Internet Engineering Task Force (IETF) A. Retana
Request for Comments: 7137 S. Ratliff
Updates: 5820 Cisco Systems, Inc.
Category: Experimental February 2014
ISSN: 2070-1721
Internet Engineering Task Force (IETF) A. Retana
Request for Comments: 7137 S. Ratliff
Updates: 5820 Cisco Systems, Inc.
Category: Experimental February 2014
ISSN: 2070-1721
Use of the OSPF-MANET Interface in Single-Hop Broadcast Networks
OSPF-MANET接口在单跳广播网络中的应用
Abstract
摘要
This document describes the use of the OSPF-MANET interface in single-hop broadcast networks. It includes a mechanism to dynamically determine the presence of such a network and specific operational considerations due to its nature.
本文档描述了OSPF-MANET接口在单跳广播网络中的使用。它包括一种动态确定此类网络存在的机制，以及由于其性质而引起的特定操作考虑。
This document updates RFC 5820.
本文件更新了RFC 5820。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation.
本文件不是互联网标准跟踪规范；它是为检查、实验实施和评估而发布的。
This document defines an Experimental Protocol for the Internet community. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
本文档为互联网社区定义了一个实验协议。本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7137.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc7137.
Copyright Notice
版权公告
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2014 IETF信托基金和确定为文件作者的人员。版权所有。
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.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Single-Hop Broadcast Networks . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Single-Hop Network Operation . . . . . . . . . . . . . . . . 4
3.1. Use of Router Priority . . . . . . . . . . . . . . . . . 4
3.2. Unsynchronized Adjacencies . . . . . . . . . . . . . . . 5
4. Single-Hop Network Detection . . . . . . . . . . . . . . . . 6
4.1. Transition from Multi-Hop to Single-Hop Mode . . . . . . 6
4.2. Transition from Single-Hop to Multi-Hop Mode . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Single-Hop Broadcast Networks . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Single-Hop Network Operation . . . . . . . . . . . . . . . . 4
3.1. Use of Router Priority . . . . . . . . . . . . . . . . . 4
3.2. Unsynchronized Adjacencies . . . . . . . . . . . . . . . 5
4. Single-Hop Network Detection . . . . . . . . . . . . . . . . 6
4.1. Transition from Multi-Hop to Single-Hop Mode . . . . . . 6
4.2. Transition from Single-Hop to Multi-Hop Mode . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
The OSPF-MANET interface [RFC5820] uses the point-to-multipoint adjacency model over a broadcast media to allow the following:
OSPF-MANET接口[RFC5820]使用广播媒体上的点对多点邻接模型来允许以下情况：
o All router-to-router connections are treated as if they were point-to-point links.
o 所有路由器到路由器的连接都被视为点对点链接。
o The link metric can be set on a per-neighbor basis.
o 可以基于每个邻居设置链路度量。
o Broadcast and multicast can be accomplished through the Layer 2 broadcast capabilities of the media.
o 广播和多播可以通过媒体的第2层广播功能来实现。
It is clear that the characteristics of the MANET interface can also be beneficial in other types of network deployments -- specifically, in single-hop broadcast capable networks that may have a different cost associated with any pair of nodes.
显然，MANET接口的特性在其他类型的网络部署中也可能是有益的——具体地说，在具有单跳广播能力的网络中，与任何一对节点相关联的成本可能不同。
This document updates [RFC5820] by describing the use of the MANET interface in single-hop broadcast networks; this consists of its simplified operation by not requiring the use of overlapping relays as well as introducing a new heuristic for smart peering using the Router Priority.
本文件通过描述单跳广播网络中MANET接口的使用来更新[RFC5820]；这包括简化操作，不需要使用重叠的中继，以及引入一种使用路由器优先级的新启发式智能对等。
The OSPF extensions for MANETs assume the ad hoc formation of a network over bandwidth-constrained wireless links, where packets may traverse several intermediate nodes before reaching their destination (multi-hop paths on the interface). By contrast, a single-hop broadcast network (as considered in this document) is one that is structured in such a way that all the nodes in it are directly connected to each other. An Ethernet interface is a good example of the connectivity model.
移动自组网的OSPF扩展假定网络在带宽受限的无线链路上自组织形成，其中数据包在到达目的地（接口上的多跳路径）之前可穿过多个中间节点。相比之下，单跳广播网络（如本文所述）的结构方式是，其中的所有节点直接相互连接。以太网接口是连接模型的一个很好的例子。
Furthermore, the single-hop networks considered may have different link metrics associated to the connectivity between a specific pair of neighbors. The OSPF broadcast model [RFC2328] can't accurately describe these differences. A point-to-multipoint description is more appropriate given that each node can reach every other node directly.
