RFC1587 日本語訳
1587 The OSPF NSSA Option. R. Coltun, V. Fuller. March 1994. (Format: TXT=37412 bytes) (Obsoleted by RFC3101) (Status: PROPOSED STANDARD)
プログラムでの自動翻訳です。
RFC一覧
英語原文
Network Working Group R. Coltun
Request for Comments: 1587 RainbowBridge Communications
Category: Standards Track V. Fuller
Stanford University
March 1994
Coltunがコメントのために要求するワーキンググループR.をネットワークでつないでください: 1587年のRainbowBridgeコミュニケーションカテゴリ: 1994年の標準化過程のV.の、よりふくよかなスタンフォード大学の行進
The OSPF NSSA Option
OSPF NSSAオプション
Status of this Memo
このMemoの状態
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
このドキュメントは、インターネットコミュニティにインターネット標準化過程プロトコルを指定して、改良のために議論と提案を要求します。 このプロトコルの標準化状態と状態への「インターネット公式プロトコル標準」(STD1)の現行版を参照してください。 このメモの分配は無制限です。
Table Of Contents
目次
1.0 Abstract ................................................. 1 2.0 Overview ................................................. 2 2.1 Motivation ............................................... 2 2.2 Proposed Solution ........................................ 3 3.0 Implementation Details ................................... 5 3.1 The N-bit ................................................ 5 3.2 Type-7 Address Ranges .................................... 5 3.3 Type-7 LSAs .............................................. 5 3.4 Originating Type-7 LSAs .................................. 7 3.5 Calculating Type-7 AS External Routes .................... 8 3.6 Incremental Updates ...................................... 10 4.0 Originating Type-5 LSAs .................................. 10 4.1 Translating Type-7 LSAs .................................. 10 4.2 Flushing Translated Type-7 LSAs .......................... 13 5.0 Acknowledgements ......................................... 13 6.0 References ............................................... 13 7.0 Security Considerations .................................. 13 8.0 Authors' Addresses ....................................... 14 Appendix A: Type-7 LSA Packet Format ......................... 15 Appendix B: The Options Field ................................ 16 Appendix C: Configuration Parameters ......................... 17
1.0要約… 1 2.0概観… 2 2.1動機… 2 2.2はソリューションを提案しました… 3 3.0 実現の詳細… 5 3.1 N-ビット… 5 3.2 タイプ-7アドレスは及びます… 5 3.3 タイプ-7LSAs… 5 3.4 由来しているタイプ-7LSAs… 7 3.5 外部としての計算のタイプ-7ルート… 8 3.6 増加のアップデート… 10 4.0 由来しているタイプ-5LSAs… 10 4.1 タイプ-7LSAsを翻訳します… 10 4.2 洗い流すのはタイプ-7LSAsを翻訳しました… 13 5.0の承認… 13 6.0の参照箇所… 13 7.0 セキュリティ問題… 13 8.0人の作者のアドレス… 14 付録A: タイプ-7LSAパケット・フォーマット… 15 付録B: オプション分野… 16 付録C: 構成パラメタ… 17
1.0 Abstract
1.0 要約
This document describes a new optional type of OSPF area, somewhat humorously referred to as a "not-so-stubby" area (or NSSA). NSSAs are similar to the existing OSPF stub area configuration option but have the additional capability of importing AS external routes in a limited fashion.
このドキュメントはいくらかユーモラスに「したがって、短く太くない」領域(または、NSSA)と呼ばれた新しい任意のタイプのOSPF領域について説明します。 NSSAsには、既存のOSPFスタッブ領域設定オプションと同様ですが、AS外部経路を輸入する追加する機能が限られたファッションであります。
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2.0 Overview
2.0 概観
2.1 Motivation
2.1 動機
Wide-area transit networks (such as the NSFNET regionals) often have connections to moderately-complex "leaf" sites. A leaf site may have multiple IP network numbers assigned to it.
広い領域輸送網(NSFNET地方版などの)には、適度に複雑な「葉」サイトには接続がしばしばあります。 葉のサイトで、複数のIPネットワーク・ナンバーをそれに割り当てるかもしれません。
Typically, one of the leaf site's networks is directly connected to a router provided and administered by the transit network while the others are distributed throughout and administered by the site. From the transit network's perspective, all of the network numbers associated with the site make up a single "stub" entity. For example, BARRNet has one site composed of a class-B network, 130.57.0.0, and a class-C network, 192.31.114.0. From BARRNet's perspective, this configuration looks something like this:
通常、葉のサイトのネットワークの1つは直接トランジットネットワークによって提供されて、他のものがサイトによって分配されて管理されていましたが、管理されたルータに関連づけられます。 トランジットネットワークの見解から、サイトに関連しているネットワーク・ナンバーのすべてがただ一つの「スタッブ」実体を作ります。 BARRNetには、例えば、130.57の.0のクラスBネットワーク、.0、およびaクラスCネットワークで構成されたあるサイト、192.31があります。.114 .0。 BARRNetの見解から、この構成はこのように見えます:
192.31.114
|
(cloud)
-------------- 130.57.4
|
|
------ 131.119.13 ------
|BR18|------------|BR10|
------ ------
|
V
to BARRNet "core" OSPF system
192.31.114 | (雲) -------------- 130.57.4 | | ------ 131.119.13 ------ |BR18|------------|BR10| ------ ------ | BARRNet「コア」OSPFシステムへのV
where the "cloud" consists of the subnets of 130.57 and network 192.31.114, all of which are learned by RIP on router BR18. Topologically, this cloud looks very much like an OSPF stub area. The advantages of running the cloud as an OSPF stub area are:
「雲」が130.57とネットワークのサブネットから成る、192.31、.114、それのすべてがルータBR18の上のRIPによって学習される。 位相的に、この雲はOSPFスタッブ領域にたいへん似ています。 OSPFスタッブ領域として雲を走らせる利点は以下の通りです。
1. Type-5 routes (OSPF external link-state advertisements
(LSAs)) are not advertised beyond the router
labeled "BR10". This is advantageous because the
link between BR10 and BR18 may be a low-speed link
or the router BR18 may have limited resources.
1. タイプ-5つのルート(OSPFの外部のリンク州の広告(LSAs))は"BR10""とラベルされたルータを超えて広告を出しません。 BR10とBR18とのリンクが低速リンクであったかもしれないかルータBR18がリソースを制限したかもしれないので、これは有利です。
2. The transit network is abstracted to the "leaf"
router BR18 by advertising only a default route
across the link between BR10 and BR18.
2. トランジットネットワークは、BR10とBR18とのリンクの向こう側にデフォルトルートだけの広告を出すことによって、「葉」ルータBR18に抜き取られています。
3. The cloud becomes a single, manageable "leaf" with
respect to the transit network.
3. 雲はトランジットネットワークに関して単一の、そして、処理しやすい「葉」になります。
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4. The cloud can become, logically, a part of the transit
network's OSPF routing system.
