JP3790050B2 - Branch device for ATM-M bus system - Google Patents

Description

【００４０】
表１に示すように、ＧＦＣ／ＶＰ／ＶＣが“０／０／０”とされたＡＴＭセルは、空きセルであり、ペイロードは全て“６Ａｈ”の繰返しとなる。
ＧＦＣ／ＶＰ／ＶＣが“０／ＶＰＩ／ＶＣＩ”とされたセルは、分岐装置からのＳＯＳセルであり、データセルのＧＦＣを“０”にして作られる。
ＧＦＣ／ＶＰ／ＶＣが“ＩＤ／０／０”とされたセルは、ＩＤによって分岐装置が指定された予約空きセルであり、ＭＢＵから下りバスに送出される。
ＧＦＣ／ＶＰ／ＶＣが“ＩＤ／ＶＰＩ／ＶＣＩ”とされたセルは、ＩＤによって分岐装置が指定された送信データセルまたは受信データセルである。
ＧＦＣ／ＶＰ／ＶＣが“ＩＤ／ＶＰＩ／ＶＣＩ”とされたセルは、ＭＢＵ１２と分岐装置５間の制御セルであり、制御専用のＶＰＩ／ＶＣＩ値が用いられる。
ＧＦＣ／ＶＰ／ＶＣが“１５／ＶＰＩ／ＶＣＩ”とされたセルは、分岐装置からのマルチキャスト用送信および受信データセルである。
ＧＦＣ／ＶＰ／ＶＣが“ＩＤ／０／５”とされたセルは、ＩＤによって分岐装置が指定された送信および受信ポイント−ポイントシグナリングセルである。
ＧＦＣ／ＶＰ／ＶＣが“ＩＤ／ＶＰＩ／３”とされたセルは、障害時の専用セルで、ＩＤによって分岐装置が指定された送信または受信ポイント−ポイント対応ＶＰ用ＯＡＭセルであり、セグメントに対応している。
ＧＦＣ／ＶＰ／ＶＣが“ＩＤ／ＶＰＩ／４”とされたセルは、障害時の専用セルで、ＩＤによって分岐装置が指定された送信または受信ポイント−ポイント対応ＶＰ用ＯＡＭセルであり、エンド−エンドに対応している。
【００４１】
ＭＢＵ−ＡＴＭスイッチ間および分岐装置−端末装置装置間を流れるセルのＧＦＣ／ＶＰは“０／０”で構成される。
【００４２】
ＭＢＵ１２の構成を、図２のブロック図を用いて説明する。
ＭＢＵ１２は、２台のＧＦＣ／ＶＰ／ＶＣ変換手段（ＡＴＣ）１２０と、セル分岐・挿入制御部１２１と、ＡＴＭユーザネットワークユニット（ＵＮＩ）１２２と、光／電気変換用インタフェース１２３と、Ｆ−ＲＯＭ１２４と、Ｓ−ＲＡＭ１２５と、ＣＰＵ１２６と、ＬＥＤ表示部１２７と、ＰＬＬ回路１２８とを有して構成される。
【００４３】
セル分岐・挿入制御部１２１は、タグ削除部１２１１と、２台のＭ−ＧＦＣ制御部１２１２，と、２台のＡＡＬ５処理部１２１３と、リセット回路１２１４と、ＯＡＭ回路１２１５と、タグ挿入部１２１６とを有して構成される。
【００４４】
次いで、ＭＢＵプロトコルについて説明する。
ＭＢＵ１２には、上りルーティングテーブルおよび下りルーティングテーブルからなる変換テーブルがＡＴＣ＃１，＃２に形成される。上りルーティングテーブル（ＡＴＣ＃２）は、バス上の通信中の呼のＧＦＣ（ＩＤ）／ＶＰ／ＶＣをＡＴＭスイッチ管理用ＧＦＣ／ＶＰ／ＶＣに相互に変換するテーブルである。下りルーティングテーブル（ＡＴＣ＃１）は、ＡＴＭスイッチ管理用ＧＦＣ／ＶＰ／ＶＣをバス上の通信中の呼のＧＦＣ（ＩＤ）／ＶＰ／ＶＣに相互変換するテーブルである。
これらのルーティングテーブルは、Ｍバス上の最大コネクション数（例えば１０２４チャネル）で、ＣＣＵによって決定されたデータを基に管理される。
これらのルーティングテーブルは、ＡＴＭスイッチ交換用のスイッチングタグの挿抜も行う。
【００４５】
ＡＴＣ１２０におけるルーティングテーブルを用いた基本的な変換法則および変換方法を表２および図３を用いて説明する。
表２（Ａ）は、シグナリングセルおよびＯＡＭセル用の共用チャネル上の変換であり、表２（Ｂ）は、ユーザセル用のユーザチャネル上の変換であり、表２（Ｃ）は、マルチキャストセル用のユーザチャネル上の変換である。
【００４６】
【表２】

【００４７】
シグナリングセルおよびＯＡＭセルを対象とした共用チャネルでは、上り方向では、ＧＦＣ／ＶＰ／ＶＣについて、Ｍバス上のセルの“ＩＤ番号／０（固定）／ＶＣＩ”を、ＭＢＵ−ＡＴＭスイッチ間のセルの“０（固定）／ＶＰＩ（ＣＣＵ管理用）／ＶＣＩ（ＣＣＵ管理用）”に変換する。一方、下り方向では、ＧＦＣ／ＶＰ／ＶＣについて、ＡＴＭスイッチ−ＭＢＵ間のセルの“０（固定）／ＶＰＩ（ＣＣＵ管理用）／ＶＣＩ（ＣＣＵ管理用）”をＭバス上のセルの“ＩＤ番号／０（固定）／ＶＣＩ”に変換する。
【００４８】
ユーザセルを対象としたユーザチャネルでは、上り方向では、ＧＦＣ／ＶＰ／ＶＣについて、Ｍバス上のセルの“ＩＤ番号／ＶＰＩ／ＶＣＩ”を、ＭＢＵ−ＡＴＭスイッチ間のセルの“０（固定）／ＶＰＩ（ＣＣＵ管理用）／ＶＣＩ（ＣＣＵ管理用）”に変換する。一方、下り方向では、ＧＦＣ／ＶＰ／ＶＣについて、ＡＴＭスイッチ−ＭＢＵ間のセルの“０（固定）／ＶＰＩ（ＣＣＵ管理用）／ＶＣＩ（ＣＣＵ管理用）”をＭバス上のセルの“ＩＤ番号／ＶＰＩ／ＶＣＩ”に変換する。
【００４９】
マルチキャスト用セルを対象としたユーザチャネルでは、上り方向では、なんら変換作業を行わず、下り方向では、ＧＦＣ／ＶＰ／ＶＣについて、ＡＴＭスイッチ−ＭＢＵ間のセルの“０（固定）／ＶＰＩ（ＣＣＵ管理用）／ＶＣＩ（ＣＣＵ管理用）”をＭバス上のセルの“１５／ＶＰＩ／ＶＣＩ”に変換する。
【００５０】
ＭＢＵ１２に設けたＧＦＣ／ＶＰ／ＶＣ変換手段（ＡＴＣ）１２０の働きを、図３を用いて説明する。ここでは、上りバスから入力された５３バイトのＡＴＭセルをＡＴＭスイッチ１１へ向けて送出する５６バイトのＡＴＭセルに変換するＡＴＣ１２０−２を例にしている。
ＡＴＣ１２０−２では、Ｍバスから入力された５３バイトのＡＴＭセルから、ＧＦＣ／ＶＰ／ＶＣを読み出すとともにスイッチングタグスペースを挿入し、変換テーブル＃２ １２０２を参照して得た出力セル用のＧＦＣ／ＶＰ／ＶＣ／スイッチングタグを入力セルにセットして５６バイトの出力セルとしてＡＴＭスイッチ１１へ向けて送出する。
ＡＴＣ１２０−１における、ＡＴＭスイッチ１１からの５６バイトのＡＴＭセルを５３バイトのＡＴＭセルとしてＭバス３へ送出するＡＴＭセルに変換する動作は、上記とほぼ同様に行われる。
【００５１】
分岐装置５は、Ｍバス３への接続時または電源投入時に、識別番号（ＩＤ）を取得する必要がある。
このＩＤ取得は、分岐装置５から「ＩＤ要求」を繰返し出力し、ＭＢＵ１２がこの「ＩＤ要求」に対して、ＩＤ自動割当手順を実行することにより行われる。
【００５２】
ここで、表３を用いて、本発明に用いるコマンドとＧＦＣの値およびその機能を説明する。
【００５３】
【表３】

【００５４】
「ＩＤ割当確認通知」は、ＭＢＵ１２から分岐装置に送られるＧＦＣが“１５”に設定されたコマンドである。「ＩＤ割当確認通知」は、ＩＤ割当開始を通知するコマンドであり、このコマンドを受けた分岐装置は、「ＩＤ要求」の送出を停止する。
【００５５】
「ＩＤリセット要求」は、上位の分岐装置から下位の分岐装置に送られるＧＦＣが“１５”に設定されたコマンドである。「ＩＤリセット要求」は、ＩＤ自動割当手順に対応するために分岐装置が所有しているＩＤを消去し、端末側レイヤ１を非活性化する指示を与える機能を有している。
【００５６】
「ＩＤ割当確認要求」は、ＭＢＵ１２から分岐装置に送られるＧＦＣに“ＩＤ”を設定したコマンドで、分岐装置のＩＤ割当状況を確認する機能を有している。「ＩＤ割当確認要求」を受信した分岐装置は、受信したコマンドに設定されたＩＤと自己のＩＤを比較し両者が一致したときに「ＩＤ割当確認応答」を出力する。
【００５７】
「ＩＤ割当確認応答」は、分岐装置からＭＢＵ１２に送られるＧＦＣに“ＩＤ”を設定したコマンドで、分岐装置のＩＤ設定済みを通知する機能を有している。
【００５８】
「ＩＤ割当要求」は、ＭＢＵ１２から分岐装置に送られるＧＦＣが“０”に設定されたコマンドで、設定するＩＤをパラメータで指示する機能を有している。ＩＤが既に設定されている分岐装置は、このコマンドをそのまま下位側に中継する。ＩＤが設定されていない（ＩＤ＝０）分岐装置はこのコマンドを受信するとパラメータで指示されたＩＤを自己のＩＤに設定してこのコマンドを搭載したセルを空きセルとして下位側に送出する。さらに、ＩＤを設定した分岐装置は、「ＩＤ割当応答」をＭＢＵ１２へ送出する。
【００５９】
「ＩＤ割当応答」は、分岐装置からＭＢＵ１２に送られるＧＦＣに“ＩＤ”を搭載したコマンドで、ＩＤの設定完了を通知する機能を有している。
【００６０】
「ＩＤ割当終了通知」は、ＭＢＵ１２から分岐装置に送られるＧＦＣに“１５”を搭載したコマンドで、ＩＤの自動割当てを終了し、全ての分岐装置にレイヤ１の活性化を指示する機能を有している。
【００６１】
「ＩＤ割当終了応答」は、分岐装置からＭＢＵ１２に送られるＧＦＣに“ＩＤ”を搭載したコマンドで、ＩＤの割当終了通知に対する応答コマンドである。
【００６２】
「ＩＤ要求」は、分岐装置からＭＢＵ１２に送られるＧＦＣに“０”を搭載したコマンドで、ＩＤの自動割当手順の実行を依頼する機能を有している。
【００６３】
これらのコマンドでＧＦＣが同一のコマンドは、セルのペイロードのデータでコマンドを区別する。