此外，所考虑的单跳网络可以具有与特定一对邻居之间的连接相关联的不同链路度量。OSPF广播模型[RFC2328]无法准确描述这些差异。如果每个节点都可以直接到达其他节点，则点对多点描述更合适。
In summary, the single-hop broadcast interfaces considered in this document have the following characteristics:
总之，本文件中考虑的单跳广播接口具有以下特点：
o direct connectivity between all the nodes
o 所有节点之间的直接连接
o different link metrics that may exist per-neighbor
o 每个邻居可能存在不同的链路度量
o broadcast/multicast capabilities
o 广播/多播功能
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].
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中所述进行解释。
The operation of the MANET interface doesn't change when implemented on a single-hop broadcast interface. However, the operation of some of the proposed enhancements can be simplified. Explicitly, the Overlapping Relay Discovery Process SHOULD NOT be executed, and the A-bit SHOULD NOT be set by any of the nodes, so that the result is an empty set of Active Overlapping Relays.
当在单跳广播接口上实现时，MANET接口的操作不会改变。但是，可以简化某些拟议增强的操作。明确地说，不应该执行重叠中继发现过程，并且任何节点都不应该设置A位，因此结果是一组空的活动重叠中继。
This document describes the use of already defined mechanisms and requires no additional on-the-wire changes.
本文档描述了已定义机制的使用，不需要额外的在线更改。
Smart peering [RFC5820] can be used to reduce the burden of requiring a full mesh of adjacencies. In short, a new adjacency is not required if reachability to the node is already available through the existing shortest path tree (SPT). In general, the reachability is verified on a first-come-first-served basis; i.e., in a typical network, the neighbors with which a FULL adjacency is set up depend on the order of discovery.
智能对等[RFC5820]可用于减少需要完整邻接网格的负担。简而言之，如果通过现有的最短路径树（SPT）已经可以到达节点，则不需要新的邻接。一般来说，可达性是在先到先得的基础上进行验证的；i、 例如，在典型网络中，与之建立完全邻接的邻居取决于发现顺序。
The state machine for smart peering allows for the definition of heuristics, beyond the SPT reachability, to decide whether or not it considers a new adjacency to be of value. This section describes one such heuristic to be used in Step (3) of the state machine, in place of the original one in Section 3.5.3.2 of [RFC5820].
智能对等的状态机允许在SPT可达性之外定义启发式，以决定它是否认为新的邻接有价值。本节描述了在状态机步骤（3）中使用的一种启发式方法，以代替[RFC5820]第3.5.3.2节中的原始启发式方法。
The Router Priority (as defined in OSPFv2 [RFC2328] and OSPFv3 [RFC5340]) is used in the election of the (Backup) Designated Router, and can be configured only in broadcast and Non-Broadcast Multi-Access (NBMA) interfaces. The MANET interface is a broadcast interface using the point-to-multipoint adjacency model; this means that no (Backup) Designated Router is elected. For its use with the MANET interface, the Router Priority is defined as:
路由器优先级（定义见OSPFv2[RFC2328]和OSPFv3[RFC5340]）用于选择（备份）指定的路由器，并且只能在广播和非广播多址（NBMA）接口中配置。MANET接口是使用点对多点邻接模型的广播接口；这意味着没有选择（备份）指定的路由器。为了与MANET接口一起使用，路由器优先级定义为：
Router Priority An 8-bit unsigned integer. Used to determine the precedence of which router(s) to establish a FULL adjacency with during the Smart Peering selection process. When more than one router attached to a network is present, the one with the highest Router Priority takes precedence. If there is still a tie, the router with the highest Router ID takes precedence.