4. トランジットネットワークのOSPFの一部がシステムを発送する場合、雲は論理的になることができます。
5. Translated type-5 LSAs that are sent into the
backbone from the cloud (which is a separate
stub area) may be considered "leaf" nodes
when performing the Dijkstra calculation.
5. ダイクストラの計算を実行するとき、雲(別々のスタッブ領域である)から背骨に送られるタイプ-5翻訳されたLSAsが「葉」ノードであると考えられるかもしれません。
However, the current definition of the OSPF protocol [1] imposes topological limitations which restrict simple cloud topologies from becoming OSPF stub areas. In particular, it is illegal for a stub area to import routes external to OSPF; it is not possible for routers BR18 and BR10 to both be members of the stub area and to import the routes learned from RIP or other IP routing protocols as type-5 (OSPF external LSAs) into the OSPF system. In order to run OSPF out to BR18, BR18 must be a member of a non-stub area or the OSPF backbone to import routes other than its directly-connected network(s). Since it is not acceptable for BR18 to maintain all of BARRNet's external (type-5) routes, BARRNet is forced by OSPF's topological limitations to run OSPF out to BR10 and to run RIP between BR18 and BR10.
しかしながら、OSPFプロトコル[1]の現在の定義はOSPFスタッブ領域になるので簡単な雲のtopologiesを制限する位相的な制限を課します。 スタッブ領域がOSPFへの外部のルートを輸入するのは、特に、不法です。 ルータのBR18とBR10がともにスタッブ領域のメンバーであり、タイプ-5(OSPFの外部のLSAs)としてRIPか他のIPルーティング・プロトコルからOSPFシステムに学習されたルートを輸入するのは可能ではありません。 BR18への外へOSPFを走らせて、BR18は、直接接続されたネットワーク以外のルートを輸入するためには非スタッブ領域かOSPF背骨の器官でなければなりません。 BR18がBARRNetの外部(タイプ-5)のルートのすべてを維持するのが、許容できないので、BARRNetはBR10への外へOSPFを走らせて、BR18とBR10の間でRIPを走らせるのがOSPFの位相的な制限で強制されます。
2.2 Proposed Solution
2.2 提案されたソリューション
This document describes a new optional type of OSPF area, somewhat humorously referred to as a "not-so-stubby" area (or NSSA) which has the capability of importing external routes in a limited fashion.
このドキュメントはいくらかユーモラスに限られたファッションで外部経路を輸入する能力を持っている「したがって、短く太くない」領域(または、NSSA)と呼ばれた新しい任意のタイプのOSPF領域について説明します。
The OSPF specification defines two general classes of area configuration. The first allows type-5 LSAs to be flooded throughout the area. In this configuration, type-5 LSAs may be originated by routers internal to the area or flooded into the area by area border routers. These areas, referred to herein as type-5 capable areas (or just plain areas in the OSPF spec), are distinguished by the fact that they can carry transit traffic. The backbone is always a type-5 capable area. The second type of area configuration, called stub, allows no type-5 LSAs to be propagated into/throughout the area and instead depends on default routing to external destinations.
OSPF仕様は2つの一般的なクラスの領域構成を定義します。 1番目は、領域中にタイプ-5LSAsが水につかっているのを許容します。 この構成では、タイプ-5LSAsは境界ルータによってその領域への内部のルータによって溯源されるか、または領域へあふれさせられるかもしれません。 トランジット交通を運ぶことができるという事実によってここにタイプ-5つのできる領域(または、まさしくOSPF仕様の平らな領域)と呼ばれたこれらの領域は区別されます。 いつも背骨はタイプ-5のできる領域です。 スタッブと呼ばれる2番目のタイプの領域構成は、タイプ-5LSAsが全く領域中で/に伝播されないのを許容して、代わりに外部の目的地へのデフォルトルーティングに依存します。
NSSAs are defined in much the same manner as existing stub areas. To support NSSAs, a new option bit (the "N" bit) and a new type of LSA (type-7) area defined. The "N" bit ensures that routers belonging to an NSSA agree on its configuration. Similar to the stub area's use of the "E" bit, both NSSA neighbors must agree on the setting of the "N" bit or the OSPF neighbor adjacency will not form.
NSSAsは既存のスタッブ領域への似たり寄ったりの方法で定義されます。 NSSAsを支持するために、新しいオプションは(「N」ビット)と領域が定義したLSA(タイプ-7)の新しいタイプに噛み付きました。 「N」ビットは、NSSAに属すルータが構成に同意するのを確実にします。 「E」ビットのスタッブ領域の使用と同様です、両方のNSSA隣人が「N」ビットの設定に同意しなければならない、さもなければ、OSPF隣人隣接番組は形成されないでしょう。
Type-7 LSAs provide for carrying external route information within an NSSA. Type-7 AS External LSAs have virtually the same syntax as the
タイプ-7LSAsがNSSAの中で外部経路情報を運ぶのに提供します。 タイプ-7AS External LSAsには、実際には同じ構文があります。
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Type-5 AS External LSAs with the obvious exception of the link-state type (see section 3.2 for more details). There are two major semantic differences between type-5 and type-7 LSAs.
リンク状態の明白な例外があるタイプ-5AS External LSAsがタイプします(その他の詳細に関してセクション3.2を見てください)。 タイプ-5とタイプ-7LSAsの間には、2つの主要な意味違いがあります。
o Type-7 LSAs may be originated by and advertised
throughout an NSSA; as with stub areas, NSSA's do not
receive or originate type-5 LSAs.
o タイプ-7LSAsがNSSA中に溯源されて広告を出すかもしれません。 スタッブ領域のように、NSSAのものは、タイプ-5LSAsを受けもしませんし、溯源もしません。
o Type-7 LSAs are advertised only within a single NSSA;
they are not flooded into the backbone area or any
other area by border routers, though the information
which they contain can be propagated into the backbone
area (see section 3.6).
o 独身のNSSAだけの中にタイプ-7LSAsの広告を出します。 それらは背骨領域か境界ルータによるいかなる他の領域へもあふれません、それらが含む情報を背骨領域に伝播できますが(セクション3.6を見てください)。
In order to allow limited exchange of external information across an NSSA area border, NSSA border routers will translate selected type-7 LSAs received from the NSSA into type-5 LSAs. These type-5 LSAs will be flooded to all type-5 capable areas. NSSA area border routers may be configured with address ranges so that several type-7 LSAs may be represented by a single type-5 LSA.
NSSA領域の境界の向こう側に外部の情報の限られた交換を許容するために、NSSA境界ルータはNSSAから受け取られたタイプ-7選択されたLSAsをタイプ-5LSAsに翻訳するでしょう。 これらのタイプ-5LSAsがすべてのタイプ-5つのできる領域へあふれるでしょう。 NSSA境界ルータは、独身のタイプ-5LSAが数タイプ-7LSAsを表すことができるように、アドレスの範囲によって構成されるかもしれません。
In addition, an NSSA area border router can originate a default type-7 LSA (IP address of 0.0.0.0) into the NSSA. Default routes are necessary because NSSAs do not receive full routing information and must have a default route to route to AS-external destinations. Like stub areas, NSSAs may be connected to the backbone at more than one area border router, but may not be used as a transit area. Note that the default route originated by an NSSA area border router is never translated into a type-5 LSA, however, a default route originated by an NSSA internal AS boundary router (one that is not also an area border router) may be translated into a type-5 LSA.
