall address management procedure is as follows: o Address Pool Management System (CASM) Coordinator configure remaining address pools centrally. There are multiple address pools which can be configured. The CASM Coordinator will then divide the address pools into addressing unit (AU) which will be allocated to the agent in devices by default. o The agent will initiate Address Pool request to the CASM Coordinator. The device judges whether the address resource used by the device meet certain conditions, the condition indicates the use status of the address resource with the device. Then it generate and issue an Address Pool request in which carried its desired size of address pool, 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 CASM Coordinator. It will also carry the DA's identification and the type of address pool. Li, et al. Expires November 5, 2017 [Page 9] Internet-Draft Address Pool Management May 2017 o CASM Coordinator 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 Address Pool reply and use them for their purpose. o If the lifetime of the address pool is going to expire, the DA should issue an Address Pool Renew request to extend the lifetime, including the IPv4, IPv6, Ports, etc. o The Address Pool Report 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 for a newly allocated one. It can also release and recycle an existing address pool if that address pool has not been used for a specific and configurable time. o When the connection of CASM Coordinator is lost or the CASM Coordinator needs the status information of certain applications, the CASM Coordinator may pre-actively query the DA for the status information. 5.2.2. Interface modeling requirements 5.2.2.1. Initial Address Pool Configuration +--------------+ +-----------------+ | Device | | CASM | | Agent | | Coordinator | +------+-------+ +--------+--------+ | | +--------+-------+ | |1.DA start-up | | +---------+------+ | | 2.Address Pool Request | |------------------------------------------>| | | | +--------+-------+ | | 3. Check | | | address pool | | +--------+-------+ | 4.Address Pool Reply | |<------------------------------------------| | | Figure 2: Initial Address Pool Configuration Li, et al. Expires November 5, 2017 [Page 10] Internet-Draft Address Pool Management May 2017 Figure 2 The procedure is as follows: 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 CASM Coordinator. 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 CASM Coordinator. It will also carry the DA's identification, the type of transition mechanism and the indication of port allocation support. 3. The CASM Coordinator determines the address pool allocated for the DA based on the parameters received. 4. The CASM Coordinator 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. 5.2.2.2. Address Pool Status Report Li, et al. Expires November 5, 2017 [Page 11] Internet-Draft Address Pool Management May 2017 +--------------+ +-----------------+ | Device | | CASM | | Agent | | Coordinator | +------+-------+ +--------+--------+ | | +--------+-------+ | |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 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 CASM Coordinator. 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 CASM Coordinator records the status and compares with the existing address information to determine whether additional address pool is needed. 4. The CASM Coordinator will confirm the address pool status report request to the DA. It will keep sending the address pool status report request to the CASM Coordinator if no confirm message is received. Li, et al. Expires November 5, 2017 [Page 12] Internet-Draft Address Pool Management May 2017 5.2.2.3. Address Pool Status Query When the status of CASM Coordinator is lost or the CASM Coordinator needs the status information of the DAs, the CASM Coordinator 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 | | CASM | | Agent | | Coordinator | +------+-------+ +--------+--------+ | | | | | 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 5.2.2.4. Address Exhaustion When the DA uses up the addresses allocated, it will renew the address pool request to the CASM Coordinator for an additional address pool. The procedure is the same as the initial address pool request. Li, et al. Expires November 5, 2017 [Page 13] Internet-Draft Address Pool Management May 2017 5.2.2.5. Address Pool Release +--------------+ +-----------------+ | Device | | CASM | | Agent | | Coordinator | +------+-------+ +--------+--------+ | | +--------+-------+ | |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 CASM Coordinator to ask the release of those addresses; 3. The CASM Coordinator updates the local address pool information to add the new addressed released; 4. The CASM Coordinator notifies the TD that the addresses have been release successfully; Li, et al. Expires November 5, 2017 [Page 14] Internet-Draft Address Pool Management May 2017 5. The DA will update the local address pool. If no Address Pool Release Notification is received, the DA will repeat step 2; 6. The DA confirms with the CASM Coordinator that the address pool has been released successfully. 6. Security Considerations 7. Acknowledgements N/A. 8. References 8.1. 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, . 8.2. Informative References [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, . Authors' Addresses Chen Li China Telecom No.118 Xizhimennei street, Xicheng District Beijing 100035 P.R. China Email: lichen@ctbri.com.cn Chongfeng Xie China Telecom No.118 Xizhimennei street, Xicheng District Beijing 100035 P.R. China Email: xiechf.bri@chinatelecom.cn Li, et al. Expires November 5, 2017 [Page 15] Internet-Draft Address Pool Management May 2017 Rakesh Kumar Juniper Networks 1133 Innovation Way Sunnyvale CA 94089 US Email: rkkumar@juniper.net Anil Lohiya Juniper Networks 1133 Innovation Way Sunnyvale CA 94089 US Email: alohiya@juniper.net 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 Li, et al. Expires November 5, 2017 [Page 16]