【００６４】
図４を用いて分岐装置５のハードウェア構成を説明する。
分岐装置５は、プログラマブルゲートアレイ（Programable Logic Device，以下、ＰＬＤという）で構成されるセル分岐・挿入制御回路５１と、Ｍバス３に接続される２台の光／電気変換用インタフェース５２−１，５２−２と、それぞれＬＳＩから構成された２台の１５５ＭbpsＡＴＭユーザネットワークインタフェース（ＡＴＭ ＵＮＩ）５３−１，５３−２と、セル分岐・挿入制御回路用の回路ロジックを格納したＰＬＤ制御用ＲＯＭ５４と、ＰＬＤで構成されるセル分配・多重化制御回路５５と、セル分配・多重化制御回路用の回路ロジックを格納したＰＬＤ制御用ＲＯＭ５６と、それぞれＬＳＩから構成された少なくとも１台の２５ＭbpsＡＴＭユーザネットワークインタフェース（ＡＴＭ ＵＮＩ）５７−１〜５７−３と、ＡＴＭ ＵＮＩに対応したパルストランス５８−１〜５８−３と、ＣＰＵ５９と、Ｆ−ＲＯＭ６０と、ＲＡＭ６１とを有して構成される。
光／電気変換用インタフェース５２は、Ｍバス３がＵＴＰで構成されるときには、パルストランスで構成される。
【００６５】
分岐装置５の機能構成を図５を用いて説明する。
分岐装置５は、上流側Ｍバスインタフェース５０１と、下流側Ｍバスインタフェース５０２と、セル分岐機能５０３と、セル挿入機能５０４と、セル分配・多重化機能５０５と、端末装置インタフェース５０６と、装置接続判定機能５０７と、分岐装置接続判定機能５０８と、選択機能５０９と、ＡＴＭセル中継機能５１０と、ループバック機能５１１とを有している。
【００６６】
上流側Ｍバスインタフェース５０１は、上位ノードに接続されたＭバス３とのインタフェースをとり、光電気変換用インタフェース５２−１と１５５ＭｂｐｓＡＴＭユーザネットワークインタフェースユニット５３−１とを有して達成される。
下流側Ｍバスインタフェース５０２は、下位ノードに接続されたＭバス３とのインタフェースをとり、光電気変換用インタフェース５２−２と１５５ＭｂｐｓＡＴＭユーザネットワークインタフェースユニット５３−２とを有して達成される。
【００６７】
セル分岐機能５０３は、上位ノードから受信したＡＴＭセルの中から自己宛のＡＴＭセルを取り込みセル分配・多重化制御回路５５へ転送するとともに該ＡＴＭセルを空きセルとして下流ノードへ送り出す機能、および、セル分岐機能５０３は、上位ノードから受信したマルチキャストセルを取り込みセル分配・多重化制御回路５５へ転送するとともに該マルチキャストセルをそのまま下流ノードへ送り出す機能である。
セル挿入機能５０４は、下りバス上と上りバス上に設けられ、いずれかのバスの空きセルに、配下の端末装置からのデータを搭載して送出する機能である。
セル分岐機能５０３とセル挿入機能５０４は、ＰＬＤで構成され、セル分岐・挿入制御回路用の回路ロジックを格納したＰＬＤ制御用ＲＯＭ５４から組み込むことによって達成される。
【００６８】
セル分配・多重化機能５０５は、セル分岐機能が取り込んだＡＴＭセルを端末装置インタフェース５０６へ分配し、端末装置インタフェース５０６が受信した端末装置からのセルを１５５ＭｂｐｓのＡＴＭセルに組み立てる機能である。
さらに、セル分配機能５０５は、下流側Ｍバスインタフェース５０２に分岐装置以外の１５５ＭｂｐｓＡＴＭ端末装置が接続されたときに、セル分岐機能が取り込んだＡＴＭセルを下流側Ｍバスインタフェース５０２へ分配し、下流側Ｍバスインタフェース５０２が受信した端末装置からのセルを１５５ＭｂｐｓのＡＴＭセルに組み立てる機能である。
【００６９】
装置接続判定機能５０７は、下流側Ｍバスインタフェース５０２に、分岐装置や１５５ＭｂｐｓＡＴＭ端末装置などの１５５Ｍｂｐｓインタフェースを持つ装置が接続されたか否かを判定する機能であり、レイヤ１を監視することによって達成される。
【００７０】
分岐装置接続判定機能５０８は、下流側Ｍバスインタフェース５０２に接続された装置が分岐装置であるか否かを判定する機能であり、上りバス上のＡＴＭセルのＧＦＣを監視して「ＩＤ要求」セルを検出したときに、ＭＢＵ１２に「ＩＤ要求」セルを中継し、ＭＢＵ１２から「ＩＤ割当確認通知」セルを受信した時点で、接続された装置が下位ノードの分岐装置であると判断する。
【００７１】
ＡＴＭセル中継機能５１０は、下流側Ｍバスインタフェース５０２に分岐装置が接続されているときに上位ノードから送られてきたＡＴＭセルを下位ノードに中継する機能である。
【００７２】
ループバック機能５１１は、下流側Ｍバスインタフェース５０２に分岐装置が接続されていないときに上位ノードから送られてきたＡＴＭセルをループバックして上流側Ｍバスインタフェースに接続された上りバスに折り返す機能である。
【００７３】
選択機能５０９は、装置接続判定機能５０７と分岐装置接続判定機能５０８からの判定結果に基づいて、下流側Ｍバスインタフェースに分岐装置が接続されているときには中継機能５１０を選択し下流側ＭバスインタフェースとはＡの接続を行い、分岐装置が接続されていないときにはループバック機能５１１を選択して下流側ＭバスインタフェースとはＢの接続を行うように構成するために、ＬＰＤ制御用ＲＯＭ５４，５６から目的とする回路ロジックを取り込む機能である。
【００７４】
分岐装置５の動作の概要を図６を用いて説明する。
Ｍバス３に接続した分岐装置５の電源を投入する（Ｓ１）と、分岐装置のＣＰＵ５９は、終端分岐装置として動作をする機能（セル分岐・挿入、ループバックおよび１５５Ｍｂｐｓ端末インタフェース）を有する回路ロジックをローディングする（Ｓ２）。これによってＰＬＤ５１にはセル分岐・挿入機能とループバック機能を有する回路が構成される。この時点では、セル分岐・挿入制御回路５１と下流側Ｍバスインタフェースユニット５０２とは、Ｂの経路で接続されている。
ＰＬＤにループバック機能を有する回路ロジックをローディングするには、ループバック機能を格納したセル分岐・挿入制御回路用ＲＯＭ５４からループバック用回路ロジックを読み出して組み立てる。
【００７５】
次いで、下流側Ｍバスインタフェースに１５５Ｍｂｐｓインタフェースを持つ装置が接続されているか否かを判断する（Ｓ３）。この判断は、下流側Ｍバスインタフェースのレイヤ１を監視することによって、物理的に相手が接続されていることを判断することができる。
【００７６】
ステップＳ３の判断で、下流側Ｍバスインタフェースに、分岐装置が接続されているときには、下流側Ｍバスインタフェースの上りバスに「ＩＤ要求」セルを確認することができる（Ｓ４）。
すなわち、本発明が適用されるＡＴＭ−Ｍバスシステムにおいては、下位ノードの分岐装置がＭバス３に接続されたときには、下位ノードの分岐装置は、ＭＢＵ１２に対して自己の識別番号（ＩＤ）の付与を要求する「ＩＤ要求」セルを繰返し上りバス上に送信し、ＩＤを取得するように構成されていることから、電源投入時に上りバスに「ＩＤ要求」セルを検出したときには、下位ノードの装置は分岐装置であると判断することができる。
【００７７】
ステップＳ４で、接続された装置が下位ノードの分岐装置であると判断されたときには、下位ノードから送られてきた「ＩＤ要求」セルをそのままＭＢＵ１２に向けて上りバス上に中継する（Ｓ５）。
【００７８】
ＭＢＵ１２は、「ＩＤ要求」セルを受信すると「ＩＤ割当確認通知」セルを送信して、ＩＤ割り当ての開始を通知する。この「ＩＤ割当確認通知」セルを上流側Ｍバスインタフェースの下りバス上に受信した（Ｓ６）分岐装置は、セル分岐・挿入制御回路５１用ＰＬＤに中継機能（ループバックなし）を有する回路ロジックをロードし直すとともに、セル分配・多重化制御回路５５用ＰＬＤに中継分岐機能をロードする（Ｓ７）。
セル分岐・挿入制御回路５１用ＰＬＤへの中継機能のロードは、中継機能を搭載したセル分岐・挿入制御回路用回路ロジックを格納したＰＬＤ制御用ＲＯＭ５４から読み出してロードすることによって、セル分配・多重化制御回路５５用ＰＬＤへの中継分岐機能のロードは、中継分岐機能を搭載したセル分配・多重化制御回路用回路ロジックを格納したＰＬＤ制御用ＲＯＭ５６から読み出してロードすることによって行われる。
【００７９】
このローディングによって、分岐装置は、上位ノードから受信した他の分岐装置宛ＡＴＭセルまたはマルチキャストＡＴＭセルを下位ノードへ中継する機能と、下位ノードから受信したＭＢＵ１２宛ＡＴＭセルを上位ノードへ中継する機能と、上位ノードから受信した自己宛のＡＴＭセルを配下の端末装置用インタフェースへ分岐するとともに該ＡＴＭセルを空きセルとして下流ノードへ送出する機能と、配下の端末装置用インタフェースから受けたデータを上りバスまたは下りバス上の空きセルに搭載して送り出す機能とを有するように構成される。
【００８０】
また、上記ローディングによって、分岐装置は、配下の端末装置とセル分岐・挿入制御回路５１をセル分解・多重化制御回路５５を介して接続する機能と、セル分岐・挿入制御回路５１と下流側Ｍバスインタフェースを直接接続する機能とを備えるように構成される。
【００８１】