さらに、NSSA境界ルータがデフォルトタイプ-7LSAを溯源できる、(IPアドレス、0.0 .0 .0) NSSAに。 NSSAsが完全なルーティング情報を受け取らないで、AS外部の目的地に発送するデフォルトルートを持たなければならないので、デフォルトルートが必要です。 スタッブ領域のように、NSSAsは1つ以上の境界ルータにおける背骨に接続されますが、トランジット領域として使用されないかもしれません。 しかしながら、NSSA境界ルータによって溯源されたデフォルトルートがタイプ-5LSAに決して翻訳されないで、NSSAの内部のAS境界ルータ(また境界ルータでないもの)によって溯源されたデフォルトルートがタイプ-5LSAに翻訳されるかもしれないことに注意してください。
It should also be noted that unlike stub areas, all OSPF summary routes (type-3 LSAs) must be imported into NSSAs. This is to ensure that OSPF internal routes are always chosen over OSPF external (type-7) routes.
また、スタッブ領域と異なって、すべてのOSPF概要ルート(タイプ-3LSAs)をNSSAsに輸入しなければならないことに注意されるべきです。 これは、OSPFの内部のルートがいつもOSPFの外部(タイプ-7)のルートに関して選ばれているのを保証するためのものです。
In our example topology the subnets of 130.57 and network 192.31.114, will still be learned by RIP on router BR18 but now both BR10 and BR18 can be in an NSSA and all of BARRNets external routes are hidden from BR18; BR10 becomes an NSSA area border router and BR18 becomes an AS boundary router internal to the NSSA. BR18 will import the subnets of 130.57 and network 192.31.114 as type-7 LSAs into the NSSA. BR10 then translates these routes into type-5 LSAs and floods them into BARRNet's backbone.
私たちの例のトポロジーの130.57とネットワークのサブネット、192.31、.114、現在のBR10とBR18の両方がNSSAにあることができます、そして、それでも、ルータBR18の上のRIPが学習されますが、BR18BARRNets外部経路のすべてを隠されます。 BR10はNSSA境界ルータになります、そして、BR18はNSSAへの内部のAS境界ルータになります。 BR18が130.57とネットワークのサブネットを輸入する、192.31、.114、NSSAへのタイプ-7LSAsとして。 BR10は次に、タイプ-5LSAsにこれらのルートを翻訳して、BARRNetの背骨へ彼らをあふれさせます。
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3.0 Implementation Details
3.0 実現の詳細
3.1 The N-bit
3.1 N-ビット
The N-bit ensures that all members of a NSSA agree on the area's configuration. Together, the N-bit and E-bit reflect an interface's (and consequently the interface's associated area's) external LSA flooding capability. As explained in section 10.5 of the OSPF specification, if type-5 LSAs are not flooded into/throughout the area, the E-bit must be clear in the option field of the received Hello packets. Interfaces associated with an NSSA will not send or receive type-5 LSAs on that interface but may send and receive type-7 LSAs. Therefore, if the N-bit is set in the options field, the E-bit must be cleared.
N-ビットは、NSSAのすべてのメンバーが領域の構成に同意するのを確実にします。 N-ビットとE-ビットはインタフェース(そして、その結果インタフェースの領域の関連もの)の外部のLSA氾濫能力を一緒に、反映します。 OSPF仕様のセクション10.5で説明されるように、タイプ-5LSAsが領域中に/へあふれないなら、E-ビットは容認されたHelloパケットのオプション・フィールドで明確であるに違いありません。 NSSAに関連しているインタフェースは、タイプ-7LSAsを発信しないか、そのインタフェースでタイプ-5LSAsを受けますが、送って、または受けるかもしれません。 したがって、N-ビットがオプション分野に設定されるなら、E-ビットをきれいにしなければなりません。
To support the NSSA option an additional check must be made in the function that handles receiving Hello packet to verify that both the N-bit and the E-bit found in the Hello packet's option field match the value of the options that have been configured in the receiving interface. A mismatch in the options causes processing of the received Hello packet to stop and the packet to be dropped.
NSSAオプションをサポートするために、Helloパケットのオプション・フィールドで見つけられたN-ビットとE-ビットの両方が受信インタフェースで構成されたオプションの値に合っていることを確かめるためにHelloパケットを受けながら、それが扱う機能で追加チェックをしなければなりません。 オプションにおけるミスマッチは止める容認されたHelloパケットとパケットの処理を落とされます。
3.2 Type-7 Address Ranges
3.2 タイプ-7アドレスは及びます。
NSSA area border routers may be configured with type-7 address ranges. Each address range is defined as an [address,mask] pair. Many separate type-7 networks may then be represented by in a single address range (as advertised by a type-5 LSA), just as a subnetted network is composed of many separate subnets. Area border routers may then summarize type-7 routes by advertising a single type-5 route for each type-7 address range. The type-5 route, resulting from a type-7 address range match will be distributed to all type-5 capable areas. Section 4.1 gives the details of generating type-5 routes from type-7 address ranges.
NSSA境界ルータはタイプ-7つのアドレスの範囲によって構成されるかもしれません。 それぞれのアドレスの範囲は[アドレス、マスク]組と定義されます。 ちょうどサブネット化したネットワークが多くの別々のサブネットで構成されるように次にネットワークがただ一つのアドレスで代表されるかもしれない多くの別々のタイプ-7つが及びます(タイプ-5LSAによって広告に掲載されているように)。 そして、境界ルータは、それぞれのタイプ-7アドレスの範囲にただ一つのタイプ-5ルートの広告を出すことによって、タイプ-7つのルートをまとめるかもしれません。 タイプ-5ルートであり、タイプ-7アドレス範囲マッチから生じるのはすべてのタイプ-5つのできる領域に分配されるでしょう。 セクション4.1はタイプ-7つのアドレスの範囲から発生タイプ-5つのルートの詳細を明らかにします。
A type-7 address range includes the following configurable items.
タイプ-7アドレスの範囲は以下の構成可能な項目を含んでいます。
o An [address,mask] pair.
o [アドレス、マスク]組。
o A status indication of either Advertise or
DoNotAdvertise.
o どちらかの状態しるし、広告、または、DoNotAdvertise。
o External route tag.
o 外部経路タグ。
3.3 Type-7 LSAs: NSSA External Link-State Advertisements
3.3 タイプ-7LSAs: NSSAの外部のリンク州の広告
External routes are imported into NSSAs as type-7 LSAs by the NSSA's AS boundary routers. An NSSA AS boundary routers is a router which
NSSAのAS境界ルータはタイプ-7LSAsとして外部経路をNSSAsに輸入します。 NSSA AS境界ルータがルータである、どれ
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Coltunと1994年の、よりふくよかな[5ページ]RFC1587OSPF NSSAオプション行進
has an interface associated with the NSSA and is exchanging routing information with routers belonging to another AS. As with type-5 LSAs a separate type-7 LSA is originated for each destination network. To support NSSA areas, the link-state database must therefore be expanded to contain a type-7 LSA.
