Patent ID: 7233570

Claim:
A method of extending the length of digital transmission links in a system area network, comprising: providing a pair of repeaters in said transmission link: incorporating virtual lane (VL) buffers into long distance ports of said repeaters; using said VL buffers to maintain absolute credit based flow control; using Service Levels (SLs) to select which VL buffers to use; and providing flow control for multiple large VL buffers wherein a repeater has at least one normal short distance port and one or more long distance port and the repeaters are made transparent to any Subnet Management function by; providing long distance links for use by data packets other than subnet management packets, a full compliment of 16 VL buffers, one for each Service Levels (Sls); transmitting on the long distance link SL 0 data packets on VL 0 , SL 1 data packets on VL 1 , and so on to SL 15 data packets on VL 15 ; receiving on the long distance link SL 0 data packets into VL 0 , SL 1 data packets into VL 1 , and so on to SL 15 data packets into VLl 5 ; and providing flow control packets for all 16 long distance link VLs.