上記のように構成された分岐装置は、上流側の下りバスに受信した「ＩＤ割当確認通知」セルを下位ノードに中継する（Ｓ８）。「ＩＤ割当要求」セルを受信した分岐装置は、ＭＢＵ１２から送られてくるＩＤを取得し、該セルを空きセルにして下位ノードへ送出する（Ｓ９）。
これ以降、分岐装置は中継機能を有するとして動作する（Ｓ１０）。
【００８２】
ステップＳ３で下流側Ｍバスインタフェースに１５５Ｍｂｐｓインタフェースを持つ装置が接続されていなかったとき、またはステップＳ４で上りバスに「ＩＤ要求」セルを検出しなかったとき、すなわち下位ノードに分岐装置が接続されていないときには、分岐装置は自ら「ＩＤ要求」セルを上りバスに送出してＭＢＵ１２からＩＤを取得する（Ｓ１１）。
【００８４】
分岐装置は内部にループバック機能を有した終端分岐装置として動作する（Ｓ１２）。
【００８５】
【発明の効果】
本発明によれば、ＡＴＭ−ＭバシステムにおけるＭバスの終端部に接続された分岐装置が自動的に内部折返しを設けるため、従来外部で接続していた“Ｕ”字接続を廃止し工事ミスを防止することができる。
さらに、下流側Ｍバスインタフェースを１５５Ｍｂｐｓの端末装置用のインタフェースとして使用することができ、経済的効果は大である。
【図面の簡単な説明】
【図１】本発明にかかる分岐装置が適用されるＡＴＭ−Ｍバスシステムの構成概念を示す概念図。
【図２】本発明にかかる分岐装置が適用されるＡＴＭ−Ｍバスシステムに用いるＭＢＵの構成を示すブロック図。
【図３】本発明にかかる分岐装置が適用されるＡＴＭ−Ｍバスシステムに用いるＭＢＵのＡＴＣにおけるＧＦＣ／ＶＰ／ＶＣの変換処理を説明する説明図。
【図４】本発明にかかるＡＴＭ−Ｍバスシステムに用いる分岐装置の構成を示すブロック図。
【図５】本発明にかかるＡＴＭ−Ｍバスシステムに用いる分岐装置の機能構成を示す図。
【図６】本発明にかかるＡＴＭ−Ｍバスシステムに用いる分岐装置の動作を説明するフロー図。
【図７】先願にかかるＡＴＭ−Ｕバスシステムの構成概念を示す概念図。
【符号の説明】
１ Ｍバス主装置（ＡＴＭ交換装置）
１１ ＡＴＭスイッチ
１２ ＡＴＭ−Ｍバスインタフェースユニット（ＭＢＵ）
１２０ ＧＦＣ／ＶＰ／ＶＣ変換手段（ＡＴＣ）
１２１ セル分岐・挿入制御部（ＰＬＤ）
１２２ ＡＴＭ ユーザネットワークインタフェース
１２３ 光／電気変換用インタフェース
１２４ Ｆ−ＲＯＭ
１２５ Ｓ−ＲＡＭ
１２６ ＣＰＵ
１２７ ＬＥＤ表示部
１２８ ＰＬＬ回路
１３ ２５Ｍbps端末インタフェースユニット
１４ ＬＡＮインタフェースユニット
１５ Ｎ−ＩＳＤＮ基本インタフェースユニット
１６ ２５Ｍbpsノード間インタフェースユニット
１７ 三者会議ユニット
１８ 音声通話タイプ変換ユニット
１９ 中央制御ユニット（ＣＣＵ）
３ Ｍバス
５ 分岐装置
５１ セル分岐・挿入制御回路（ＰＬＤ）
５２ 光／電気変換用インタフェース
５３ １５５Ｍｂｐｓユーザネットワークインタフェース（ＡＴＭ−ＵＮＩ）
５４ セル分岐・挿入制御回路用ＲＯＭ
５５ セル分配・多重化制御回路（ＰＬＤ）
５６ セル分配・多重化制御回路ＲＯＭ
５７ ２５Ｍｂｐｓユーザネットワークインタフェース（ＡＴＭ−ＵＮＩ）
５８ パルストランス
５９ ＣＰＵ
６０ Ｆ−ＲＯＭ
６１ ＲＡＭ
７１ ２５ＭｂｐｓＡＴＭ−ＫＴ
７２ １５５ＭｂｐｓＡＴＭ端末装置
７５ ２５ＭｂｐｓＡＴＭ端末装置
５０１ 上流側Ｍバスインタフェース
５０２ 下流側Ｍバスインタフェース
５０３ セル分岐機能
５０４ セル挿入機能
５０５ セル分岐・挿入機能
５０６ 端末装置インタフェース
５０７ 装置接続判定機能
５０８ 分岐装置接続判定機能
５０９ 選択機能
５１０ ＡＴＭセル中継機能
５１１ ループバック機能[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bus system applied to an ATM (Asynchronous Transfer Mode) exchange system, and in particular, a branch in a multimedia bus (M bus) system for exchanging data between terminal devices accommodated in an ATM exchange. Relates to the device.
[0002]
[Prior art]
The applicant Japanese Patent Laid-Open No. 10-210045 ( Japanese Patent Application No. 9-10231 ) Has proposed a bus system called “ATM-U bus system”.
This ATM-U bus system is composed of a main device having an ATM switch and an ATM 155 Mbps interface, and a plurality of branch devices accommodated in series in the main device via a bus. The branch device accommodates a terminal device and is connected to the upstream bus and the downstream bus of the ATM 155 Mbps interface. The bus is a bus that is accommodated in the main device by folding the end of the downstream bus from the main device and is called a U bus.
[0003]
The U bus main device used in this bus system converts all voice / image / data etc. into ATM cells, has a unique ATM bus interface (I / F) in the 155 MbpsM bus interface, and a plurality of standard ATM terminal devices under the ATM bus interface (I / F) And a high-speed ATM terminal device directly accommodated in the M bus interface, so that the exchange processing can be performed in a unified manner.
Figure shows the configuration of a U bus main unit for small-scale offices using this U bus system. 7 Shown in The U-bus main device 100 has a function as an ATM switching device, and is configured to include an ATM switch (ATM-SW) 101 and a 155 Mbps ATM interface 102 with U-GFC control. The power supply unit includes a omitted 100 Mbps LAN interface, an existing WAN interface, a control unit, and a storage battery.
[0004]
An ATM switch (ATM-SW) 101 is the same as a normal ATM switch, and in this example, has eight ports of 155 Mbps.
[0005]
The 155 Mbps ATM interface 102 of the U bus main unit (ATM switch) 100 is an interface package that can directly accommodate the U bus 120, the ATM 155 Mbps terminal device and the ATM 155 Mbps line, and uses the GFC portion provided in the header of the ATM cell. It has a U-GFC control function.
[0006]