NSSAに関連しているインタフェースを持って、別のASに属すルータとルーティング情報を交換しています。 タイプ-5LSAsのように、別々のタイプ-7LSAは各送信先ネットワークのために溯源されます。 したがって、NSSA領域を支持するなら、タイプ-7LSAを含むようにリンク州のデータベースを広げなければなりません。
Type 7-LSAs are identical to type-5 LSAs except for the following (see section 12.3.4 "AS external links" in the OSPF specification).
タイプ7-LSAsは以下を除いたタイプ-5LSAsと同じです(OSPF仕様でセクション12.3.4「ASの外部のリンク」を見てください)。
1. The type field in the LSA header is 7.
1. LSAヘッダーのタイプ分野は7です。
2. Type-7 LSAs are only flooded within the NSSA.
The flooding of type-7 LSAs follow the same rules
as the flooding of type 1-4 LSAs.
2. タイプ-7LSAsがNSSAの中で水につかっているだけです。 タイプ-7LSAsの氾濫はタイプ1-4LSAsの氾濫と同じ規則に続いて起こります。
3. Type-7 LSAs are kept within the NSSA's LSDB (are
area specific) whereas because type-5 LSAs are
flooded to all type-5 capable areas, type-5 LSAs
global scope in the router's LSDB.
3. ところが、タイプ-5LSAsがすべてのタイプ-5つのできる領域(ルータのLSDBのタイプ-5のLSAsのグローバルな範囲)へあふれるので、タイプ-7LSAsがNSSAのLSDB(領域特有である)の中に保たれます。
4. At the area border router, selected type-7 LSAs are
translated into type 5-LSAs and flooded into the
backbone.
4. 境界ルータでは、タイプ-7選択されたLSAsがタイプ5-LSAsに翻訳されて、背骨へあふれます。
5. Type 7 LSAs have a propagate (P) bit which is
used to flag the area border router to translate the
type-7 LSA into a type-5 LSA. Examples of how the P-bit
is used for loop avoidance are in the following sections.
5. タイプ7LSAsがaに噛み付かれた(P)を伝播させます(タイプ-7LSAをタイプ-5LSAに翻訳するために境界ルータに旗を揚げさせるのに使用されます)。 P-ビットが輪の回避にどう使用されるかに関する例が以下のセクションにあります。
6. Those type-7 LSAs that are to be translated into type-5
LSAs must have their forwarding address set.
Type-5 LSAs that have been translated from type-7 LSAs
for the most part must contain a forwarding address.
The execption to this is if the translation to a type-5
LSA is the result of an address range match, in which
case the type-5 LSA will not contain a forwarding address
(see section 4.1 for details).
The forwarding address contained in type-5 LSAs will
result in more efficient routing to the AS external
networks when there are multiple NSSA area
border routers. Having the forwarding address in the
type-7 LSAs will ease the translation of type-7 into
type-5 LSAs as the NSSA area border router will
not be required to compute the forwarding address.
6. Those type-7 LSAs that are to be translated into type-5 LSAs must have their forwarding address set. Type-5 LSAs that have been translated from type-7 LSAs for the most part must contain a forwarding address. The execption to this is if the translation to a type-5 LSA is the result of an address range match, in which case the type-5 LSA will not contain a forwarding address (see section 4.1 for details). The forwarding address contained in type-5 LSAs will result in more efficient routing to the AS external networks when there are multiple NSSA area border routers. Having the forwarding address in the type-7 LSAs will ease the translation of type-7 into type-5 LSAs as the NSSA area border router will not be required to compute the forwarding address.
If the network between the NSSA AS boundary router and the
adjacent AS is advertised into OSPF as an internal OSPF
If the network between the NSSA AS boundary router and the adjacent AS is advertised into OSPF as an internal OSPF
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route, the forwarding address should be the next hop
address as is currently done in type-5 LSAs, but unlike
type-5 LSAs if the intervening network is not advertised
into OSPF as an internal OSPF route, the forwarding
address should be any one of the router's active OSPF
interface addresses.
route, the forwarding address should be the next hop address as is currently done in type-5 LSAs, but unlike type-5 LSAs if the intervening network is not advertised into OSPF as an internal OSPF route, the forwarding address should be any one of the router's active OSPF interface addresses.
Type-5 and type-7 metrics and path types are directly comparable.
Type-5 and type-7 metrics and path types are directly comparable.
3.4 Originating Type-7 LSAs
3.4 Originating Type-7 LSAs
NSSA AS boundary routers may originate type-7 LSAs. All NSSA area border routers must also be AS boundary routers since they all must have the capability of translating a type-7 LSAs into a type-5 LSAs (see section 3.6 routes for the translation algorithm). NSSA area border routers must set the E-bit (external bit) as well as the B-bit (border bit) in its router (type-1) LSAs (both in the backbone and in the NSSA area).
NSSA AS boundary routers may originate type-7 LSAs. All NSSA area border routers must also be AS boundary routers since they all must have the capability of translating a type-7 LSAs into a type-5 LSAs (see section 3.6 routes for the translation algorithm). NSSA area border routers must set the E-bit (external bit) as well as the B-bit (border bit) in its router (type-1) LSAs (both in the backbone and in the NSSA area).
When an NSSA internal AS boundary router originates a type-7 LSA that it wants to be translated into a type-5 LSA by the NSSA area border router (and subsequently flooded into the backbone), it must set the P-bit in the LS header's option field and add a valid forwarding address in the type-7 LSA.
When an NSSA internal AS boundary router originates a type-7 LSA that it wants to be translated into a type-5 LSA by the NSSA area border router (and subsequently flooded into the backbone), it must set the P-bit in the LS header's option field and add a valid forwarding address in the type-7 LSA.
If a router is attached to another AS and is also an NSSA area border router, it may originate a both a type-5 and a type-7 LSA for the same network. The type-5 LSA will be flooded to the backbone (and all attached type-5 capable areas) and the type-7 will be flooded into the NSSA. If this is the case, the P-bit must be reset in the type-7 NSSA so the type-7 LSA isn't again translated into a type-5 LSA by another NSSA area border router.
If a router is attached to another AS and is also an NSSA area border router, it may originate a both a type-5 and a type-7 LSA for the same network. The type-5 LSA will be flooded to the backbone (and all attached type-5 capable areas) and the type-7 will be flooded into the NSSA. If this is the case, the P-bit must be reset in the type-7 NSSA so the type-7 LSA isn't again translated into a type-5 LSA by another NSSA area border router.
A type-7 default route (network 0.0.0.0) may be originated into the NSSA by an NSSA area border router or by an NSSA AS boundary router which is internal to the NSSA. The type-7 default route originated by the NSSA area border router must have the P-bit reset so that the default route originated by the NSSA area border router will not find its way out of the NSSA into the rest of the AS system via another NSSA area border router. The type-7 default route originated by an NSSA AS boundary router which is not an NSSA area border router may have the P-bit set. Type-7 routes which are originated by the NSSA area border router will not get added to other NSSA area border router's routing table.