路由器优先级为8位无符号整数。用于确定在智能对等选择过程中与哪个路由器建立完全邻接的优先级。当存在连接到网络的多个路由器时，具有最高路由器优先级的路由器优先。如果仍然存在平局，则具有最高路由器ID的路由器优先。
The heuristic for the state machine for smart peering is described as:
智能对等的状态机启发式描述如下：
(3) |
,'''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
| ............................ |
| |Determine if the number of| |
| |existing adjacencies is < | |
| |the maximum configured | |
| |value | |
| '`'''''''\'''''''''''''''/'' |
| \ / |
| ................\.........../.............. |
| |Determine if the neighbor has the highest| |
| |(Router Priority, Router ID) combination | |
| ''''''''''''`'''/'''''''\'''''''''''''''''' |
| / \ |
'`'''''''''''''''''''''/'''''''''''\'''''''''''''''''''''''
(3) |
,'''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
| ............................ |
| |Determine if the number of| |
| |existing adjacencies is < | |
| |the maximum configured | |
| |value | |
| '`'''''''\'''''''''''''''/'' |
| \ / |
| ................\.........../.............. |
| |Determine if the neighbor has the highest| |
| |(Router Priority, Router ID) combination | |
| ''''''''''''`'''/'''''''\'''''''''''''''''' |
| / \ |
'`'''''''''''''''''''''/'''''''''''\'''''''''''''''''''''''
Smart Peering Algorithm
智能对等算法
In order to avoid churn in the selection and establishment of the adjacencies, every router SHOULD wait until the ModeChange timer (Section 4) expires before running the state machine for smart peering. Note that this wait should cause the selection process to consider all the nodes on the link, instead of being triggered based on receiving a Hello message from a potential neighbor. The nodes selected using this process are referred to simply as "smart peers".
为了避免在选择和建立邻接时出现混乱，每个路由器都应该等到ModeChange计时器（第4节）过期后，再运行状态机进行智能对等。请注意，此等待会导致选择过程考虑链路上的所有节点，而不是基于接收来自潜在邻居的hello消息而触发。使用此过程选择的节点简称为“智能节点”。
It is RECOMMENDED that the maximum number of adjacencies be set to 2.
建议将最大邻接数设置为2。
An unsynchronized adjacency [RFC5820] is one for which the database synchronization is postponed, but that is announced as FULL because SPT reachability can be proven. A single-hop broadcast network has a connectivity model in which all the nodes are directly connected to each other. This connectivity results in a simplified reachability check through the SPT: the adjacency to a specific peer MUST be advertised as FULL by at least one smart peer.
非同步邻接[RFC5820]是数据库同步被推迟的邻接，但由于可以证明SPT的可达性，因此被宣布为完全邻接。单跳广播网络具有一个连接模型，其中所有节点直接相互连接。这种连接性导致通过SPT进行简化的可达性检查：与特定对等点的邻接必须由至少一个智能对等点发布为已满。
The single-hop nature of the interface allows then the advertisement of the reachable adjacencies as FULL without additional signaling. Flooding SHOULD be enabled for all the unsynchronized adjacencies to take advantage of the broadcast nature of the media. As a result, all the nodes in the interface will be able to use all the LSAs received.
接口的单跳特性允许在没有额外信令的情况下，将可到达的邻接作为完整的播发。应为所有未同步的邻接启用泛洪，以利用媒体的广播特性。因此，接口中的所有节点都将能够使用接收到的所有LSA。
A single-hop network is one in which all the nodes are directly connected. Detection of such an interface can be easily done at every node by comparing the speaker's 1-hop neighbors with its 2-hop neighborhood. If for every 1-hop neighbor, the set of 2-hop neighbors contains the whole set of the remaining 1-hop neighbors, then the interface is a single-hop network; this condition is called the Single-Hop Condition.
单跳网络是所有节点直接连接的网络。通过比较说话人的1-hop邻居和2-hop邻居，可以很容易地在每个节点检测这样的接口。如果对于每个1-hop邻居，2-hop邻居集包含剩余1-hop邻居的整个集合，则接口是单跳网络；这种情况称为单跳情况。
A new field is introduced in the MANET interface data structure. The name of the field is SingleHop, and it is a flag indicating whether the interface is operating in single-hop mode (as described in Section 3). The SingleHop flag is set when the node meets the Single-Hop Condition on the interface. If the Single-Hop Condition is no longer met, then the SingleHop flag MUST be cleared.
在MANET接口数据结构中引入了一个新字段。该字段的名称为SingleHop，它是一个标志，指示接口是否在单跳模式下运行（如第3节所述）。当节点满足接口上的单跳条件时，设置单跳标志。如果不再满足单跳条件，则必须清除单跳标志。
A new timer is introduced to guide the transition of the interface from/to multi-hop mode (which is the default mode described in [RFC5820]) to/from single-hop mode:
引入了一个新的计时器，用于引导接口从/到多跳模式（这是[RFC5820]中描述的默认模式）转换到/从单跳模式：
o ModeChange: Every time a node changes the state of the SingleHop flag for the interface, the corresponding ModeChange timer MUST be set. The ModeChange timer represents the length of time in seconds that an interface SHOULD wait before changing between multi-hop and single-hop modes. It is RECOMMENDED that this timer be set to Wait Time [RFC2328].
o ModeChange：每次节点更改接口的SingleHop标志的状态时，必须设置相应的ModeChange计时器。ModeChange timer表示在多跳和单跳模式之间切换之前，接口应等待的时间长度（以秒为单位）。建议将此计时器设置为等待时间[RFC2328]。
The following sections describe the steps to be taken to transition between interface modes.