The ATM interface 102 is a VP / VC conversion means for converting a GFC, a virtual path (VP), and a virtual channel (VC) in an ATM cell and assigning a tag for switching, and a user network interface 155 Mbps ATM which is an ATM 155 Mbps specification. A unit, an optical / electrical conversion interface, an SRAM storing a reference table for GFC / VP / VC conversion, and U-GFC control for performing U-GFC control which is inherent GFC control on the U bus of the transmission / reception cell For example, it is mounted on a card-like package.
[0007]
The U-GFC control unit includes a downlink cell FIFO memory for storing an ATM cell (downlink cell) ID sent to the downlink bus, an uplink cell FIFOI memory for recording an uplink cell ID received from the uplink bus, and a downlink cell FIFO. Comparing means for checking the coincidence between the downlink cell ID stored in the memory and the uplink cell ID recorded in the FIFO memory for the uplink cell is provided.
[0008]
The ATM 155 Mbps interface 102 is connected to an ATM bus 120 called an U bus, an ATM terminal device, another ATM exchange via ATM-PNNI, and an ATM-WAN via an ATM-user network interface (UNI).
In addition, an existing LAN network of 100 Mbps is connected to the LAN interface.
Further, an ISDN line or an analog line, a dedicated line, an OCN, or the like is connected to the existing WAN interface.
[0009]
The control unit performs exchange control, package control, and network management control of the U bus main device 100.
[0010]
The U bus 120 is a bus to which an ATM terminal device can be connected, and is accommodated in the ATM 155 Mbps interface 102 with U-GFC control. The U bus 120 includes, for example, a 25 Mbps ATM key telephone (ATM-KT) 151, a 155 Mbps ATM terminal device 152, and a 3.1 KHz audio (64 Kbps) analog telephone 153 such as a plurality of multimedia terminal devices and image terminal devices. ISDN terminal device 154, 25 Mbps ATM terminal device 155 is connected via branch device 130, analog telephone 153, ISDN terminal device 154, etc. are connected via existing terminal device branch device 130-3, and 155 Mbps An ATM terminal device 152 such as a server / computer is connected.
[0011]
For example, 155 Mbps ATM terminal device 152, 25 Mbps ATM terminal device 155, ATM key telephone 151, etc. have a traffic capacity of 155 Mbps U bus 120 via U branch device 130-1, 130-2, 130 -n. Consider multiple connections.
[0012]
As an interface accommodated exclusively for the U bus, there is an ATM key telephone (ATM-KT) 151 which is a multi-function button telephone. This ATM key telephone has a CLAD inside the telephone and is connected to the U bus 120 via an ATM 25 bps interface.
[0013]
As described above, this ATM-U bus system is a system in which an identifier is assigned to each branch device, and the identifier of the branch device that is the destination of the ATM cell is sent to the GFC field of the header of the ATM cell sent from the main device. is there.
Furthermore, this ATM-U bus system branches the cell addressed to itself received by the branching device and sends it to the terminal device. When there is no transmission data from the terminal device accommodated in the branching device, the branching device receives it. The cell identifier addressed to itself is deleted and sent to the downstream node as an empty cell. When there is transmission data from the terminal device accommodated in the branching device, the transmission data is sent to the cell addressed to itself or the empty cell received by the branching device. To send out.
[0014]
Also, this ATM-U bus system is provided with a plurality of transmission buffers for temporarily storing transmission data from the terminal device in the branch device, and when the value of the transmission buffer reaches a predetermined value, the cell addressed to the branch device is set. When the "SOS" cell is received, the main device forcibly sends a reserved empty cell to which the identifier of the branching device is assigned to a downlink cell other than the shared channel. .