A type-7 default route (network 0.0.0.0) may be originated into the NSSA by an NSSA area border router or by an NSSA AS boundary router which is internal to the NSSA. The type-7 default route originated by the NSSA area border router must have the P-bit reset so that the default route originated by the NSSA area border router will not find its way out of the NSSA into the rest of the AS system via another NSSA area border router. The type-7 default route originated by an NSSA AS boundary router which is not an NSSA area border router may have the P-bit set. Type-7 routes which are originated by the NSSA area border router will not get added to other NSSA area border router's routing table.
A default route must not be injected into the NSSA as a summary (type-3) LSA as in the stub area case. The reason for this is that the preferred summary default route would be chosen over all more
A default route must not be injected into the NSSA as a summary (type-3) LSA as in the stub area case. The reason for this is that the preferred summary default route would be chosen over all more
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specific type-7 routes. Because summary routes are preferred to external routes and to ensure that summary routes are chosen over external within the NSSA, all summary routes (unlike stub areas in which this is optional) must be imported into an NSSA.
specific type-7 routes. Because summary routes are preferred to external routes and to ensure that summary routes are chosen over external within the NSSA, all summary routes (unlike stub areas in which this is optional) must be imported into an NSSA.
3.5 Calculating Type-7 AS External Routes
3.5 Calculating Type-7 AS External Routes
This section is very similar to section 16.4 (Calculating AS external routes) in the OSPF specification. An NSSA area border router should examine both type-5 LSAs and type-7 LSAs if either type-5 or type-7 routes need to be updated. Type-7 LSAs should be examined after type-5 LSAs. An NSSA internal router should examine type-7 LSAs when type-7 routes need to be recalculated.
This section is very similar to section 16.4 (Calculating AS external routes) in the OSPF specification. An NSSA area border router should examine both type-5 LSAs and type-7 LSAs if either type-5 or type-7 routes need to be updated. Type-7 LSAs should be examined after type-5 LSAs. An NSSA internal router should examine type-7 LSAs when type-7 routes need to be recalculated.
In relation to the steps to calculate the routing table as presented in the OSPF specification (chapter 16, "Calculation of the Routing Table"), type-7 LSAs should be examined after step 5 where the routes to external destinations are calculated.
In relation to the steps to calculate the routing table as presented in the OSPF specification (chapter 16, "Calculation of the Routing Table"), type-7 LSAs should be examined after step 5 where the routes to external destinations are calculated.
Type-7 routes are calculated by examining type-7 LSAs. Each of LSAs are considered in turn. Most type-7 LSAs describe routes to specific IP destinations. A type-7 LSA can also describe a default route for the NSSA (destination = DefaultDestination). For each type-7 LSA:
Type-7 routes are calculated by examining type-7 LSAs. Each of LSAs are considered in turn. Most type-7 LSAs describe routes to specific IP destinations. A type-7 LSA can also describe a default route for the NSSA (destination = DefaultDestination). For each type-7 LSA:
1. If the metric specified by the LSA is LSInfinity, the
age of the LSA equals MaxAge or the advertising router
field is equal to this router's router ID, examine the
next advertisement.
1. If the metric specified by the LSA is LSInfinity, the age of the LSA equals MaxAge or the advertising router field is equal to this router's router ID, examine the next advertisement.
2. Call the destination described by the LSA N. Look up the
routing table entry for the AS boundary router (ASBR) that
originated the LSA. If no entry exists for the ASBR
(i.e., ASBR is unreachable), do nothing with this LSA and
consider the next in the list.
2. Call the destination described by the LSA N. Look up the routing table entry for the AS boundary router (ASBR) that originated the LSA. If no entry exists for the ASBR (i.e., ASBR is unreachable), do nothing with this LSA and consider the next in the list.
If the destination is the default route (destination =
DefaultDestination) and if the originator of the LSA and
the calculating router are both NSSA area border routers
do nothing with this LSA and consider the next in the list.
If the destination is the default route (destination = DefaultDestination) and if the originator of the LSA and the calculating router are both NSSA area border routers do nothing with this LSA and consider the next in the list.
Else, this LSA describes an AS external path to destination
N. If the forwarding address (as specified in the forwarding
address field of the LSA) is 0.0.0.0, the packets routed
to the external destination N will be routed to the
originating ASBR. If the forwarding address is not 0.0.0.0,
look up the forwarding address in the routing table. Packets
routed to the external destination N will be routed within
the NSSA to this forwarding address. An intra-area path
Else, this LSA describes an AS external path to destination N. If the forwarding address (as specified in the forwarding address field of the LSA) is 0.0.0.0, the packets routed to the external destination N will be routed to the originating ASBR. If the forwarding address is not 0.0.0.0, look up the forwarding address in the routing table. Packets routed to the external destination N will be routed within the NSSA to this forwarding address. An intra-area path
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must therefore exist to the forwarding address. If no such
path exists, do nothing with the LSA and consider the next
in the list.
must therefore exist to the forwarding address. If no such path exists, do nothing with the LSA and consider the next in the list.
Call the routing table distance to the forwarding address
(or the distance to the originating ASBR if the forwarding
address is 0.0.0.0) X, and the cost specified in the type-7
LSA Y. X is in terms of the link-state metric, and Y is a
Type-1 or Type-2 external metric.
Call the routing table distance to the forwarding address (or the distance to the originating ASBR if the forwarding address is 0.0.0.0) X, and the cost specified in the type-7 LSA Y. X is in terms of the link-state metric, and Y is a Type-1 or Type-2 external metric.
3. Now, look up the routing table entry for the destination
N. If no entries exist for N, install the AS external path
to N, with the next hop equal to the list of next hops to
the forwarding address/ASBR, and the advertising router equal
to ASBR. If the external metric type is 1, then the
path-type is set to Type-1 external and the cost is equal
to X + Y. If the external metric type is 2, the path-type
is set to Type-2 external, the link-state component of the
route's cost is X, and the Type-2 cost is Y.
3. Now, look up the routing table entry for the destination N. If no entries exist for N, install the AS external path to N, with the next hop equal to the list of next hops to the forwarding address/ASBR, and the advertising router equal to ASBR. If the external metric type is 1, then the path-type is set to Type-1 external and the cost is equal to X + Y. If the external metric type is 2, the path-type is set to Type-2 external, the link-state component of the route's cost is X, and the Type-2 cost is Y.
4. Else, if the paths present in the table are not Type-1 or
Type-2 external paths, do nothing (AS external paths have
the lowest priority).
4. Else, if the paths present in the table are not Type-1 or Type-2 external paths, do nothing (AS external paths have the lowest priority).
5. Otherwise, compare the cost of this new AS external path
to the ones present in the table. Note that type-5 and
type-7 routes are directly comparable. Type-1 external
paths are always shorter than Type-2 external paths.
