The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 20, 2004
Filed:
Feb. 17, 2000
Robbert Van Renesse, Ithaca, NY (US);
Other;
Abstract
A scalable multicast protocol buffers the multicast messages at a subset of “C” members, where C is selected to reduce to an acceptable level the probability that a given message will be lost before it reaches at least one of the C members. When a member receives a multicast message, the member determines whether or not it should buffer the message by manipulating a string of bytes that is unique to both the message and the member and determining if the result is less than a calculated value C/n, where “n” is the number of known members. When one of the C bufferers thereafter receives a gossip message that indicates that the multicast message has been lost to the gossiping member, the bufferer retransmits the message to the gossiping member. When a member that is not one of the C bufferers receives such a gossip message, the member determines which members are bufferers of the lost message and requests that one of the bufferers retransmit the message to the gossiping member. The selected member identifies the bufferers by manipulating the byte strings associated with the lost message and the respective members that are known to the selected member. The selected member then sends to one of the identified bufferers a request for retransmission of the lost message to the gossiping member. The multicast protocol may further include a mechanism to detect catastrophic failures in the multicast transmission. Each member includes the buffer discussed above and a relatively small, fixed-size “short-term” buffer that holds a limited number of the received messages in the order in which the messages are received. A member monitors any holes or gaps in the sequences of incoming messages, and detects a catastrophic failure when a received gossip message identifies one of the same holes or gaps. When such a failure is detected, the member sends a request for multicast retransmission of the associated missing message to the sender, and the sender multicasts the message to the group from the short term buffer.