[0015]
The branching device used for the ATM-U bus system is connected to the ATM-U bus, has an upstream interface, a downstream interface, and an input / output interface to the terminal device, and is attached to the header of the received ATM cell. A bus control means having a function of extracting the identified identifier and branching the cell addressed to itself, a cell disassembly / assembly (CLAD) function, and a cell insertion function of placing transmission data in the cell addressed to itself or an empty cell .
[0016]
The ATM 155 Mbps interface used in the ATM-U bus system is connected to the ATM bus and stores a FIFO memory for storing an identifier attached to the GFC of the ATM cell transmitted to the downstream bus, and an identifier attached to the GFC of the ATM cell received by the upstream bus. And a means for comparing the identifier attached to the GFC of the ATM cell sent to the downstream bus with the identifier attached to the GFC of the ATM cell received on the upstream bus. There is no accumulation of identifiers attached to GFCs of ATM cells to be performed, and there is a function of assigning empty cells designating terminal devices to downstream buses when identifiers attached to GFCs of ATM cells received by upstream buses are stored. Yes.
[0017]
This ATM-U bus system is
(1) A standard ATM-switch (SW) can be used, and each 155 Mbps interface of the main unit ignores or invalidates the above-mentioned “U-GFC flow control”, thereby enabling a standard ATM 155 Mbps port. The terminal device of each branching device can transmit fairly and efficiently, and can guarantee the maximum characteristics such as the maximum cell delay.
(2) Symmetric services such as existing terminal devices such as voice can be guaranteed transmission only by the receiving cell of the terminal device.
(3) For asymmetric services such as server access and Internet access, U-GFC flow control and “SOS” cells enable effective use of cells.
(4) A terminal device on the U bus can perform “multicast” communication.
(5) It becomes possible to connect the terminal equipment to multipoints under the branching equipment.
(6) By connecting a branching device with CLAD, it is possible to directly accommodate existing terminal devices.
(7) Since U-bus system software processing is rarely necessary other than initial setting, OAM management, and U-bus management, the U-bus system can be easily realized.
(8) Since the hardware only provides the ATM 155 Mbps interface, and only UTOPIA bus control, cell insertion / branching, and buffer processing increase, the U bus method can be easily realized.
This is a method that produces the excellent effect.
[0018]
Each branch device has three interfaces, an upstream M bus interface, a downstream M bus interface, and a terminal device side interface. The branch device farthest from the main device has a downstream M bus interface. The downstream bus connected to the downstream bus output unit is folded and connected to the upstream bus input unit of the downstream M bus interface.
[0019]
[Problems to be solved by the invention]
Hereinafter, in the present specification, the above-mentioned “ATM-U bus” is referred to as “ATM-M bus”, and “ATM-U bus system” is referred to as “ATM-M bus system”.
The present invention provides an ATM-M bus system branching device that enables external folding at the farthest end of the ATM-M bus within the branching device connected to the farthest end in the ATM-M bus system. For the purpose.
That is, the present invention provides an ATM-M bus interface branching device in which internal folding is automatically provided by recognizing that the branching device at the farthest end is the branching device at the farthest end. The purpose is to provide.
[0020]
It is another object of the present invention to provide an ATM-M bus system branch device that can use the downstream M bus interface of the farthest end branch device as a terminal device interface of 155 Mbps.
That is, according to the present invention, in the branching device used in the ATM-M bus system, the branching device at the farthest end recognizes that it is the branching device at the farthest end, and automatically turns it back into itself. Is provided, and the downstream M bus interface can be used as a terminal device interface of 155 Mbps.
[0021]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an M bus interface unit accommodated in an ATM switch, and an M bus having both ends accommodated in the M bus interface unit and folded at the farthest end to be a downstream bus and an upstream bus. In an ATM-M bus system branch device comprising a bus and a plurality of branch devices connected in series to the bus, an upstream M bus interface to which an M bus from an upper node is connected and an M bus to a lower node Three-way interface means of a downstream M bus interface to be connected and a terminal device interface to which a terminal device is connected, and an ATM cell input to the upstream M bus interface is relayed to the output side of the downstream M bus interface ATM cell relay means and an ATM cell input to the upstream M bus interface are connected to the upstream M bus interface. ATM cell return means for sending back to the output side of the case, device connection determination means for determining that any device is connected to the downstream M bus interface, and a device connected to the downstream M bus interface are branch devices Branch device connection determination means for determining whether or not, and means for causing the downstream M bus interface to function as a terminal device interface.
[0021]
That is, the present invention provides the ATM-M bus system branching device in which an ATM cell return means is provided inside when the downstream M bus interface is not connected to the downstream M bus interface, An ATM cell relay means is provided when the branch device is connected.
[0022]
Further, according to the present invention, in the above-described ATM-M bus system branching device, when the branching device connection determination means detects an “ID request” cell in the upstream bus of the downstream M bus interface, the connected device branches. It was determined that this was a device, and a relay function was provided.
[0023]
Further, according to the present invention, in the branch device for the ATM-M bus system, when the branch device is not connected to the downstream M bus interface, the downstream M bus interface is used as the terminal device side interface. .
[0024]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an ATM-M bus system branching apparatus according to the present invention will be described below with reference to the drawings.
[0025]
The present invention adopts a method according to the ATM-U bus system according to the above-mentioned prior application, and is a multimedia bus (hereinafter referred to as M bus), an M bus main device, and a terminal device interface branching device (hereinafter referred to as “M bus”). The present invention relates to a branching device used in an ATM-M bus system configured simply by a branching device.
[0026]
An outline of the ATM-M bus system according to the present invention will be described with reference to FIG.
The ATM-M bus system is composed of an M bus main device 1, a 155 Mbps M bus 3, and a plurality of branch devices 5 connected to the M bus. Each branch device 5 has an ATM-M bus of 25 Mbps. KT71, 155Mbps ATM terminal device 72, 25Mbps ATM terminal device 75, etc. are accommodated via connection lines.
[0027]
The M bus main unit 1 has a function as an ATM switch, and includes an ATM switch (ATM-SW) 11, an M bus interface unit (MBU) 12 that functions as a gateway for accommodating the M bus 3 in the ATM switch, An N-ISDN basic interface unit (BCOU) 15 and a central control unit (hereinafter referred to as CCU) 19 are configured.
Further, the M bus main unit 1 includes a 25 Mbps terminal unit interface unit 13, a LAN unit 14, a 25 Mbps inter-node interface unit (25MNU) 16, a three-party conference unit (CNFU) 17, a voice call type conversion unit (VTU) 18, and the like. Can have.
[0028]
The MBU 12 transmits and receives ATM cells to and from the branch device 5 via the M bus. A unique cell header on the M bus is set in the ATM cell on the M bus.
[0029]
The M bus 3 includes a down bus and an up bus connected to the MBU 12, and a plurality of branch devices 5 are connected in cascade. The downstream bus is turned up in the terminal branching device to be an upstream bus.
The M bus 3 is configured as a 155 Mbps ATM bus using a multimode optical fiber (hereinafter referred to as MMF) or a 100Ω copper wire cable (hereinafter referred to as UTP).
[0030]
In the branching device 5-n at the farthest end from the MBU 12, the downstream bus and the upstream bus of the M bus 3 are folded back by folding means provided in the branching device 5-n.
The ATM cell sent from the MBU 12 to the down bus is looped back by the loop-back means, sent to the up bus, and returned to the MBU 12.
[0031]
The branching device 5 is connected to the down bus and the up bus of the M bus 3 and relays the ATM cell received from the upper node through the down bus to the lower node, and relays the ATM cell received from the lower node through the up bus to the upper node. An ATM cell relay function, a cell branch function that takes in the data of the ATM cell received by the downlink bus and distributes it to the terminal device under control, and places the data from the terminal device on the empty cell to the downlink bus or uplink bus It has a cell insertion function to send out.
Further, the branching device 5 has a VPI / VCI acquisition and management function of the corresponding user cell by signaling, a GFC control function of the corresponding user cell, and a failure monitoring function of the M bus and terminal interface port.