Type-1 external paths are compared by looking at the sum
of the distance to the forwarding address/ASBR and the
advertised Type-1 paths (X+Y). Type-2 external paths are
compared by looking at the advertised Type-2 metrics,
and then if necessary, the distance to the forwarding
address/ASBR.
5. Otherwise, compare the cost of this new AS external path to the ones present in the table. Note that type-5 and type-7 routes are directly comparable. Type-1 external paths are always shorter than Type-2 external paths. Type-1 external paths are compared by looking at the sum of the distance to the forwarding address/ASBR and the advertised Type-1 paths (X+Y). Type-2 external paths are compared by looking at the advertised Type-2 metrics, and then if necessary, the distance to the forwarding address/ASBR.
When a type-5 LSA and a type-7 LSA are found to have the
same type and an equal distance, the following priorities
apply (listed from highest to lowest) for breaking the tie.
When a type-5 LSA and a type-7 LSA are found to have the same type and an equal distance, the following priorities apply (listed from highest to lowest) for breaking the tie.
a. Any type 5 LSA.
b. A type-7 LSA with the P-bit set and the forwarding
address non-zero.
c. Any other type-7 LSA.
a. Any type 5 LSA. b. A type-7 LSA with the P-bit set and the forwarding address non-zero. c. Any other type-7 LSA.
If the new path is shorter, it replaces the present paths
in the routing table entry. If the new path is the same
cost, it is added to the routing table entry's list of
paths.
If the new path is shorter, it replaces the present paths in the routing table entry. If the new path is the same cost, it is added to the routing table entry's list of paths.
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3.6 Incremental Updates
3.6 Incremental Updates
Incremental updates for type-7 LSAs should be treated the same as incremental updates for type-5 LSAs (see section 16.6 of the OSPF specification). That is, if a new instance of a type-7 LSA is received it is not necessary to recalculate the entire routing table. If there is already an OSPF internal route to the destination represented by the type-7 LSA, no recalculation is necessary. Otherwise, the procedure in the proceeding section will have to be performed but only for the external routes (type-5 and type-7) whose networks describe the same networks as the newly received LSA.
Incremental updates for type-7 LSAs should be treated the same as incremental updates for type-5 LSAs (see section 16.6 of the OSPF specification). That is, if a new instance of a type-7 LSA is received it is not necessary to recalculate the entire routing table. If there is already an OSPF internal route to the destination represented by the type-7 LSA, no recalculation is necessary. Otherwise, the procedure in the proceeding section will have to be performed but only for the external routes (type-5 and type-7) whose networks describe the same networks as the newly received LSA.
4.0 Originating Type-5 LSAs
4.0 Originating Type-5 LSAs
4.1 Translating Type-7 LSAs Into Type-5 LSAs
4.1 Translating Type-7 LSAs Into Type-5 LSAs
This step is performed as part of the NSSA's Dijkstra calculation after type-5 and type-7 routes have been calculated. If the calculating router is not an area border router this translation algorithm should be skipped. All reachable area border routers in the NSSA should now be examined noting the one with the highest router ID. If this router has the highest router ID, it will be the one translating type-7 LSAs into type-5 LSAs for the NSSA, otherwise the translation algorithm should not be performed.
This step is performed as part of the NSSA's Dijkstra calculation after type-5 and type-7 routes have been calculated. If the calculating router is not an area border router this translation algorithm should be skipped. All reachable area border routers in the NSSA should now be examined noting the one with the highest router ID. If this router has the highest router ID, it will be the one translating type-7 LSAs into type-5 LSAs for the NSSA, otherwise the translation algorithm should not be performed.
All type-7 routes that have been added to the routing table should be examined. If the type-7 LSA (associated with the route being examined) has the P-bit set and a non-zero forwarding address, the following steps should be taken.
All type-7 routes that have been added to the routing table should be examined. If the type-7 LSA (associated with the route being examined) has the P-bit set and a non-zero forwarding address, the following steps should be taken.
The translation procedure must first check for a configured type-7
address range. Recall that an type-7 address range consists of an
[address,mask] pair and a status indication of either Advertise or
DoNotAdvertise. At most a single type-5 LSA is made for each
range. If the route being examined falls within the type-7
address range, (the [address,mask] pair of the route equal to or a
more specific instance of the [address,mask] pair of the type-7
address range), one of following three actions may take place.
The translation procedure must first check for a configured type-7 address range. Recall that an type-7 address range consists of an [address,mask] pair and a status indication of either Advertise or DoNotAdvertise. At most a single type-5 LSA is made for each range. If the route being examined falls within the type-7 address range, (the [address,mask] pair of the route equal to or a more specific instance of the [address,mask] pair of the type-7 address range), one of following three actions may take place.
1. When the range's status indicates Advertise and the
route's address and mask are equal to the address
and mask of the type-7 range a type-5 LSA should be
originated if:
1. When the range's status indicates Advertise and the route's address and mask are equal to the address and mask of the type-7 range a type-5 LSA should be originated if:
o there currently is no type-5 LSA originated from
this router corresponding to the type-7 LSA,
o there currently is no type-5 LSA originated from this router corresponding to the type-7 LSA,
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o the path type or the metric in the corresponding
type-5 LSA is different from the type-7 LSA or
o the path type or the metric in the corresponding type-5 LSA is different from the type-7 LSA or
o The forwarding address in the corresponding
type-5 LSA is different from the type-7 LSA.
o The forwarding address in the corresponding type-5 LSA is different from the type-7 LSA.
The newly originated type-5 LSA will describe
the same network and have the same network mask,
metrics, forwarding address, external route tag
and path type as the type-7 LSA, however, the
advertising router field will be the router ID
of this area border router.
The newly originated type-5 LSA will describe the same network and have the same network mask, metrics, forwarding address, external route tag and path type as the type-7 LSA, however, the advertising router field will be the router ID of this area border router.
2. When the range's status indicates Advertise and the
route's address or mask indicates a more specific
route (i.e., the route's address is subsumed by the
range or the route has a longer mask), a type-5 LSA
is generated with link-state ID equal to the range's
address (if necessary, the link-state ID can also have
one or more of the range's "host" bits set; see
Appendix F of the OSPF specification for details),
the network mask, external route tag and
path type will be set to the configured type-7 range
values. The advertising router field will be the
router ID of this area border router.
The forwarding address will not be set.
The path type should always be set to the highest
path type that is subsumed by the net range.
The metric for the type-5 LSA will be set as follows:
2. When the range's status indicates Advertise and the route's address or mask indicates a more specific route (i.e., the route's address is subsumed by the range or the route has a longer mask), a type-5 LSA is generated with link-state ID equal to the range's address (if necessary, the link-state ID can also have one or more of the range's "host" bits set; see Appendix F of the OSPF specification for details), the network mask, external route tag and path type will be set to the configured type-7 range values. The advertising router field will be the router ID of this area border router. The forwarding address will not be set. The path type should always be set to the highest path type that is subsumed by the net range. The metric for the type-5 LSA will be set as follows:
o if the path type is externl type 2, the type-5
metric should be set to the largest type-7 metric
subsumed by this net range + 1.
o if the path type is externl type 2, the type-5 metric should be set to the largest type-7 metric subsumed by this net range + 1.
o if the path type is external type 1, the type-5
metric should be set to the largest metric.
o if the path type is external type 1, the type-5 metric should be set to the largest metric.
