Considerations on IPv6 Address Assignment
Author(s): Qiongfang Ma, Tianle Yang
This document discusses general principles and rules of IPv6 address assignment and gives an example to illustrate....
Internet Engineering Task Force Q. Ma Internet-Draft T. Yang Intended status: Informational China Mobile Expires: July 5, 2013 Jan 2013 Considerations on IPv6 Address Assignment draft-ma-v6ops-ipv6-address-assignment-00 Abstract This document discusses general principles and rules of IPv6 address assignment and gives an example to illustrate. Status of this Memo This Internet-Draft is submitted to IETF 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 July 5, 2013. Copyright Notice Copyright (c) 2013 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 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. Ma & Yang Expires July 5, 2013 [Page 1] Internet-Draft IPv6 address assignment Jan 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. The General principles of IPv6 address assignment . . . . . . . 3 3. Prefix length assignment to end site . . . . . . . . . . . . . 3 4. IPv6 address pool assignment for network device . . . . . . . . 4 5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 9. Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Ma & Yang Expires July 5, 2013 [Page 2] Internet-Draft IPv6 address assignment Jan 2013 1. Introduction IPv6 address space available to each network operator is very large compared with IPv4. Unreasonable IPv6 address assignment will result in the rapid expansion of routing table. In order to improve the utilization of IPv6 address and avoid wasting, The principle and rules of IPv6 address assignment need to be researched. There are three types of IPv6 addresses: unicast, multicast and anycast address, what operators can assign is the 001 Global Unicast Address. The document discusses the general principles and rules of IPv6 address assignment, gives some specific recommendations and sets an example to illustrate the principles and rules. 2. The General principles of IPv6 address assignment (1)The requirement of route aggregation - End sites should be assigned fixed prefix length, for example /48, /56, /64, etc, for route aggregation and easy to manage - It is recommended to contain the location information in the IPv6 address, and address space assigned to each area should be contiguous as far as possible to improve route aggregation and reduce router pressure (2)Address continuity requirements - Take into account the subscriber growth and service development, to assign enough address space for each type of Business (3)The needs of management - Address assignment and management should be simple and convenient - Allocation granularity to meet management requirements such as QoS, ACL (4)Meet the needs of business and subscribers development - Under the premise of not dramatically affect the route aggregation, meet some special address demands of subscriber 3. Prefix length assignment to end site Reference to the existing Specifications, we recommend some rules: Ma & Yang Expires July 5, 2013 [Page 3] Internet-Draft IPv6 address assignment Jan 2013 (1) A single PC or mobile phone , with no additional need to subnet, should receive a /64 prefix[RFC3177] (2) In the wireless network, user equipment can access through MiFi device. As an access point, MiFi need to request an address space and assign a /64 prefix for hosts through DHCP prefix delegation. MiFi or mobile phone used as MiFi should receive a /60 prefix for downstream interface, can address 2^4 hosts (3) In the broadband network, CPE (Customer Premise Equipment) or home gateway request an address space and assign a /64 prefix for hosts through DHCP prefix delegation. Generally speaking, the number of users and business address demand in the h ome broadband is larger than in the wireless network, so the CPE should receive a /56 prefix [RFC6177 and BBF TR-177] for downstream interface, can address 2^8 hosts (4) For enterprise, the CE router should receive one or more /48 prefix [RFC3177], according to the number of hosts in the subnet (5) When it is absolutely known that one and only one device is connecting, the device, mainly refers to the network equipment, should receive a /128 prefix as loopback interfaces (6) The two interfaces of a link should configurate a /127 prefix[RFC6164, RFC6547]. This rule refer to not only routers, switches and management equipment in the core network, but also servers in the IDC, DNS system and service platform. 4. IPv6 address pool assignment for network device For easy to route aggreation, The IPv6 address pool in the access control device should be configurated according to the equipment performance and user capacity. The size of the pool can be calculated with the user cpicaty multiplied by the address space assigned to one user. Take the address pool in GGSN for example, assume that user capcity configurated in a GGSN is One million, each UE need a / 64 address. The size of the address pool is: 1,000,000*1=1,000,000, nearly 2^20, so the address pool in GGSN should be configured to /44. The calculation of address pool in BRAS is slightly more complicated. In the broadband network, assume that user capcity configurated in a BRAS is 30 thousand, Each CPE need a / 64 LAN interface address and a / 56 WAN interface address， equivalent to 257 /64 address. By calculating, the size of the address pool is: 30,000*257=7,710,000, Ma & Yang Expires July 5, 2013 [Page 4] Internet-Draft IPv6 address assignment Jan 2013 nearly 2^23, so the address pool in BRAS should be configured to /41. 5. Example we set an example to illustrate the principle and rules of address assignment described above.IPv6 address assignment cannot be generalized. It should be taken on case to case basis and meet the requirement of route aggregation. | 64 bits | 64 bits | +-------------------------------+---------------------------------+ | P0 | P1 | P2 | P3 | P4 | P5 | interface ID | +-------------------------------+---------------------------------+ Figure 1: address assignment The field of address is divided as shown above. where, - P0: Global routing prefix obtained from a local Internet registry. - P1: Type flag, used to distinguish between the network address and user address. The network address refers to the equipment Loopback address and the interface address. The user address refers to the dynamic or static address assigned to the hosts, including IP address pool in the service control equipment, such as BRAS, AC, GGSN and PGW etc. - P2: Network flag, used to distinguish between different networks, if there are several networks available. Different networks occupy different address space, the address space in same network should be continuous as far as possible. - P3 and P4: Province flag and City flag, the location information in the IPv6 address. Address assignment of the same region should be continuous as far as possible. - P5: The field is assigned in the city internally In this example, the IPv6 address field is divided in detail, which increase the complexity of the address assignment, but is beneficial to route aggregation and address management. The length of each Ma & Yang Expires July 5, 2013 [Page 5] Internet-Draft IPv6 address assignment Jan 2013 field is assigned according to the development of service and users. Each field can be partially reserved according to the expansion demands. 6. Conclusion The document discussed the general principles and rules of IPv6 address assignment, give some specific recommendations and set an example to illustrate the principles and rules. In fact, IPv6 address assignment cannot be generalized. It should be taken on case to case basis and meet the requirement of route aggregation. 7. Security Considerations It needs to be further identified. 8. IANA Considerations TBD 9. Reference [RFC3177] IAB and IESG, "IAB/IESG Recommendations on IPv6 Address Allocations to Sites", RFC3177, September 2001. [RFC6177] T. Narten, G. Huston and L. Roberts, "IPv6 Address Assignment to End Sites", RFC6177, March 2011 [RFC6164] M. Kohno,B. Nitzan,R. Bush, etc., "Using 127-Bit IPv6 Prefixes on Inter-Router Links", RFC6164,April 2011 [RFC6547] W. George, "RFC 3627 to Historic Status", RFC6547, December 2011 [BBF TR-177] "IPv6 in the context of TR-101", BBF TR-177, November 2010 Ma & Yang Expires July 5, 2013 [Page 6] Internet-Draft IPv6 address assignment Jan 2013 Authors' Addresses Ma Qiongfang China Mobile 32, Xuanwumenxi Ave. Xicheng District, Beijing 01719 China Email: firstname.lastname@example.org Yang Tianle China Mobile 32, Xuanwumenxi Ave. Xicheng District, Beijing 01719 China Email: email@example.com Ma & Yang Expires July 5, 2013 [Page 7]