公开(公告)号：US06611520B1

公开(公告)日：2003-08-26

申请号：US09386482

申请日：1999-08-31

申请人： Daniel M O'Keeffe ,  Justin A Drummond-Murray ,  Annette E Sohor ,  Paul Flood

发明人： Daniel M O'Keeffe ,  Justin A Drummond-Murray ,  Annette E Sohor ,  Paul Flood

IPC分类号： H04L1256

CPC分类号： H04L49/901 ,  H04L47/6215 ,  H04L49/103 ,  H04L49/205 ,  H04L49/351 ,  H04L49/55 ,  H04L49/90 ,  H04L49/9031 ,  H04L49/9036 ,  H04L49/9057

摘要： A multi-port data communication device includes a common central memory through which all data packets must pass. Packet data is written to and read from the common memory space in bursts in response to receive write requests and transmit read requests. A transmit read request for a first burst of data in a packet has in a central arbiter a relatively low priority and transmit read requests for a second and any subsequent burst of data in a packet have in the central arbiter a relatively high priority. Preferably the receive write requests have in said central arbiter a priority intermediate said relatively low priority and said relatively high priority. The priority system reduces the likelihood of underrun and overrun particularly when the burst size is generally smaller than the packet size.

摘要翻译： 多端口数据通信设备包括所有数据分组必须通过的公共中央存储器。 响应于接收写入请求并发送读取请求，分组数据以脉冲串的形式写入公共存储器空间并从其读取。 分组中的第一数据突发的发送读请求在中央仲裁器中具有相对较低的优先级，并且对分组中的第二和任何后续数据突发的发送读请求在中央仲裁器中具有相对高的优先级。 优选地，所述接收写入请求在所述中央仲裁器中具有所述相对较低优先级和所述相对较高优先级的优先级。 优先级系统降低了运行和超限的可能性，特别是当突发大小通常小于分组大小时。

公开(公告)号：US06731633B1

公开(公告)日：2004-05-04

申请号：US09556788

申请日：2000-04-25

申请人： Annette E Sohor ,  Eoin O'Brien ,  Neil J Clifford ,  Derry M O'Donoghue

发明人： Annette E Sohor ,  Eoin O'Brien ,  Neil J Clifford ,  Derry M O'Donoghue

IPC分类号： H04L1228

CPC分类号： H04L45/00 ,  H04L9/0643 ,  H04L45/745 ,  H04L2209/04 ,  H04L2209/12 ,  H04L2209/38

摘要： A network unit includes a forwarding database which includes entries relating packet addresses to forwarding data and is operative to form linked chains of entries wherein the entries in a chain represent different packet addresses which are reduced by hashing to the same pointer for the database. A seed for a hashing algorithm is provided by a combination, such as an exclusive-OR combination, of part of an input address word and a selected word. Hashing is preferably performed in at least two cycles, wherein in one cycle a hash function is applied to a portion of the input address not including the part which is combined with the selected word to constitute a hash seed and in another (preceding) cycle a further part of the address and the aforementioned hash seed are subject the hash function. The selected word may be a software programmable mask and it is possible thereby to ensure a high degree of randomness in the hash seed and to reduce the incidence of convergence of different addresses to a common pointer.

摘要翻译： 网络单元包括转发数据库，​​其包括将分组地址与转发数据相关联的条目，并且可操作以形成链接的链条，其中链中的条目表示通过散列减少到用于数据库的相同指针的不同分组地址。 用于散列算法的种子由输入地址字和所选字的一部分的组合（例如异或组合）提供。 哈希优选在至少两个循环中执行，其中在一个周期中，散列函数被应用于输入地址的不包括与所选择的单词组合的部分以构成散列种子的部分，并且在另一（循环）周期a 地址的另一部分和上述散列种子都受到散列函数的影响。 所选择的字可以是软件可编程掩码，并且因此可以确保散列种子中的高度的随机性并且减少不同地址到公共指针的收敛的发生。