For example, given a net range of [10.0.0.0, 255.0.0.0]
for an area that has type-7 routes of:
For example, given a net range of [10.0.0.0, 255.0.0.0] for an area that has type-7 routes of:
10.1.0.0 path type 1, metric 10
10.2.0.0 path type 1, metric 11
10.3.0.0 path type 2, metric 5
10.1.0.0 path type 1, metric 10 10.2.0.0 path type 1, metric 11 10.3.0.0 path type 2, metric 5
a type-5 LSA will be generated with a path type of 2
and a metric of 6.
a type-5 LSA will be generated with a path type of 2 and a metric of 6.
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As another example, given a net range of
[10.0.0.0, 255.0.0.0] for an area that has
type-7 routes of:
As another example, given a net range of [10.0.0.0, 255.0.0.0] for an area that has type-7 routes of:
10.1.0.0 path type 1, metric 10
10.2.0.0 path type 1, metric 11
10.3.0.0 path type 1, metric 5
10.1.0.0 path type 1, metric 10 10.2.0.0 path type 1, metric 11 10.3.0.0 path type 1, metric 5
a type-5 LSA will be generated with a path type of 1
and a metric of 11.
a type-5 LSA will be generated with a path type of 1 and a metric of 11.
These metric and path type rules will avoid routing
loops in the event that path type 1 and 2 are both
used within the area.
These metric and path type rules will avoid routing loops in the event that path type 1 and 2 are both used within the area.
3. When the range's status indicates DoNotAdvertise,
the type-5 LSA is suppressed and the component networks
remain hidden from the rest of the AS.
3. 範囲の状態がDoNotAdvertiseを示すとき、タイプ-5LSAは抑圧されます、そして、ASの残り隠されたままで、コンポーネントネットワークは残っています。
By default (given that the P-bit is set and the LSA has a
non-zero forwarding address) if a network is not contained
in any explicitly configured address range, a type-7 to
type-5 LSA translation will occur.
デフォルトで(P-ビットが設定されて、LSAに非ゼロフォーワーディング・アドレスがあるなら)、ネットワークがどんな明らかに構成されたアドレスの範囲にも保管されていないと、タイプ-5LSAへのタイプ-7翻訳は現れるでしょう。
A new instance of a type-5 LSA should be originated and
flooded to all attached type-5 capable areas if one of the
following is true.
以下の1つが本当であるなら、タイプ-5LSAの新しい例は、すべてのタイプ-5つの付属できる領域へ溯源されて、あふれるべきです。
1. There currently is no type-5 LSA originated from this
router corresponding to the type-7 LSA.
1. 現在、タイプ-7LSAに対応するこのルータから溯源されたタイプ-5LSAが全くありません。
2. The path type or the metric in the corresponding
type-5 LSA is different from the type-7 LSA.
2. 対応するタイプ-5LSAの経路タイプかメートル法がタイプ-7LSAと異なっています。
3. The forwarding address in the corresponding
type-5 LSA is different from the type-7 LSA.
3. 対応するタイプ-5LSAのフォーワーディング・アドレスはタイプ-7LSAと異なっています。
The newly originated type-5 LSAs will describe the same
network and have the same network mask, metrics, forwarding
address, external route tag and path type as the type-7 LSA.
The advertising router field will be the router ID of this
area border router.
タイプ-5新たに溯源されたLSAsが同じネットワークについて説明して、同じネットワークマスクを持つでしょう、測定基準、タイプ-7LSAとしてアドレス、外部経路タグ、および経路タイプを転送して。 広告ルータ分野はこの境界ルータのルータIDになるでしょう。
As with all newly originated type-5 LSAs, a type-5 LSA that
is the result of a type-7 to type-5 translation (type-7 range
or default case) is flooded to all attached type-5 capable
areas.
すべてのタイプ-5新たに溯源されたLSAsのように、7対タイプ-5タイプ-翻訳(タイプ-7の範囲か不履行格)の結果であるタイプ-5LSAはすべてのタイプ-5つの付属できる領域へあふれます。
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4.2 Flushing Translated Type-7 LSAs
4.2 洗い流すのはタイプ-7LSAsを翻訳しました。
If an NSSA area border router has translated a type-7 LSA to a type-5 LSA that should no longer be translated, the type-5 LSA should be flushed (set to MaxAge and flooded). The translated type-5 LSA should be flushed whenever the routing table entry that caused the translation changes so that either the routing table entry is unreachable or the entry's associated LSA is not a type-7 with the P-bit set and a non-zero forwarding address.
NSSA境界ルータがもう翻訳されるべきでないタイプ-5LSAにタイプ-7LSAを翻訳したなら、タイプ-5LSAは洗い流されるべきです(MaxAgeにセットして、浸水します)。 翻訳されたタイプ-5LSAは翻訳変化が経路指定テーブルエントリーが手が届かなくて、エントリーのものであるように引き起こされて、LSAを関連づけた経路指定テーブルエントリーがP-ビットがあるタイプ-7セットとまたは非ゼロフォーワーディング・アドレスでないときはいつも、洗い流されるべきです。
5.0 Acknowledgements
5.0 承認
This document was produced by the OSPF Working Group, chaired by John Moy.
このドキュメントはジョンMoyによってまとめられたOSPF作業部会によって製作されました。
In addition, the comments of the following individuals are also acknowledged:
また、さらに、以下の個人のコメントは承諾されます:
Phani Jajjarvarpu cisco
Dino Farinacci cisco
Jeff Honig Cornell University
John Moy Proteon, Inc.
Doug Williams IBM
Phani Jajjarvarpuコクチマスディーノファリナッチコクチマスジェフホニッグコーネル大学ジョンMoy Proteon Inc.ダグウィリアムズIBM
6.0 References
6.0の参照箇所
[1] Moy, J., "OSPF Version 2", RFC 1583, Proteon, Inc., March 1994.
[1]Moy、J.、「OSPF、バージョン2インチ、RFC1583、Proteon Inc.、1994インチ年3月。
[2] Moy, J., "Multicast Extensions to OSPF", RFC 1584, Proteon, Inc.,
Proteon, Inc., March 1994.
[2]Moy、J.、「OSPFへのマルチキャスト拡大」、RFC1584、Proteon Inc.、Proteon Inc.、1994年3月。
7.0 Security Considerations
7.0 セキュリティ問題
Security issues are not discussed in this memo.
