RPR ups efficiency of metro Ethernet(2)

Another major advantage of RPR's dual-rotating ring design is that Ethernet traffic is sent in both directions on the ring to achieve the maximum bandwidth utilization. Unlike older ring-based data networks such as token ring or FDDI, RPR uses a spatial reuse mechanism. Rather than requiring traffic to traverse the entire ring even though a destination node is only a hop away, RPR sends it there directly, keeping the rest of the ring bandwidth available for use by other stations on the network.

To further enhance the network efficiency and support multimedia applications, the IEEE has included a classification scheme and a fairness algorithm in the RPR specification. This guarantees that jitter- and delay-sensitive traffic is always given higher-priority access to the network. Meanwhile, best effort (Internet type) data traffic is ensured equal access and a “fair” share of the remaining ring bandwidth.

RPR also uses statistical multiplexing so that bandwidth can be oversubscribed, while establishing committed information rate (CIR) and peak-rate thresholds on a per-application basis. This guarantees each enterprise application a CIR and the ability to burst up to the peak rates when bandwidth is available. With such a mechanism, each department is charged only for using extra bandwidth rather than being billed for a larger, nailed-up circuit, regardless of use.

Widespread corporate adoption of RPR will help usher in the cost-effective transport of popular Ethernet and IP communications services. RPR transport will provide efficient bandwidth protection, accommodate bursty data traffic and provide the quality of service needed for these advanced packet applications. (End)

時文選讀

彈性分組環(huán)( RPR)技術(shù)提升城域以太網(wǎng)的效率(2)

RPR雙旋轉(zhuǎn)環(huán)設(shè)計的另一個優(yōu)點是，以太網(wǎng)的數(shù)據(jù)流在環(huán)上是雙向傳送的，以獲得最大的帶寬利用率。它與較老的基于環(huán)的數(shù)據(jù)網(wǎng)(如令牌環(huán)或FDDI)不一樣，RPR使用了空間復(fù)用機制。它不要求流量跨越整個環(huán)(即使離目的地節(jié)點只有一跳之遙)，而是直接發(fā)送流量，將環(huán)其余部分的帶寬留給網(wǎng)上其他站使用。

為了進一步提高網(wǎng)絡(luò)效率和支持多媒體應(yīng)用， IEEE已經(jīng)將分級方案和公平算法包含在RPR規(guī)范中。這就保證了對抖動和延遲敏感的流量始終給予較高的訪問網(wǎng)絡(luò)的優(yōu)先權(quán)。同時，最大努力(因特網(wǎng)類型)的數(shù)據(jù)傳輸也保證有平等的訪問和“公平”分享剩余環(huán)的帶寬。

RPR也采用統(tǒng)計復(fù)用，因而帶寬能被超額定購，同時建立了在每個應(yīng)用程序基礎(chǔ)上的約定信息速率(CIR)和峰值速率門限。這就保證了每個企業(yè)應(yīng)用程序有一CIR以及在有帶寬可用時提升峰值速率。有了這樣的一個機制，每個部門只按使用超額的帶寬計費，而不是不管用不用都按更大的、定死的電路計費。

公司廣泛采用 RPR 將有助于引入成本有效的傳輸流行的以太網(wǎng)和 IP 通信服務(wù)。 RPR 傳輸將提供高效的帶寬保護，適應(yīng)脈沖式的數(shù)據(jù)流量，以及提供那些高級分組應(yīng)用程序所需的服務(wù)質(zhì)量。