以下各节描述了在接口模式之间转换要采取的步骤。
Detection of the Single-Hop Condition triggers the transition into single-hop mode by setting both the SingleHop flag and the ModeChange timer.
通过设置SingleHop标志和ModeChange定时器，检测到单跳条件会触发转换到单跳模式。
Once the ModeChange timer expires, the heuristic defined in Section 3.1 MAY be executed to optimize the set of adjacencies on the interface. Note that an adjacency MUST NOT transition from FULL to 2-Way unless the simplified reachability check (Section 3.2) can be verified.
一旦ModeChange计时器过期，可执行第3.1节中定义的启发式，以优化接口上的邻接集。请注意，除非可以验证简化可达性检查（第3.2节），否则邻接不得从完全过渡到双向。
Not meeting the Single-Hop Condition triggers the transition into multi-hop mode by clearing the SingleHop flag and setting the ModeChange timer. The A-bit MUST be set if the Single-Hop condition is no longer met because of one of the following cases:
不满足单跳条件会通过清除单跳标志并设置ModeChange定时器触发到多跳模式的转换。如果由于以下情况之一而不再满足单跳条件，则必须设置A位：
o an increase in the set of 1-hop neighbors, without the corresponding increase of the 2-hop neighborhood
o 增加1跳邻居集，而不相应增加2跳邻居
o a decrease of the 2-hop neighborhood while maintaining all the previous 1-hop neighbors
o 减少2-hop邻居，同时保持以前的所有1-hop邻居
Once the ModeChange timer expires, the multi-hop operation described in [RFC5820] takes over.
一旦ModeChange定时器到期，[RFC5820]中描述的多跳操作将接管。
Note that the cases listed above may result in the interface either gaining or losing a node before the ModeChange timer expires. In both cases, the heuristic defined in Section 3.1 MAY be executed to optimize the set of adjacencies on the interface.
请注意，上面列出的情况可能会导致接口在ModeChange计时器过期之前获得或丢失节点。在这两种情况下，可执行第3.1节中定义的启发式，以优化接口上的邻接集。
In the case that a node joins the interface, the Designated Router and Backup Designated Router fields in the Hello packet [RFC2328] MAY be used to inform the new node of the identity (Router ID) of the current smart peers (and avoid the optimization).
在节点加入接口的情况下，Hello分组[RFC2328]中的指定路由器和备份指定路由器字段可用于通知新节点当前智能对等方的身份（路由器ID）（并避免优化）。
No new security concerns beyond the ones expressed in [RFC5820] are introduced in this document.
除[RFC5820]中所述的安全问题外，本文件中未引入任何新的安全问题。
The authors would like to thank Anton Smirnov, Jeffrey Zhang, Alia Atlas, Juan Antonio Cordero, Richard Ogier, and Christer Holmberg for their comments.
作者要感谢安东·斯米尔诺夫、杰弗里·张、艾莉亚·阿特拉斯、胡安·安东尼奥·科德罗、理查德·奥吉尔和克里斯特·霍姆伯格的评论。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2328]Moy，J.，“OSPF版本2”，STD 54，RFC 2328，1998年4月。
[RFC5820] Roy, A. and M. Chandra, "Extensions to OSPF to Support Mobile Ad Hoc Networking", RFC 5820, March 2010.
[RFC5820]Roy，A.和M.Chandra，“支持移动自组网的OSPF扩展”，RFC 5820，2010年3月。
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, July 2008.
[RFC5340]Coltun，R.，Ferguson，D.，Moy，J.，和A.Lindem，“IPv6的OSPF”，RFC 53402008年7月。
Authors' Addresses
作者地址
Alvaro Retana Cisco Systems, Inc. 7025 Kit Creek Rd. Research Triangle Park, NC 27709 USA
阿尔瓦罗·雷塔纳思科系统公司，地址：美国北卡罗来纳州三角研究园基特克里克路7025号，邮编：27709
EMail: aretana@cisco.com
EMail: aretana@cisco.com
Stan Ratliff Cisco Systems, Inc. 7025 Kit Creek Rd. Research Triangle Park, NC 27709 USA
Stan Ratliff Cisco Systems，Inc.美国北卡罗来纳州三角研究园Kit Creek路7025号，邮编27709
EMail: sratliff@cisco.com
EMail: sratliff@cisco.com