このメモで安全保障問題について議論しません。
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8.0 Authors' Addresses
8.0 作者のアドレス
Rob Coltun RainbowBridge Communications
ロブColtun RainbowBridge Communications
Phone: (301) 340-9416 EMail: rcoltun@rainbow-bridge.com
以下に電話をしてください。 (301) 340-9416 メールしてください: rcoltun@rainbow-bridge.com
Vince Fuller BARRNet Stanford University Pine Hall 115 Stanford, CA, 94305-4122
ビンス・よりふくよかなBARRNetスタンフォード大学松のHall115スタンフォード、カリフォルニア、94305-4122
Phone: (415) 723-6860 EMail: vaf@Valinor.Stanford.EDU
以下に電話をしてください。 (415) 723-6860 メールしてください: vaf@Valinor.Stanford.EDU
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Appendix A: Type-7 Packet Format
付録A: タイプ-7パケット・フォーマット
0 32
-----------------------------------
| | OPTS | 7 |
| ------------------
| Link-State Header |
| |
-----------------------------------
| Network Mask |
----------------------------------- ______
|E| Tos | metric | .
----------------------------------- . repeated for each TOS
| Forwarding Address | .
----------------------------------- .
| External Route Tag | ______
-----------------------------------
0 32 ----------------------------------- | | 選びます。| 7 | | ------------------ | リンク州のヘッダー| | | ----------------------------------- | ネットワークマスク| ----------------------------------- ______ |E| Tos| メートル法| . ----------------------------------- . 各TOSのために、繰り返されます。| フォーワーディング・アドレス| . ----------------------------------- . | 外部経路タグ| ______ -----------------------------------
The definitions of the link-state ID, network mask, metrics and external route tag are the same as the definitions for the type-5 LSAs (see A.4.5 in the OSPF specification) except for:
以下を除いて、リンク州のID、ネットワークマスク、測定基準、および外部経路タグの定義はタイプ-5LSAsのための定義と同じです(OSPF仕様でA.4.5を見ます)。
The Forwarding Address
フォーワーディング・アドレス
If the network between the NSSA AS boundary router and the adjacent AS is advertised into OSPF as an internal OSPF route, the forwarding address should be the next hop address but if the intervening network is not advertised into OSPF as an internal OSPF route, the forwarding address should be any one of the router's active OSPF interface addresses.
NSSA AS境界ルータと隣接しているASの間のネットワークが内部のOSPFルートとしてOSPFに広告に掲載されるなら、フォーワーディング・アドレスは次のホップアドレスであるべきですが、介入しているネットワークが内部のOSPFルートとしてOSPFに広告に掲載されないなら、フォーワーディング・アドレスはルータのアクティブなOSPFインターフェース・アドレスのいずれであるべきですも。
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Appendix B: The Options Field
付録B: オプション分野
The OSPF options field is present in OSPF Hello packets, Database Description packets and all link-state advertisements. See appendix A.2 in the OSPF specification for a description of option field.
OSPFオプション分野はOSPF Helloパケット、Database記述パケット、およびすべてのリンク州の広告に存在しています。 オプション・フィールドの記述のためのOSPF仕様で付録A.2を見てください。
------------------------------------
| * | * | * | * | N/P | MC | E | T |
------------------------------------
------------------------------------ | * | * | * | * | N/P| M.C.| E| T| ------------------------------------
The Type-7 LSA options field
Type-7 LSAオプション分野
T-bit: The T-bit describes the router's TOS capability.
T-ビット: T-ビットはルータのTOS能力について説明します。
E-bit: Type-5 AS external link advertisements are not
flooded into/through OSPF stub and NSSA areas.
The E-bit ensures that all members of a stub area
agree on that area configuration. The E-bit is
meaningful only in OSPF Hello packets. When the
E-bit is reset in the Hello packet sent out a
particular interface, it means that the router
will neither send nor receive type-5 AS external
link state advertisements on that interface (in
other words, the interface connects to a stub
area). Two routers will not become neighbors
unless they agree on the state of the E-bit.
電子ビット: タイプ-5つのASの外部のリンク広告はOSPFスタッブを通した/とNSSA領域に水につかっていません。 E-ビットは、スタッブ領域のすべてのメンバーがその領域構成に同意するのを確実にします。 E-ビットはOSPF Helloパケットだけで重要です。 E-ビットがいつHelloパケットにリセットされるかが特定のインタフェースを出して、それは、ルータがそのインタフェースに関するタイプ-5つのASの外部のリンク州の広告を送付でない、また受け取らないことを意味します(言い換えれば、インタフェースはスタッブ領域に接続します)。 彼らがE-ビットの状態に同意しないなら、2つのルータは隣人にならないでしょう。
MC-bit: The MC-bit describes the multicast capability of
the various pieces of the OSPF routing domain
[2].
ビットM.C.: ビットM.C.はOSPF経路ドメイン[2]の様々な片のマルチキャスト能力について説明します。
N-bit: The N-bit describes the the router's NSSA
capability. The N-bit is used only in Hello
packets and ensures that all members of an NSSA
agree on that area's configuration. When the
N-bit is reset in the Hello packet sent out a
particular interface, it means that the router
will neither send nor receive type-7 LSAs on that
interface. Two routers will not form an adjacency
unless they agree on the state of the N-bit. If
the N-bit is set in the options field, the E-bit
must be reset.
N-ビット: N-ビットはルータのNSSA能力について説明します。 N-ビットは、Helloパケットだけで使用されて、NSSAのすべてのメンバーがその領域の構成に同意するのを確実にします。 N-ビットがいつHelloパケットにリセットされるかが特定のインタフェースを出して、それは、ルータがそのインタフェースでタイプ-7LSAsを送付でない、また受けないことを意味します。 彼らがN-ビットの状態に同意しないと、2つのルータは隣接番組を形成しないでしょう。 N-ビットがオプション分野に設定されるなら、E-ビットをリセットしなければなりません。
P-bit: The P-bit is used only in the type-7 LSA header.
It flags the NSSA area border router to translate
the type-7 LSA into a type-5 LSA.
P-ビット: P-ビットはタイプ-7LSAヘッダーだけで使用されます。 それは、タイプ-7LSAをタイプ-5LSAに翻訳するためにNSSA境界ルータに旗を揚げさせます。
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Appendix C: Configuration Parameters
付録C: 設定パラメータ
Appendix C.2 in the OSPF specification lists the area parameters. The area ID, list of address ranges for type-3 summary routes and authentication type remain unchanged. Section 3.2 of this document lists the configuration parameters for type-7 address ranges.
OSPF仕様による付録C.2は領域パラメタをリストアップします。 領域IDであり、アドレスのリストはタイプ-3つの概要ルートに及びます、そして、認証タイプは変わりがありません。 このドキュメントのセクション3.2はタイプ-7つのアドレスの範囲のための設定パラメータをリストアップします。
For NSSAs the external capabilities of the area must be set to accept type-7 external routes. Additionally there must be a way of configuring the NSSA area border router to send a default route into the NSSA using a specific metric (type-1 or type-2 and the actual cost).
NSSAsにおいて、タイプ-7個の外部経路を受け入れるように領域の外部の能力を設定しなければなりません。 さらに、メートル法で(タイプ-1かタイプ-2と実費)詳細を使用することでデフォルトルートをNSSAに送るNSSA境界ルータを構成する方法があるに違いありません。
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