[0032]
The branching device 5 is an ATM cell on the downstream bus. The 155 Mbps upstream M bus interface that outputs ATM cells as input to the upstream bus, 155 Mbps downstream M bus interface that outputs ATM cells to the downstream bus and inputs ATM cells on the upstream bus, and one or more terminals It has a device interface.
[0033]
A maximum of 14 branch devices 5 are cascade-connected to the M bus 3.
[0034]
The terminal device interface of each branching device 5 is a 25 Mbps ATM terminal device such as a 25 Mbps ATM button telephone (ATM-KT) 71, 25 Mbps ATM standard terminal device 75, 155 Mbps ATM standard terminal device 72, and analog supporting Q2931. Terminal devices, ISDN terminal devices and the like are accommodated.
[0035]
Further, the branching device 5 according to the present invention has a loopback function for transmitting an ATM cell received by the downstream bus of the upstream M bus interface to the upstream bus of the upstream M bus interface. It has the characteristics.
Further, the branching device 5 determines whether or not any device is connected to the downstream M bus interface, and determines whether or not the device connected to the downstream M bus interface is a branching device. When the branch device is connected to the downstream M bus interface, the relay function is selected. When the branch device is not connected to the downstream M bus interface, the loop back function is selected. ing.
Further, the branch device 5 has a function of using the downstream M bus interface as a terminal device interface when the loopback function is selected.
[0036]
Here, the ATM-M bus system will be described.
In an ATM communication system, the general flow control (GFC: 4 bit) field of the header of an ATM cell is not defined in NNI (Network Node Interface) and is used as an end-to-end function. The field is used only for the user network interface (UNI) portion.
In the M bus system according to the present invention, a plurality of branch devices are cascade-connected to the M bus, and only between the branch devices (M bus section), the identification number of each branch device (hereinafter, referred to as 4 bits of GFC of the ATM cell header). ID)) and routing is performed with the ID installed in the GFC.
[0037]
In this specification, the GFC control protocol in the ATM-M bus system is defined as the M-GFC control protocol.
The M-GFC control protocol is a bus control protocol realized by hardware (partially software intervening) of the MBU 12 and the branching device 5. The preconditions for realizing the M-GFC flow control are shown below.
A bus transmitted from the MBU 12 is referred to as a downstream bus, and a bus that is turned back by the branching device 5-n at the farthest end and is directed to the MBU 12 is referred to as an upstream bus.
The identifier ID of each branch device 5 is determined by an identifier automatic assignment process from the MBU 12 described later.
In the transmission and reception of the ATM cell on the bus in the branching device 5, the reception cell can be fetched only from the downlink bus, and the transmission cell can be set to any empty cell on the downlink bus or the uplink bus. However, if transmission is possible to either, priority is given to sending to the upstream bus.
[0038]
The cell type managed by the M bus is defined by GFC / VP / VC. Table 1 shows the contents of the definition.
[0039]
[Table 1]

[0040]
As shown in Table 1, an ATM cell in which GFC / VP / VC is “0/0/0” is an empty cell, and the payload is all “6Ah”.
A cell in which GFC / VP / VC is set to “0 / VPI / VCI” is an SOS cell from the branch device, and is created by setting the GFC of the data cell to “0”.
A cell in which GFC / VP / VC is set to “ID / 0/0” is a reserved empty cell in which a branch device is designated by the ID, and is transmitted from the MBU to the downlink bus.
A cell in which GFC / VP / VC is set to “ID / VPI / VCI” is a transmission data cell or a reception data cell in which a branch device is designated by the ID.
A cell in which GFC / VP / VC is set to “ID / VPI / VCI” is a control cell between the MBU 12 and the branch device 5, and a VPI / VCI value dedicated to control is used.
A cell in which GFC / VP / VC is set to “15 / VPI / VCI” is a multicast transmission and reception data cell from the branching device.
A cell in which GFC / VP / VC is set to “ID / 0/5” is a transmission and reception point-point signaling cell in which a branch device is specified by ID.
A cell in which GFC / VP / VC is set to “ID / VPI / 3” is a dedicated cell at the time of failure, and is an OAM cell for a transmission or reception point-point correspondence VP in which a branching device is designated by ID, It corresponds.
A cell in which GFC / VP / VC is set to “ID / VPI / 4” is a dedicated cell at the time of failure, and is an OAM cell for transmission or reception point-point correspondence VP in which a branching device is designated by the ID. It corresponds to the end.
[0041]
The GFC / VP of the cell flowing between the MBU-ATM switch and between the branch device and the terminal device is configured as “0/0”.
[0042]
The configuration of the MBU 12 will be described using the block diagram of FIG.
The MBU 12 includes two GFC / VP / VC conversion means (ATC) 120, a cell branch / insertion control unit 121, an ATM user network unit (UNI) 122, an optical / electrical conversion interface 123, and an F-ROM 124. And an S-RAM 125, a CPU 126, an LED display unit 127, and a PLL circuit 128.
[0043]
The cell branch / insertion control unit 121 includes a tag deletion unit 1211, two M-GFC control units 1212, two AAL5 processing units 1213, a reset circuit 1214, an OAM circuit 1215, and a tag insertion unit 1216. And is configured.
[0044]
Next, the MBU protocol will be described.
In the MBU 12, a conversion table including an upstream routing table and a downstream routing table is formed in the ATC # 1 and # 2. The upstream routing table (ATC # 2) is a table for mutually converting GFC (ID) / VP / VC of a call in communication on the bus to GFC / VP / VC for ATM switch management. The downlink routing table (ATC # 1) is a table for mutual conversion of GFC / VP / VC for ATM switch management into GFC (ID) / VP / VC of a call on the bus.
These routing tables are the maximum number of connections on the M bus (for example, 1024 channels) and are managed based on data determined by the CCU.
These routing tables also insert and remove switching tags for ATM switch replacement.
[0045]
A basic conversion rule and conversion method using a routing table in the ATC 120 will be described with reference to Table 2 and FIG.
Table 2 (A) is the conversion on the shared channel for the signaling cell and OAM cell, Table 2 (B) is the conversion on the user channel for the user cell, and Table 2 (C) is the multicast cell. Conversion on the user channel.
[0046]
[Table 2]

[0047]
In the shared channel for the signaling cell and the OAM cell, in the upstream direction, for the GFC / VP / VC, the “ID number / 0 (fixed) / VCI” of the cell on the M bus is the cell between the MBU-ATM switch. To “0 (fixed) / VPI (for CCU management) / VCI (for CCU management)”. On the other hand, in the downstream direction, for GFC / VP / VC, “0 (fixed) / VPI (for CCU management) / VCI (for CCU management)” of the cell between the ATM switch and the MBU is changed to “ID” of the cell on the M bus. Number / 0 (fixed) / VCI ".
[0048]
In the user channel for user cells, in the uplink direction, for GFC / VP / VC, the “ID number / VPI / VCI” of the cell on the M bus is set to “0 (fixed)” of the cell between the MBU-ATM switches. / VPI (for CCU management) / VCI (for CCU management) ”. On the other hand, in the downstream direction, for GFC / VP / VC, “0 (fixed) / VPI (for CCU management) / VCI (for CCU management)” of the cell between the ATM switch and the MBU is changed to “ID” of the cell on the M bus. Number / VPI / VCI ”.
[0049]
In the user channel for the multicast cell, no conversion work is performed in the upstream direction, and in the downstream direction, “0 (fixed) / VPI (CCU) of the cell between the ATM switch and the MBU for GFC / VP / VC. (For management) / VCI (for CCU management) "is converted to" 15 / VPI / VCI "of the cell on the M bus.
[0050]
The operation of the GFC / VP / VC conversion means (ATC) 120 provided in the MBU 12 will be described with reference to FIG. Here, an ATC 120-2 that converts a 53-byte ATM cell input from the upstream bus into a 56-byte ATM cell that is sent to the ATM switch 11 is taken as an example.
The ATC 120-2 reads the GFC / VP / VC from the 53-byte ATM cell input from the M bus, inserts a switching tag space, and obtains the GFC / for the output cell obtained by referring to the conversion table # 2 1202. The VP / VC / switching tag is set in the input cell and is sent to the ATM switch 11 as a 56-byte output cell.
The operation of converting the 56-byte ATM cell from the ATM switch 11 to the ATM cell sent to the M bus 3 as the 53-byte ATM cell in the ATC 120-1 is performed in substantially the same manner as described above.
[0051]
The branch device 5 needs to obtain an identification number (ID) when connected to the M bus 3 or when the power is turned on.
This ID acquisition is performed by repeatedly outputting an “ID request” from the branch device 5 and the MBU 12 executing an automatic ID assignment procedure for this “ID request”.
[0052]
Here, using Table 3, the command and GFC values used in the present invention and their functions will be described.
[0053]
[Table 3]

[0054]
The “ID assignment confirmation notification” is a command in which the GFC sent from the MBU 12 to the branch device is set to “15”. The “ID assignment confirmation notification” is a command for notifying the start of ID assignment, and the branching device that has received this command stops sending the “ID request”.
[0055]
The “ID reset request” is a command in which the GFC sent from the upper branch device to the lower branch device is set to “15”. The “ID reset request” has a function of erasing the ID owned by the branching apparatus to respond to the automatic ID assignment procedure and giving an instruction to deactivate the terminal side layer 1.
[0056]
The “ID assignment confirmation request” has a function of confirming the ID assignment status of the branching device with a command in which “ID” is set in the GFC sent from the MBU 12 to the branching device. The branch device that has received the “ID assignment confirmation request” compares the ID set in the received command with its own ID, and outputs an “ID assignment confirmation response” when the two match.
[0057]
The “ID assignment confirmation response” has a function of notifying that the branch device ID has been set by a command in which “ID” is set in the GFC sent from the branch device to the MBU 12.
[0058]
The “ID allocation request” is a command in which the GFC sent from the MBU 12 to the branching device is set to “0”, and has a function of specifying the ID to be set with a parameter. The branching device whose ID has already been set relays this command to the lower side as it is. Upon receiving this command, the branch device with no ID set (ID = 0) sets the ID indicated by the parameter to its own ID, and sends the cell carrying this command to the lower side as an empty cell. Further, the branching device that has set the ID sends an “ID assignment response” to the MBU 12.
[0059]
The “ID assignment response” is a command in which “ID” is loaded in the GFC sent from the branch device to the MBU 12, and has a function of notifying completion of ID setting.
[0060]
“ID allocation end notification” is a command in which “15” is installed in the GFC sent from the MBU 12 to the branching device, and has a function of ending automatic allocation of IDs and instructing all branching devices to activate layer 1. is doing.
[0061]
The “ID assignment end response” is a command in which “ID” is mounted on the GFC sent from the branching device to the MBU 12, and is a response command to the ID assignment end notification.
[0062]
The “ID request” is a command in which “0” is loaded in the GFC sent from the branch device to the MBU 12, and has a function of requesting execution of an automatic ID assignment procedure.
[0063]
Of these commands, commands having the same GFC are distinguished from each other by cell payload data.
[0064]
The hardware configuration of the branching device 5 will be described with reference to FIG.
The branching device 5 includes a cell branch / insertion control circuit 51 configured by a programmable gate array (hereinafter referred to as PLD), and two optical / electrical conversion interfaces 52-1 connected to the M bus 3. , 52-2, two 155 Mbps ATM user network interfaces (ATM UNI) 53-1, 53-2 each composed of an LSI, and a PLD control ROM 54 storing circuit logic for a cell branch / insertion control circuit, , A cell distribution / multiplexing control circuit 55 composed of PLD, a PLD control ROM 56 storing circuit logic for the cell distribution / multiplexing control circuit, and at least one 25 Mbps ATM user network interface each composed of LSI (ATM UNI) 57-1 to 57-3 and ATM UNI And a pulse transformer 58-1～58-3, the CPU 59, and the F-ROM 60, constructed and a RAM 61.
The optical / electrical conversion interface 52 is configured by a pulse transformer when the M bus 3 is configured by UTP.
[0065]
A functional configuration of the branching device 5 will be described with reference to FIG.
The branch device 5 includes an upstream M bus interface 501, a downstream M bus interface 502, a cell branch function 503, a cell insertion function 504, a cell distribution / multiplexing function 505, a terminal device interface 506, and a device connection. A determination function 507, a branch device connection determination function 508, a selection function 509, an ATM cell relay function 510, and a loopback function 511 are provided.
[0066]
The upstream M bus interface 501 interfaces with the M bus 3 connected to the upper node, and is achieved by including an opto-electric conversion interface 52-1 and a 155 Mbps ATM user network interface unit 53-1.
The downstream M bus interface 502 interfaces with the M bus 3 connected to the lower node, and is achieved by including an opto-electric conversion interface 52-2 and a 155 Mbps ATM user network interface unit 53-2.
[0067]
The cell branch function 503 takes in an ATM cell addressed to itself from the ATM cells received from the upper node, transfers the ATM cell to the cell distribution / multiplexing control circuit 55, and sends the ATM cell to the downstream node as an empty cell, and The cell branch function 503 is a function that takes in a multicast cell received from an upper node, transfers it to the cell distribution / multiplexing control circuit 55, and sends the multicast cell as it is to a downstream node.
The cell insertion function 504 is a function that is provided on the downlink bus and the uplink bus, and transmits data from a terminal device under its control in an empty cell of either bus.
The cell branch function 503 and the cell insertion function 504 are configured by a PLD, and are achieved by incorporating them from a PLD control ROM 54 that stores circuit logic for a cell branch / insertion control circuit.
[0068]
The cell distribution / multiplexing function 505 is a function for distributing the ATM cells taken in by the cell branch function to the terminal device interface 506 and assembling the cells from the terminal device received by the terminal device interface 506 into 155 Mbps ATM cells.
Furthermore, when a 155 Mbps ATM terminal device other than the branch device is connected to the downstream M bus interface 502, the cell distribution function 505 distributes the ATM cell taken in by the cell branch function to the downstream M bus interface 502, and This is a function for assembling a cell from a terminal device received by the M bus interface 502 into an ATM cell of 155 Mbps.
[0069]
The device connection determination function 507 is a function for determining whether or not a device having a 155 Mbps interface such as a branch device or a 155 Mbps ATM terminal device is connected to the downstream M bus interface 502, and is achieved by monitoring layer 1. The
[0070]
The branch device connection determination function 508 is a function for determining whether or not a device connected to the downstream M bus interface 502 is a branch device. The branch device connection determination function 508 monitors the GFC of the ATM cell on the upstream bus and performs “ID request”. When the cell is detected, the "ID request" cell is relayed to the MBU 12, and when the "ID assignment confirmation notification" cell is received from the MBU 12, it is determined that the connected device is a branch device of a lower node.
[0071]
The ATM cell relay function 510 is a function for relaying an ATM cell sent from an upper node to a lower node when a branch device is connected to the downstream M bus interface 502.
[0072]
The loopback function 511 is a function that loops back an ATM cell sent from an upper node when a branch device is not connected to the downstream M bus interface 502 and returns the ATM cell to the upstream bus connected to the upstream M bus interface. It is.
[0073]
The selection function 509 selects the relay function 510 when the branch device is connected to the downstream M bus interface based on the determination results from the device connection determination function 507 and the branch device connection determination function 508, and selects the downstream M bus interface. Is selected from the LPD control ROMs 54 and 56 in order to select the loopback function 511 and connect to the downstream M bus interface B when the branch device is not connected. This function captures the target circuit logic.
[0074]
An outline of the operation of the branching device 5 will be described with reference to FIG.
When the power of the branch device 5 connected to the M bus 3 is turned on (S1), the CPU 59 of the branch device has a function (cell branch / insertion, loopback and 155 Mbps terminal interface) that operates as a terminal branch device. Is loaded (S2). As a result, the PLD 51 is configured with a circuit having a cell branching / inserting function and a loopback function. At this time point, the cell branch / insertion control circuit 51 and the downstream M bus interface unit 502 are connected via the path B.
In order to load circuit logic having a loopback function into the PLD, the loopback circuit logic is read from the cell branch / insertion control circuit ROM 54 storing the loopback function and assembled.
[0075]
Next, it is determined whether or not a device having a 155 Mbps interface is connected to the downstream M bus interface (S3). In this determination, it is possible to determine that the other party is physically connected by monitoring layer 1 of the downstream M bus interface.
[0076]
If it is determined in step S3 that a branch device is connected to the downstream M bus interface, an “ID request” cell can be confirmed on the upstream bus of the downstream M bus interface (S4).
That is, in the ATM-M bus system to which the present invention is applied, when the branch device of the lower node is connected to the M bus 3, the branch device of the lower node has its own identification number (ID) with respect to the MBU 12. Since the “ID request” cell for requesting grant is repeatedly transmitted on the upstream bus and the ID is acquired, when the “ID request” cell is detected on the upstream bus when the power is turned on, It can be determined that the device is a branching device.
[0077]
If it is determined in step S4 that the connected device is a branch device of a lower node, the “ID request” cell sent from the lower node is relayed directly to the MBU 12 on the upstream bus (S5).
[0078]
Upon receiving the “ID request” cell, the MBU 12 transmits an “ID assignment confirmation notification” cell to notify the start of ID assignment. The branch device that has received this “ID assignment confirmation notification” cell on the downstream bus of the upstream M bus interface (S6) has a circuit logic having a relay function (no loopback) in the PLD for the cell branch / insertion control circuit 51. At the same time, the relay branch function is loaded into the PLD for the cell distribution / multiplexing control circuit 55 (S7).
The loading of the relay function to the PLD for the cell branch / insertion control circuit 51 is performed by reading and loading from the PLD control ROM 54 storing the circuit logic for the cell branch / insertion control circuit equipped with the relay function. The relay branch function is loaded into the PLD for the control control circuit 55 by reading from the PLD control ROM 56 storing the cell distribution / multiplexing control circuit circuit logic equipped with the relay branch function and loading it.
[0079]
By this loading, the branching device has a function of relaying ATM cells addressed to other branching devices or multicast ATM cells received from the upper node to the lower node, and a function of relaying ATM cells addressed to the MBU 12 received from the lower node to the upper node. A function of branching an ATM cell addressed to itself received from an upper node to a subordinate terminal device interface and sending the ATM cell to a downstream node as an empty cell, and data received from the subordinate terminal device interface to an upstream bus Alternatively, it is configured to have a function of being mounted on an empty cell on the down bus and sending it out.
[0080]
Also, by the above loading, the branching device has a function of connecting the subordinate terminal device and the cell branching / insertion control circuit 51 via the cell decomposing / multiplexing control circuit 55, and the cell branching / insertion control circuit 51 and the downstream M And a function of directly connecting the bus interface.
[0081]
The branching device configured as described above relays the “ID allocation confirmation notification” cell received on the upstream downstream bus to the lower node (S8). The branching device that has received the “ID assignment request” cell acquires the ID sent from the MBU 12, makes the cell an empty cell, and sends it to the lower node (S9).
Thereafter, the branching device operates as having a relay function (S10).
[0082]
When a device having a 155 Mbps interface is not connected to the downstream M bus interface in step S3, or when an “ID request” cell is not detected in the upstream bus in step S4, that is, a branch device is connected to the lower node. If not, the branching device sends out an “ID request” cell to the upstream bus and acquires the ID from the MBU 12 (S11).
[0084]
The branching device operates as a terminal branching device having a loopback function inside (S12).
[0085]
【The invention's effect】
According to the present invention, since the branching device connected to the terminal portion of the M bus in the ATM-M system automatically provides an internal wrapping, the “U” -shaped connection that has been conventionally connected to the outside is abolished and a construction error is made. Can be prevented.
Further, the downstream M bus interface can be used as an interface for a terminal device of 155 Mbps, and the economic effect is great.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration concept of an ATM-M bus system to which a branching device according to the present invention is applied.
FIG. 2 is a block diagram showing a configuration of an MBU used in an ATM-M bus system to which a branching apparatus according to the present invention is applied.
FIG. 3 is an explanatory diagram for explaining a GFC / VP / VC conversion process in an ATC of an MBU used in an ATM-M bus system to which a branching device according to the present invention is applied.
FIG. 4 is a block diagram showing a configuration of a branching device used in the ATM-M bus system according to the present invention.
FIG. 5 is a diagram showing a functional configuration of a branching device used in the ATM-M bus system according to the present invention.
FIG. 6 is a flowchart for explaining the operation of the branching device used in the ATM-M bus system according to the present invention.
FIG. 7 is a conceptual diagram showing a configuration concept of an ATM-U bus system according to a prior application.
[Explanation of symbols]
1 M bus main device (ATM switching device)
11 ATM switch
12 ATM-M bus interface unit (MBU)
120 GFC / VP / VC conversion means (ATC)
121 Cell branch / insertion controller (PLD)
122 ATM user network interface
123 Interface for optical / electrical conversion
124 F-ROM
125 S-RAM
126 CPU
127 LED display
128 PLL circuit
13 25Mbps terminal interface unit
14 LAN interface unit
15 N-ISDN basic interface unit
16 25Mbps interface unit between nodes
17 Tripartite Conference Unit
18 Voice call type conversion unit
19 Central Control Unit (CCU)
3 M bus
5 branching device
51 Cell branch / insertion control circuit (PLD)
52 Interface for optical / electrical conversion
53 155 Mbps User Network Interface (ATM-UNI)
54 ROM for cell branch / insertion control circuit
55 Cell Distribution / Multiplexing Control Circuit (PLD)
56 Cell distribution / multiplexing control circuit ROM
57 25Mbps user network interface (ATM-UNI)
58 pulse transformer
59 CPU
60 F-ROM
61 RAM
71 25Mbps ATM-KT
72 155Mbps ATM terminal equipment
75 25Mbps ATM terminal equipment
501 Upstream M bus interface
502 Downstream M bus interface
503 Cell branch function
504 Cell insertion function
505 Cell branch / insert function
506 Terminal device interface
507 Device connection determination function
508 Branch device connection determination function
509 Selection function
510 ATM cell relay function
511 Loopback function

Claims (3)

An M bus interface unit accommodated in an ATM switch, an M bus having both ends accommodated in the M bus interface unit and folded back at the farthest end into a downstream bus and an upstream bus, and a plurality of buses connected in series to the bus In an ATM-M bus system branching device used for an ATM-M bus system comprising the following branching devices:
Three-way interface means: an upstream M bus interface to which an M bus from an upper node is connected; a downstream M bus interface to which an M bus to a lower node is connected; and a terminal device interface to which a terminal device is connected;
ATM cell relay means for relaying ATM cells input to the upstream M bus interface to the output side of the downstream M bus interface;
ATM cell return means for sending back the ATM cell input to the upstream M bus interface to the output side of the upstream M bus interface in the branch device;
Device connection determination means for determining that any device is connected to the downstream M bus interface;
Branch device connection determination means for determining whether or not the device connected to the downstream M bus interface is a branch device;
Have a means for exerting a downstream M bus interface as an interface for the terminal device,
When a branch device is connected to the downstream M bus interface, the ATM cell input to the upstream M bus interface is relayed to the downstream M bus interface, and the branch device is not connected to the downstream M bus interface. An ATM-M bus system branching device characterized in that ATM cells input to the upstream M bus interface are folded back to the upstream M bus interface . 2. The ATM-M bus system according to claim 1, wherein the branch device connection determination means determines that the connected device is a branch device when an "ID request" cell is detected in the upstream bus of the downstream M bus interface . Branch device. 2. A branching device for an ATM-M bus system according to claim 1 , wherein when the branching device is not connected to the downstream M bus interface, the downstream M bus interface is used as a terminal device interface .

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